Automatic Train Control in Rail Rapid

Transit

May 1976

NTIS order #PB-254738
OFFICE OF TECHNOLOGY ASSESSMENT

CONGRESSIONAL BOARD

Representative Olin E. Teague, Texas, Chairman

Senator Clifford P. Case, New Jersey, Vice Chairman

SENATE HOUSE

Edward M. Kennedy Morris K. Udall

Massachusetts Arizona

Ernest F. Hollings George E. Brown, Jr.

South Carolina California

Hubert H. Humphrey Charles A. Mosher

Minnesota Ohio

Richard S. Schweiker Marvin L. Esch

Pennsylvania Michigan

Ted Stevens Marjorie S. Holt

Alaska Maryland

Emilio Q. Daddario, ex officio

— — —

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C. 20402- Price $3.15

ii
OFFICE OF TECHNOLOGY ASSESSMENT

DIRECTOR’S OFFICE

Emilio Q. Daddario, Director

Daniel V. De Simone, Deputy Director

URBAN MASS TRANSIT ADVISORY PANEL

George Krambles, Chairman, Chicago Transit Authority

Walter J. Bierwagen Bernard M. Oliver

Amalgamated Transit Union Hewlett-Packard Corporation

Robert A. Burco Simon Reich

Oregon DOT Train Control Consultant

Jeanne J. Fox Thomas C. Sutherland, Jr.

Joint Center for Political Studies Princeton University

Lawrence A. Goldmuntz Frederick P. Salvucci

Economics and Science Planning Massachusetts DOT

Dorn McGrath Stewart F. Taylor

George Washington University Sanders and Thomas,

OTA TRANSPORTATION PROGRAM STAFF

Gretchen S. Kolsrud, Program Manager

Mary E. Ames Larry L. Jenney

V. Rodger Digilio Bev Johnson

Thomas E. Hirsch III Teri Miles

Inc.

TECHNICAL CONSULTANTS

Battelle Columbus Laboratories

. . .

111
Prepared by the Office of Technology Assessment with th e

assistance of its Urban Mass Transit Advisory Panel, this

report describes the technology of automatic train contro l

systems and assesses the operational, planning, and polic y

issues arising from the use of automated devices to contro l

and direct rail rapid transit vehicles . The report als o

contains background material useful for understanding th e

application of automation technology in urban rail transit

systems.

Sincerely , Sincerely ,
This report was prepared by the Office of Technolog y

Assessment with the assistance of its Urban Mas s

Transit Advisory Panel, composed of representative s

of the transit industry, engineering firms, plannin g

and development organizations, universities, orga -

nized labor , and citizen participation groups .

v
Preface

This report, prepared by OTA at the request of the Senate Committee on

Appropriations on behalf of the Transportation Subcommittee, is an assessment of the technology of automatic train control in rail rapid transit systems.

Automatic train control (ATC) is the general designation for a variety of

techniques by which machines regulate the movement of rail rapid transit

vehicles for the purposes of safety and efficiency. Functionally, ATC includes:

● Train Protection . Train Supervision

● Train Operation ● Communicatio n

The use of the term “automatic” does not imply that train control or any

of its constituent functions is carried out wholly without human involvement

in operating the equipment or in overseeing automated devices. Rather,

automatic is used to denote systems in which machines perform a substantial

part of the routine functions and there is minimal reliance on man as an

operational element. Man’s role in such systems is to monitor the performance of automatic elements and to act as the ultimate safety backup.

The history of train control technology has seen extensive, but not complete, replacement of the human operator by machines. The number of people required to run trains, operate wayside equipment, and supervise traffic

has been reduced by automation to the point where the newest transit

systems now have only a single on-board operator for the train, regardless of

its length, and a small cadre of centrally located supervisors.

The increasing reliance on automation, both in existing transit systems

and those under development, raises several basic issues about this application of technology. The importance of these issues was recognized by the

Senate Committee on Appropriations Transportation Subcommittee who requested the Office of Technology Assessment to study automation in

federally supported rail rapid transit projects. Correspondence relating to the

request is contained in Appendix I of this report; the following is a paraphrase

of the fundamental questions posed in the letter of request:

How does reduction of man’s responsibility for direct

operational control affect the safety of transit systems?

What operational advantages are to be gained from

automation?

Is automation cost-effective, considering both capital

and operating costs?

vii
Does the planning, development, and testing of

automatic train control systems give adequate attention to

the safety, performance, and cost implications of automation?

Are there policy and institutional factors that influence the selection of a level of automation or that condition the application of automatic train control technology?

Because of the number and complexity of the issues to be addressed, the

technology assessment was divided into three separate, but coordinated,

studies dealing with (1) the planning process, (z) automated small vehicle

systems, and (3) automatic train control in rail rapid transit. Reports on the

first two topics have been published in separate volumes. 1 This report deals

with the third topic, specifically the degree of automation which is technically feasible, economically justifiable, or otherwise appropriate for rail

rapid transit.

The technology assessment presented here is the product of a combined

effort of the OTA Urban Mass Transit Advisory Panel and the staff of the

OTA Transportation Program. Major assistance was received from Battelle

Columbus Laboratories in collecting data and providing technical background information. These materials and other information collected independently were combined by the panel and staff to prepare this report. The

panel and staff are also indebted to the urban transit system officials and

representatives of the transit industry who gave access to their records and

participated in numerous technical discussions.

Since this report is the result of a joint effort, the findings should not be

construed as the view of any individual participant. Divergent opinions are

included; and, where the subject matter is controversial, an attempt has been

made to present a balanced treatment.

The OTA staff members participating in this study were: Dr. Gretchen S.

Kolsrud, Program Manager; Larry L. Jenney, Project Director; V. Rodger

Digilio, Thomas E. Hirsch III, Bev Johnson, and Teri Miles.

lsee An Assessment of Community Planning for Mass Transit, February 1976 (Report NOS. OTA–T–16

through OTA–T-27) and Automated Guideway Transit: An Assessment of PRT and Other New Systems (Report

No. OTA-T-8), June 1975,

,..

Vlll
CONTENTS

Page

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... ... ... ...xi

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ... ..o. o..xii

CHAPTER 1: FINDINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........1

Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........2

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........3

Policy and Institutional Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

The Planning, Development, and Testing Process . . . . . . . ........4

Operational Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ......5

Assessment of ATC Technology . . . . . . . . . . . . . . . . . . . . . . ........6

CHAPTER 2: BACKGROUND. . . . . . . 0 . . . . ....0.... . . . . 0 . . ........9

Rail Rapid Transit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Objectives ... ... t.t.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......12

Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......0...........012

Study Method.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......13

Organization. o. . . . . . . . . . . . . . . 0 . . . . . . . . . . . . . . . . . . . . . . . .......13

CHAPTER 3: AUTOMATIC TRAIN CONTROL . . . . . . . . . . . . .......15

Train Control System Functions . . . . . . . . . . . . . . . . . . . . . . . . .......17

Automation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......20

Automatic Train Control Technology . . . . . . . . . . . . . . . . . . . .......22

A Walk Through a Transit System . . . . . . . . . . . . . . . . . . . . . . .. ....33

Levels of Automation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......40

CHAPTER 4: TRANSIT SYSTEM DESCRIPTIONS . . .....0.........43

Bay Area Rapid Transit (BART) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~ 45

Chicago Transit Authority (CTA) . . . . . . . . . . . . . . . . . . . . . . .......49

Massachusetts Bay Transportation Authority (MBTA) . . . . .......55

New York City Transit Authority (NYCTA). . . . . . . . . . . . . .......60

Port Authority Transit Corporation (PATCO). . . . . . . . . . . . .......65

Systems Under Development . . . . . . . . . . . . . . . . . .. .. ... ..s ...1..69

CHAPTER 5: OPERATIONAL EXPERIENCE . . . . . . . . . . . . . . . ...0...75

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....77

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....0.... . . . . . . ...0...77

Issue O-1: Train Protection . . . . . . . . . . . . . . . . . . . . . . .......78

Issue O-2: Train Operation . . . . . . . . . . . . . . . . . . . . . . . .......81

Issue O-3: Design Safety . . . . . . . . . . . . . . .. * . . . . . . . . .......84

Issue O-4: Passenger Security . . . . . . . . . . . . . . . . . . . . .......87

Performance. . .. .. .. .. .. .. .. .. . . $ . . . . . . . . . . . . . . . . . . . . .......90

Issue O-5: Ride Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90

Issue O-6: Level of Service . . . . . . . . . . . . . . . . . . . . . . . .......93

Issue o-7: Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......99

Issue O-8: Maintainability . . . . . . . . . . ..............0.....105

ix
Page

Cost. ... ......o . . . . . . . . .0.00..00 .0 + 00 . . 0 .0.0.0.., o, *.,*,... 1 0 9

Issue O-9: Capital Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Issue O-lo: Operational Cost. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

Issue O-11: Workforce Reduction. . . . . . . . . . . . . . . . . . . . . . . . . 115

Issue O-12: Workforce Distribution, . . . . . . . . . . . . . . . . . . . . . . 116

Issue O-13: Energy Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

Human Factors. . ..............,,.,,,.....,,., ,,, ,,, ....,,,,. 12 1

Issue O-14: The Human Role . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Issue O-15: Effects of Automation on

Employees and Passengers, . . . . . . . . . . . ,..,.. 127

CHAPTER 6: THE PLANNING AND DEVELOPMENT PROCESS . . . 133

Introduction . . . . . . . . . . . . . . . ., .,. .., .,.O,O, .., ,O. ,,, ,O,,,, ,,, 135

Issues

Issue D-1: Design Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

Issue D-2: System Development. . . . . . . . . . . . . . . . . . . . . . . . . 139

Issue D-3: Procurement Specifications . . . . . . . . . . . . . . . . . . . 141

Issue D-4: Specification of Reliability,

Maintainability, and Availability .,..... . . . . . 142

Issue D-5: Equipment Suppliers. . . . . . . . . . . . . . . . . . . . . . . . . 144

Issue D-6: Contractor Selection.. . . . . . . . . . . . . . . . . . . . . . . . 145

Issue D-7: Contract Management., . . . . . . . . . . . . . . . . . . . . . . 147

Issue D-8: Testing, ...,,.,.,,.,., . . . . . . . . . . . . . . . . . . . . . . 148

Issue D-9: R&D Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

Issue D-lo: Test Tracks..,,,,.,.,., . . . . . . . . . . . . . . . . . . . . . 151

Issue D-11: Research Needs .,, , .,, , ...,,..,, . . . . . . . . . . . . 153

CHAPTER 7: POLICY AND INSTITUTIONAL FACTORS . . . . . . ., , . 157

Introduction . ...............,,,....,...,,0 . .,,...,.,,,,,,,,, 16 1

Summary of Existing Legislation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

Issues

Issue P-l: Impact of Existing Legislation . . . . . . . . . . . . . . . . . . 163

Issue P-2: Regulation . ., .,, .,,..,, . . . . . . . . . . . . . . . . . . . . . . 166

Issue P-3: Acceptance Testing and Qalification . . . . . . . . . . . 168

Issue P-4: Standardization, ,,..,. ., ., .. .,, ... OO. ,,O,,., . . 169

Issue P-5: Safety Assurance ...., . . . . . . . . . . . . . . . . . . . . . . . . 171

Issue P-6: Public Expectations . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

APPENDICES

A. Train Control System Functions. ,. .., ,. .., .. .$.....,,..,,. 177

B. Automatic Train Control Technology . . . . . . . . . . . . . . . . . . . . . . 191

C. Design Characteristics of Selected Rapid Rail Transit Systems 199

D. Glossary of Train Control Terms. , .,, .,, .,.,,..,,, ..,,,.,, 207

E. Chronology of Train Control Development, .,, ,..,... . . . . . . 215

F. Persons and Organizations Visited. ., . .,, . ..,,...,. . . . . . . . . 221

G. Biographies of Urban Mass Transit Advisory Panel,, .. .,..., 231

H. References. ........,.. ,,, ..,,..,,....,.,,,., , ...,,.,,,., 235

I Congressional Letters of Request .,,..,,,. , ....,,.,,,..,,., 237

x
TABLES

TABLE 1.

TABLE 2.

TABLE 3.

TABLE 40

TABLE 5.

TABLE 6.

TABLE 7.

TABLE 8.

TABLE 9.

TABLE 10.

TABLE 11.

TABLE 12.

TABLE 13.

TABLE 14.

TABLE 15.

TABLE 16.

TABLE 17.

TABLE 18.

TABLE 19.

TABLE 20.

TABLE 21.

TABLE 22.

TABLE 23,

TABLE 24.

TABLE 25.

TABLE 26.

TABLE 27.

TABLE 28.

TABLE 29,

TABLE 30.

TABLE 31.

Page

Levels of Automation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

BART System Facts. . . . . . . . . . . . . ., . . . . . . . . . . . . . . . 46

CTA System Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

MBTA System Facts . . . . . . . . . . . . . . . . . . . . . . . ., . . . . 56

NYCTA System Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

PATCO System Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Automated Feature of Three Transit Systems Under

Development. . . . . . . . . . . . . . . . . . . . . ., . . . . . . . . . . . 69

Train Protection Methods in Existing and Planned

Transit Systems ... , ., . . . . . . . . . . . . . . . . . . . . . . . . . 78

Analysis of CTA Accident Record, 1965-74, ... , , . . . . 80

Passenger Injuries Due to Train Operation ., , , ... , , 81

Passenger Accident Summary . . . . . . . . . . . . . . . . . . . . . 82

Fatalities in the United States by Transportation Mode

During 1973 ...., . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., 83

Passenger Assaults and Robberies for Selected Transit

Systems . . . . . . . . . . . . . . . . , . . . , . . . . . . . . . . . .. ....88

Train Operation Methods Related to Ride Quality. , ..92

Service Characteristics in Typical Transit Systems .. .94

Schedule Adherence in PATCO, 1970-74............96

Schedule Adherence on CTA Dan Ryan Line, 1970-74 96

Schedule Adherence in BART, August 1973-August

1974. ., . . . . . . . . ● , 00, ..0, , . * ● 0.. ● ● , ... , , , . . . . . . .98

PATCO Car Component Performance, July-October

1974...0, .. ..0, . ...00...60, . * . . . . . . . . . . . . . . ● .. 101

Summary of Disabling Equipment Failures in PATCO,

August 1973-July 1974 . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Summary of Equipment Failure in BART, 1974 -75.... 102

Car Component Performance on CTA West-South

Route, July-October 1974. . . . . . . . . . . . . . . . , , . . . . . . 104

Maintenance Time for Selected PATCO Car Components. , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106

Capital Costs in New Transit Systems . .............110

Cost Estimates for ATC Equipment . ...............111

Summary of Rail Rapid Transit Operating Costs.. ....113

Effect of Automation on Size of Workforce. . ........116

Analysis of Operations and Maintenance Workforce. .118

Rail Rapid Transit Energy Consumption . . . ... ... ...120

Man and Machine Roles in Rail Rapid Transit Systems

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

Significant Dates in the Engineering Planning, Procurement, and Testing of ATC for Various Transit

Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

xi
Page

TABLE 32. Type of Specification Used in Recent ATC Procurements . . . . . . . . . . . . , . . . ., . . . . . . . . . , , ., . . . . . . . . . 142

TABLE 33. Contractor Selection Approaches . .................14 6

TABLE 34. UMTA Budget for Fiscal Year 1976, ,, .,..,. . .......164

TABLE A–1. Primary Means of Communicating Information Related to Train Control., . . . . . . . . . . . . . . . . . . . . . . . . 188

FIGURES

FIGURE 1.

FIGURE 2.

FIGURE 3.

FIGURE 4.

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FIGURE 6.

FIGURE 7.

FIGURE 8.

FIGURE 9.

FIGURE 10.

FIGURE 11.

FIGURE 12.

FIGURE 13.

FIGURE 14.

FIGURE 15.

FIGURE 16.

FIGURE 170

FIGURE 18.

FIGURE 19.

FIGURE 20.

FIGURE 21.

FIGURE 22.

FIGURE 23.

FIGURE 24.

FIGURE 25.

FIGURE 26.

FIGURE 27.

FIGURE 28.

xii

Train Control System Functions, . . . , ., , . . . . . . . . . . . 18

Generalized Control Process . . . . . . . . . . . . . . . . . . . . . . 21

Simple D.C. Track Circuit . . . . . ... , ., ., , , . . . ... , , .22

Three-block, Three-Aspect Wayside Signal System, . 24

Cab Signals . . . . . , . . . . . ., , ., , . . . . . . . . . . . , . . . . . . . . 26

Three-block, Three-Aspect Cab Signal System. ... , . 26

Cab Signal System With Automatic Overspeed Protection . . . . . . . . . . . , . . . . . . . . . . . . . . . . , . . . ... , . . . . . . 27

Automatic Train Operation System. . . . ... , ... , . . . . 29

Typical Interlocking Location. ... , ., . . . . . . . . . . . . . . 30

Entrance-Exit Interlocking Control Panel. , ., . . . . . , . 31

Model Board and Train Control Console . . . . . . . . . . . 32

General View of Rail Rapid Transit Station . . . . . . . . 33

Trip Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Track Circuit Wiring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Wayside Equipment Case . . . . . . . . . . . . . . . ... , . . . ., 34

Track Apparatus at an Interlocking. . . . . . . . . . . . . . . . 35

Central Train Control Facility . . . . . . . . . . . . . . . . . . . . 35

Two Views of a Central Control Facility Wit h

Electromechanical Equipment. . . . , . . . . . . . . , , . . . . 36

Tower for Local Control of Interlocking. . . . . . . . . . . . 36

Carborne Receiver Coil for Coded Track Circuit Signals. . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . 37

Train Operator’s Console for System With ATO .. ..37

Aerial View of Rail Rapid Transit Yard and Maintenance Facility. , . . . . . ... , . . . . . . . . . . . . . . . . . . . . . . 38

Rail Rapid Transit Car Maintenance Shop. ., . . . . . . . 39

BART Route Map . . . . . . . . . . . . . . . . . . . . . . . . .......45

BART Train in Underground Station ... , . . . .......47

Interior of BART Car . . . . . . . . . . . . . . . . . . . . . .......48

BART Train Passing Through the Transbay Tube. ..49

CTA Route Map. . . . . . . . . . . . . . . . . . . . . . . . . . .......50
FIGURE 29.

FIGURE 30.

FIGURE 31.

FIGURE 32.

FIGURE 33.

FIGURE 34.

FIGURE 35.

FIGURE 36.

FIGURE 37.

FIGURE 38.

FIGURE 39.

FIGURE 40.

FIGURE 41.

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FIGURE 44.

FIGURE 45,

FIGURE 46.

FIGURE 47.

FIGURE 48.

FIGURE 49.

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FIGURE 51.

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FIGURE 53.

FIGURE 54.

FIGURE 55.

FIGURE 56.

FIGURE 57.

FIGURE 58.

FIGURE 59.

FIGURE 60.

FIGURE 61.

FIGURE 62.

FIGURE 63.

FIGURE 64.

FIGURE 65.

FIGURE 66.

FIGURE 67.

FIGURE 68.

FIGURE 69.

Page

CTA Train on the West-Northwest Route in the Median of the Kennedy Expressway. . . . . . . . . .......53

Interior View of CTA Train . . . ., . . . . . . . , ... , . . . ..53

Lake-Dan Ryan Train Entering the Loop . . . . .......54

MBTA Route Map. ... , . . . . . . . . . . . . . . . . . . . . . . . . ..55

MBTA Orange Line Train . . . . . . . . . . ... , , ... , . . . ..57

Red Line Train Arriving at Wollaston Station. .. ....57

The Old and the New. . . . . . . ., . . . . . . . . . . . . .......59

NYCTA Route Map. . . . . . . . . . . . . . . . . . . . . . . .......60

IND F Train on Elevated Line in Brooklyn , . . . . . . ..63

Examples of NYCTA Transit Cars, . . . . . . ., ., ., , .. .63

The Graffiti Epidemic. . . . . . . . . . . . . . . . . . . . . . . .. ...64

PATCO Route Map. . . . . . . . . . . . . . . . . . . . . . . . . . .. ..65

PATCO Train in Lindenwold Yard, . . . . . . . . .......67

Outbound on the Benjamin Franklin Bridge . .......68

PATCO Train Operator Monitoring ATC Equipment 68

WMATA Route Map . . . . . . . . . . . . . . . . . . . . ., ., .. ..71

MARTA Route Map. . . . . . . . . . . . . . . . . . . . . . .......72

Baltimore MTA Route Map. ., ., , . . . . . . . . . . . . .. ...74

Interlocking Control Tower for Train Protection .. ..79

CTA Passengers Alighting at Belmont Station .. .....82

History of Train Motion Accidents . . . . . . . . . .......83

Unmanned Train at Seattle-Tacoma Airport. .. .....85

Fully Automated AIRTRANS Train . . . . . . . . .......86

Approach to Brightly Lighted Station . . . . . . . .......89

Lonely Station at Off-Peak Hour ., ., . . . . . . . .......89

Comfort Features of Modern Transit Cars. . . .......92

The Wait and the Rush To Leave . . . . . . . . . . .......95

AIRTRANS Availability and Service Interruptions ..97

Carbone and Wayside ATC Equipment . ...........100

Maintenance of Transit Vehicle Truck. . . . . . . . . .. ..106

Cab Signal Maintenance. . . . . . . . . . . . . . . . . . . . . .. ...107

Car Washer. . . . . . . . . . . . . . . . . . . . . . ...............108

Influence of Maintenance on Car Availability in

BART, May 1974-January 1975 . . . . . . . . . . . . . . .. ..109

Transit System Construction. . . . . . . . . . . . . . . . . . . . . .112

Winter on the Skokie Swift Line . .................114

Reduction of Train Crew. . . . . . . . . . . . . . . . . . . . . . . . .117

Proportion of Operations and Maintenance Employees

in Total Workforce . . . . . . . . . . . . . . . . . . . . . .......118

Distribution of Maintenance Force as a Function of

Automation. . . . . . . . . . . . . . . . . . . . . . .............119

State-of-the-Art Car . . . . . . . . . . . . . . . . . . . . . . . . . . . , .121

Student Conductors Training on the Job. . ..........122

Motorman at Work . . . . . . . . . . . . . . . . . . . . . .........123

,..

Xlll
FIGURE 70.

FIGURE 71.

FIGURE 72.

FIGURE 73.

FIGURE A–1.

FIGURE A–2.

FIGURE A–3.

FIGURE B–1.

FIGURE B–2.

FIGURE B–3.

FIGURE B–4.

Page

Line Supervisors. . . . . . . . . . . . . . . . . . . . . . ...........123

Transit System Maintenance Workers . ............129

DOT Test Track, Pueblo, Colo.. . ..................15 4

ATC Research and Development Priorities and Relative Cost. . . . . . . . . . . . . . . . . . . . . . ................156

Conceptual Diagram of an ATP System, . ..........178

Train Separation in a Conventional Block Signaling

System ... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......180

Conceptual Diagram of Service Brake Flare-Out Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

Simple D.C. Track Circuit . . . . . . . . . . . . . . . . . . . . .. ..192

Simple Power-Frequency A.C. Track Circuit . ......193

Simple High-Frequency A.C. Track Circuit. . .......194

Alternate High-Frequency A.C. Track Circuit .. ....195

xiv
. ,

.

-.

.

Chapter 1

FINDINGS

,’ .

\,

1
Definitions2

Train Control—the process by which the movement of rail rapid

transit vehicles is regulated for the purposes of safety and efficiency. The system that accomplishes train control performs four

types of functions:

Train Protection-assurance that trains maintain a safe

following distance, that overspeed is prevented, and that

conflicting movements at junctions, crossings, and

switches are precluded;

Train Operation--control of train movements—specifically

regulating speed, stopping at stations, and opening and

closing doors;

Train Supervision-assignment of routes, dispatch of trains,

and maintaining or adjusting schedule;

Communication—interchange of command and status information among trains, wayside elements, stations, and

central control.

Automatic Train Control (ATC)—the use of machines to perform

all or most of the functions of train control in the normal mode of

operation. Human involvement in ATC systems consists mainly of

monitoring and back-up. The acronyms ATP (automatic train protection), ATO (automatic train operation), and ATS (automatic

train supervision) denote particular groups of automated functions.

Rail Rapid Transit-an electrified rail system operating in urban

areas on exclusive rights-of-way. Rail rapid transit is considered

here to exclude commuter railroad systems and light rail systems,

although the technology of train control is similar for all three.

ZA glossary of train control terms is presented in Appendix D. Explanation of the fundamentals

of train control and descriptions of typical train control equipment are contained in Chapter 3.
INTRODUCTION

In requesting this assessment, the Senate Committee on Appropriations posed four major questions concerning automatic train control technology:

1. What is the state of ATC technology?

Z. What application is made of ATC technology

in existing and planned rail rapid transit

systems?

3. Are the testing programs and methods for

ATC systems adequate?

4. How is the level of automation selected, and

what tradeoffs are considered?

These questions served initially as the basic

framework for organizing and directing the assessment. As the study progressed, it became apparent

that each issue raised by the requesting committee

had many ramifications and that there were corollary questions that had to be addressed. Therefore,

the study was expanded in scope and detail to consider not just the matters enumerated in the letter of

request but, more generally, the entire field of

automation technology in train control systems.

The findings of this broader investigation dealing

with policy, planning, and operational concerns are

summarized below. Supporting data and discussion

are presented in chapters 5, 6, and 7. At the conclusion of this chapter is a brief interpretation of the

findings that responds directly and specifically to

the issues raised by the Senate Committee on Appropriations.

POLICY AND INSTITUTIONAL

FACTORS

The development of rail rapid transit systems is

influenced by three major pieces of Federal legislation: the Urban Mass Transportation Act of 1964,

the Department of Transportation Act of 1966, and

the National Mass Transportation Assistance Act of

1974. Transit system planning, development, and

(since 1975) operation are supported by these acts

and the annual appropriations that flow from them.

The administrative agency for Federal support of

transit development programs is the Urban Mass

Transportation Administration (UMTA). Neither

the existing legislation nor the administrative

programs of UMTA deal specifically with ATC

systems as such. Research in train control technology and development of individual ATC

systems are carried on within a more general

program of activities relating to rail rapid transit as

a whole.

Findings pertaining to policy and institutional

considerations are as follows:

Regulation

At the Federal level, regulation of rail rapid transit (and ATC specifically) is of recent origin,

Regulation is vested in two agencies—UMTA and

the Federal Railway Administration (FRA), whose

respective areas of responsibility are not clearly

defined, It is not surprising, therefore, that so far

neither agency has done much to regulate or standardize ATC systems. However, FRA has recently

indicated the intention to start rulemaking procedures concerning ATP and the safety aspects of

door operation.

The National Transportation Safety Board

(NTSB) is charged with overseeing rail rapid transit

safety and with accident investigation. Implementation of NTSB recommendations is left to either

FRA or UMTA or is handled as a matter of voluntary compliance by transit agencies.

Most regulation of rail rapid transit (and ATC

specifically) is carried out either by State public

utility commissions or by the transit agencies themselves as self-regulating bodies. The concern of

State regulatory bodies is primarily safety, Little attention is given to operational concerns, such as

reliability, maintainability, level of service, efficiency, and economics.

Advantages in increased Federal regulation, particularly in the areas of safety assurance and equipment standardization, must be weighed carefully

against the disadvantages of preempting State and

local authority and raising possible barriers to innovation.

Institutions

Decisions relating to ATC design and development are influenced by several nongovernmental

institutions or groups. The strongest influence is

that of the local planning or operating authorities,

which rely heavily on engineering and technical

consultants employed to assist in planning and

development activities,

Other institutions and groups acting to shape the

course of ATC design and development are equip72-683 0 - 76 -2

3
ment manufacturers, industry associations, and

organized labor. Except in isolated cases, only the

equipment manufacturers exercise any significant

influence during the ATC design and development

process. The influence of labor is usually brought to

bear only as a new system is being readied for

operation and a contract with the union local is

being negotiated.

Community planners, public-interest groups, and

the public at large play only a small role in the

design and development of ATC systems. There is

some evidence that these groups may be assuming

more influence, not in technical concerns, but in the

area of establishing priorities and general service

characteristics.

Policy Impacts

Federal policy from 1964 to 1974 may have

tended to encourage the development of new, technologically advanced transit systems employing

highly automated forms of train control. In part, this

policy appears to have stemmed from the expectation that automation would lead to increased productivity-a benefit that, in the case of ATC, has

not been substantiated. This policy may be in the

process of change as a result of the National Mass

Transportation Assistance Act of 1974.3

Transit agencies, when planning new systems,

have also been inclined to favor technological advancement-partly as a reflection of how they perceived Federal Government policy and partly

because they or their consultants believed advanced

technology was necessary to win public support for

development and patronage of the system.

This situation has created a tendency for system

designers to turn to highly automated forms of train

control as a means of offering improved performance and service. The superiority of automated over

manual methods of train control is not certain,

however, except in the area of train protection

(ATP).

The cost of automatic train control has negligible

influence on the public primarily because it is small

in relation to the total cost of the system (typically

between 2 and 5 percent). A question on train control system automation, as a specific issue, has

never been submitted to the public for decision by

referendum.

THE PLANNING, DEVELOPMENT,

AND TESTING PROCESS

The evolution of a rail rapid transit system from

concept to start of revenue service may span 10 to

20 years. The process has three major phases: planning, engineering development, and testing,

Research and development to support design are

conducted throughout but tend to be concentrated

in the middle phase, where detail design and

development takes place. The design and engineering of the train control system, while generally concurrent with the development cycle of the whole

transit system, is usually neither the pacing item

nor a dominant technical concern.

Findings concerning the planning, development,

and testing process for ATC systems are as follows:

Planning

Formulation of the ATC design concept and

determination of the extent to which the system

will be automated are greatly influenced by nontechnical factors, notably social and political concerns, the prevailing attitude of decisionmakers and

system designers toward technological innovation,

and reaction to the recent experience of other transit agencies.

Cost-benefit analyses conducted during the

system design process seldom, if ever, include

evaluation of alternative ATC concepts and

different levels of automation, perhaps because

ATC represents only 2 to 5 percent of total system

cost and benefits are not easily quantified.

The public appears to attach greater importance The comparative operational costs of alternative

to dependability of service and personal security levels of ATC are given very little consideration.

than to ATC system performance characteristics.

Engineering Development

ATC procurement specifications vary greatly in

.

3The OTA study, An Assessment of Community P]anning terms of approach and level of detail; but the trend

for Urban Mass Transit, February 1976 (Report Nos.

OTA–T–16 through OTA–T–27), deals extensively with the in newer systems is toward a more quantitative

history and current trends of planning and public policy in mass form of specification, particularly for reliability,

transit. maintainability, and availability requirements.

4
There is a recognized need in the transit industry

for improvement in the writing of specifications

and in setting realistic requirements for reliability,

maintainability, and availability.

In new transit systems, the ATC equipment is

procured as a package through a single contractor.

In existing transit systems, ATC equipment is often

acquired piecemeal as additions or improvements to

equipment already in operation.

In most instances, contractor selection is based

on low bid from technically qualified competitors.

This procedure is usually required by State law or

local ordinance. Noncompetitive procurement is

seldom used,

contract.

Testing

Testing is

development

except for a follow-on to an earlier

conducted at several points in the

process, generally for one of three

purposes: qualification and validation of component and subsystem design, assurance of conformity to specification, and demonstration of total

system performance prior to final acceptance and

start of revenue service.

Performance verification and acceptance testing

of train control systems, coming near the end of the

development cycle, may be slighted because of

pressure to open the system for service. The preoperational test program may be either abbreviated

or deferred until after the start of revenue service

and often extends into the first year of operation or

longer.

The quality and extent of assurance and acceptance testing vary greatly among transit systems,

largely as a function of the qualifications and experience of the organization managing the development of the system. There is a need for more

detailed and comprehensive test plans, more clearly

defined criteria and methods of measurement, more

rigorous procedures for conducting tests, and more

complete documentation of test findings.

Research and Development

There are no test tracks and experimental

facilities for carrying out R&D activities related to

train control, except at individual transit systems or

at a manufacturer’s plant as part of a product

development program. The Pueblo facility does not

permit detailed study of ATC design and engineering problems in a realistic operational setting.

The state of ATC technology is such that the

greatest R&D need is refinement of existing designs

and not development of innovative or more advanced technology. Yet, relatively little R&D effort

is concentrated on presently known operational

problems, such as reliability, maintainability, and

availability, performance testing methods and

standards, and development of a uniform data base

on ATC system performance.

OPERATIONAL EXPERIENCE

No rail rapid transit system now operating or

under development in the United States has a train

control system that is completely automatic. All

employ some mixture of manual and automatic

control, and all have at least one person on board

the train to carry out some control functions. Only

two rail rapid transit systems operating in the

United States at the end of 1975—BART in San

Francisco and the PATCO Lindenwold Line in

Philadelphia and suburban New Jersey-are automated to the extent that the trainman has little or

no direct part in operating the train. In all other U.S.

rail rapid transit systems, trains are operated

manually, with automation employed only for train

protection and some supervisory functions. New

transit systems being planned and developed in

Washington, Baltimore, and Atlanta show the influence of BART and PATCO with respect to both

the level of automation and the use of advanced

ATC technology.

A survey of the operational experience with

ATC leads to the following findings:

Safety

Automatic Train Protection (ATP) systems are

superior to manual methods of preventing collisions

and derailments, principally because ATP

safeguards against human error and inattention.

The use of ATP is becoming universal in the U.S.

transit industry.

Automatic Train Operation (ATO) offers no

clear safety advantages over manual modes of

operation.

Automatic Train Supervision (ATS) does not

produce additional safety benefits beyond those attainable with traditional manual or machine-aided

forms of supervision carried out by dispatchers,

towermen, and line supervisors.

5
In conjunction with increased automation, the

size of the train crew is often reduced to one. Oneman operation does not appear to have an adverse

effect on passenger security from crime or on protection of equipment from vandalism.

Performance

Under normal operating conditions, the ride

quality provided by ATO is comparable to that of

manually operated trains. The principal advantage

of ATO is that it eliminates variation due to the individual operator’s skill and provides a ride of more

uniform quality. Manual operation is considered to

be the more effective mode of control under certain

unfavorable weather and track conditions.

Systems with ATC have experienced problems

of schedule adherence during the start-up period,

but it is not certain how much of this is a result of

train control automation and how much is due to

other factors such as the complexity and reliability

of other new items of transit system equipment.

Reliability of ATC equipment has been a major

operational problem. Failure rates for both wayside

and carborne components have been higher than

anticipated, but not greater than those of other transit system components of comparable complexity

and sophistication (e.g., communications equipment, propulsion motors, electrical systems, airconditioning equipment, and door-operating

mechanisms).

Maintenance of ATC equipment, like other

items of new technology, has been troublesome

because of longer repair time, more complicated

troubleshooting procedures, higher levels of skill required of maintenance personnel, and the lack of

people with these skills. A shortage of spare parts.

has also hindered maintenance efforts.

On the whole, however, ATC equipment contributes proportionally no more to vehicle downtime or service interruptions than other transit

system components. The problem is that ATC, like

any other new element added to a transit system,

has an effect that is cumulative and tends to lower

the general reliability of the system.

costs

ATC typically accounts for 2 to 5 percent of the

capital cost of rail rapid transit; the variation is

almost directly proportional to the level of automation,

Because of the reduction in train crew that often

accompanies ATO and because of the centralization

and consolidation of train supervisors brought

about by ATS, automated systems are somewhat

cheaper to operate than manual systems. These savings are offset, however, by the increased labor

costs of maintaining ATC equipment. In comparison with manual systems, the maintenance

force for ATC systems is larger, skill requirements

and the corresponding salary levels are higher,

training of technicians must be more extensive and

hence costly, and repairs are more frequent and

take longer. The combined operation and maintenance costs of automated systems are about the

same as those of manual systems, There is no evidence that ATC systems lead to more efficient train

operation or to any significant change in energy

consumption. Vehicle weight, route layout, and

propulsion system characteristics are far more

dominant factors in energy use than automated or

manual operation.

Human Factors

Monotony and light responsibility make it

difficult for operators of highly automated systems

to maintain vigilance. There has also been a tendency for ATC system designers, notably in BART, to

make insufficient use of the human operator to

back up or enhance automatic system performance.

The designers of systems now under development

are seeking to integrate the operator more effectively into the ATC system, to give man a more

meaningful set of responsibilities, and to make

automatic equipment more amenable to human intervention.

For maintenance employees and train supervision personnel, ATC systems impose new and higher skill qualifications and more demanding performance requirements.

The effect of automation on passengers is

negligible, except insofar as it maybe more difficult

for them to obtain information with fewer transit

system employees on the train.

ASSESSMENT OF ATC TECHNOLOGY

The following is an analysis and interpretation of

the findings in light of the concerns expressed in the

letter of request from the Senate Committee on Appropriations. 4

4Thjs letter and related correspondence are contained in appendix I.

6
The State of ATC Technology

ATC technology is a mature technology insofar

as train protection (ATP) and train operation

(ATO) functions are concerned. The major

difficulties encountered in these areas have arisen

from the application of new, unproven techniques

that represent departures from conventional train

control system engineering. Train supervision

(ATS), except for certain well-established dispatching and routing techniques, is the least advanced

area of ATC technology. Research and development efforts are now underway to devise computer

programs and control techniques to permit comprehensive, real-time supervision and direction of

train movement by automated methods.

Operational experience indicates that automatic

train protection (ATP) enhances the safety of a

transit system because it safeguards against collisions and derailments more effectively than manual

and procedural methods. Performance and service

characteristics of ATC systems are as good as, and

perhaps better than, manual systems once the

somewhat lengthier period of debugging and

system shakedown has passed. Reliability and

maintenance continue to be serious problems for

systems using higher levels of ATC and probably

account for an increase in operating costs that outweighs any manpower savings achieved through

automation.

Application of ATC Technology in New

Systems

In assessing the application of technology in new

transit systems, a distinction must be made between

train protection (ATP) and train operation and

supervision (ATO and ATS). All systems-old,

new, and planned—rely on automatic devices to accomplish train protection functions. Two forms of

technology are employed. One uses wayside signals

with trip stops, the other uses cab signals. The trend

in the transit industry today is toward cab signaling,

which is the newer technology, because it offers

somewhat more flexible protection than wayside

signaling, and because it provides an evolutionary

path to partially or fully automated train operation.

The new systems in Washington, Atlanta, and

Baltimore and the recent extensions to existing

systems (e.g., the CTA Dan Ryan extension and the

MBTA Red Line) all employ cab signaling and the

more automated forms of operation derived from it.

With regard to ATO and ATS, the new systems

under development and those in the planning stages

will employ more advanced technology and higher

levels of automation than those built and put in

operation before 1969. With some exceptions, such

as door closure or train starting, train operation in

the new systems will be entirely automatic, but

supervised by an on-board operator who will intervene in case of emergency or unusual conditions,

Central control functions (ATS) will be assisted, or

in some cases accomplished entirely, by automatic

devices. Thus, train operation and supervision in

new systems will resemble those of PATCO and

BART, and the general trend is toward extensive

use of ATO and ATS.

There is almost no research and development

now in progress to produce new ATC technology

for rail rapid transit. The development work currently underway is devoted primarily to refinement

of existing techniques and their application in particular localities. The transit industry has watched

closely the experience of BART and PATCO. The

results of the PATCO approach, which made use of

conventional technology, have been compared to

those of BART, where innovative technology and

more extensive automation were employed. The

designers of the Washington, Atlanta, and

Baltimore systems have generally opted for a middle ground with regard to automation and have

followed a cautious approach to new technology,

inclining more toward PATCO than BART. Particular care has been given to the role of the human

operator in backing up or augmenting the performance of ATO. and ATS equipment. The experience of BART and PATCO has also led the

newer systems to give careful attention to the

reliability and maintainability of ATC equipment

and to developing strategies for assuring system

performance in adverse conditions or degraded

modes of operation. It is certain that WMATA, the

next of the new systems to be put in operation, will

be scrutinized by the transit industry for other

lessons to be learned.

The Testing Process

As train control systems have grown more complex, the testing process has been burdened in two

ways: there are more elements that must be tested

from prototype through final installation, and there

are more interrelationships that must be checked

out before the system can be placed in revenue

service. The problem of testing is especially

7
difficult in a new transit system, where all the

equipment is new and untried and where all the

parts need to be tested before initiating passenger

operations.

The experience of BART has underscored both

the basic need for testing and the importance of giving careful attention to test methods, procedures,

and documentation of results. The application of

new technology on a large scale in a transit system

involves more than just development and installation of equipment; it also involves the application of

management techniques to integrate the parts of the

system and to test and evaluate the performance of

these parts, singly and in the system as a whole.

Perhaps the greatest shortcoming in the area of testing in the transit industry today is the lack of a

satisfactory method for comprehensive evaluation

of transit system performance, under realistic conditions, in the preoperational period, This is often

compounded by political, social, and economic

pressures to open the system for revenue service as

soon as possible, with the result that the test

program may be truncated or deferred until after

opening day and the full certification of the system

may not come until months or years later.

The managers of the new systems under

development appear to be mindful of these

problems. Improved testing methods and procedures are being devised. More complete programs

of preoperational testing, even at the expense of

postponing revenue service, are being planned. An

incremental approach to testing and full system

operation has been adopted, with each step building

on the results of earlier phases and with testing

timed to the pace of system growth. Methods of

testing in revenue service, both in regular hours of

operation and during nighttime periods, are being

explored. More attention is being given to documentation of test plans and results.

Selecting the Level of Automation

There is no single procedure for selecting the

type of train control system and the level of

automation. Individual transit authorities follow

rules of their own devising. Some rely on the advice

of consultants; others draw upon the experience of

their own technical staff, Only a few generalizations can be made about the nature of this process.

The decisionmaking process does not appear to

be deeply analytical. Criteria of choice are not often

defined, the rules of choice are not made explicit,

and the analysis of alternatives is not documented

except in a fragmentary fashion by internal

memoranda and working papers.

Established transit systems, where extensions or

new lines are being planned, give considerable attention to the engineering characteristics of the proposed train control system, primarily to assure that

new ATC equipment can be successfully integrated

with other parts of the existing system, In this case,

engineering criteria serve primarily as constraints

upon the type of ATC equipment that can be used

or upon the level of automation to be selected. The

established rules and procedures of the transit

system act in much the same way to limit the choice

of design alternatives. But there is no evidence to

indicate that the planning and design process includes studies directed specifically at determining

an optimum train control system or at balancing

train control system design features against the

service and operating characteristics of other equipment or of the transit system as a whole.

In new transit systems, the process for selecting a

train control system is governed even less by system

engineering and trade-off studies. The level of

automation appears to be selected, more or less arbitrarily, early in the system development cycle. It

is treated more as a postulate or a design goal than

as a point for analysis and trade-off. It also appears

that characteristics of the proposed ATC system are

derived more from general, nontechnical decisions

about the nature of the whole system and its desired

service features (speed, headways, station spacing,

etc.) than from technical considerations of control

system design or automation technology.

During the planning process, the development

and acquisition costs of ATC equipment are considered, but formal cost-benefit studies specific to

the ATC system are usually not conducted. ATC

costs-and, to a lesser extent, benefits—are sometimes factored into cost-benefit studies for the transit system as a whole; but the objective of these

studies is to analyze other aspects of the system or

to justify a more general choice regarding transit

mode, system size, or route structure. The operational costs of ATC are seldom included in system

cost-benefit studies, and they are not subjected to

separate analysis to determine their potential influence on the life-cycle costs of the transit system,

8
Chapter 2

BACKGROUND

.

9
RAIL RAPID TRANSIT

Rail rapid transits is an old and established part

of the national transportation system. It carries

large numbers of people at high speeds within

central business districts and to and from outlying

areas. The patronage in Chicago, for example, is

over half a million people on a typical weekday; in

New York City as many as 3-1/2 million riders are

carried daily. Nationwide, rail rapid transit serves

about 2 billion passengers per year. In the newer

systems, top speeds of 70–80 miles per hour are attained, with average speeds of 30–40 miles per hour

for an entire trip. In cities where there is an existing

rail rapid transit system, it is difficult to conceive

how they could function properly, or at all, without

this mode of transportation.

Most rail rapid transit systems in this country

were built over 30 years ago. The New York,

Boston, and Chicago systems date from the turn of

the century. In recent years, other major cities have

turned to rail rapid transit as a solution to the

problems of urban transportation and automobile

traffic congestion. The Lindenwold Line (PATCO)

in New Jersey and BART in San Francisco were

built within the last 10 years, and rail rapid transit

systems are planned or under construction in Atlanta, Baltimore, and Washington, D.C. The major

cities with existing systems (New York, Chicago,

Boston, Philadelphia, and Cleveland) have undertaken programs to extend and improve their service.

Along with the new attention to rail rapid transit

has come an increased concern with technology.

The basic technology of rail rapid transit, which

derives largely from railway engineering, is quite

old. Propulsion and braking systems, for example,

are products of the late nineteenth century. The

electric track circuit, used to detect the presence of

trains and to assure safe separation of trains, was

developed over 100 years ago. The cam controller (a

mechanism for controlling the application of power

to d.c. propulsion motors) was first used in the

Chicago subway system in 1914. Cab signaling

systems, functionally similar to those of today, were

in use in the 1930’s. While this technology has been

refined and improved over years of operational experience, many transit system planners and

5Rai] rapid transit is an electrified rail system operating in

urban areas on exclusive rights-of-way, Rail rapid transit is considered here to exclude commuter railroad systems and light rail

systems, although the technology of train control is similar for

all three.

engineers believe that new and

forms of technology need to be

more sophisticated

applied in order to

achieve systems of higher safety, performance, and

efficiency,

Generally, two avenues of technological innovation are proposed for rail rapid transit: substitution

of electronic for electromechanical components and

more extensive use of automation, One such application of new technology is in the area of train

control, where the replacement of men with

electronic monitoring and control mechanisms is

thought to offer several advantages--greater consistency of performance, safeguarding against

human error, more extensive and precise control of

train operations, and reduced labor costs in operating the system. However, some transit engineers

have misgivings about the ability of the newer

automatic train control systems to perform as safely

and efficiently as manual systems, There is also

some doubt about the cost-benefit of automation.

Automated control systems are more expensive to

design and produce, and their complexity may

make them less reliable and more costly to maintain. Automatic train control is, thus, a controversial matter in rail rapid transit, especially as a result

of the difficulties encountered by the BART system

in San Francisco. BART is the newest and most

technologically advanced transit system in the

United States, but it has not yet lived up to the

levels of performance and service predicted during

its planning and development, or even to the standards set by older and technologically less advanced

transit systems now in operation. Some critics contend that problems of BART stem from its extensive

use of unproven innovative technology for train

operation and control,

A part of the controversy over automation may

stem from a common misconception that it is synonymous with computers. Electronic data processing is certainly one way to achieve automatic operation, but there are others. The track circuit, the

electromechanical relay, the emergency air brake,

the trip stop, and recorded passenger information

announcements are all automatic devices; and none

involves a computer in the usual sense of the term.

Another misconception is that automation is something new, a product of aerospace technology.

While it is true that automated equipment has been

employed extensively in advanced aviation and

space systems, the birthplace was certainly not

there. Automation has been with us since the beginning of the industrial revolution. All of the

11
automatic

use in rail

devices mentioned above have been in

rapid transit for many years.

Thus, the issue is not whether automation should

be applied in rail rapid transit train control.

Automatic train control devices of various types

have been used in rail rapid transit for many years.

The real concerns are where should automation be

applied, how far should the train control process be

automated, and what technology should be used. As

phrased by the OTA staff in planning this assessment of automatic train control in rail rapid transit,

the central question is: “What degree of system

automation is technically feasible, economically

justifiable, or otherwise appropriate for rail rapid

transit?” The answer, which entails examination of

safety, performance, and cost, is crucial to the

future development of rail rapid transit and its

value as a public transportation system.

OBJECTIVES

This study was undertaken with the following

objectives:

1. to examine the design characteristics of

automatic train control systems and

evaluate the state of automatic train control technology;

Z. to assess the operating experience and

performance of transit systems which

employ various forms of automatic train

control;

3. to analyze the process by which automatic

train control systems are planned,

developed, and tested;

4. to examine the policy and institutional

factors that influence the application of

automatic train control technology in rail

rapid transit.

Thus, the emphasis of this report is not on technology as such. While there is considerable attention given to technical matters in the early chapters,

it is intended as background for subsequent examination of the results and implications that ensue

from the application of automation in rail rapid

transit systems. The bulk of this report is devoted to

an assessment of the practical results of ATC in

operating transit systems and to the practical results

of ATC in operating transit systems and to an

evaluation of the planning and development process by which ATC systems evolve in the context of

public institutions and government policy.

SCOPE

The scope of this report is limited to automatic

train control technology in rail rapid transit

systems. No attempt has been made to deal either

with rail rapid transit technology as a whole or with

the application of ATC to small-vehicle fixedguideway systems. 6 The parts of this report that

deal with the planning and development process are

confined to matters relating to the evolution of the

train control system. It is recognized that ATC

design and development does not occur in isolation,

but as a part of the larger process by which the entire transit system is planned and built. A more

general assessment of mass transit planning is the

subject of a separately published report.7

Five operating rail rapid transit systems are examined in this report:

Bay Area Rapid Transit System (BART) in the

San Francisco area,

Chicago Transit Authority (CTA),

Massachusetts Bay Transportation Authority

(MBTA) in the Boston area,

New York City Transit Authority (NYCTA),

Port Authority Transit Corporation (PATCO),

the Lindenwold Line, in Philadelphia and

suburban New Jersey.

These systems were selected for study because they

embrace a broad range of system characteristics.

They vary from a simple one-line system (PATCO)

to complex and dense transit networks (CTA and

NYCTA). They represent a range of automation,

from predominantly manual (NYCTA and CTA) to

highly automated (BART). They differ greatly with

respect to age--NYCTA, MBTA, and CTA being

the oldest and PATCO and BART the newest. They

also employ several forms of train control technology--conventional (CTA, MBTA, NYCTA), advanced (PATCO), and innovative (BART).

eAn assessment of the technology of transit systems employing automatically operated small vehicles on fixed guideways

was issued by OTA in June 1975 under the title, Automated

Guideway Transit (Report No. OTA–T-8).

TAn Assessment of Community Planning for Mass Transit,

Office of Technology Assessment, February 1976 (Report Nos.

OTA-T–16 through OTA-T–27).

12
In addition to these five operating systems,

others in the planning and development stage are

considered in the parts of the report that deal with

the process by which transit systems are conceived,

designed, and built. The principal rail rapid transit

systems under development are:

Metropolitan Atlanta Rapid Transit Authority

(MARTA)

Mass Transit Administration (MTA) in

Baltimore

Washington Metropolitan Area Transit

Authority (WMATA)

STUDY METHOD

This assessment was a joint undertaking by the

OTA Transportation Program Staff and the Urban

Mass Transit Advisory Panel, an 11-memher group

made up of representatives of the transit industry,

State department of transportation, planning consultants, organized labor, and public-interest

groups. Battelle Columbus Laboratories acted as

technical consultants and provided major assistance

in collecting data and conducting interviews with

transit system officials, planning organizations, and

equipment manufacturers. The OTA staff also carried out an independent program of visits to interview transit system officials at five sites and to collect data on their operational experience with ATC

equipment. The findings of the Battelle investigation were presented to the panel in a series of background and technical documents. This material was

combined with the results of the OTA staff effort to

form the basis for this technology assessment.

ORGANIZATION

This report is organized to accommodate readers

of different interests and technical backgrounds,

The next two chapters, entitled “Automatic Train

Control” and “Transit System Descriptions,” are intended to acquaint the reader with basic train control technology and the operational characteristics

of the rail rapid transit systems selected for study.

These chapters are written with a minimum of

technical detail and provide a general background

for the subsequent examination of operational,

planning, and policy issues. Those already familiar

with train control technology and transit operations

may wish to skim this material or to pass on directly

to chapters 5, 6, and 7, which deal with operational

experience, planning and development, and policy

issues relating to automatic train control technology. As an accommodation to differing reader

interests, these chapters are organized in three

levels of detail. The first level is a summary of the

major issues at the beginning of each chapter. Next

is a presentation of the individual issues, each

headed by a capsule statement and a synopsis of the

principal findings and conclusions. The third level

consists of supporting detail and discussion of the

implications for each issue. Thus, the reader can

pursue each topic to whatever depth desired.

At the end of the report are various technical appendices, intended primarily for those who wish

more specific information on train control technology and system engineering features. Appendix

D—Glossary of Terms, and Appendix E—

Chronology of Train Control Development, may

also be of interest to the general reader.

13
.

Chapter 3

AUTOMATIC TRAIN CONTROL

.

15
Train control is the process by which the movement of rail rapid transit vehicles is regulated for

the purposes of safety and efficiency. The process is

carried out by a combination of elements-some

men, some machines—located on the train, along

the track, in stations, and at remote central

facilities. These elements interact to form a command and control system with four major functions:

. Train Protection prevention of collisions and derailments,

. Train Operation control of train

movement an d

stopping at stations,

● Train Supervision direction of train

movement in relation to schedule,

. Communication interchange of information among

the elements of the

system.

The train control system is analogous to the sensory organs and central nervous system of the

human body. It senses and processes information,

makes decisions, and transmits commands. Also as

in the human body, the execution of commands is

not a function of the train control system but of

other parts specialized for that purpose. For example, the train control system may sense train speed,

determine that it should be increased, provide an

appropriate command signal to the motors, and

monitor to see that the desired result is achieved.

The means by which a speed change is effected,

however, are not part of the train control system.

All the equipment for getting electric power to the

wayside, bringing it into the train, converting it to

mechanical energy, and providing tractive effort is

external to the train control system. Similarly, the

equipment to select a route for a particular train and

transmit commands to aline switches accordingly

are within the train control system, but the parts of

the trackwork that actually move (the switch

points) are not elements of the train control system.

TRAIN CONTROL

SYSTEM FUNCTIONS

Presented below is a description of the specific

functions performed by a train control system and

of the way in which functional elements interact.

These functional relationships are also illustrated

by the diagram in figure 1. Since the purpose is only

to provide the reader with a general background for

understanding the nature of train control, the

definitions presented here are brief and nontechnical.8

Train Protection

Train protection is a family of functions whose

purpose is to assure the safety of train movement by

preventing collisions and derailments. 9 rain protection functions and requirements override all

other control system functions either through

equipment design or, in a completely manual mode,

by rules and procedures. The functions that make

up train protection are:

Train detection—monitoring of the track to

determine the presence and location of trains;

Train separation-assuring that trains on the

same track maintain a safe following distance

to prevent collisions;

Route interlocking—preventing trains on crossing, merging, or branching routes from making

conflicting (unsafe) moves that would cause a

collision or derailment;

Overspeed protection—assuring that train

speed remains at or below the commanded or

posted civil speed limit10 as to prevent collisions resulting from going too fast to stop

within the available distance and to prevent=

derailments due to excessive speed on curves

or through switches;

Train and track surveillance-observing conditions on and in the vicinity of the track ahead

of the train and monitoring safety-related conditions on board the train.

Train Operation

Train operation consists of those functions

necessary to move the train and to stop it at stations

F. For more detailed technical descriptions of train control

system functions and technology, see appendices A and B.

gThere is no unive~]ly accepted terminology and scheme of

definitions for train control system functions within the transit

industry. The terms and classification employed here are based

on several sources and represent the best of current usage.

IOA g]os5ary of train control and rail rapid transit terms is

provided in appendix D.

1 7
PROTECTION

I

PERFORMANCE

MODIFICATION

k

r I

(Train

Presence)

1

I 1

I L I

A

Movement Order

I 1

Movement Report

Operation

OPERATION

J I

“ To simplify the diagram, the functions of Alarmlng and Recordkeepinq are not shown
to board and discharge passengers. Train movement, as controlled by train operation functions, is

under the direction of train supervisory functions

and always within the constraints of train protection functions. Train operation involves the following:

Speed regulation-controlling train speed, within the constraints of overspeed protection, to

make the run according to schedule;ll

Station stopping—bringing the train to a stop

within some specified area in a station;

Door control--opening of doors in stations to

permit passengers to enter or leave the train

and closing of doors when the train is ready to

start;

l2

Train starting—initiating train departure from a

station after the doors are closed (and provided the train protection system permits it),13

Train Supervision

Train supervision involves monitoring the movement of individual trains in relation to schedule and

route assignments and overseeing the general disposition of vehicles and flow of traffic for the

system as a whole. The train supervision system

may thus be thought of as making strategic decisions which the train operation system carries out

11Speed regulation involves more than matching actual to

command speed. It also includes control of acceleration, jerk

limiting (controlling the rate of change of acceleration), slipslide control (correction of wheel spinning during acceleration

and skidding during braking), and flare-out (gradual relaxation

of braking effort as the train comes to a stop). Flare-out is considered by some transit engineers to be a subsidiary function of

speed regulation, and hence part of the train control system. Acceleration control, jerk limiting, and slip-slide control are

regarded by transit engineers to be propulsion and braking

system functions, but they are mentioned here because of their

relationship to the train control functions of speed regulation

and station stopping.

12The mechanisms that actually open and close doors are not

part of the train control system, but the signals to actuate these

mechanisms and the interlocks to assure that doors are closed

before starting and that they remain closed while the train is in

motion are generated within the train control system. Because of

the safety implications of door control, some transit engineers

consider it to be a part of train protection.

13Train starting is sometimes classified as part of the door

control function. It is separated here for two reasons: (1) in some

automated systems, door control is automatic while train starting is retained as a manual function; (2) in manual systems, the

door control and train starting functions are often assigned to

different persons.

tactically, In addition, train supervision includes

certain information processing and recording activities not directly concerned with train safety and

movement but necessary to the general scheme of

operations. Train supervision functions are:

Schedule design and implementation—preparing a plan of service in light of expected

demand, available equipment, and environmental conditions and issuing a schedule to

implement the plan;

Route assignment and control--selecting and

assigning routes to be followed by trains (and

rerouting as necessary);

Train dispatching-controlling train departures

from terminals or waypoints in accordance

with the schedule;

Performance monitoring—following th e

progress of trains against the schedule by obtaining periodic updates of train identity, location, and destination;

Performance modification—adjusting movement commands and revising the schedule in

response to train, traffic, and environmental

conditions.

Alarms and malfunction recording-alerting to

malfunctions, breakdowns, or problems, and

recording their time, location, and nature;

Recordkeeping —maintaining operational logs

and records for business and payroll purposes,

for scheduling maintenance, for ordering supplies and equipment, and for computing technical statistics.

Communication

The communication system is the means by

which the information needed to carry out all other

train control functions is transmitted and exchanged .

l4 This information may take any of

several forms-voice, visual, auditory, and digital

14On the function diagram in figure 1, communication functions are indicated by the lines connecting the boxes which

represent train protection, operation, and supervision functions,

1 9
or analog electrical signals.l5Unlike other train control functions, which involve information processing and decisionmaking, communication is largely a

facilitative process-serving to convey information

but without producing any unique functional outcomes of and by itself. For this reason, the

categorization given below indicates not functions

as such but major classes of information that must

flow throughout the system in order for other train

control functions to take place:

Train protection—information necessary to

locate individual trains, to assure their safe

separation, to prevent overspeed, and to control movement at route interlockings;l6

Command and status—information on the

operational state of the system, command signals to control train and switch movement,

and feedback to determine the response of

system elements to command inputs;l6

Emergency—information on the nature and

location of emergency events and summons

for help to elements within the transit system

or to outside agencies (e.g., fire, police, medical, and rescue);

Passenger service—information relating to train

service and system operation for the purpose

of assisting passengers using transit facilities;

Maintenance—information needed to plan or

conduct preventive and corrective maintenance;

Business operations--operational information

used to maintain a record of (and to plan for)

work force allocation, vehicle utilization, procurement of supplies and equipment, operating expenses, and system patronage.

15Some transit engineers limit the definition of communication to verbal or visual communication (radio, telephone, TV,

and the like). Machine-to-machine communications, since they

tend to be very specialized, are considered part of the function

which they serve. This seems to be unnecessarily restrictive and

makes an artificial distinction between information exchange by

human operators and other forms of information exchange involved in operating the system (i.e., man to machine or machine

to machine). The definition offered here is generic and embraces

all types of information flow, regardless of how effected.

16Customarily, this part of the communication system is completely separate from the network used for other types of information and is considered to be an integral part of the train protection system.

AUTOMATION

At one time or another, all of the train control

functions listed above have been performed by

human operators, and many still are, even in the

most technologically advanced transit systems.

Theoretically, any of these functions could also be

performed by automatic devices, and more and

more have, in fact, been assigned to machines over

the years, Before examining the technology by

which train control automation has been achieved,

it is first necessary to consider what is meant by

automation and to clarify the terminology used in

this report.

Figure 2 is a generalized diagram of the process

by which any train control function is accomplished. It involves receiving information about

some operational state of the system and some

desired state. This information must then be interpreted—for example, by comparing the two

states and deriving a quantitative expression of the

difference, Next, an appropriate control response to

null the difference must be selected, and some

specific command message to the controlled element must be formulated and transmitted. A final,

and all-important, step is monitoring the results of

the control action to ascertain that the desired

system state or condition has been achieved. This

last step, called feedback, provides an input signal

to start the process all over again, thereby creating a

loop that permits the control process to be continuous and adaptive.l7

If all of the steps in the general sequence shown

in Figure 2 are performed by a human operator, the

process is called manual, even though manual action in the strict sense may not be involved. Thus,

manual denotes a process that may include visual,

auditory, and other forms of sensory perception as

well as purely cognitive activities such as interpretation, weighing alternatives, and decisionmaking. The command output might be accomplished by some manual activity such as pressing a button or moving a control lever, or it might

take the form of a voice command or simply a nod

of the head. The essential feature of a manual process, as the term is used here, is that all the basic control steps to accomplish a function are human activities.

l~his cIescriptiOn overlooks the difference between closedand open-loop control systems. For a discussion of the application of each in train control technology, see appendix B.

20
It is also possible for all of the steps in the control

loop to be accomplished by some mechanical or

electrical device. If so, the process is called automated. The device need not necessarily be complicated, nor is a computer required in order for the apparatus to process information and make a “decision.” A simple junction box with a two-state logic

circuit (ON or OFF) would satisfy the definition of

an automated control device, provided no human

actions were required to receive and interpret input

signals, select and order a response, and monitor the

result.

Between the extremes of purely manual control

and fully automatic control, there are numerous

combinations of mixed man-machine control loops.

These are called semi-automated or partially automated—the terms are used synonymously to denote

a process (or a system) in which there are both

manual and automatic elements. Thus, automation

is not to be taken in an absolute, all-or-nothing

sense. The machine can be introduced by degrees

into a system to perform specific functions or parts

of functions. When comparing parts of a train control system or when comparing one system with

another, it is therefore possible to speak of automation in comparative terms and to say that one is

more or less automated than another, depending on

how many specific functions are performed by

machines.

For brevity, acronyms are used to describe certain areas where automation is applied in train control. ATC (automatic train control) refers generally

to the use of machines to accomplish train control

functions. It does not necessarily suggest a completely automated system. It can be applied to a

system where certain functions or groups of functions are performed automatically while others are

performed manually. ATP (automatic train protection), ATO (automatic train operation), and ATS

(automatic train supervision) are used to designate

major groups of functions that may be automated.

For example, if a system is said to have ATP, it

means that train protection is accomplished (either

completely or mostly) by automatic devices without

direct human involvement. If a system is described

as having ATC consisting of ATP and some ATS,

this indicates that train protection is assured by

automatic devices and that train supervision is a

mixture of manual and automatic elements. By implication, train operation in such a system would be

manual.

While automation involves the substitution of

machine for human control, this does not mean that

the human operator is removed from the system

altogether. An automated system is not always an

unmanned system, even though all functions are

routinely performed by machines. For instance,

train protection and train operation may be completely automatic in a given transit system, but

there could still be an operator or attendant on

board the train to oversee equipment operation and,

most importantly, to intervene in the event of

failure or malfunction. This emergency and backup

role is, in fact, a major type of human involvement

in even the most automated train control systems,

In all rail rapid transit train control systems now in

2 1
operation or under development, automation is

utilized only for normal modes of operation, with

manual backup as the alternative for unusual conditions, breakdowns, and emergencies.

In passing, it should also be noted that automation is not synonymous with remote control, even

though the two may at times go hand in hand. In

train supervision, for example, many functions are

accomplished manually by controllers who are

physically far removed from the train and wayside.

In central control facilities, the operators may never

actually see the vehicles or track and yet perform all

or most of the functions necessary to set up routes,

dispatch trains, and monitor traffic. Conversely,

automated functions are often performed locally,

i.e., by devices on board the train or at a station or

switch. In general, the location of the controlling

element in relation to the controlled element is independent of how the functions are accomplished.

However, it is also true that automation does facilitate the process of remote control, and systems with

a high level of ATC tend also to employ more

centralized forms of train control, especially for

supervisory functions.

AUTOMATIC TRAIN

CONTROL TECHNOLOGY

The automatic equipment that accomplishes

train control functions is often of complex design,

but the basic technology is quite simple. The purpose of this section is to provide an acquaintance

with the fundamental elements of an ATC

system—track circuits, signaling apparatus, train

operating devices, interlocking controls, and supervisory equipment, The details of this technology

and the design features of ATC equipment now in

use in rail rapid transit systems are omitted here but

are provided in appendices B and C.

Track Circuits

For safety and efficient operation of a transit

system, it is imperative to know the locations of

trains at all times. The sensing device providing this

information is the track circuit, which was invented

over 100 years ago and has remained essentially

unchanged in principle even though extensively

refined and modified in its engineering details.

FIGURE 3.—Simple D.C. Track Circuit

22
The track circuit is an electrical circuit consisting

of a power source, the running rails, and a signal

receiver (relay).

l8 The track is divided into

electrically isolated segments (called blocks) by insulated joints placed at intervals in the running

rails. l9 This forms a circuit with a power source

connected to the rails at one end of the block and a

relay at the other. The relay, in turn, forms part of a

second electrical circuit which has its own independent power supply (commonly a battery) and includes a signaling device such as wayside colored

lights,

When no train occupies the block, the relay is

energized by the track circuit battery, causing the

relay to “pick up, ” i.e., a movable element (armature) is moved to and held electromagnetically in

a position opposed to the force of gravity. This

closes an electrical contact in the secondary signal

circuit. When a train enters the block, the wheels

and axles conduct electricity between the running

rails, thereby short circuiting (shunting) the track

circuit and reducing the current to the relay. This

weakens the electromagnetic force holding up the

armature, allowing it to drop under the force of

gravity. This action opens the contact that was previously closed and closes a different contact in the

signal circuit. The relay, therefore, acts as a switch

in the secondary signal circuit and creates one

 electrical path when it picks up and another when it

drops.

Thus, the basic principle of the track circuit is the

shunting phenomenon produced by the train

wheels passing along the electrically energized running rails. The presence of the train is detected in

the track circuit as a reduction of electrical current,

which-by means of the relay—is used to control

the secondary signal circuit and operate various

types of track occupancy indicators.

The track circuit is designed according to the failsafe principle. In order for a clear (unoccupied

block) indication to be given, the track circuit must

be in proper working order. If one of the rails were

18Track circuits may utilize one or both running rails, may

operate on direct or alternating current, and may have

electromechanical relays or solid-state electronic receivers. The

type described here is a double-rail dc track circuit with a relay.

The other types are similar in principle and operation.

19Block length in rail rapid transit systems varies considerably as a function of track and traffic conditions and signal

system design. Some are as short as 40 feet; others are over half a

mile long,

to break, the relay would receive no current; and

the armature would drop just as if a train were present. A broken electrical connection, a failure of the

power source, or a burned-out relay coil would also

have the same effect.

Wayside Signals

One of the earliest types of signal devices

employed to control train movement, and one still

widely used, is the automatic wayside block signal,

It consists of a color-light signal, in appearance

much like the traffic signal on city streets, located

beside the track at the entrance to each block, This

signal is controlled by the track circuit relay, as

described above. The signal directs train movement

by displaying red, yellow, or green lights (aspects)

to indicate track circuit occupancy ahead,

Since it would be impractical for the train to

creep ahead block by block, waiting to be sure each

block is clear before entering, the wayside signals

are arranged to give the operator advanced indication of speed and stopping commands. Figure 4 is an

illustration of a three-block, three-aspect wayside

signal system, This signaling arrangement tells the

train operator the occupancy of the track three

blocks ahead of the train and conveys three

different movement commands (indications)—

green (proceed), yellow (proceed prepared to stop at

the next signal), red (stop).

In the illustration, Train A is stopped in Block 4

and Train B is approaching from the rear. Since

there is a separation of at least three blocks between

them, Train B receives a green aspect at the

entrance to Block 1, allowing it to proceed at the

maximum allowable speed. At the entrance to

Block Z, however, Train B receives a yellow aspect,

indicating that the train operator should be prepared to stop at the next signal because there may

be a train ahead. At the entrance to Block 3, Train B

is commanded to stop by a red signal aspect. When

Train A leaves Block 4 and moves on to Blocks 5

and 6, the signal at the entrance to Block 3 changes

to yellow and then green, allowing Train B to proceed.

The wayside signaling system is made fail-safe

through design and by operating rules. Dual, or

sometimes triple, lamps are used to illuminate each

signal aspect. Redundant power sources are sometimes provided. The ultimate safeguard, however, is

23
FIGURE 4.—Three-Block, Three-Aspect Wayside Signal System

procedural. A complete failure of the signal lamps

or a loss of power would result in a dark (unlighted)

signal, which standard operating rules require the

train operator to observe as if it were a red signal.

Trip Stops

In the wayside signal system described above,

safe train movement depends solely on the compliance of the operator with signal indications. To

guard against error, inattention, or incapacitation of

the train operator, wayside signals can be supplemented with an automatic stop-enforcing mechanism, called a trip stop.

The trip stop is a device located beside the track

at each wayside signal. The type commonly used in

the United States consists of a mechanical arm that

is raised or lowered in response to the track occupancy detected by the track circuit. When the arm is

in the raised position, it engages a triggering device

on the train and actuates (trips) the emergency

24

brake. 20 A train entering a block in violation of the

wayside signal indication would thus be brought to

a complete stop before colliding with the train in

the next block regardless of what action the train

operator took, or

In addition to

sions, trip stops

failed to take.

protecting against rear-end collican also be used in conjunction

with the track circuits and other signal appliances to

provide automatic protection against overspeed. For

this application, a timing device is added to the circuit controlling the trip stop. When a train enters a

20An alternative system employing inductive train stops is

used on main-line railroads in the United States and on rail

rapid transit systems abroad. The device is somewhat more complex than the mechanical trip stop, but it avoids mechanical contact between a stationary wayside element and a moving train

and is less vulnerable to blockage by snow or debris. Both trip

stops and inductive train stops have the inherent disadvantage

of requiring strict alinement of wayside devices. Further, if

either type of device is removed, the system will operate in a

mode that is not fail-safe.
block, the trip stop at the entrance to the next block

is in the raised position but will be lowered after a

time interval corresponding to the minimum time

(the maximum speed) permitted for a train to traverse the block. This arrangement is commonly

used on curves, downgrades, and other such sections of track where excessive speed could cause a

derailment. A variation of this scheme is commonly

used at stations to allow a following train to close in

on a leading train, provided the follower moves at

appropriately diminishing speed as it approaches its

leader.

Like track circuits and signals, the trip stop is

designed to operate in a fail-safe manner. The trip is

raised to the stopping position by gravity or a heavy

spring and lowered by a pneumatic or electric

mechanism. Thus, failure of the trip stop actuating

mechanism or its source of energy will result in the

trip stop being raised to the stop position.

Cab Signals

Automatic block signal systems with wayside

signals and trip stops, while offering effective train

protection, have certain operational disadvantages.

Sometimes the signals are obscured by fog, rain, or

snow. In such cases, operating rules require that the

operator consider the signal as displaying its most

restrictive aspect and operate the train accordingly.

If the signal is actually displaying a more permissive indication, time is lost unnecessarily. A second disadvantage is that wayside signals convey

commands only at the entrance to a block. The train

operator must reduce speed to the maximum permitted by the signal and maintain that speed until

reaching the next signal. If conditions change immediately after the train enters the block and it

becomes safe to proceed at a greater speed, the train

operator has no way of knowing this since the signal is behind him. Again, time is lost. With wayside

block signals there is also the possibility that the

operator will fail to observe the signal correctly,

read the wrong signal in multiple-track territory, or

forget the indication of the last signal passed. If

there are trip stops, these kinds of human failure do

not result in an unsafe condition, but the efficiency

of train operation can be adversely affected.

One way to overcome these disadvantages is to

provide signal displays within the cab of the train,

This is called cab signaling, A display unit, mounted

in the cab within the train operator’s forward field

of view, shows indicator lights similar to those of

wayside signals, e.g., red, yellow, and green aspects.

Cab signals can thus convey the same movement

commands as wayside signals, but they do so continuously in response to the instantaneous condition of the track ahead. They can also convey precise speed commands instead of just stop-and-go information, thus providing more flexible operation

and paving the way to ATO. The cab signal unit has

an audible warning that sounds whenever the signal aspect becomes more restrictive and continues

to sound until the operator silences it by an

acknowledging device. Figure 5 is an illustration of

a typical cab signal.

Transferring the display of information from the

wayside to the cab involves an alternate type of

track circuit technology. To operate cab signals, the

current passing through the track circuit (usually

a.c. is not steady, as for conventional wayside signals, but is pulsed (turned on and off) at several

different repetition rates in response to track occupancy. Each pulse rate is a code to indicate allowable train speed. This pulsed d.c. energy is passed

through the rails, picked up inductively by a

receiver (antenna) on the train, and decoded to

retrieve speed command information, This information is used to actuate the appropriate cab signal

display. Because the train is continuously receiving

pulses of energy, a change in the pulse rate of the

coded track circuits indicating a change of conditions ahead of the train is instantaneously received

by carborne equipment and displayed by cab signals

regardless of where the train happens to be within a

block.

Figure 6 illustrates how cab signals control a

train in a three-block, three-aspect signaling

system. In this example, the code rates transmitted

through the rails (expressed as pulses per minute)

correspond to the following signal aspects:

180 Green (Proceed)

75 Yellow (Proceed at medium speed

prepared to stop)

O Red (stop)21

21Note that O code-the absence of a code—is the most

restrictive, Thus, any failure of the track circuit or the carborne

receiver is a fail-safe condition since it is interpreted by the cab

signal equipment as a command to stop.

25
HOW IT WORKS: Receiver coils, mounted on the train near the rails, receive pulse-coded track signals, which

are decoded and used to pick up relays that energize the cab signal lamp indicating track

conditions ahead.

FIGURE 5.-Cab Signals

FIGURE 6.—Three-Block, Three-Aspect Cab Signal System

26
The situation depicted here is the same as in the illustration of wayside signals (figure 4). Train B is

approaching Train A, which is completely stopped,

Note that the moment Train A starts to move and

clears the block, Train B receives a green signal immediately—not at the entrance to the next block, as

it would with wayside signals. Note also that a O

code appears in the part of the block immediately

behind Train B as it moves along the track and that

Train B can approach

required to stop,

Speed Control

 closer to Train A before being

With the addition of speed sensing and brake

control mechanisms, cab signals can also be used to

provide automatic overspeed protection. Figure 7 is

a schematic diagram of such a system. It is the same

as the schematic shown in figure 5, except for the

addition of speed and code rate comparison equipment and the direct connections to the propulsion

and braking systems.

This arrangement allows the train operator to

control speed so long as it does not exceed the commanded speed shown on the cab signal unit. If the

commanded speed is exceeded or if the block speed

changes to a lower value because of another train

ahead, the operator receives an audible warning.

The operator has a fixed time (typically 2 to 3 seconds) to initiate the required braking manually. If

this is done, the brakes can be released when the

commanded lower speed is reached. If not, the

brakes are applied automatically and irrevocably by

the ATC system, and the train is brought to a full

stop before the operator can resume control. This is

analogous to the overspeed control provided by

wayside signals with trip stops, except that braking

can be initiated anywhere within a block not just at

the entrance. Another difference is that trip stops

act to stop the train after an overspeed condition has

occurred over a measured course, usually several

hundred feet in length. Cab signals do the same, but

instantaneously, thus eliminating the delay inherent in the preliminary measured course and perTrain Wheels

/

& Axle

FIGURE 7.—Cab Signal System With Automatic Overspeed Protection

27
mit trains to follow one another more closely for a

given block length.

Automatic Train Operation

Basically cab signaling provides carborne

automatic train protection in the form of collision

prevention. With the addition of on-board equipmerit for sensing and comparing command (allowable) and actual speed, cab signaling makes it possible to expand the train protection function to permit

speed regulation. This, in turn, forms the basis for

extending automation into the area of train operation.

Several forms of automatic train operation

(ATO) are possible, but all have two basic

features-automatic speed regulation and station

stopping.

Automatic speed regulation (ASR), as the name

implies, is basically a comparator circuit for matching actual speed to command speed. Speed comands

received from coded track circuits are picked up by

a carborne receiver, decoded, and compared to actual train speed sensed by a tachometer in the drive

mechanism. Up to this point, an automatic speed

regulation system is like cab signaling. The

difference arises in how this comparison is used.

With cab signals, the comparison is used to actuate

a penalty brake application to stop the train when

actual speed exceeds command speed. With ASR,

the comparison is used to control the motors and

brakes in an effort to minimize the difference between actual and command speed. An advisory display of speed commands and train speed may be

provided for the operator. In effect, ASR removes

the human operator from the control loop for running the train and provides for an essentially instantaneous and invariant response by propulsion and

braking systems, without the delay of human reaction time and without the variability and possibility

for misinterpretation inherent in manual train

operation.

The other basic element of ATO is station stopping, which involves bringing the train to stop

automatically at a predetermined location in each

station. This is accomplished by special wayside

control units working in cooperation with position

receivers, logic circuits, and automatic speed

regulation equipment on the train. One method

uses wayside “triggers” spaced some distance from

the station as reference points for programed stopping. The first trigger, farthest from the station,

transmits a command signal that

board the train, a velocity-distance

generates, on

profile which

the train is to follow to a stop. Additional triggers,

nearer the station platform, correct the generated

velocity-distance profile for the effects of wheel

slip and slide. The ASR system monitors the

velocity-distance profile and controls the braking

effort to bring the train to a stop at a predetermined

point. Another method of programed stopping

makes use of long wayside antenna to provide a

series of position signals to a carborne control

system as the train passes along its length. The carborne control system determines train position and

combines this with speed and deceleration information (sensed on board the train), to produce an appropriate propulsion or braking command for the

traction control system.

To this basic ATO system, other automated

features may be added. Doors can be opened

automatically after the train is brought to a stop in a

station, This requires a circuit to actuate door opening mechanisms and appropriate safety interlocks to

assure that the train is in fact stopped and at a station. Door closure may also be automated by adding

a timing circuit to measure how long the doors have

been open and to initiate a door closure signal

automatically after a predetermined dwell time has

elapsed. Train departure can also be initiated

automatically by introducing another control circuit

to apply propulsion power after receipt of a signal

confirming that doors are closed and locked.

For each of these levels of ATO, the train operator may be provided with an advisory display to

show what commands are being received and what

response is being made by automatic mechanisms.

The operator may also be provided with manual

override controls to inhibit automatic functions or

to vary automatic system operation. For example,

the operator may intervene manually to adjust the

stopping point, to prevent some or all doors from

opening, to vary station dwell time, or to initiate or

prevent departure. Figure 8 shows a functional

diagram of a typical ATO system and a picture of

the train operator’s console.

Interlocking

An interlocking is an arrangement of signals and

signal appliances so interconnected that functions

must succeed each other in a predetermined sequence, thus permitting safe train movements along

a selected route without collision or derailment. An

28
FIGURE 8.—Automatic Train Operation System

29
FIGURE 9.—Typical Interlocking Location

interlocking thus consists of more than just

switches to allow trains to move along crossing,

merging or branching routes; it is also made up of

signals and control devices that automatically prevent conflicting or improper movements. Interlocking may be manually controlled or equipped with

automatic devices that sort trains through branches

and junctions according to desired destinations,

Several forms of automatic interlocking are in

use. One of the oldest and simplest is an arrangement of hand-operated switches, each of which

controls an individual signal or track turnout. The

switches are mechanically or electrically interconnected such that once a particular route is selected,

the switch points locked in place, and the signals

cleared, no other route for a potentially conflicting

move can be established until the train bound for

the cleared route has safely passed, This arrangement represents a semiautomated form of movement control, Manual operation is required to select

a route and move the control levers, but all else

follows automatically, including inhibition of

further switch movement until the train has traversed the limits of the interlocking.

A more advanced, but still not completely automated, type of interlocking is a system that permits

a towerman or central supervisor to select the

entrance and exit points for a train to pass through

an interlocking, with the switches and signals for

the appropriate route then being set u p

automatically by an arrangement of electrical

relays, Figure 10 shows such a control panel for a

system called entrance-exit route interlocking, The

tower operator moves the control knobs to designate a desired route. Internal logic circuits

automatically select the best available nonconflicting route, aline and lock switches, and activate the

appropriate wayside signals to allowing train movement while holding other signals at stop to prevent

conflicting moves. This level of automation may be

characterized as automatic execution in response to

manual inputs,

30
FIGURE 10.—Entrance-Exit Interlocking Control Panel

Fully automatic interlocking are also in use. In

addition to track circuits, switch operation, and signal control elements, the automatic interlocking

must have some device for identifying a specific

train in order to create the necessary input to the

logic circuits.22 One method to identify trains is by

means of wayside optical device that scans a panel

on the lead car which gives destination, route, and

other needed information. Another method makes

use of a carborne transponder that is interrogated by

a wayside device. With either technique, however,

train identity becomes the substitute for manual inputs that allows trains to be sent along predetermined routes without human involvement.

22A rudimentary form of automatic interlocking is one that

uses a simple in-out logic circuit to switch trains from one track

to another. This device is commonly used at terminals and operates to switch each entering train from the inbound to the outbound track and thus does not require train identity information.

Train Supervision Equipment

Train supervision embraces a wide variety of

functions. The special-purpose equipment that has

been developed to perform these functions is

equally varied. In a general survey of train control

technology it is not possible to describe all types of

automatic and semiautomatic devices that are in

use. The following, therefore, is a brief catalog of

some of the more important systems.

Train dispatching is concerned with the timing of

train departures from terminals in accordance with

the schedule of operations. In conventional transit

systems this function is accomplished by

preprogrammed dispatching machines that

automatically ring a bell or flash a light as a signal

to the train operator that it is time to leave a terminal or intermediate waypoint. In some systems,

the dispatch function may be assigned to a central

train control computer that transmits electric start31
ing signals to the train in accordance with a master

schedule stored in the computer memory.

Route assignment and control is a train supervisory function that is allied to the train protection

function of route interlocking. Route control is a

strategic function, consisting of selecting routes for

trains and transmitting the orders to wayside points,

where the orders are implemented tactically by interlocking equipment. In conventional transit

systems, route assignment and control is performed

locally, either manually or automatically, With

remotely controlled route interlocking, however, it

becomes operationally practical to place the

strategic and tactical management of routing in a

computer. The programing to accomplish this is

relatively simple and straightforward, and a computer is ideally suited to handle what is an essentially repetitious task with a limited number of

alternative courses of action. The safety aspects of

route interlocking are assured not by central computer control, but locally by conventional interlocking equipment at the wayside,

Performance monitoring involves comparing the

overall movement of traffic with the schedule and

taking action to smooth out irregularities of traffic

flow. In most transit systems this function is carried

out by central control personnel aided by automatic

display devices. One such device is a pen recorder

that marks a moving paper graph to record the

passage of trains past check points, Each spike on

the graph indicates the presence of a train, as

detected by the track circuits, at some time and

place along the route. A train supervisor, by checking this graph against the schedule, can monitor the

progress of all trains operating on line and detect

delays or queuing up of trains, (Figure 18, page 36

shows such a device, )

Another form of performance monitoring aid is

the model board (figure 11), which is a schematic

representation of the track plan of the transit

system with indicator lights to denote track circuit

occupancy and, hence, the position of each train on

the line, This is the functional equivalent of the

pengraph recorder, but in a more pictorial form of

display. Another type of model board used in newer

transit systems has, in addition to the master track

plan, small cathode ray tube displays that permit individual supervisors to obtain more detailed or expanded views of selected track sections

special-purpose presentations of data,

or to call up

.

FIGURE Il.—Model Board and Train Control Console

32
Pengraphs, model boards, and the like are not

fully automatic supervisory devices. The human

operator is still needed to interpret the display and

to formulate orders to individual trains. In the most

advanced systems routine performance monitoring

is assigned to computers, which keep a continuous

watch on traffic movement and automatically

calculate and transmit performance commands to

trains. Man, in this circumstance, acts in a completely different supervisory capacity. He does not

monitor and regulate traffic. Instead, he supervises

machines which, in turn, monitor and regulate

traffic.

There are two general types of action that can be

taken to smooth out irregularities in traffic flow.

Both are accomplished in response to commands

from central control. One is to hold a train in a station for a time longer or shorter than the scheduled

dwell time or, in extreme cases, to direct a train to

bypass a station in order to close up a gap. The other

method is to alter the speed of the train between

stations. This latter method is called performance

level modification and takes the form of a proportional reduction of train speed below the speed normally allowed in each block. In systems supervised

by a central computer and with automatic train

operation, performance level modification is accomplished without human intervention. The required reduction is calculated by the central computer and automatically transmitted to stations or

other critical locations, where the signals are picked

up by carborne ATO equipment that modifies the

response to the normal speed commands transmitted by the coded track circuits. These systems may

also include provisions for manual inputs and displays at central control or on the train, but the normal mode of operation is automatic.

A WALK

THROUGH A TRANSIT SYSTEM

To place ATC in perspective, it maybe helpful to

make a brief tour of the facilities of a transit system,

pointing out the type and location of the equipment

that carries out train control functions.

Station

The passenger’s first point of contact with a transit system is the station. The most prominent

features-vending and fare collection facilities

(possibly automated), escalators and elevators,

heating and air conditioning, and platform

amenities—have nothing to do with train control.

There may also be public address systems and video

or audio surveillance equipment for fare collection

and platforms. These are not, strictly speaking, part

of the train control facility even though they maybe

connected to the central control facility and

monitored by central supervisory personnel, About

the only direct manifestations of ATC are the automated train departure and destination signs or

loudspeakers found in some transit systems. These

public announcement devices are connected to the

ATC system and use information inputs derived

from track circuits and train identification equipment, There may be an ATC equipment room in the

station, but it is out of sight and locked. Its presence

is usually unknown to passengers.

FIGURE 12.—General View of Rail Rapid Transit Station

33
These are the impedance bonds that isolate the

track into blocks. At the ends of the blocks, there

are small boxes, containing relays, with electrical

connections from the track circuits to the signaling

apparatus,

FIGURE 14,—Track Circuit Wiring

Other signal equipment is contained in small

cases placed at intervals along the right-of-way.

There are also telephones or other communication

equipment and antennas or transmitters used for

precision station stopping, train identification, or

performance level modification, In certain locations, ATC apparatus and other trackside equipment may be housed in small sheds to protect the

equipment from the weather and to facilitate maintenance by wayside workers.

FIGURE 13.—Trip Stop

Wayside

An observant passenger might notice two

wayside features that can be seen from the station

platform. Looking down the tracks in the direction

of train movement, there are wayside signal lights

that change aspect from time to time. Often, just

beyond the downstream end of the platform and

alongside the rail, there is a trip stop which can be

seen to raise behind a train that has just left the station and later lower as the train recedes.

Moving out along the tracks, other wayside elements can be found. The track circuits themselves

are not plainly visible since they are largely in

wayside housings. However, at intervals there are

small flat equipment cases situated between the

rails and connected to them by electrical wiring.

FIGURE 15.—Wayside Equipment Case (contains multiplex

equipment for transmitting information between trains and

station control rooms)

At junctions and crossovers there is switch apparatus, the most visible parts of which are the

switch points, frogs, levers, and motive equipment,

This is the wayside equipment, known as a switch

machine, that performs the function of interlocking

for train protection,

34
FIGURE 16.—Track Apparatus at an Interlocking

By far the largest part of the equipment, train but along the wayside and in central control

facilities, and structures along the right-of-way— facilities.

trackage, tunnels, bridges, the third rail, and power

distribution equipment-are not related to train Central Control

control. Nevertheless, the wayside is where the

bulk of the ATC equipment in a transit system is lo- Supervisory control of the system may be exercated. The proportion varies as a function of the cised in a central control room equipped with model

level of automation, but generally about 80 percent boards, communication, equipment, system

or more of all train control equipment is not on the monitoring apparatus, and individual supervisor’s

FIGURE 17.-Central Train Control Facility

35
FIGURE 18.—Two Views of a Central Control Facility

with Electromechanical Equipment

left-a clock-driven paper tape device for dispatching trains

above-pengraph device for monitoring train movement

consoles. If the system has ATS, the computers and

other data processing equipment are also located in

the central control building, which often houses administrative and training facilities as well.

Not all transit systems have a single centralized

control facility. Some disperse control and supervision to outlying towers, situated at major interlocking along the routes. Figure 19 is a photograph of

such a local control tower.

FIGURE 19.—Tower for Local Control of Interlocking

36
Vehicles

Most of the ATC equipment on transit vehicles is

carried in equipment cases under the body or in the

train operator’s cab. About the only features

distinguishable from outside the train are a receiver

coil mounted on the lead car to pick up coded track

circuit signals (figure 20) and—for systems with optical scanners-small identification panels mounted

on the side of each car.

FIGURE 21.—Train Operator’s Console for System

with ATO

The operator’s cab contains the displays and controls necessary to operate the train or to monitor the

functions of ATC equipment. The amount and

sophistication of this equipment varies greatly—

ranging from very simple and utilitarian apparatus

in manually operated systems to highly complex

consoles in the newest and most automated

systems, The console typically includes propulsion

and brake controls, a speedometer and command

speed indicator, lighted placards indicating the

operating state of automatic elements, warning

lights, pushbuttons or control knobs to make data

inputs or to select various operating modes, a train

phone or radio for communicating with central

supervisors, a passenger address microphone, and a

deadman control to prevent the train from operating in case the operator is inattentive or incapacitated.

Yards and Shops

A large part of the important activity of a transit

system does not occur in revenue service on the

main lines, but in the yards and shops, These

facilities, though seldom seen by the riding public,

contribute greatly to the quality and level of service

that the transit system offers.

The yards are usually located near terminals and

consist of a vast complex of tracks for storing vehicles and making up trains to be operated on the

lines. Even in systems with the most advanced

levels of automation, train operation in yards is

under manual control. Train sorting and classification is also an essentially manual operation,

although some systems have a limited amount of

automatic switching in the yards, principally to and

from revenue tracks.

Car shops and maintenance facilities are usually

located within the yard complex. The shops contain

facilities for light and heavy maintenance, component repair, car washing, and checkout of vehicles

before they are dispatched back into service,

The maintenance facility may also include a test

track and special test equipment to qualify vehicles

and components for acceptance or to carry out trials

of equipment modifications.

37
FIGURE 22.—Aerial View of Rail Rapid Transit Yard and Maintenance Facility

38
39
LEVELS OF AUTOMATION

It was suggested earlier that train control

automation can be viewed as a continuum. At one

extreme, all functions are performed by human

operators; at the other, all are performed by

machines. The transit systems now in operation or

under development in this country lie at various

points between these extremes, with their relative

positions corresponding roughly to the age of the

system. The older systems generally have the

LEVEL

Essentially Manual

Wayside Signal Protection

.

Carborne Train Protection

Automatic Train Operation

Automatic Train Supervision

Unmanned Operation

Full Automation

lowest levels of automation—primarily ATP with

some ATS. The newer systems have ATP and ATO

and more extensive ATS, None are completely

automated.

Historically, the conversion from manual to

automatic train control in rail rapid transit has been

incremental and has followed a more or less common course for all systems. These major technological stops along the road to automation are outlined

briefly below and summarized in table 1.

TABLE I.—Levels of Automation

CHARACTERISTICS

Train protection by rules and procedures

Train operation manual (with or without the aid of

advisory wayside signals)

Train supervision by towermen and/or central dispatched

Wayside block signals with trip stops for train

separation and overspeed protection

Train operation manual

Supervision manual with some automation of dispatching and route interlocking

Cab signals and equipment-enforced train protection

Train operation manual

Supervision as above

Automatic Train Protection as above

Train operation either completely automatic or with

manual door operation and train starting

Train supervision as above

ATP and ATO as above

Train supervision automatic

central computer control

ATP, ATO, ATS as above

No on-board operator

(or mostly so) under

System manned only by small number of central

control personnel

ATP, ATO, ATS as above, with automatic, not

manual backups for each

Skeleton force at central control

Yard operation automated

EXAMPLE

CTA

(Ravenswood and

Evanston Lines)

NYCTA

CTA

PATCO

BART

AIRTRANS

None

40
Essentially Manual

At this level, train protection, operation, and

supervision are carried out by train operators and

towermen or central supervisors with little or no aid

from automatic equipment. Trains are protected

and operated either by rules and procedures alone

or with the aid of advisory wayside signals. There

are no automatic stop-enforcing mechanisms either

on the wayside or on board the train. Train dispatching is carried out by personnel at terminals or

at control towers along the routes, using either a

written schedule or timing devices that act as

prompters to signal train departure. Route assignment and interlocking control are accomplished by

manually activated equipment that may have some

automatic safety features but are entirely controlled

by human operators. Communications are by means

of visual signals (lights, hand signals, posted civil

speeds, etc. ) or by telephone from stations and

towers to central control.

Many of the older transit systems in this country

began operation at the manual level, but they have

since advanced to more automated forms of train

control. One of the last vestiges of a purely manual

system is on the Ravenswood and Evanston lines of

the Chicago Transit Authority, which as late as

1975 operated without any automatic block signal

protection,

Wayside Train Protection

Wayside signals with trip stops form the basis for

automatic train protection, by assuring separation

of following trains and preventing conflicting

moves at interlocking. Incorporation of timing

devices with the trip stops also provides equipmentenforced overspeed prevention. While train protection thus becomes automatic, train operation is still

completely manual. Train supervision also remains

an essentially manual activity, although track circuits and signals used primarily for train protection

do permit some automation of route interlocking

and dispatching—usually in the form of semiautomatic devices (i. e., manually activated but

automatically operating).

All transit systems in the United States have a t

least this level of automation. The most notable example of an entire system with enforced wayside

signaling is the New York City Transit Authority .

Portions of the Chicago, Boston, and Clevelan d

systems and all of the Philadelphia (SEPTA) system

also employ this form of automatic train protection.

Carborne Train Protection

Cab signaling, using coded track circuits and

automatic carborne stopping and speed limit enforcement, represents the same level of ATP as

wayside signals with trip stops. To this extent, this

level of automation is equivalent to the preceding.

Generally, however, cab signaling is considered a

higher level of automation since it also provides

some automatic aids to train operation—principally

automatic and continuous display of speed information to assist the operator in running the train and

stopping at stations. Other aspects of train operation

are still essentially manual. Cab signaling does not

necessarily lead to any increase in the automation

of supervisory function nor is it accompanied by

any change in the communications systems.

This level and form of automation is generalIy

regarded as the minimum for a new transit system,

and most of the older transit systems either have

converted or plan to convert to cab-signaled ATP.

Automatic Train Operation

The major advantage of cab signaling over

wayside signaling is that bringing the speed command on board the train also permits evolution to

automatic train operation. All of the information

needed to operate the train automatically is either

inherent in the cab signal system or readily available through modular additions. At this level, the

human is removed from the speed control, station

stopping, door control, or starting loops--or any

combination of them. The human no longer functions as an operator but as an overseer of carborne

control systems.

Along with ATO, there is often (but not

necessarily) an increase in the level of automation

of train supervisory functions. ATS functions that

are sometimes considered operationally desirable to

implement at the time ATO is installed include

automatic dispatching, route assignment, and performance level modification.

The two newest transit systems in this country—

Bay Area Rapid Transit and the Port Authority

Transit Corporation —both have ATO. The new

systems under development in Washington, Atlanta, and Baltimore will also have it.

41
Automatic Train Supervision

Train supervision functions (except for dispatching and route control) are among the last to be automated. To be effective and operationally practical,

ATS usually can be introduced only when there is a

high level of automation in the areas of ATP and

ATO.

23 Automatic train supervision also requires a

rather complex and sophisticated communication

network, not only for voice messages but also for

the interchange of large quantities of data among

automatic system elements on a real-time basis.

The distinguishing feature of ATS, however, is the

use of a central computer (or computers) to process

and handle data, make decisions, and formulate instructions.

The Bay Area Rapid Transit system was the first

rail rapid transit system to make extensive use of

ATS. The new Washington, Atlanta, and Baltimore

systems will also have highly automated train

supervision based on computer control. While there

are some differences among them in the type and

amount of control vested in ATS computers, these

four stand apart from all other transit systems in

this country in the extent to which automation

technology is applied to train supervision.

Unmanned Operation

At all the levels of automation described previously, there is at least one operator on board each

train and some supervisory personnel in central

control. While these people are not part of the normal control loop, they do exercise important functions as overseers of automatic equipment and

back-ups in case of failure or emergency; A more

advanced form of automation is one where the

trains are unmanned, with all ATP and ATO functions performed by automatic devices. The few remaining human operators in the system are at

central control, but even these personnel may be

23Even with ATP and ATO, ATS is not truly necessary until

the demands imposed by the complexity of the route structure

and the required level of service outstrip the capacity for effective real-time supervision by manual methods. ATS may also

become necessary when the load in peak periods approaches 100

percent of system capacity.

reduced in number as more supervisory tasks are

allocated to machines.

No rail rapid transit system in the United States,

or anywhere in the world, is now operating at this

level of automation. The technology to do this,

however, is available; and it has been applied in

various people-mover systems, such as the Morgantown Personnel Rapid Transit (PRT) and several

airport transportation systems. A notable example

of an unmanned airport transit system is

AIRTRANS at the Dallas-Fort Worth Airport,

where small unmanned transit vehicles circulate on

fixed guideways over a complex of interconnecting

routes. The entire system is operated and supervised from a central location by a few persons aided

by a train control computer,

Full Automation

Complete removal of man from control of transit

system operation-even removing him from the

central control point—is probably not technically

feasible or desirable, For safety and continuity of

operation, it will always be necessary to have someone to monitor the system and intervene to restore

operations or assist passengers in an emergency.

The number of such supervisors would be only a

handful, however, and it is doubtful that they could

ever conduct normal operations manually as a backup to automatic systems.

Such a “fully automatic” transit would require

an extremely sophisticated and costly ATC system,

which would include ATP, ATO, and ATS for normal modes of operation and—most important—

automatic back-ups of these mechanisms for contingencies and emergency states, The communication network would also have to be highly sophisticated, providing not only voluminous real-time interchange among automatic components but also

extensive two-way voice links between passengers

and the supervisory cadre. Another requirement of

such a system would be automatic operation,

switching, and assembly of trains in yards. The

technology for automatic yard operation is available

today in rudimentary form in automated freight

classification yards, but it would need to be refined

extensively before application to a rail rapid transit

system,

42
Chapter 4

TRANSIT SYSTEM DESCRIPTIONS
There are eight operating rail rapid transit

systems in the United States and three more in the

process of planning and construction. Rail rapid

. transit systems are also under consideration in other

cities, but none has yet reached the point where

there is a definite commitment to build a rail rapid

transit system in preference to some other mode of

urban mass transit. Visits were made to these .

operating transit properties and planning agencies

during the course of this study. A list of the

organizations and individuals interviewed is presented in appendix F.

Five operating rail rapid transit systems were

selected for detailed examination. They represent a

wide range of characteristics and forms of train control technology. They vary from old to new, simple

to complex, and essentially manual to highly automated. This chapter provides a brief description of

the five operating systems and the three currently

under development.

BAY AREA RAPID TRANSIT (BART)

System Characteristics

BART is the newest rail rapid transit system in

the United States, and the most highly automated, It

also serves the largest geographical area of any

operating rail rapid transit system in the country.

As shown in the vignette map above, the BART

routes form an X-shaped pattern, whose dimensions are roughly 26 miles East-West and 30 miles

North-South.

From the route map it is evident that BART

serves two major purposes: to connect the East Bay

suburban communities with the Oaklan d

metropolis and to link all of these with San Francisco by means of the Transbay Tube under San

Francisco Bay. The Oakland “Wye,” a junction and

switching complex at the eastern end of the

FIGURE 24.—BART Route Map

45
TABLE 2.—BART System Facts

STATIONS

VEHICLES

ROUTE MILES Surface

Elevated

Subway

Number

Avg. Spacing (mi.)

Number

Weight (tons)

Length (ft.)

Capacity (psgrs.)1

Av. Age (yrs.)

CAR MILES (mill./yr.)

25

23

23

7 1

34

2.1

450

28.5–29.5

70–75

144

2

21.6

TRAIN LENGTH (cars) Max. 10 “

Min. 2

SPEED (mph) Max, 80

Av. 40

SCHEDULED MINIMUM HEADWAY (min.)

2

6

MANNING No. in Train Crew 1

()& M Employees/Car3 42 . 6

PASSENGERS Annual (mill.) 28,8

Av. Weekday (thou.) 125

TRAIN DEPARTURES PER DAY (each way) 280

MAIN LINE TRAIN CONTROL

Train Protection Automatic train separation and overspeed protection with advisory cab) signals, automatic rolling, and interlocking control.

Train Operation Automatic speed regulation, station stopping, and door operation

Train Supervision Centralized computer control with centralized manual control and local manual control available as back-up

modes

(1974/75 Data)

I Fll] I (;omplf:mf.nt of sf:tltf:(~ p~lssengf;rs p]lls Stan(]f;(?s in r~asonabl~ (;onfort; crtlsh ]oad is somewhat greater.

~Will he retll~ceci to 2 miniltes when system is flllly operational.

O&M (operations an{l ma intcnam:e) employees inclu[ie O&M sllperv isors, blit not station, a(imin istrative, engineering, planning

anti ma nag f’merf t pf~ rsonnel.

~~;stimat(~(j stat)lf? year staffing.

Transbay Tube, is the engineering feature that

makes it possible to provide through service, without changing trains, between any of the East Bay

lines and San Francisco.

The BART system consists of 71 miles of doubletrack routes. ” Approximately one-third of the

system is underground, one-third on elevated structure, and one-third on fenced surface right-of-way

with no grade crossings.

BART has a total of 34 stations (14 underground,

13 elevated, 7 surface), with an average spacing of

slightly over 2 miles.

The BART fleet presently consists of 450 cars,

which are of two types: A-cars, containing the

25 The San Francisco Muni line, a light rail system, runs

parallel to the BART line on 4 miles of underground track

beneath Market Street in San Francisco. While the two share

stations, the Muni system is not part of BART and is operated by

a separate transit agency.

operator’s cab and train control electronics, and BBears, which cannot operate independently in

revenue service. The non control end of A-cars and

both ends of B-cars are equipped with hostling

panels to permit individual car movement in the

yards and on storage tracks. The basic train makeup (consist) for revenue service is an A-car at either

end and up to eight B-cars between. Ten-car trains

are run during peak periods, Four- to six-car consists are operated in the base period.

The maximum operating speed of trains is 80

mph. The average line speed (including station

stops) is about 42 mph, At present, trains operate on

6-minute headways through the Transbay Tube and

on the San Francisco portion of the system. Headways are 12 minutes on the Concord and Fremont

feeder routes and on the through route from Richmond to Fremont. When BART reaches its full level

of service, headways will be reduced to 2 minutes in

San Francisco and 6 minutes elsewhere during peak

periods,

46
In fiscal 1974–75, BART

28,8 million passengers, fo r

carried an estimated

a total of nearly 447

million passenger-miles, Thus, the average length

of a passenger trip was 15.5 miles, and the average

duration 22 minutes. The average fare per ride was

approximately 60¢.

ATC Features

Train control in the BART system is highly automated and accomplishes three major functions: (1)

overspeed protection, assurance of safe separation

between trains, and route interlocking control, (2)

train operation, including station stops and door

operation, (3) train supervision, including dispatching, schedule maintenance and adjustment. There is

one operator on board the train, regardless of its

length. The normal responsibilities of the operator

are limited to surveillance of the track, monitoring

of the train condition, and making passenger announcements. The operator can override certain

automatic train operation functions, such as door

closure, and can adjust some of the parameters of

automatic operation, but the operator does not normally intervene in train protection and operation

processes.

The automated equipment which carries out

train control functions is partly on board the train,

partly at the wayside and in stations, and partly in a

central computer complex. Generally speaking,

train protection and operation functions are accomplished by wayside, station and carborne equipment. Dispatching and schedule maintenance and

adjustment are functions of the central computer,

wayside equipment, and carborne equipment.

The role of the human operator in BART, either

on the train or in central control, is intended to be

largely supervisory in nature. The operator can also

exercise certain override and back-up functions in

the event of equipment failure or unusual conditions not provided for in the computer programs,

Thus, the train operator can always apply emergency braking, keep the train in the station, prevent the

doors from closing, or modify the train performance

mode to a more restricted level. The dispatcher at

central control can manually set and cancel routes,

hold trains at stations, order station run-throughs,

adjust schedules, insert train identification in the

computer schedule, and modify train performance—although all of these train supervision functions are normally handled by the central computer.

Problems and Issues

The BART system has been the subject of intense controversy from the very beginning, Long

before the first line opened for service in 1972, critics alleged that the system was too costly and too

complex, partly because of unnecessary sophistication and technological innovation in the train control system design. This complexity and reliance on

unproven technology, critics contend, has also

resulted in a system of lower inherent reliability

and serviceability that costs more to operate and

FIGURE 25.—BART Train in Underground Station

47
FIGURE 26.—Interior of BART Car

gives poorer service than a system employing conventional technology. It is further contended that

the ATC system is basically unsafe for two reasons.

First, there are automated elements that could fail

and compromise the safety of train operation. Second, the human operator has been designed out of

the system to the point where he has no effective

means of intervention in such circumstances, except to bring the train to an emergency stop and

thus degrade the performance (and perhaps the

safety) of the system as a whole.

The defenders of BART rebut these charges by

pointing out that the complexity is a necessary consequence of the high level of performance and

sophistication required in the system engineering

specifications. The design, they contend, was purposely innovative because it was necessary to break

new ground in order to build a viable transportation

system for a public that has had a long-standing

preference for the automobile. The safety of the

system is defended in two ways: on theoretical

grounds, it is asserted that BART has all the failsafe provisions of the conventional system, but accomplished in different ways that are not adequately appreciated by engineers of traditional train

control equipment. On practical grounds, it is

pointed out that the BART safety record is comparable to other transit systems, but operating

difficulties and accidents in BART receive much

greater attention because of the public controversy

surrounding the system.

Fuel was added to the fire less than a month after

the inauguration of service when a train ran off the

end of the track at the Fremont Station. There were

no fatalities and only minor injuries, but the safety

of the ATC system was opened to serious question.

Investigations of BART were undertaken by the

California Senate, the California Legislative

Analyst, the California Public Utilities Commission,

and the National Transportation Safety Board. The

cause of the accident was traced to a faulty crystal

oscillator in the carborne electronics which, by

operating at the wrong frequency, generated too

high a speed command. This design defect has since

been remedied by providing a redundant speed control circuit; but the investigations exposed other

fundamental problems, especially in the train detection system.

As a result, the California Public Utilities Commission has issued a series of rulings which will

result in additional tests and demonstrations before

BART can be placed in full operation. The major

area under scrutiny is the train detection system.

Rail-to-rail shunting through the train axle and

wheels, which decreases the signal in the track circuits and thereby indicates the presence of a train,

does not always occur to a sufficient degree in the

BART system. Also, there are other factors that disturb the transmission of track circuit signals and

sometimes cause the train detection system to give

a false indication of track occupancy. To compensate for these faults and to assure positive detection

48
FIGURE 27.—BART Train Passing Through the Transbay Tube

of trains at all times, a logical back-up system has

been installed. This involves the use of special

minicomputers at the stations to monitor the outputs of the primary track circuit detection system

and to clear trains for movement only if certain

logical conditions and criteria are met, These design

modifications are completed and tested but have

not yet been approved by the California PUC.

Therefore, the BART system has not yet attained

full operational status.

As BART has made the transition from design

and development to operations, other problems

have emerged. Reliability of equipment, particularly the cars, has been disturbingly low. Most

of the time as much as half of the car fleet is out of

service for repairs. Of the trains dispatched in the

morning, only about two-thirds complete the day

without a breakdown, This has been compounded

by problems of maintenance. Electronic components take somewhat longer to troubleshoot and

repair and other types of components, and a higher

level of training and skill is required in maintenance technicians. The carborne equipment is not

easily accessible in some cases, requiring more time

to get at the failed component or making it necessary to remove one item in order to reach another.

Spare parts are in short supply. Often the troubles

reported in service are intermittent and cannot be

confirmed or located when the cars reach the yard

or shop. The apparently healthy car is then restored

to service, only to fail again in a short time.

49
CHICAGO TRANSIT AUTHORITY (CTA)

System Characteristics

CTA is an integrated rail-bus transit system serving the city of Chicago and 34 suburbs in Cook

County. It is the second largest public transit system

in North America,26 operating a fleet of 2,500 buses

26The largest combined bus-rail system in North America is

the New York City Transit Authority. Considering only the rail

portion of the system, Chicago is also second only to NYCTA.

FIGURE 28.-CTA Route Map
Table 3.—CTA System Facts

ROUTE MILES Surface

Elevated

subway

STATIONS

VEHICLES

Number

Avg. Spacing (mi.)

Number

Weight (tons)

Length (ft.)

Capacity (psgrs.)1

Av. Age (yrs.)

CAR MILES (mill./yr.)

41

39

10

9 0

142

0.6

1.094

20–2 4

4 8

75

16

48.9

TRAIN LENGTH (cars) Max.

Min.

SPEED (mph) Max.

Av.

SCHEDULED MINIMUM HEADWAY (min.)

MANNING No. in Train Crew

O&M Employees/Car4

PASSENGERS Annual (mill.)

Av. Weekday (thou.)

TRAIN DEPARTURES PER DAY (each way)

8

1

2

1

/ 4

3

2

2.2

129.2

512

1,450

MAIN LINE TRAIN CONTROL

Train Protection Mixture of cab signals with automatic overspeed protection and wayside signals with trip stops5

Train Operation Manual operation

Train Supervision Mixture of centralized and local manual control

(1974 Data)

1 Full (complement of seated passengers pllis standees in reasonable comfort; crush load is somewhat greater.

~Newer cars are capable of 70 mph hut are governed to 55 mph.

One-man train crew on the SkoA ie Swift Line and the Evanston Shuttle during off-peak hours,

-r( )& M (()[)(,l.,l t Ions i] nl i m,, in I l~n(l n(:(~) [, mplo;,flf,+ i n(,l II( It> ()& M sllpf’rt’isnrs.I)llt not station. aI imin istra t i t’t’. [~n~ I no”rl” [1x, pi, in o’i n~

,In[{ milnilp,(’ml’nt personn(’t

‘)14’ h(’n (; i I rn ‘n t I ;r pr{)g r,l mcl i I nst a I l{] t I on> ,] r(’ (;ompl (’ to i n t h(’ sp r i n~ of 1976.

and 1,100 rail rapid transit vehicles. The rail portion

of the system consists of seven lines, of which all

but the Skokie Swift line pass through or circulate

within the downtown area. Two of the six downtown lines are in subways, entering and leaving by

tunnels under the Chicago River. The remaining

four are elevated lines that run on common tracks

on the Loop El. Access to the loop area is over two

bascule bridges, which are raised several times

daily during the navigation season to permit the

passage of ships. Thus, the throughput for over half

of the CTA system is determined by the volume of

traffic that can be accommodated on the tracks of

the 75-year-old Loop El structure and its associated

movable bridges.

CTA operates a total of 90 miles of routes (191.6

track-miles). Almost half (41 miles) are at grade.

Elevated routes comprise 39 miles, and subway

routes 10 miles, There are 142 stations (41 surface,

85 elevated, 16 subway), with an average spacing of

about two-thirds of a mile,

CTA maintains a fleet of 1,094 cars, consisting of

five types, All but four cars used on the Skokie

Swift Line are 48 feet in length and of conventional

steel construction. Their weight is between 40,500

and 47,000 pounds, depending on the type, Th e

2000-, 2200-, and 6000-series cars are operated a s

“married pairs, ” consisting of a permanentl y

coupled A-car and B-car. The pairs can be operated

from either end as two-car trains, and they can be

joined with other pairs to form trains of up to eight

cars in length. The fourth type of car (the 1–5 0

series) is designed to operate as a single and has an

operator’s cab at either end. The 1–50 series cars

can also be joined to form trains. The fifth type is a

three-compartment, articulated car, of which there

are only four, all assigned to the Skokie Swift line,

These cars are about 89 feet long and weigh 93,000

51

72-6, x? () - 76 - j
pounds. The rolling stock is of varied age. The 6000-

series cars are almost 25 years old; the 2200-series

was acquired in 1969–70, The average age of the

cars is about 16 years.

Trains of one to eight cars are run in peak periods

on headways that range from 2 to 6 minutes for individual lines. The maximum speed of trains is 50 to

58 mph, depending on the type of equipment.

Average speed is between 20 and 30 mph. Two factors combine to keep the average speed relatively

low--close station spacing (0.64 mile, average) and

the nature of the right-of-way. Four lines operate,

for at least some portion of their route, on the elevated tracks of the Loop El. This structure, which

dates from the turn of the century, has extremely

sharp turns (90-ft. radius) that must be negotiated at

low speed. The Loop El is also a congested part of

the system; the four lines using it operate on a composite headway of about 1 minute at peak periods.

Including originating passengers and transfers

from bus routes, the CTA rail rapid transit system

carried a total of 126.8 million passengers in 1973

and an estimated 129.2 million in 1974. The average

length of a passenger trip is about 7.9 miles or 16

minutes (compared to 15.5 miles and 22 minutes in

BART). The average passenger fare is roughly 28

cents per ride.

ATC Features

The train control system in CTA has undergone

extensive change since the property was acquired

from the Chicago Rapid Transit Company in 1947.

At that time, trains were operated almost completely under manual control by the motorman

using visual observation and compliance with rules

to regulate speed, station stopping, and following

distance behind other trains. Color-light wayside

block signals existed over about 10 percent of the

trackage, mainly on curves and in the subways.

Wayside signals with trip stops for train protection

were installed only in the State Street subway

(about 10 track-miles). In all other areas, the motorman had no display of information in the cab or at

the wayside, except signposts advising of speed

limits on curves or downgrades. The train crew consisted of a motorman, a conductor, and sufficient

guards to man the doors, collect fares, and provide

passenger information. Only a few cars had door

controls sufficiently sophisticated to permit a trainman to operate the door at the far end of a car, so

that trains required a crew of two to seven men, depending on length and type of cars,

Between 1947 and 1960, CTA installed wayside

signals with trip stops in the remaining portions of

the subway lines and some of their extensions. The

elevated lines in the Loop, however, remained unsignaled; and train control was still essentially a

manual operation accomplished by the motorman,

with the assistance of towermen at interlocking.

In 1965, CTA began to install cab signaling, first

on the Lake portion of what is now the West-South

line and then the new Dan Ryan and Kennedy extensions, which were opened for service in 1969 and

1970, respectively. By 1974 the conversion to cab

signaling was completed on the West-Northwest

and North-South lines, The remaining lines—

Skokie Swift, Ravenswood, and Evanston (including the Loop El)--are scheduled for conversion in

early 1976, At the completion of the project, about

75 percent of the system will be cab signaled, and

the remainder will be protected by stop-enforcing

wayside signals.

With the installation of cab signaling, CTA has

gone from the almost completely manual system to

a semiautomated form of operation, Train separation and overspeed protection are automatic. Train

operation is manual, but with machine-aiding of the

motorman by means of the cab display unit. Supervision of trains (schedule maintenance, traffic

monitoring, and routing) are essentially manual

operations accomplished by dispatchers in central

control or by towermen at interlocking, with some

remote control and automatic interlocking.

Except for the Skokie Swift and off-peak

Evanston shuttle trains, which are manned by a

single operator, all CTA trains have a two-man

crew, The motorman operates the train from the

cab and controls all movement. The conductor, stationed at least one car length to the rear of the

motorman, controls the opening and closing of

doors at stations and makes passenger information

announcements. At certain stations, during offpeak hours when collection booths are closed, the

conductor also receives fares.

Thus, the human operator (especially the motorman) plays an indispensable role in the CTA

system. Except for train protection and speed limit

enforcement performed by wayside or cab signaling, the motorman controls the operation of the

train, The skill with which propulsion and braking

52
FIGURE 30.—Interior View of CTA Train

(Note conductor at rear of car.)

are handled determine the smoothness of the ride,

the precision of station stops, the adherence to

schedule, and the response to incursions on the

right-of-way.

Problems and Issues

The basic problems facing CTA are typical of the

mature rail rapid transit systems in this country.

The right-of-way, structures, rolling stock, and signals are in need of modernization or replacement,

There is also a need to expand the service in

response to the growth and extension of the

metropolitan area, Paradoxically, however, the

patronage of CTA has been declining in recent

years. The ridership for the combined bus and rail

system in 1973 was off about 24 percent (about 188

million passengers) from that of 1966, a drop of

roughly 3 percent per year.27 The figures for 1974

show an upturn (30 million), which may indicate a

switch by the public away from the automobile as a

result of a growing concern with energy usage and

conservation of resources. While the revenues from

transit operations have generally declined, the costs

have risen. This has created mounting operating

deficits, which amounted to $22.1 million for CTA

in 1973, despite nearly $37 million in emergency

grants from State, county, and municipal funds.

CTA thus finds itself in a position where it must expand and improve the system to meet public needs,

but with a shortage of farebox resources to do so.

The conversion to cab signaling was motivated

by more than a desire to modernize the system and

thereby attract more patrons. There was also a fundamental concern with the safety of a system which

offered only a very limited level of signal protection. Operation of trains on rather close headways

by means of visual reference and procedural separation created safety problems. CTA has had an intenZTInc]udes originating and transfer passengers.

53
sive safety training and awareness program since

1954. While this has resulted in a steady and heartening decline of 40 percent in. the traffic and

passenger accident rate over 20 years, the problems

of collisions and derailments persisted, Between

1964 and 1974 there were 35 collisions between

trains which resulted in injuries and 48 derailments

(only seven of which produced passenger injuries).

This amounted to eight mishaps per year, or one

about every 6 weeks.

Human operator error was determined to be a

causal factor in every collision, Typically, the

motorman either failed to observe a train ahead, did

not maintain the proper following distance, or misjudged the stopping distance. In derailments, about

half of the accidents were also caused by human error or improper operation (most commonly switching mishaps or overspeed on curves), The installation of a modern cab signaling system was seen by

CTA as the way to prevent these types of accidents.

On theoretical grounds, this would appear to be a

very effective measure, but it is still too early to

draw any firm conclusions from CTA operating experience since the conversion to cab signals.

The cab signaling program has brought with it

certain new operational problems. The reliability of

the new equipment, particularly during the transitional period, has been rather low. CTA engineers

have found that the installation and debuggin g

process takes several months: but, when completed,

cab signals do not pose an inordinate maintenance

problem from the point of view of equipment

reliability,

Another aspect of cab signal conversion which

represents a problem is in the area of human factors. Installation, checkout, and servicing of the

equipment calls for new skills in maintenance personnel. CTA has encountered a shortage of

qualified signal maintainers and has had to undertake an extensive training (and retraining) program

for shop personnel, Train operators, too, have had

to be instructed in the use of the cab equipment, and

there is some anecdotal evidence that the process of

learning to run the train in this new mode of operation is taking longer than expected.

The long-range program for CTA involves two

major undertakings in the area of train control. First

is the replacement of the antiquated Loop El with a

modern subway system. A part of this project will

be installation of a cab signaling system for all underground lines in the downtown area. The second

project will involve the incorporation of more

automation in train supervisory and dispatching

functions. This includes installation of a modern

model board in central control and computer aid for

schedule maintenance and adjustment.

FIGURE 31.—Lake-Dan Ryan Train Entering the Loop

54
MASSACHUSETTS BAY TRANSPORTATION AUTHORITY (MBTA)

A BROADWAY

FIGURE 32.—MBTA Route Map

System Characteristics

MBTA, serving the metropolitan area of Boston,

is one of the oldest rail rapid transit systems in the

United States. Service on the first line, now a part of

the Orange Line, began in 1901. MBTA is an integrated rail and bus system, the rail portion consisting of three rapid transit lines (designated Red,

Orange, and Blue) and a trolley (light rail) line

known as the Green Line (shown as a dashed line in

the route map). Only the three rail rapid transit

lines are considered in this report.

The MBTA lines comprise 30 route miles, of

which a little over half (16 miles) are on protected

surface right-of-way. Of the remainder, 10 miles of

55
TABLE 4.—MBTA System Facts

ROUTE MILES Surface

Elevated

subway

STATIONS Number

Avg. Spacing (mi.)

VEHICLES Number

Weight (tons)

Length (ft. )

Capacity (psgrs.) 1

Av. Age (yrs.)

CAR MILES (mill. /yr.)

16

4

10

3 0

43

0.7

354

22–3 5

48–7 0

125–25 0

18

10.3

TRAIN LENGTH (cars) Max.

Min.

SPEED (mph) Max.

Av.

SCHEDULED MINIMUM HEADWAY (min.)

MANNING No. in Train Crew

O&M Employees/Cars

PASSENGERS Annual (mill.)

Av. Weekday (thou.)

TRAIN DEPARTURES PER DAY (each way)

4

2

2

50

3

20

2

1

/ 2

4

2– 3

3.0

8 5

283

590

MAIN LINE TRAIN CONTROL

Train Protection Mixture of cab signals with automatic overspeed protection and wayside signals with trip stops

Train Operation Mixture of manual operation and automatic speed regulation

Train Supervision Mixture of centralized and local manual control

(1974 Data)

IFIIII (complement of seated passenge~ plUS stan(]ees in reasonah]e comfort; crllsh load is somewhat greater.

~NwfJr (:,lrs (In th(’ R[’~1 I.inv i)r(’ (:~]pill)lo {If 70 mph I)llt ilr(’ gov~’rn[’l i to 50 mph

IAv(’rilg(’ sp~J{II 1 of new (:i] rs on th[’ RPI I 1. i n[~ is iIl)OII t 30 mph .

.lTra in crew ~onslsts of motorman and one train gllar{] (condllctor) for each pair of (;ars.

~O& M (operat ions an(] main tenan~e) (~rnplov(les incl I I(]() (l& M supervisors, but not station, a{lministrative, engine~ring, planning

and management personnel.

route are in subways, and 4 are on elevated structure. All trackage in the central business area of

Boston is underground. MBTA has 43 stations (20

subway, 17 surface, 6 elevated), with an average

spacing of about 0.7 mile.

A distinguishing feature of the system is the age

and diversity of the rolling stock. Five different

types of cars are in operation. The cars on the Blue

Linte are oldest. consisting of 40 cars dating from

1923 and 48 from 1953. They weight 44,000 and

46,000 pounds, respectively, and are 48 and 49 feet

in length. Orange Line cars are 17 years old, weigh

58,000 pounds, and have an overall length of 55 feet.

The Red Line has the newest equipment--90 socalled “Bluebirds” acquired in 1963 and 76 “Silverbirds” acquired in 1970. Both types are 70 feet long.

The Silverbirds weigh 64,000 pounds, and the older

Bluebirds 70,000 pounds. All cars are operated as

married pairs in consists of two or four. Some of the

Red Line Silverbirds are capable of single-car operation, but they are not so used at the prsent time.

Because there is no connecting trackage and

common yards and because of varying platform

heights and car widths, cars cannot be exchanged

between lines, In effect, MBTA operates as a

system with three separate parts, linked only by

passenger transfer stations where routes intersect.

One consequence of this arrangement is a fleet with

a relatively high proportion of reserve cars—about

150 in a fleet of 354, or 43 percent.

Another distinguishing feature of MBTA is the

composition of the train crew which, in addition to

the motorman, is made up of one train guard (conductor) for each pair of cars. The rush hour consist

of four cars thus requires a crew of three. The train

56
guards are stationed either on a platform between

each pair of cars or inside at the rear of each pair of

cars and are responsible for door operation. The

origin of this manning formula is obscure, but it is

reputed to be a safety measure for emergencies or

breakdowns, where the train guards could help

evacuate passengers. It may also be a carryover

from the time when sophisticated door operating

equipment was not available, and a pair of cars was

all that one person could handle. Whatever the

origin, this manning formula is now a part of the

contract with the labor union and has not been

changed even though all MBTA cars are equipped

with doors that can be operated by one man regardless of train length.

FIGURE 34.—Red Line Train Arriving at Wollaston Station

Depending on the type of car, the maximum

design train speed is between 30–70 mph—the

newer equipment having the greater top speed,

However, because of close station spacing and

Massachusetts Department of Public Utilities safety

rules, train speed is governed to 30 mph on the Blue

Line, 35 mph on the Orange Line, and 50 mph on the

Red Line. Average line speed (including station

stops) is between 20 and 28 mph. Trains are operated on headways of 21/2 to 31/2 minutes in peak

periods and 41/2 to 9 minutes in the base period.

In 1974, MBTA carried a total of 85 million

passengers. Average weekday patronage was approximately 283,000, including bus and light rail

transfer passengers. The typical passenger trip is

about 3.1 miles in length and consumes a little less

than 8 minutes.

ATC Features

MBTA has only a minimal level of train control

automation. Most of the system (all but the

Andrew-Quincy Center branch of the Red Line) has

wayside signals and trip stops for train in separation

and automatic interlocking contro1 but no other

ATC features. Since 1971, the Andrew-Quincy

Center (or South Shore) branch of the Red Line has

been equipped for cab signals. However, t h e

Massachusetts Department of Public Utilities has

not yet authorized cab signal operation because of

questions as to the safety of the installation, As an

interim measure. Red Line trains are run on a

“manual block” system with one-station separation

between trains. Under this procedure, a following

train may not leave a station until a radio message

has been received from a dispatcher that the leading

train has departed,

Train operation (speed regulation, station stops,

and door control) is manual, except for Silverbird

cars, which are equipped with automatic speed

regulation. There is some machine-aiding of the

motorman in running the train, in the form of slipslide control (for Silverbirds only).

Train supervision is essentially manual, except

for automatic train dispatching devices, Train

progress is monitored by personnel at central control by means of three separate train boards (one for

each line), activated by track circuits. Contact with

individual trains and with wayside and station personnel is maintained from central control by voice

radio. Except for a few locations equipped with

automatic interlocking to control train turnaround

at terminals, all route assignment functions are performed manually.

57
Problems and Issues

MBTA is an old system in the process of modernization and transition. Rolling stock on the Orange

and Blue Lines is approaching the end of its service

life and will be replaced with the help of a recently

received $70 million grant from UMTA. Track,

way, and structures in older parts of the system are

being refurbished, and extensions of the lines are

under construction or in the planning stage. 28 T h e

power generation and distribution system29 is antiquated and no longer adequate to meet demand. A

long-range program of replacement is underway.

Like other parts of MBTA, the signal and train

control system is undergoing modernization. Here,

the situation is much like that in CTA a few years

ago at the start of their cab signal conversion

program, There is wayside signal and trip stop protection on most lines and the beginnings of a conversion to cab signaling on two extensions (the Red

Line Quincy branch and the Orange Line Wollaston

extension). The remainder of the Red Line is

scheduled for conversion to cab signaling, and the

new cars for the Orange and Blue Lines will be

equipped with cab signal equipment to permit

eventual conversion of these lines too,

The Red Line cab signal installation has had

several problems, The Massachusetts Department

of Public Utilities has not yet certified the safety of

the installation, DPU concern centers in two areas:

the reliability of the equipment and the possibility

of incorrect speed commands. Pending DPU approval, the Red Line has been operating under a

manual block system (in effect, without cab signals)

since 1971,

The operational experience with cab signals has

been disappointing. In addition to problems of

ZBThe We]iington extension of the Orange Line opened for

service in September I!li’!i

z9MBTA, unlike other transit systems, still generates much of

its propulsion power (25 Hz a.c.). New lines and most stations,

however, run on 60 Hz a.c. power purchased from local utility

companies.

reliability, there have been maintenanc e

difficulties. Shop facilities have not been adequate. 30 Spare parts are in short supply. There has

been insufficient funding for maintenance work,

with the result that not enough repairmen can be

hired. Cab signal equipment tends to need maintenance more often and to require more maintenance

time than other kinds of transit equipment. MBTA

maintenance supervisors estimate that a major part

of the maintenance effort is devoted to repairing

breakdowns, with the result that preventive maintenance and overhaul must be somewhat slighted.

A complicating factor in the maintenance situation is the shortage of qualified maintenance personnel, Union rules permit transportation department employees (motormen and train guards) with

seniority to bid for openings in car shop jobs without regard for work skills and experience. The

limited funding available for maintenance does not

allow a complete formal training program for such

personnel, who must receive much of their training

on the job by informal methods. This has not

proven to be an effective way to develop the skills

needed for maintenance of sophisticated electronic

equipment.

The problems of MBTA are typical of a system in

transition to a new form of technology. Installation

and checkout of new equipment disrupts the

established pattern of operation and maintenance.

The new equipment must be integrated with the existing system. Debugging is a troublesome process.

Learning to make effective use of the equipment

takes time and places demands on the labor force to

adapt to new procedures and techniques. The entire

system must find a new equilibrium. MBTA, like

other older transit systems, is finding that the process of incorporating new technology is not always

smooth and trouble-free.

~OMBTA is currently building three modern rail transit maintenance facilities, the first two of which (for the Red Line and

the Orange Line extension) were dedicated in 1975,

58
I

Tower C, at one time the busiest

control and interlocking tower in

the MBTA system, now replaced

by a modern automated facility.

Remodeled

Arlington St.

Station.

Construction of the

new Community College

Station on the Orange

Line Extension.

(Overhead is Interstate

Highway I-93.)

FIGURE 35.—The Old and The New

59
NEW YORK CITY TRANSIT AUTHORITY (NYCTA)

System Characteristics half of the total rail rapid transit track-miles in the

country. On an average weekday NYCTA carries

NYCTA is the largest and most complex rail more passengers than the total population of

rapid transit system in the United States. NYCTA Chicago. Of the roughly 2 billion rail rapid transit

has more route-miles than BART, CTA, MBTA, passengers in the United States each year, half are

and PATCO combined; and it has approximately NYCTA patrons. NYCTA has almost 29,500

60
TABLE 5.—NYCTA System Facts

ROUTE MILES Surface

Elevated

Subway

STATIONS

VEHICLES

Number

Avg. Spacing (mi.)

Number

Weight (tons)

Length (ft.)

Capacity (psgrs.)2

Av. Age (yrs.)

CAR MILES (mil1./yr.)

23

72

137

2 3 2

463

0.5

16,681

34–43

51–75

136–204

17

320.6

TRAIN LENGTH (cars) Max.

Min.

SPEED (mph) Max.

Av.

SCHEDULED MINIMUM HEADWAY (min.)

MANNING No. in Train Crew

O&M Employees/Car4

PASSENGERS Annual (mill.)

Av. Weekday (thou.)

TRAIN DEPARTURES PER DAY (each way)

11

2

50 3

20

11/2

2

3.1

1,0!36

3,740

8,000

MAIN LINE TRAIN CONTROL

Train Protection Wayside signals with trip stops

Train Operation Manual operations

Train Supervision Mixture of centralized and local manual control

I Does not incl(l(]e

zFu1l complement

(1974/75 Data)

754 new R–46 cars now being delivered.

of seated passengers plus standees in reasonable comfort; crush load is somewhat greater.

~Loca 1 service; express service averages about 28 mph.

40&M (operations and rnaintenanc~) employees include O&M supervisors, but not station, administrative, engineering. planning

and management personnel,

‘) The npwer R —44 and R —46 series cars are eq II ipped for automatic speed regulation and programed station stopping in anticipation

of use on planned or new lines and extensions.

employees, 31 not counting the 5,100 transit police

who constitute the eighth largest police force in the

United States. The annual operating budget for

NYCTA in 1974–75 ($951 million) is equivalent to

10 percent of that of the entire U.S. Department of

Transportation for FY 1975 and only slightly less

than the DOT funds budgeted for all of mass transit

and railroads in the same period ($965 million).

The complexity and density of the NYCTA network can be appreciated by comparing the

schematic route map above with those of other

systems. The geographic area served by NYCTA is

roughly 15 x 20 miles, which is only slightly larger

than the CTA area but less than half that covered

31 NYCTA also employs about 8,6oo in bus operations,

ing a total workforce of 38,066 (43,167 including police).

mak -

by BART. Within this area, however, NYCTA operates 29 routes (26 regular, 3 shuttle) as compared to

7 in CTA and 4 in BART. Expressed as the ratio of

route-miles to area served, NYCTA has 0.77 miles

of transit route per square mile; CTA and MBTA

have 0.36; and BART has 0.09. In other words, the

NYCTA network is about twice as dense as CTA

and MBTA and eight times denser than BART.

Density alone, however, does not account for the

whole difference between NYCTA and other

systems since the complexity of the system increases exponentially as a function of the number

of lines on common tracks. In NYCTA

the lines in Manhattan and Brooklyn

with at least one and as many as three

virtually all

share track

other lines.

The NYCTA system is made up of two operating

divisions—Division A (the former IRT lines) and

61
Division B (the former BMT and IND lines)32—

comprising 232 miles of route. Over half of the

route-miles are in subways (127 miles). There are

72 miles of elevated route and 23 miles on protected

surface right-of-way. NYCTA has 463 stations (265

subway, 160 elevated, 38 surface), with an average

spacing of 0.5 mile.33

The fleet consists of 28 different types of cars,

ranging in age from R–1 series (1930) to the R–46

series acquired in 1975. The newest equipment (300

R–44 cars and 754 R–46 cars) is 75 feet in length

and weighs 80,000 and 86,000 pounds, respectively.

Older equipment (the R–38 to R–42 series) is 60

feet long and weighs 68,000 to 74,000 pounds. There

are also about 1,600 51-foot cars acquired in

1946–58. The total fleet now numbers 6,681 and

will grow somewhat when- delivery of the R–46

series is completed and older equipment is phased

out.

Platform length and operating practice govern

the size of the peak period consist, which is eight

75-feet cars, ten 60-feet cars, or eleven 51-feet cars.

The maximum operating speed of trains is 50 mph.

The average line speed (including station stops) is

18.5 mph for local service and about 28 mph for express trains. Minimum peak period headway on an

individual line is scheduled at 2 minutes, but the

signal system is designed for 90-second headways.

The composite headway at some interlocking may

be as short as 50–60 seconds.

In fiscal year 1973–74, NYCTA carried 1,096

million passengers for a total of 5,480 million

passenger-miles. Average weekday ridership was

about 3.7 million. Only slightly more than half of

these riders (53 percent) were carried in the rush

hours. 34 This suggests a unique pattern of ridership

for NYCTA in comparison with other U.S. systems,

New Yorkers tend to use the NYCTA throughout

the day (not just for trips to and from work) and for

short trips. The average trip length is estimated to

be slightly over 5 miles and to take about 17

minutes. 35

szIRT—Interborough Rapid Transit, BMT—Brooklyn

Manhattan Transit, IND—Independent.

ssThis is sWcing between local stations. The spacing of express stations is greater, on the order of 1 mile,

sqIn other systems, peak-period ridership customarily accounts for about two-thirds of the daily traffic.

sSTrip len@ is also partially a function of the compactness

of the boroughs of Manhattan and Brooklyn where most trips occur.

ATC Features

NYCTA has a relatively low level of automation.

Train protection (train separation and interlocking

control) is accomplished automatically by wayside

signals with trip stops to prevent block violation.

Some portions of the system (principally curves and

grades in the subways) also have time signals and

trip stops for overspeed protection, but elsewhere

this function is accomplished manually by the

motorman using operating rules and posted civil

speed limits.

Train operation is manual. The crew is two

(motorman and conductor), regardless of train

length. The train is under the control of the motorman who regulates speed by estimation. (There is

no speedometer in the cab except for the new R–44

and R–46 cars,) Station stopping and door control

are manual operations-the former by the motorman, the latter by the conductor.

Except for automatic train dispatching equipment, automatic train identity systems, and some

automatic interlocking, train supervision is

manual, Scheduling, route assignment (except at

automatic interlocking), and performanc e

monitoring are performed by supervisory personnel

at central control and by towerman at remote locations. Train supervision is somewhat more decentralized in NYCTA than in other systems, primarily because the size and complexity of the

system make central control by manual means impractical. ‘Automated train identification equipment

is used in some locations, but for most of the system

this function is performed by manual methods.

Computer-assisted maintenance scheduling and

record keeping is employed. Equipment for

automatic recorded passenger information

announcements is installed at some stations, primarily major transfer points.

Problems and Issues

NYCTA has embarked upon an ambitious

program of modernization and expansion, More

than 1,800 new cars have been delivered or are on

order. New lines to ease the congestion in heavily

traveled corridors are in the planning stage. These

new lines, notably the proposed Second Avenue

line, will have cab-signaled ATP and ATO. It is also

planned to upgrade train control on existing lines

over a 20-year period by converting to cab-signaled

ATP, Another part of this modernization program,

already in progress, is installation of a centralized

62
FIGURE 37.—IND F Train on Elevated Line in Brooklyn

R–16 BMT-IND (1953)

R–36 IRT (1962) R–44 BMT-IND (1970)

FIGURE 38.—Examples of NYCTA Transit Cars

63
communication center for train supervision at

NYCTA headquarters in Brooklyn. A new two-way

train radio and police communications system has

recently been completed.

Continuing, and worsening, deficits in transit

operations have recently been forced a cutback in

the program. Funds intended for system improvement have had to be siphoned off to meet operating

expenses. The financial crisis of New York City as a

whole has also had an impact on NYCTA, forcing

even further curtailments in the planned new transit lines and procurement of replacement equipment.

The new R–44 and R–46 series cars are

equipped with cab signal units; but since the associated track and wayside equipment has not yet been

installed, trains are run with cab signals deactivated, relying on wayside signal and trip stop protection. The maintenance and reliability problems

that have been encountered with the R–44 cars and

with the recently delivered R–46 cars are thus not

ATC problems, and there is no way of estimating

what influence the ATP and ATO equipment of

these cars may have on car availability.

The gravest maintenance problem for the

NYCTA has nothing to do with ATC as such, but

does influence the ability of the shop force to keep

train control equipment running. The NYCTA has

been stricken with an epidemic of vandalism. The

most obvious form is graffiti, which completely

covers the outside and inside of cars. Officials estimate that 95 percent of the cars are defaced on the

outside and 80 percent on the inside. There is also

extensive breakage of windows, safety equipment,

train radios, and motorman consoles. The vandalism even extends to yards and track equipment.

The Flushing line averages 40 broken windows a

day, and 70 or more trains are vandalized (and often

rendered unserviceable) on the BMT each week,

The funds and maintenance force that must be

committed to coping with the damage are of such

magnitude that other forms of corrective and preventive maintenance suffer.

64
PORT AUTHORITY TRANSIT CORPORATION (PATCO)

System Characteristics

PATCO, also known as the

Speed Line, consists of a single

FIGURE 40.—PATCO Route Map

Lindenwold Hiroute connecting

seven southern New Jersey suburban communities

with the city of Philadelphia, PATCO is a hybrid

system, resembling a commuter railroad in suburban New Jersey and a subway transit system in

downtown Camden and Philadelphia, Th e

Camden-Lindenwold segment of the line was

opened for operation in January 1969; through service to Philadelphia over the Benjamin Franklin

Bridge began a month later. The line is owned by a

New Jersey -Pennsylvania bi-State agency, the

Delaware River Port Authority (DRPA).

Like BART, PATCO was planned and built as an

alternative to another automobile bridge or tunnel

to link the growing suburbs and a central business

area separated by a body of water.36

accumulated in its 6-year history

PATCO has been successful in

patronage of the automobile driver.

The evidence

suggests that

winning the

Surveys have

shown that about 40 percent of PATCO patrons are

former motorists. It has also been established that

PATCO now carries about 30 percent of all daily

commuter trips between South Jersey and centercity Philadelphia. A side benefit is that PATCO has

served to reduce traffic congestion on parallel highway arteries. For instance, the average rush hour

speed on White Horse Pike (running alongside the

PATCO line) increased by 30 percent from 1960 to

sBUn]ike BART, however, PAT(20 did not involve building a

separate water crossing, PATCO trains run on right-of-way of

the former Camden-Philadelphia Bridge line on the Benjamin

Franklin Bridge.

65
TABLE 6.—PATCO System Facts

ROUTE MILES Surface

Elevated

Subway

STATIONS

VEHICLES

Number

Avg. Spacing (mi.)

Number

Weight (tons)

Length (ft.)

Capacity (psgrs.)1

Av. Age (yrs.)

CAR MILES (mill./yr.)

9

1

4

14

12

1.2

75

39

68

120

6

4.3

TRAIN LENGTH (cars) Max.

Min.

SPEED (mph) Max.

Av.

SCHEDULED MINIMUM HEADWAY (min.)

MANNING No, in Train Crew

O&M Employees/Car2

PASSENGERS Annual (mill.)

Av. Weekday (thou.)

TRAIN DEPARTURES PER DAY (each way)

6

1

75

4 0

2

1

2.7

11.2

4 0

182

MAIN LINE TRAIN CONTROL

Train Protection Cab signals with automatic train separation, overspeed protection, and interlocking control

Train Operation Automatic speed regulation and programed station stopping

Train Supervision Centralized manual control

(1974 Data)

I Fll]] ~omplement of seate(i pass~ng~rs plllS stan(~ees in reasonal)le (;omfort: crllsh load is somewhat greater.

zO&M (operations and maintenance) employees include O&M supervisors, hut not station, administrative. engineering, planning

and management personnel.

1970, primarily as a result of the start-up of rail

rapid transit service.

The PATCO line is approximately 14 miles long

(9 miles on surface right-of-way or in cuts, 1 mile on

elevated structure, and 4 miles of subways in

Camden and Philadelphia). There are 12 stations (6

elevated or surface and 6 subway), with an average

spacing of 1.2 miles.

The car fleet is made up of 75 vehicles—25 married pairs and 25 singles. The married pairs are

semipermanently coupled A-cars and B-cars, containing one set of train control equipment per pair,

and may be operated from either end. The singles

are double-ended cars, capable of independent

operation or of running in trains with other singles

or married pairs. The cars all weigh about 78,000

pounds and are 67.5 feet in length. Capacity, with

standees, is about 120 passengers in the A-cars or BBears and slightly less in the singles, because of the

two operator cabs. Six-car trains are run in peak

periods, two-car trains in base periods, and single

cars nights and Sundays.

The cars are designed to run at 75 mph, a speed

which is regularly attained on the suburban portions of the line. Maximum operating speed on the

bridge and in tunnels is considerably lower (15–40

mph) because of grades and curvature. The average

speed for an entire run, including station stops, is

about 38 mph. Trains operate on 2-minute headways in peak periods.

In 1974, PATCO carried approximately 11.2

million passengers-over 40,000 on an average

weekday, Total passenger-miles amounted to

slightly over 95 million, The average trip, therefore,

was 8.5 miles in length and took about 131 / 2

minutes. The average fare per passenger was 57

cents.

66
ATC Features

The PATCO train control system is a blend of

manual and automatic operation. The design

philosophy reflects two basic principles. First, the

design of the system made use of technology that, at

the time, represented the best of available, proven

equipment. Technological innovation (and risk) at

the component and subsystem level was held to a

minimum. The combination and integration of elements, however, resulted in a system of highly advanced character. Second, the human operator was

to be fully integrated into the system, such that he

could act as a back-up to automated equipment and

as the means of enhancing system performance in

response to unusual conditions.

All train protection (ATP) functions are automated, accomplished by a mixture of carborne,

wayside, and track equipment. Train operation

(ATO) is also automatic, with two important exceptions. The single on-board operator (who is the

equivalent of a motorman and a conductor) controls

door opening and closing. The operator also controls train departure by pushing a start button on the

cab console. Providing the doors are closed, this

manual action initiates an automatic sequence of

events in which the train accelerates (with

automatic jerk limiting and slip-slide control), runs

to the next station, decelerates, and brakes to a stop.

Speed throughout the run is controlled to within +/-2

mph of command speed, and station stopping is

with an accuracy of +/-50 feet.

Although train operation is normally automatic,

it is also possible to operate under varying degrees

of manual control (within the constraints of overspeed protection). This is often used in bad weather

when the rails are slippery, especially on grades.

The operator can order the train to bypass a station,

without otherwise interfering with the automatic

control process. The train can also be run in a completely manual mode (except for ATP). It is a procedural rule of PATCO that each train operator

must run the train manually for an entire trip once a

day in order to retain his operating skills. Thus,

train control in PATCO can be characterized as an

automatic system under supervision of an on-board

operator who has the capability for manual intervention to compensate for malfunctions and to augment system performance.

In contrast, train supervision (ATS) is largely

manual. PATCO uses dispatchers at a central train

control board to oversee train movements. order

schedule adjustments, and monitor overall system

performance, Routing (switch control at interlocking) is automatic, but it can be overridden by

central control. Communication with the train is by

means of train phone, which uses the third rail as

the conductor. Police, wayside maintenance personnel, and the Lindenwold car shop are linked

with central control by a radio network.

FIGURE 41.—PATCO Train in Lindenwold Yard

67
FIG(JRE 42,—Outbound on Ben Franklin Bridge

PATCO stations are entirely unattended, fares

being collected by an automatic vending and gate

system under closed-circuit television surveillance.

One or two employees at central control oversee

station activities by TV, make public address announcements, and handle calls for assistance from

patrons by direct-line telephones at the fare gates.

Problems and Issues

The PATCO train control system has been

singularly trouble-free, The engineers of the system

attribute this to the design philosophy that made

use of only proven elements and conventional technology. However, it is also true that the PATCO

system is relatively simple, consisting of a single

line without merging points and complex interlocking. The PATCO approach was not so ambitious as

that of BART, to which it is often compared. While

it can be said that PATCO accomplished its objectives more fully, it should also be noted that less

was attempted. Still, the PATCO system is an admirable transit system engineering achievement,

and it is widely publicized as an example of prudent

and effective use of automation.

There appears to be no recurr ng reliability and

maintenance problems associated with the ATC

equipment in PATCO, Certain deficiencies of

design and manufacturing quality control came to

light during the initial year of operation, faulty wiring connections and termina1s being the most prevalen t. PATCO maintenance Supervisors consider

these to be no more than the usual start-up and

debugging difficulties, even though it did take

almost a year to wring the system out. In general,

car availability has been excellent throughout the 6

years of operation, The number of cars needed to

provide scheduled peak-hour service has been

available 99.2 percent of the time or more each year,

although this requires a two-shift maintenance activity that is not common in the transit industry,

ATC equipment has not contributed a dlisproportionate share to the overall pattern of equipment

failures and maintenance time.

In the initial planning of PATCO, it was proposed to build a three-branch system in New Jersey

with a common trunk line over the bridge into

Philadelphia. This plan was dropped in favor of the

single-line system that was eventually built, Planning is now underway to build the two additional

branches (to Mount Laurel and Glassboro) and to

extend the existing Lindenwold line to WaterfordFIGURE 43.—PATCO Train Operator

Monitoring ATC Equipment

68
Berlin. This will result in a three-pronged route

plan, very much like the BART system but somewhat smaller in scale. The junction of the three

branches, equivalent to the Oakland Wye in BART,

is a train control engineering problem of concern to

PATCO, Experience with the existing system has

shown that the PATCO ATC system is adequate for

a single route. However, the level of automation

(especially in the area of ATS) may not be sufficient to handle three routes merging and running on

a single line over the Benjamin Franklin Bridge. In

order to maintain the regularity and level of service

now offered, it may be necessary to install more

sophisticated and highly automated equipment to

control interlocking and supervise traffic movement.

SYSTEMS UNDER DEVELOPMENT

There are three rail rapid transit systems now

under construction—WMATA (Washington, D.C.),

MARTA (Atlanta), and MTA (Baltimore). Of these,

WMATA is nearest completion; the first 4.6-mile

segment is scheduled to open with limited revenue

service (7 a.m. to 7 p.m.) in the spring of 1976.

Ground breaking for MARTA took place in February 1975, and initial service is planned for 1978–79,

The Baltimore system is in the advanced planning

stage and scheduled for completion in 1981 –82.

All three systems will employ advanced train

control technology, at levels of automation in the

range between the PATCO and BART systems. Table 7 is a summary of the ATC features planned or

TABLE 7. Automated Features of Three Transit Systems Under Development

ATC FUNCTIONS

ATP

Train in Separation

Overspeed Protection

Route Interlocking

A TO

Velocity Regulation

Programmed Stoppin g

Door Control and Train Starting

ATS

Dispatching and Monitoring

Performance Level Control

COMMUNICATIONS

Operator- Passengers

Central Control–Passengers

operator-Central Control

WMATA

Fully automatic

Fully automatic

Fully automatic

Fully automatic, with alternative of manual operation

Fully automatic, with alternative of manual operation

Fully automatic, controlled by

local timer subject to

manual override

Console and display board

supported by computer

Four levels of run

tween stations, w

time beith separate control of acceleration

rate, dwell time, and skipStop

One-way PA and noise monitor system

One-way PA

Two-way radio phone

MARTA

Fully automatic

Fully automatic

Fully automatic

Fully automatic

Fully automatic

Fully automatic

Aided, hut not directly controlled, by computer

Computer modification of

speed, acceleration, and

dwell time, with manual

override

one-way PA

One-way via train PA

Two-way radio phone

MTA

Fully automatic

Fully automatic

Fully automatic

Fully automatic

Fully automati c

Manua l

Centralized traffic control

machine and automati c

dispatching units

Six levels of speed.

train opf’rater in

to visual signals at stations

set in by

response

One-way PA

One-way via train PA

Two-way radio phone

69
FIGURE 44.—WMATA Route Map

70
proposed for each. Note that only the WMATA

train control system is a firm design at this point;

MARTA and MTA are tentative and subject to

modification as the system evolves.

Washington Metropolitan Are a

Transit Authority (WMATA )

The WMATA Metro System is being built as a

seven-phase project, with the last phase scheduled

for completion in 1982. 37 At that time, WMATA

will consist of 98 route-miles. serving 86 stations.

There will be 47 route-miles underground, 42 miles

at surface, and 9 miles on elevated structure. The

WMATA system will serve the largest geographic

area of any rail rapid transit system in the country

(30 miles N-S and 35 miles E-W). However, the

density of the network (route miles per square mile)

will be rather low—about 0.09. which is the same as

BART.

The WMATA fleet will be made up of 556 cars,

75 feet in length and weighing 72,000 pounds. Car

capacity will be 175 (81 seated and 94 standees).

The cars are designed to operate as semipermanently coupled A and B units (married pairs) to b e

run in consists of two to eight.

The train control system will have fully

automatic train protection (ATP), including separation assurance, overspeed prevention, and route interlocking. The normal mode of train operation will

be automatic (ATO), under the supervision of an

on-board operator. Door closure, train starting,

velocity regulation, programed station stopping, and

door opening will be automated functions. Train

operation will, therefore, be similar to the ATO

system of BART, except that station dwell time will

be under control of a local timing device in

WMATA instead of a BART-like central computer.

Unlike the BART system, however, the WMATA

train operator will have several methods for intervening in the automatic operating process either to

augment system performance or compensate for

partial failures. In this regard, the WMATA train

operation system will be similar to PATCO. Train

supervision (ATS) will be computer assisted and

will permit either manual or automatic adjustment

of performance level, station stopping, and dwell

time. In general, the WMATA approach to ATC has

been to employ proven, existing hardware and advanced, but not revolutionary, technology.

Metropolitan Atlanta Rapid Transit

Authority (MARTA)

MARTA has recently begun construction of a 70-

mile system of rail rapid transit integrated with

high-speed busways, serving the Atlant a

metropolitan area in De Kalb and Fulton Counties.

The rail portion of the system will consist of approximately 50 route-miles, radiating from downtown Atlanta. The first segment (13.7 miles) is expected to be finished by 1980.

The MARTA fleet will have 200 cars, operating

as married pairs in trains of up to eight. Speeds of up

to 75 mph on 2-minute headways are proposed initially, with eventual reduction to 90-second headways in heavy demand corridors. The train will

have one operator, who will monitor automatic

train control equipment and provide limited manual

back-up.

The train control system to be used in MARTA is

still in the early stage of definition; a general functional design has been developed, but detailed

engineering specifications had not been issued at

the time this report was prepared. With regard to

ATP and ATO, the MARTA system will be very

much like BART.38 Train protection and operation

will be fully automatic, the on-board operator serving as a performance monitor. The operator will

also be able to impose modifications of train operation functions. It is envisaged that the operator will

act as a back-up to ATO equipment for emergency

and degraded states of operation, but without the

capability of running the train at full performance

levels.

The supervisory functions carried out by central

control will be aided extensively by a computer but

will not be under direct computer control. A unique

feature of the ATS system design is that it will be

implemented in two stages. The first stage will provide for semiautomatic operation--computer-executed routing, dispatching, and monitoring in

response to manual inputs and override by central

personnel. The second stage will provide for

automation of the routing and dispatching functions

and will incorporate an Automatic Line Supervision

(ALS) system for computer-controlled traffic

regulation (dwell, performance level, schedule adjustment, reverse running, and station runthrough). The implementation strategy is to use the

‘lTThe first 4.8-mile segment was opened for service on

March 27, 1976,

3cMARTA has engaged the same general engineering Consultant, Parsons Brinkerhoff-Tudor-Bechtel, who designed the

BART system.

71
FIGURE 45.—MARTA Route Map

72
Baltimore Region Rapid Transit System—Phase 1
first, semiautomated stage as a baseline to get the

system into operation and debugged and then to

upgrade the central ATS complex to full automation when traffic demand increases. However, the

first stage will be retained in an operable state, as a

backup to automated central control for emergencies and nonnormal modes.

Mass Transit Administration of

Maryland (MTA)

MTA in Baltimore is proposing to build a 28-mile

rail rapid transit system extending from the northwest area of the city through downtown and terminating south of the Baltimore-Washington International Airport. So far, Federal grants have been

advanced for only the northern half of the system;

funding for the remainder is in question .

Groundbreaking for construction of the northwest

line was held in the fall of 1974.39 Revenue service

is scheduled to begin in 1981.

The ATC system for Baltimore has not

progressed much beyond the preliminary design

stage, The design concept calls for an automated

~gconcern over the cost of the proposed system led to a

suspension of construction activity in the fall of 1975, pending a

full review of costs and available sources of funding.

system similar to BART in technology but with

more direct involvement in train operation by an

on-board attendant. ATP will be fully automatic, as

in WMATA and MARTA, Train operation (ATO)

will be automatic under normal conditions, except

for door control and train starting, which will be

manually initiated (like PATCO). There will also

be provision for train operation at full performance

levels in a semiautomated cab signal mode, A novel

feature of the proposed ATC system is that the onboard operator will be able to set the train speed

profile to any of six levels in response to commands

from centraI control transmitted by visual signals at

the stations. Train supervision (ATS) will incorporate several automated features, but the general

level of automation of central control facilities will

be somewhat lower than that of WMATA o r

MARTA ,

A noteworthy aspect of the Baltimore system

design is the requirement that it be compatible with

WMATA, thus making it feasible to link up the two

systems at some future time if demand and

metropolitan area growth patterns so dictate, At

this time, however, there is some question in the

minds of the designers as to whether compatibility

should be limited to physical characteristics (such

as clearances, platform height, car size, and traction

voltage) or whether it should also include the signaling and train control system.

74
Chapter 5

OPERATIONAL EXPERIENCE

i

1
INTRODUCTION

The advocates of automatic train control advance three general arguments to support their

case-safety, performance, and cost.

An automated system, they contend, has a higher

level of safety than one in which the basic controlling element is the human operator, Automatic

devices function with a consistency an d

repeatability that man simply cannot match. In a

well-designed automatic system. hazardous events

are precluded by the engineering of the system; and

if an automated device should fail, there are other

design features to assure that the system will revert

to a condition known to be safe (the “fail-safe”

principle). In short, because the behavior of

machines is predictable, contingencies can be foreseen and compensated for in the design. The human

operator, by contrast, is not as predictable. Man is

prone to errors of judgment, inattention, fatigue,

and other frailties. Furthermore, the human operator takes longer to process information and to respond, with the danger that he may not do so correctly. And so, the argument runs, the automated

device should be preferred over the human because

it leads to a system of greater inherent safety.

The second argument is that an automated train

control system leads to superior performance. Here,

the argument rests on the superiority of machine

over human capabilities, Automated devices work

rapidly, with greater precision, and in a manner always consistent with the objectives of the system.

In the case of computers, they have a recognized advantage over man in their ability to process, store,

and retrieve large amounts of information and to

apply this information in the solution of complex

problems. Thus, an automated train control system

can move traffic at higher speeds and on closer

headways; and-equally important—it can make

rapid compensations and adjustments in response

to changing conditions.

Automated train control systems are also

asserted to be less expensive than manual systems

in the long run. The initial capital costs of an automated system are admittedly higher, simply

because there is more equipment to design and

build, It is claimed, however, that these costs are

more than offset by the reduced operating expenses

of an automated system. Automated systems are

cheaper to run because they have fewer operators,

and it is labor costs that represent the bulk of

operating expense, Automation can also produce

other savings. An automated system is claimed to

be more economical in its energy use because the

equipment is operated at optimal speeds and acceleration-decelcration profiles. This leads to a Second form of economy. less wear and tear on the

equipment due to improper operation. Finally, the

optimum mode of operation brought about by

automation supposedly leads to a more efficient

system, making it possible to provide the same

amount of passenger service with less rolling stock.

All of these assertions about the safety, performance, and cost advantages of automated systems are

subject to question. The purpose here, however, is

not to enter into debate. Instead, the arguments advanced for automation will be treated as hypotheses, to be tested by the empirical evidence and

operating experience of transit systems where

various automated control features are in use. The

aim is to look at the operational record to see if

there are differences among transit systems which

are attributable to the level of automation. The discussion is presented as a series of propositions or

issues, grouped under the general headings of

safety, performance, and cost. As a corollary, an examination is also made of the role and effectiveness

of man in systems with different levels of automation.

SAFETY

Safety has two aspects. There is the immediate

question of passenger accidents and injuries which

may be attributable to some aspect of automated

train control. There is also the question of the inherent safety of the system, i.e., the extent to which

the design of the system helps prevent accidents.

The first question has to do with the narrower,

historical concern of whether accidents have occurred, while the second deals with the larger topic

of safeguards incorporated in the design against

possible future accidents.

Allied to these questions is the matter of

passenger security. Automated systems, with fewer

transit property employees on board the trains and

in the stations, might be assumed to offer the

passenger less protection from assault, robbery, and

other criminal actions. This point needs to be examined first because of its implications for public

safety and, second, because of its influence on the

decision to replace humans with automated devices

in other, future, transit systems.

77
ISSUE O-1: TRAIN PROTECTION

Are automatic train protection (ATP) devices

more effective, and inherently safer, than

manual train protection methods?

The experience of the transit industry indicates clearly that ATP provides a surer method

of train protection, and all new systems now

under development will employ ATP in

preference to manual means.

Train protection involves three basic control

functions: train separation, overspeed protection,

and route interlocking. In a manual system, these

functions are performed by the train operator who

maintains visual observation of the track ahead and

runs the train in conformance with established

rules and procedures. When these functions are

automated, there are mechanical devices and

electrical circuits at the wayside and on the train itself to assure that proper following distance is

maintained (train separation), that train speed does

not exceed that required for safe stopping or

negotiating curves (overspeed protection), and that

conflicting moves along the lines or through

switches are prevented (route interlocking).

The degree of automation and sophistication of

control varies from system to system. In the

simplest form, ATP is accomplished by automatic

wayside block signals and mechanical trip stops

that activate the emergency brakes for any train entering a block illegally or exceeding the allowed

speed. At higher levels of automation, train movement is regulated continuously to maintain safe

speed, following distance, and routing.

Train control engineers and transit properties

universally consider ATP to be the first and basic

method of preventing collisions and derailments.

The newer systems built and those now under construction all incorporate fully automatic train protection mechanisms, Older properties (such as

NYCTA, CTA, and MBTA) have long had wayside

signals with trip stops to provide ATP, but they are

installing fully automated cab signal equipment as

they build new lines or modernize the existing

lines. Table 8 is a summary of ATP provisions in

existing and planned transit systems.

The operating experience of existing transit

systems with automatic train protection devices atTABLE 8.—Train Protection Methods in Existing and Planned Transit Systems

TRANSIT SYSTEM TRAIN SEPARATION OVERSPEED PROTECTION

Existing Systems:

BART (San Francisco)

CTA (Chicago)

CTS (Cleveland)

Dallas-Ft. Worth Airport

MBTA (Boston)

NYCTA (New York)

PATCO (Lindenwold Line)

Seattle-Tacoma Airport

In Planning/Construction:

MARTA (Atlanta)

MTA (Baltimore)

WMATA (Washington, DC.)

Automatic, with advisory cab signals

Mixture, converting to cab signalsl

Airport Ext. automatic trip stops on rest

Automatic

Red Line Ext. automatic, trip stops on

rest

Wayside signals with trip stops2

Automatic, with advisory cab signals

Automatic

Automatic, with advisory cab signals

Automatic, with advisory cab signals

Automatic, with advisory cab signals

Automatic, with advisory cab signals

Mixture of manual, trip stops with

timers, and cab signals

Airport Ext. automatic trip stops with

timers on rest

Automatic

Red Line Ext. automatic, manual on rest

Trip stops with timers

Automatic, with advisory cab signals

Automatic

Automatic, with advisory cab signals

Automatic, with advisory cab signals

Automatic, with advisory cab signals

lpresent system is a mixture of n. signals, wayside signals with trip stops, and Cab signals with automatic stop enforcement.

Zconversion to cab signals is planned for new lines and extensions.

78
tests to the general effectiveness and reliability of

such equipment. PATCO, AIRTRANS, and SEATAC have never had a collision or derailment in

passenger service attributable to malfunction of

ATP equipment, BART has had one ATP accident,

In 1972, shortly after inauguration of service, a train

ran off the end of the track at the Fremont Station.

The cause of the accident was traced to a faulty

crystal oscillator in the carborne speed control

electronics, causing the train to speed up when it

should have slowed to enter the station. A redundant speed control circuit has been added to prevent

recurrence of such a mishap and there have been no

other accidents related to ATP in the succeeding

three years of passenger service.40

The most frequent types of accidents in a manual

train protection system are the result of one train

following another too closely, misjudging stopping

distance, exceeding safe speed on curves, or entering improperly alined switches. All are products of

human error. ATP is specifically designed to prevent these types of accidents by interposing

automatic safeguards to keep trains properly spaced

and running at a safe speed on the correct route,

regardless of human error or inattention. The safety

record of rail rapid transit owes much to the effectiveness of such automatic protective devices which

apply the fail-safe principle to assure that the train

qOThe collision between a BART test train and a maintenance

vehicle in January 1975 occurred at night on a weekend, when

the system was shut down. The cause was found to be human error and improper opera ting procedure by the maintenance vehicle driver and the train supervisor in central control.

will maintain a known safe condition

an automated element malfunctions.

in the event

The operating experience of the Chicago Transit

Authority over the past 10 years offers an instructive example of the safety advantages of automatic

over manual train protection methods. The case of

CTA is singled out because it is typical of the

operating experience that has led existing transit

systems to conclude that ATP is a necessity.

CTA can be characterized as a mixed system.

Ten years ago CTA had wayside signals with trip

stops on some lines or parts of lines and no signal

protection on the remainder. In the unsignaled portion of the system the safety of train operation depended solely on the alertness of the motorman and

compliance with operating rules designed to prevent collisions and derailments, As the new Dan

Ryan and Kennedy extensions were built, they

were equipped with cab signals and automatic overspeed protection, In some cases, however, these

new lines merged with older portions of the system

having either no signals or wayside signals with trip

stops. Beginning in 1965, CTA undertook a modernization program, part of which involved installation

of cab signaling to protect segments of trackage formerly not signaled. This work is now nearing completion, but in late 1975 the system remained a mixture of wayside and cab signals, with a few sections

still not signaled at all. A train operator on the

North-South line or the West-Northwest line, for

example, runs the train under all three forms of

train protection at one time or another during the

course of a single trip.

FIGURE 47.—Interlocking Control Tower for Train Protection

79
The

1965 to

record of collisions and derailments from

1974 illustrates the consequences of operating under incomplete signal protection or by

manual and procedural methods alone. There were

35 collisions and 52 derailments in this period, a n

average of about one accident every 6 weeks. Most

were minor accidents, but there were tw o

fatalities—both in a 1966 derailment produced by

equipment falling off the train. An analysis of accident causes (Table 9) shows that human error was a

contributing factor in every collision and in almost

two-thirds of the derailments.41 Collisions typically

resulted from the train operator misjudging stopping distance or following too closely. Derailments

were most often caused by overspeed on curves o r

by the operator entering an improperly alined

switch while proceeding on hand signals.

The record also shows that cab-signaled ATP

was a contributing factor in only one accident. In

this case, the motorman was operating in cab-signal

territory for the first time on the first day of operation of a newly extended line. The cab signaling

unit had not cut in as the train passed from unsignaled into cab-signaled territory, and not noticing

this, the motorman failed to operate accordingly.42

The train rounded a curve in the subway and hit a

standing train ahead because the motorman was

unable to stop in time. CTA determined the cause

of the accident to be a combination of cab signal

equipment failure and human error. CTA has taken

measures to prevent recurrence by tighter instructions, modification of procedures for entering cab

signal territory, and more conservative turn-on and

qlApart from human error, the greatest contributing cause in

derailments was car defects (16 of 52 cases).

4ZCTA procedures prescribe that, in this circumstance, the

motorman should continue to operate under manual rules and be

prepared to stop within line-of-sight distance,

testing procedures when initiating service with new

cab signal equipment.

Two points emerge from this analysis. First, ATP

is superior to manual methods of train protection

because it safeguards against most types of human

error, which cause the majority of collisions and

derailments. 43 Second, a mixture of signaled and

unsignaled lines requires two distinctly different

(and perhaps incompatible) modes of response from

the train operator, with the attendant risk of confusion between the two at a critical moment. 44 Both

these points were recognized by CTA, which cited

prevention of accidents resulting from human error

and attainment of a uniform level of signal protection for the whole system as prime reasons for undertaking the cab signal conversion program.

q3No automatic system is foolproof. After the collision of

trains in the Mexico City transit system on October ZO, 1975, in

which 27 people were killed, the investigation disclosed that the

train operator (in violation of established rules) had disconnected ATP equipment that would normally have stopped the

train.

qAIn a different way, the recent collision in Boston illustrates

the risk associated with mixing manual and automatic methods

of train protection, On August 1, 1975, in the tunnel between the

Charles Street and Park Street stations, an MBTA Red Line train

was struck from the rear by a following train. About 2 minutes

later, the second train was hit by a third entering the tunnel.

There were no fatalities, but 130 were reported injured. This

part of the Red Line is protected by wayside signals and trip

stops. However, about an hour before the accident, a trip stop

had malfunctioned; and trains were being moved past the trip

stop under manual rules requiring that the motorman proceed

slowly and be prepared to stop within line-of-sight distance. The

exact cause of the accident has not been officially determined,

but it seems to have resulted not from a failure of the ATP

system but from a lapse in the manual back-up procedure, This

suggests that a transit system becomes vulnerable to human error at a time when the normal automatic protection methods are

inoperative and train operators must revert to unaccustomed

manual and procedural methods.

TABLE 9.—Analysis of CTA Accident Record, 1965–74

CONTRIBUTING FACTORS*

Car Track Wayside Cab Human

TYPE OF ACCIDENT TOTAL Defect Defect Weather Signals Signals Error Vandals

Collision 35 5 0 2 1 1 35 3

Derailment 52 16 4 0 6 0 31 1

● Some accidents had more than one contributing factor.

80
ISSUE O–2: TRAIN OPERATION

Does automatic train operation (ATO) have

an influence on safety, as measured by the type

and number of passenger injuries?

Based on analysis of the records of four representative transit systems, there is no difference

in the injury rates between manual and

automatic modes of train operation. Passenger

inexperience is more of a causal factor than the

mode of operation.

There are two types of passenger accidents that

might be influenced by automatic train operation—

falls on board due to train motion and door closure

accidents. If either automatic or manual train operation resulted in a characteristically smoother ride,

the frequency of passenger falls and injuries due to

lurching of the train during starts, stops, and running on curves would be expected to be lower.

Automatic door operation might be expected to produce more instances of passengers being struck or

caught by closing doors because there is no train attendant to regulate door operation for the tardy or

unwary passenger,

An analysis of accident records for four representative transit systems (NYCTA, CTA, PATCO,

and BART) does not substantiate either of these hypotheses. The frequency of train motion accidents

in the NYCTA and CTA systems, where trains are

run manually by a motorman, is essentially the

same as in PATCO and BART, where train operation is automatic under the supervision of an operator in the control cab. Similarly, the rate of door

closure accidents does not differ regardless of

whether doors are operated manually (either by a

conductor or train operator) or automatically. (See

table 10.)

A word of caution must be given regarding transit passenger injury statistics. There are no common

definitions of injury (or its causes) employed by the

four systems considered here or by the transit industry as a whole. For this reason, the injury rates

for various kinds of accidents are not precisely comparable from system to system and should be taken

only as general indications of the safety record. It

should also be noted that the figures given are for

claimed injuries, i.e., passenger reports of injury at

the time of the accident without regard to severity

or substantiation by medical examination. The

number of actual injuries (e.g., those requiring

medical treatment or those that lead to a later claim

for compensation) is considerably lower, perhaps

by as much as half.

It must also be emphasized that passenger injuries due to any aspect of train operation are

events of extremely low frequency—literally about

one in a million. By far, the greater proportion of injuries to transit system patrons (60–80 percent of all

accidents) occurs in stations. Falls on stairways, for

example, typically account for more injuries than

all types of train accidents combined. Table 11, a

summary of passenger accident statistics in four

systems, illustrates the general nature of the rail

rapid transit safety record.

With regard to fatalities, rail rapid transit is one

of the safest of all modes of transportation. In 1973,

15 people lost their lives in rail rapid transit acciTABLE 10.—Passenger Injuries Due to Train Operation

TRANSIT TRAIN MOTION DOOR CLOSURE

SYSTEM Mode of Operation Rate 1 Mode of Operation Rate 1

BART (1974) Alltomatic 21 . 0 Automati c 1.6

. CTA (1973) Manual 0.7 Conductor 1.3

NYCTA (1973/74) Manual 0.4 Conductor 0.4

PATCO (1973) Automatic 0.6 Train Operator 1.4

1 Reported in jllries per million passengers.

‘Z The BART figllre is for all on-board accidents, which include falls dlle to train motion and other types of mishaps. The rate of acci -

IIents dlle to train motion alone is therefore somewhat lower, probably about the same as the other systems.

81
FIGURE 48.-CTA Passengers Alighting at Belmont Station

TABLE Il.—Passenger Accident Summary

TYPE OF BART (1972-74) CTA (1969-73) PATCO (1969-73) NYCTA (1973–74)

INJURY Rate1Percent Rate 1Percent Rate1Percent Rate1Percent

STATIONS 3.4 61

Falls on Stairs. . . . . . . . . . . . . 24.1 61 3.3 24 3.1 21 NA 2 

–

Gates/Turnstiles. . . . . . . . . . . NA 2 

– 0.2 1 2.0 14 NA 2 

–

All Other . . . . . . . . . . . . . . . . . 8.5 21 7.2 52 4.4 30 NA 2 

–

TRAINS

Boarding/Alighting. . . . . . . . . 1.3 3 0.7 5 0.7 5 0.4 7

Doors. . . . . . . . . . . . . . . . . . . . . 3.8 10 1.2 9 1.8 12 0.4 7

Train Motion. . . . . . . . . . . . . . 1.4 4 0.8 6 0.9 6 0.4 7

All Other. . . . . . . . . . . . . . . . . 0.3 1 0.4 3 1.6 11 1.0 18

TOTAL. . . . . . . . . . . . . . . . . 39.4 13.8 14.5 5.6

IRepOrted injuries per 1 million passengers.

ZNot avai]able.

dent s

4 5

--a rate of 0.0075 fatalities per millio n

passengers. Fatality data for other modes o f

transportation during 1973 are shown in table 12 .

Rail rapid transit ranks among the safest o f

transportation modes in terms of fatality rate, a s

well as in absolute numbers. In the period 1970–72,

the rate was 0.83 deaths per billion passenger-miles

in rail rapid transit, 46 as compared to 0.69 in transit

qsThere were also 94 deaths due to suicide jumps from station platforms or trespassing on the right-of-way.

qeExcludes suicides and trespasser deaths.

8 2

buses, 1.03 in scheduled air carriers, 2.6 in passenger

railroads, 20,8 in private motor vehicles, and 21.1 in

elevators (Battelle, 1975), To set the rail rapid transit fatality rate in additional perspective, the figure

of 0.83 per billion passenger-miles is the equivalent

of a six-car train, carrying a total of 900 passengers,

traveling over 53 times around the earth before a

death occurs.

Of the passenger deaths in rail rapid transit,

about 80 percent are the result of falling while

walking between cars on a train in motion. The re-
TABLE 12.—Fatalities in the United States by Transportation

Mode During 1973

TRANSPORTATION MODE NUMBER OF DEATHS

Private Auto

Trucks

Motorcycle/Motor Bike

Marine, recreational

Marine, commercial

Aviation, private

Aviation, commercial

Grade Crossing

All Railroads

Taxicabs

Buses

Pipeline

Rail Rapid Transit, passengers

Rail Rapid Transit, suicides and trespassers

33,500

5,700

3,130

1,754

320

1,340

227

1,215

698

170

170

70

15

94

SOURCES: New York City Council on Economic Environment, 1974; and National Safety Council, 1974.

mainder are produced by a variety of causes, no one

of which accounts for a significant proportion.

Thus, train control (either manual or automated) is

a contributory factor in only a tiny fraction of rail

rapid transit

death in the

fatalities—probably not

approximately 2 billion

more than one

people carried

2

1-

0

each year, During the 5-year period studied for CTA

and PATCO and during the 3 years of BART operation, there have been no passenger deaths on trains

or station platforms as a result of transit operations.

In NYCTA between July 1969 and October 1973,

there were five deaths related to train operation

(three caught in doors and two killed in a collision).

Examination of the accident records for newer

transit systems reveals that the patrons’ experience

with rail rapid transit seems to be more of a contributing factor than the difference between manual

and automated modes of operation. Accident rates

in the first year of operation of a new transit system

to be three or four times higher than for older and

established systems or for the same system after the

public has gained riding experience. Figure 49

shows the history of train motion accidents for the

PATCO Lindenwold Line and the Dan Ryan extension of the CTA West-South Line, both opened for

service in 1969. Comparable data for the first 3 years

of BART operation are also shown. PATCO and

BART have automated train operation. Trains are

operated manually with cab signals on the Dan

Ryan Line. For comparison, the train motion accident

year

rates for CTA as a whole are shown for the 5-

period 1969–73. Here, the rate for a presuma83

72-683 [) - 76 - 7
bly experienced riding public is steady between 0.6

and 1.0 per million passengers, a range which includes the latest figures for PATCO and BART.

A similar learning phenomenon appears in the

pattern of door closure accident rates. The rate in

BART for the first year (1972–73) was 5.5 per

million, but it declined to 4.3 and then 1.6 in the

next year and a half. In PATCO, the decline was

from 2.7 to 1.4 over a 4-year period (1970–73). In

CTA as a whole, it fluctuated in the narrow range

of 1.0 to 1.4. Since car door operation is automatic in

BART and manual in PATCO and CTA, automation does not appear to have anything to do with the

accident rate. All three systems seem to be approaching, or to have reached, a common floor of

about 1.0 to 1,5 per million passengers.

ISSUE O-3: DESIGN SAFETY

With respect to design and engineering, are

ATC systems safe?

On theoretical grounds, ATC is at least as safe

as manual control, and probably safer. However,

there is insufficient evidence from actual transit

operations (except in the area of ATP) to evaluate safety empirically. There is also some

difference of opinion in the transit industry on

how to assure the safety of a design.

The rail rapid transit industry is extremely conscious of safety, which is customarily defined as

“freedom from fatalities or injuries resulting from

system operation. ” Safety-consciousness is

reflected not only in the approach to transit operations but also in the design and engineering of track,

wayside equipment, and rolling stock. All components judged to be critical to safety (“vital” components, in transit engineering parlance) are designed

according to the fail-safe principle. Stated simply,

fail-safe is “a characteristic of a system which ensures that any malfunction affecting safety will

cause the system to revert to a state that is generally

known to be safe"47 (NTSB, 1973).

qTThe exact interpretation of the fail-safe principle is

difficult under some conditions, especially where it may lead to

stoppage of a train in hazardous circumstances, e.g., a tunnel

fire. A discussion of this point is presented later, beginning on

~)il~l’ 86,

The fail-safe principle appears to be applied as

rigorously to the design of ATC as to other transit

system components, and probably even more so

because of the concern engendered by removing the

human operator from direct involvement in train

control functions. Therefore, at the design level at

least, there is no reason to conclude that automated

train control systems are not as safe as manual

systems. They may even be safer because possible

hazards due to human error and variability have

been eliminated by substitution of machine components.

But has this substitution merely replaced one

form of hazard with another, perhaps to the general

detriment of system safety? This question goes to

the heart of the automation issue, but it is largely

unanswerable at present for two reasons. First,

there is very little empirical evidence from automated systems by which to judge safety historically,

except for the case of ATP.48 Second, there are no

generally acceptable criteria by which to evaluate

safety from a theoretical viewpoint, especially

when comparing dissimilar systems.

At present, there are only two operational rail

rapid transit systems in the United States with a

substantial degree of automation for functions other

than ATP. PATCO, opened in 1969, has ATP and

ATO, However, PATCO is a system consisting of

only one line, and therefore neither representative

of a large urban mass transit system nor a true test

of automation technology. On the other hand, the

safety features of PATCO are impressive, reflecting

both safety-consciousness in design and awareness

of the realities of rapid transit operation. The safety

record attained by PATCO is excellent and attests

to the basic safety of ATO, at least at that level of

automation and in a system of that complexity.

The San Francisco BART system is more highly

automated than PATCO, incorporating ATS as well

as ATP and ATO, but the system is relatively new

and still undergoing start-up problems. Testing and

evaluation prior to full operational certification are

still being conducted by the California Public

Utilities Commission, However, even before

qcThe traditional view of transit engineers is that the safety

of a transit system is wholly assured by train protection functions and that ATO and ATS play no part in safety. This is correct if safety is defined simply as the prevention of collisions

and derailments. However, if safety is defined more broadly as

the freedom from injuries or fatalities resulting from system

operation (the view taken here), then the safety of ATO and

ATS equipment becomes highly germane.

84
*

revenue operations began in late 1972, BART was

the subject of intense public controversy over the

safety of ATC design, and the debate continues

even now. The concern over ATC in the transit industry and in State and Federal Government bodies

seems to have been engendered by the BART experience. Nevertheless, it appears that the

difficulties besetting BART result more from

specific engineering defects and management

problems than from any inherent shortcoming of

ATC technology itself.

The application of automation technology in rail

rapid transit is not, of course, limited to PATCO and

BART. There are individual lines within larger

systems (e.g., the CTA Dan Ryan extension and the

Quincy extension of the MBTA Red Line), but the

extent of automation is not so great as in PATCO

and BART, consisting only of ATP and machineaided train operation by means of cab signaling.

Also, the results in CTA and MBTA are hard to distinguish because of the merger of the cab-signaled

portions into lines with other forms of signaling and

train control.

Outside of rail rapid transit there are some nine

automated guideway transit (AGT) systems49 in the

U. S., such as the Dallas/Fort Worth (AIRTRANS)

and the Seattle-Tacoma (SEA-TAC) airport

systems, operating without a human controller on

board. The adequacy of ATC with respect to design

safety has been generally established in these

systems, which employ a technology derived from

rail rapid transit. However, there is some question

whether this experience is transferable back to the

parent rail rapid transit technology. Speeds are

generally lower in AGT; vehicles are smaller; and

the lines are fewer, with less complex interlocking.

Thus, the pool of operational experience with

ATC in rail rapid transit is rather small, consisting

of 6 years of relevant data from a simple one-line

system (PATCO) and 3 years from a complex

system (BART), There is also fragmentary evidence

from the CTA Dan Ryan and MBTA Red lines,

where the level of automation is lower and not

characteristic of the system as a whole, The data

from AGT may or may not be applicable to rail

qgAutomated Guide way Transit (ACT) is a general designation for transportation systems operating relatively small, unmanned vehicles+ ither singly or in trains-on fixed guideways along an exculsive right-of-way, See the OTA report,

Automated Guidewoy Transit (Report No, OTA–T–8), June

1975, for an assessment of this type of transit technology.

FIGURE 50-Unmanned Train at Seattle-Tacoma Airport

rapid

scale

transit because of certain basic differences of

and complexity.

The opinion of transit system managers with

regard to the safety of ATC is significant. A recent

survey of transit system safety problems, conducted

under UMTA sponsorship, did not identify ATC as

an area of concern. Priority action was recommended for several safety problems; but train control systems and automation were not mentioned,

even though these topics were listed in the survey

form circulated among transit system operating

authorities (Transit Development Corporation,

1975).

85
FIGURE 51.—Fully Automated AIRTRANS Train

The matter of available data on operating experience aside, there remain more fundamental

questions of methodology and criteria. How is

safety to be measured, either empirically and

theoretically? How safe is safe enough? What is

meant by safety? Is ATC Safety equitable with the

train protection function, or are there safety implications in ATO and ATS? Not all these questions

have answers generally accepted by experts in the

field of safety and train control engineering.

A study of ATC safety conducted by the DOT

Transportation System Center (1974) reached the

conclusion that it is “literally impossible to achieve

fail-safe design in a large complex control system

having many interacting elements and functions.”

No matter how carefully designed and tested a

system may be, there will always be certain combinations of component failure or operational conditions that cannot be wholly compensated for. The

probability of such events, although infinitesimally

small (1 X 10–6 or less), represent potential safety

hazards that must be dealt with. In other words, no

system as large and complex as a rail rapid transit

system can be made perfectly safe. Some risk must

always be taken.

And so, on theoretical grounds, the question of

ATC safety reduces to a matter of probabilities and

acceptable levels of confidence, At the present time,

there is some disagreement within the transit industry and among Federal and State regulatory agencies as to how these probabilities are to be estimated

or what measure of risk is tolerable.so

The traditional design approach followed in the

transit industry for ATP has been the fail-safe concept, where the essential concern is the immediate

or short-range response to protect the system from

the consequences of component or human failure.

Customarily, this protection is achieved by initiating a shutdown or reversion to a lower level of performance (e.g., decreased speed, greater headways,

sOTransit system professionals have also taken issue with the

general approach and some of the conclusions of the TSC study.

86
longer station dwell time). The difficulty with this

approach is that most modern transit systems operate on very short headways. Thus, if a failure occurs, it is not simply a matter cf stopping one train.

The effect reverberates through the entire system,

or a large part of it, requiring that many other trains

be stopped or slowed until the failure can be corrected, Such sudden and unexpected changes in the

operating mode of the system can produce a risk

situation that pervades far beyond the point of

failure and persists long after the failure has been

corrected. Thus, application of the fail-safe principle may produce a response which is safe for the

immediate and local circumstances but which also

produces longer-term and more far-reaching consequences for the general safety of the system. 51

(NTSB, 1973)

As a supplement to the fail-safe approach, NTSB

has advanced the concept of total system safety.

The first step of this approach is to select system

goals, e.g., prevention of collisions and derailments.

The system is then analyzed with respect to these

goals to determine where the system could fail and

allow a collision or derailment to happen. The

analysis permits construction of a “fault tree, ”

which includes not just single component failures,

but also multiple failures and environmental interactions, making it possible to identify those parts

of the system which are critical to safety and to

trace out the paths where failure must be prevented

from compromising any of the system safety goals.

This, in turn, shows the designer the parts of the

system which must be provided with redundant

components, functionally equivalent mechanisms,

self-checking circuits, or inhibitory devices.

Through application of statistical techniques, it is

also possible to evaluate the likelihood of failures

and adverse circumstances and thereby place the

assessment of risks on a quantitative basis. (NTSB,

1973; Battelle, 1975)

The approach suggested by NTSB recognizes that

the safety of the system as a whole is not equivalent

to the safety of its parts and offers an alternative

method to assess interactive and combinatorial

effects of component failure. The NTSB approach

also offers a way to identify hazards on a systemwide basis and to make explicit the level of risk imposed by each. However, both the methodology and

Slsome memhers of the transit industry have disputed these

conclusions on the grounds that NTSB has misinterpreted the

fail-safe principle and that the concept of pervading risk is appropriate to aviation hot not to a transit system.

validity of this approach have been challenged by

transit system engineers. Some maintain that the

fail-safe principle-correctly applied—is adequate

and proven by experience and that there is no need

for recourse to a total system safety concept, Others

contend that the NTSB approach offers nothing

new and that it is only a restatement of the safety

analysis methodology customarily applied as part of

the fail-safe approach.

In summary, the safety of ATC design (except

for ATP) has not been conclusively determined.

With respect to the theoretical safety of ATC, adequate precautions appear to be taken in the design

process to assure that automated devices result in a

level of safety at least as high as that conventionally

attainable with manual means of train control. The

absolute safety of ATC devices cannot be ascertained by any safety methodology, criteria, or

design philosophy currently employed in the transit

industry. Empirically based judgments about the

safety of ATO and ATS can be only tentative at

present because data are limited to a few systems

for only relatively short periods. With respect to

ATP, the available evidence indicates that

automatic methods are safer than manual train protection. In practical terms, accidents due to defects

of train control (either manual or automatic) are

events of very low probability-estimated here to

be on the order of one injury per million passengers

and one fatality per billion passengers, rates which

are among the lowest of all modes of transportation.

ISSUE O-4: PASSENGER SECURITY

Does reduction in the number of on-board personnel, brought about through ATC, have an adverse effect on passenger security from crime?

There is no evidence to suggest that passenger

security on trains is affected by reducing the size

of the train crew.

The security of passengers from criminal acts in

stations and on trains is a matter of serious concern

to rail rapid transit operating authorities. It has been

conjectured that automation, because it tends to

reduce the number of transit property employees on

trains and in stations, might have an adverse effect

on passenger security. Passengers, especially on

long trains with a crew of only one, might be more

vulnerable to assault, robbery, and other criminal

87
acts because the only transit employee

render assistance is located at the front

train, often in an isolated compartment,

who could

end of the

giving full

time and attention to train operation or supervision

of ATC equipment.

This line of reasoning has been advancd primarily as an argument against reducing the number

of on-board employees as a result of automating

train control functions. The argument also bears indirectly on the justification for ATC itself, If personnel in addition to the train operator (the socalled second and third men) are to be kept on board

anyway for security purposes, then they could

assist in train operation by performing manually

such functions as door operation, train announcements, and equipment monitoring.

The managers of operating transit systems tend

to the belief that personnel on board the train have

a favorable influence on security, both in protecting

passengers from robbery and assault and in deterring vandalism to the train itself. Agencies planning

new systems generally hold the same view, and

those planning to have only one or no on-board attendant intend to compensate by having more station personnel and roving security employees,

The operating transit systems have greatly varying approaches to passenger protection and train

policing. NYCTA maintains a very large transit

police force (5,100, the eighth largest police force in

the country), with patrolmen posted in stations and

on the trains themselves during certain hours and in

high crime areas. PATCO has a rather small transit

police force (20 men), which includes a dog unit

that patrols the property during the rush and base

periods and rides the train during owl service.

BART also has its own police force; but considering

the size of the property, the force is small (99 members, of which 63 are in patrolling platoons). In contrast, CTA has no transit police force as such;

passenger security protection is provided by the

police departments of the municipalities served.

There is, however, no firm statistical evidence to

support the contention that presence of operating

personnel or police on the train does, in fact, promote passenger security, Crime statistics for

four transit systems (BART, CTA, PATCO, and

NYCTA) are presented in

systems are not available,

tion suggests that the rates

to those shown.

88

table 13. Data for other

but anecdotal informaare roughly comparable

Caution should be observed in interpreting these

data. The four transit systems shown here differ

greatly in such characteristics as hours of operation,

security measures, and types of communities

served. There are also slightly differing definitions

among the four as to what constitutes robbery or

assault. For example, some include purse snatching

in the category of robbery, while others do not.

Some list sex offenses separately; some combine

such crimes with other forms of assault. An attempt

has been made to reduce the statistics presented

here to a common base, but some distortions undoubtedly remain. Therefore, the rates given in table 13 should be taken only as an indication of the

rough dimension of the problem and should not be

considered to show the relative degree of passenger

security in the four systems.

TABLE 13.—Passenger Assaults and Robberies for Selected

Transit Systems

ASSAULT/ROBBERY RATE

SYSTEM (per million passengers)

BART (1973–74) 2.96

CTA (1969–73) 1.44

NYCTA (1973/74)” 3.49

PATCO (1969–73) 0.24

● July 1973 to June 1974.

While only limited conclusions can be drawn

from this sample of data, there does not seem to be

any clear relationship between crime rates and the

number of operating personnel on the trains, For

example, PATCO with only one operator on the

train and unmanned stations has a rate that is an

order of magnitude lower than NYCTA, where

there are two men on board and police actively

patrol trains and stations. Also, the rates in BART

and NYCTA do not appear to differ substantially

even though the two systems are vastly different in

terms of automation and the level of train and station manning.

The dominant factors influencing security seem

to be the size of the city and the sociological characteristics of the areas served. It should also be observed that, if ATC has any influence at all, it is

likely to be small since the preponderance of crime

in rapid transit systems (75–80 percent) does not
FIGURE 52.—Approach to Brightly Lighted Station

take place on trains, but in and near stations. A and that patrols are concentrated there. In light of

study conducted by the American Transit Associa- this, it is perhaps significant that most transit-proption (1973) concluded that station security was by erties list all assault and robbery statistics under the

far the more critical problem and that station crime general heading of station incidents.

was concentrated in neighborhoods of generally

high crime, usually near the residence of the crim- As a final comment, a distinction must be made

inals, Anecdotal evidence from transit properties between the real (i.e., statistically measurable)

interviewed also indicates that the areas of greatest security of passengers and their perception of

concern are stations, access ways, and parking lots security while using a transit system, In the area of

FIGURE 53,—Lonely Station at Off-Peak Hour

89
perceived security, most transit operators and planning agencies agree that the on-board employee

plays a useful and reassuring role. Communications

of any and all forms are also believed to be useful

for enhancing perceived (and real) security of

patrons. Two-way communication with passengers

is regarded as mandatory for systems with unattended vehicles. Surveillance of train interiors by

closed-circuit television is technically feasible, but

most properties consider the cost of purchasing and

operating the equipment to be prohibitive in comparison to the potential benefits.

Data on the perceptions of passengers themselves do not exist in any meaningful quantity. In

one of the few studies made of passenger attitudes,

a telephone survey of 1,586 bus and rail rapid transit

patrons in Chicago, it was found that passengers

would derive the greatest sense of security from the

presence of a police officer on the train or platform

and from the knowledge that help was available

quickly from station personnel or the police. Few

respondents (8 percent) mentioned the presence of

a conductor or motorman as a reassuring factor.

This survey also found that CTA patrons tended to

regard subway stations and elevated platforms as

more dangerous than the trains themselves. (ATA,

1973)

PERFORMANCE

The operational characteristics of ATC can

affect the general performance of a transit system in

several ways. Some may be qualititative; others

quantitative. Some may directly affect transit

patrons and be perceived by them as benefits. Other

performance characteristics may be of concern primarily to the operating authority and go largely unnoticed by the riding public. Those selected for

examination here are the more tangible and

measurable aspects of system performance, where

differences between manual and automated forms

of train control might be manifested as benefits for

either the transit patron or the operating authority.

They are:

Ride Quality—the smoothness and comfort of

the ride, expressed in terms of speed and its derivatives (acceleration and jerk);

Level of Service—the convenience and dependability of the transit system, measured as headway,

trip time, available seating, and adherence to

schedule;

Availability—the ability of the system to sustain

the required level of daily service, as indicated by

the reliability and maintainability of equipment.

As in the preceding discussion of safety, the performance of ATC systems is treated as a series of

issues, with operational experience from various

cities presented in tabular format to substantiate the

conclusions. This method of presentation tends to

invite comparisons among transit systems; and it is

intended that the reader do so, but only within the

limits set forth in the discussion of the issue. Some

differences are more apparent than real, They arise

either from different definitions and recordkeeping

methods or from differences among systems that

have nothing to do with train control (e.g., track

geometry, right-of-way conditions, station spacing,

environmental factors, age of equipment, and so

on). An effort has been made to reduce all data to a

common base and to use standardized terms, but

there still remains a need for caution in making

direct comparisons across systems.

ISSUE O-5: RIDE QUALITY

What effects does automatic train operation

(ATO) have on ride quality and comfort?

ATO systems provide a ride quality equal to

that of manual modes of operation. Some consider ATO systems superior in that the ride

quality is more uniform.

Ride quality is a general

smoothness and comfort of

ceived by the passenger. It is

term referring to the

train motion as permeasured in terms of

the acceleration and deceleration characteristics of

the vehicle while running at speed and during arrival and departure from stations. Ride quality is influenced by many factors—propulsion and braking

system characteristics, vehicle suspension, track

geometry, condition of the right-of-way, wheel-rail

adhesion, signal system design, and speed regulation technique. Of these, only the last two fall within the province of the train control system, and they

usually do not have a major influence on ride

quality. Vehicle and track characteristics are by far

the dominant factors. However, the train control

system can play a part in enhancing ride quality or

in compensating for adverse effects produced by

other factors.

90
In terms of train control functions, ride quali

governed by those elements of the system

regulate speed and execute programed station s

ty is

that 

tops.

Three aspects of motion must be controlled: speed,

acceleration, and the rate of change of acceleration.

Acceleration and deceleration (the rate at which

speed changes) is related to, but not actually a part

of, the speed regulation function of the train control

system. 52 For passenger comfort, as well as safety,

the changes in velocity must be kept within certain

limits when running the train up to speed and when

coming to a stop at stations. Different rates may be

employed-a nominal rate for service braking and a

somewhat higher rate for emergency stops.

It is important to control not only acceleration

but also jerk—the rate of change of acceleration, so

named because of the uncomfortable (and potentially hazardous) effect produced by abrupt changes

in acceleration or speed. 53 Control of jerk, more

than control of acceleration itself, contributes to a

smooth ride and, for the standing passenger, a

somewhat safer one. Jerk limiting applied during

stopping is sometimes called flare-out control. It is

identical to the technique employed by a skilled

automobile driver when coming to a stop. By easing

off on the brake, the transition from deceleration to

full stop is smoothed or feathered out. Because

there are safety implications to relaxing braking

effort while stopping, flare-out control (a train

operation function) is overridden by the train protection (ATP) system such that flare-out is prevented during emergency braking.

Maintaining optimum wheel-rail adhesion is

called slip-slide control. Slip denotes the slipping or

spinning of wheels during the application of power.

Slide denotes the sliding or skidding of wheels

when brakes are applied. Both are operationally un -

~~Acceleration and deceleration control is considered by

transit engineers to be a part of the traction system. While it is

true that the equipment controlling acceleration and deceleration is physically a part of the traction system, the functional

boundary between this system and the train control system is

somewhat fllzzy, and a case can be made for treating accelera -

tion and deceleration control as part of either one, In practical

terms, th[~ (Distinction is [unimportant since speed regulation, accelerat ion and deceleration control. and jerk limiting all intera(; t

to prodm:e a smooth ride.

5.JJerL li~l tjng IS also considered te(;hn ically a function of the

traction system. The train control system commands a specific

level of acceleration. and the propulsion system responds by appl i cat ion of power or brah i ng to produce accelera -

tion/{lecelera tion a t a rate w i th i n allowable equipment or

human tolerances,

desirable because they represent inefficiency in

running the train and may cause damage to tracks,

wheels, or the propulsion and braking system of the

train. For the passenger’s perception of ride quality,

slip-slide control is only marginally important, but

it does affect jerk characteristics. There are also

safety implications; the system is usually designed

so that failure of slip-slide control does not allow

release of brakes when safety requires that they be

applied.

In transit systems where trains are operated

manually, speed regulation, slip-slide control, and

flare-out are usually performed by the motorman.54

The ride quality resulting for the passenger is thus

determined by the skill or artistry of the individual

motorman and the consistency with which he applies proper technique. In transit systems with

ATO, these three functions are usually automatic.

The use of automatic mechanisms is generally considered to offer two advantages. First, the train is

more likely to be operated within the limits acceptable for passengers and equipment because the control system is designed to preclude human error and

improper technique. Second, automatic operation

leads to less variation; human control varies considerably with individuals and time.

Table 14 is a summary of the speed regulation,

jerk limiting, and slip-slide control methods

employed in five operating transit systems. The

new transit systems planned for Washington,

Atlanta, and Baltimore will all employ automatic

techniques similar to those of PATCO or BART.

There is almost no empirical evidence to support

or refute the advantages claimed for ATO on

theoretical grounds. Systematic studies in experimental settings or under actual operating conditions

have not been conducted, and there is no effort now

under way to do so. The opinion of some transit

system engineers is that ATO leads to a ride quality

and type of train operation that is at least as good as

manual control, and perhaps even superior because

of the ability of automatic devices to operate within

prescribed tolerances more consistently. Transit

system managers also seem inclined to this view.

There is, however, some dissenting opinion from

both engineers and managers. Perhaps the most

conclusive indication that ATO is preferable to

manual control is that all the transit systems now

under development and most of the proposed extensions or improvements to existing systems will

S~Jerk limiting is a u toma tic on a 11 operating transit systems

and is built into the propulsion system.
FIGURE 54.—Comfort Features of Modern Transit Cars

TABLE 14.—Train Operation Methods Related to Ride Quality

TRANSIT ACCELERATION RATE

SYSTEM ACCELERATION JERK LIMITING FLARE-OUT

NYCTA Automatic] Automatic Manual, except on new R–44 and

R-46 cars when operating with

ATO

CTA Automatic] Automatic Manual

MBTA Automatic Automatic Manual

PATCO Automatic Automatic Automatic on service brakes, except

in manua1 backup mode: none on

emergency brakes

BART Automatic Automatic Automatic on service brakes, except

in manuall back-up mode: none on

emergency brakes

SLIP-SLIDE

Manual, except on new R–44 and

R–46 cars

Manual

Manual, except on new Red Line

cars

Automatic in all propulsion and

braking modes, includin g

emergency braking

Automatic in all propulsion and

braking modes, includin g

emergency braking

1

Inherent in propulsion system design.

92
incorporate automatic control of acceleration, jerk, run according to schedule, making the prescribed

flare-out, and slip-slide. stops, and with the requisite number of cars.55

ISSUE O-6: LEVEL OF SERVICE

Do transit systems with ATC provide a level

of service that is comparable to manually controlled systems?

Generally yes, although some systems with

ATC have encountered difficulty in maintaining

schedules, especially during the initial months of

service.

Table 15 is a summary of the service-related performance characteristics of five transit systems

with various degrees of automation of train operation and supervision functions. Also shown are the

service characteristics of the AIRTRANS system at

Dallas-Fort Worth Airport. Although AIRTRANS is

an airport people-mover system in the AGT class

and not a true rail rapid transit system, it has been

included as example of a wholly automated system

operating without on-board personnel. No existing

rail rapid transit system operates in this manner.

The data for AIRTRANS, BART, PATCO, and

NYCTA apply to the entire system. The CTA and

MBTA data are for only the most automated lines.

Level of service is a general term that includes The speeds and headways for the two rail rapid

both the characteristics of the service offered transit systems with ATO (BART and PATCO) are

(speed, trip time, frequency of trains) and the de- generally equivalent or superior to those of the

bendability of that service. Designers of transit systems with manual train operation. 56 It must be

systems consider these aspects of service, along noted, however, that maximum speed is little inwith comfort and convenience, to be determining fluenced by ATO. Speed is mainly a function of

factors in gaining and holding public patronage. The track condition, vehicle characteristics, age of

assumption is that if travel time can be saved by

using rail rapid transit, if service is available when

wanted, and if there is assurance that the trip will

be completed according to schedule, a large share of

the public will choose rail rapid transit over other

modes of transportation, Advocates of automation

contend that ATC offers the means to upgrade

service by making it possible to operate trains at

greater speeds, on shorter headways, in closer conformance to schedule, and with greater regularity,

Maintaining a high level of service depends on

how well both the train operation and train supervision functions are carried out. The elements of the

system responsible for operating trains, whether the

motorman or an automatic device, must assure that

trains are run at the prescribed speeds, making the

scheduled stops and departing from stations after

the specified dwell times. The train supervision

function, either by humans or computers, entails

monitoring the performance of individual trains in

relation to overall passenger demand and making

compensating adjustments of schedule, running

time, station stops, and dwell time as necessary to

overcome irregularities of train operation, variations in demand, or adversities of weather. The success of this combined train operation and supervision activity is measured by schedule adherence,

i.e., the percentage of time that trains are actually

equipment, and station spacing, to name a few.

Thus, the higher speeds attained in BART and

PATCO do not necessarily reflect an y superiority of

ATO over manual operation. These systems are

newer, in better condition, and built for different

purposes. 57 The track and rolling stock have been

designed for high-speed operation. Station spacing

permits longer runs at maximum speed, thereby

raising the average line speed, Still, the data do suggest that systems with ATO are capable of providing a level of service at least equivalent to that of

manual systems,

With regard to headways, ATO does seem to

offer advantages over a manual system. Headway is

basically determined by the level and qua lit y of signal protection (ATP) and the regularity with which

Ssu]timate]y, level of service depends more on management

policy than technological features, since it is management that

sets the desired level of service and determines the degree of

commitment to maintaining service in the face of adverse circumstances,

SoSpeed in the AIRTRANS system is substantially lower, but

this is a result of very close station spaci ng (typica]ly

1,000–2,000 feet) which does not permit vehicles to operate at

maximum speed for more than a few seconds.

5 7BART and PATCO are basically interurban systems more

comparable to the Long Island Rail Road or Penn Central’s commuter services than to the NYCTA or CTA urban transit

systems <

93
TABLE 15.-Service Characteristics in Typical Transit Systems

One-Way

Maximum Trips/Day Trip Time

AUTOMATION SPEED (mph) HEADWAY (min.) Train (each way) in Peak

TRANSIT Length Period

SYSTEM ATP ATO ATS

2 Max, Av. Peak Base (cars) (min.)

NYCTA J 50 20 2 10–12 11 8,000 359

CTA (Dan Ryan) ~ 55 30 3 5 8 225 42 1/2

MBTA (Red Line) 4

J

4

50 30 2 ‘/2 4 ‘/2 4 255 25

PATCO l l J 75 40 2 10 6 182 22 1/2

BART J J J 80 40 56 6 10 5

280 54–57

AIRTRANS J d d 17 9

6

1 — 2 —6 —6

1A check (~ indicates the function is automated. All but AIRTRANS have an on-board operator to run the train or monitor

automatic system performance.

ZAutomation here specifically means computer-aided central control.

Ssystem-wide average; trip time on individual lines varies considerably as a function of line length and whether service is local or

express.

4A portion of the rol~te is eqllipped for AT() but current]y operates under manual control, Cars are capable of 70 mph top speed

but are governed to so mph for manual operation.

SThe figures are for interim level of service; when fully operational, approximately 600 trips per day will be run at headways of 2

minutes during peak periods and 4 minutes during the base period.

BAIRTRANS operates 17 overlapping loop routes of varying length. Trains circulate continually throughout the day on a schedule

determined by aircraft arrivals and departures.

trains are operated, i.e., the invariance of running

time. There is a large, but not unanimous, body of

opinion among transit engineers and managers that

ATO is necessary in order to operate trains at high

speeds on short headways. Given a signal and train

protection system of good quality, trains can be run

manually on short headways, viz., NYCTA or CTA,

where scheduled headways on individual lines are

on the order of 1–2 minutes and composite headways on merged lines sharing a single track may be

40–50 seconds. Given the proper equipment and

track conditions, trains can also be run at high speed

under manual control. Metroliners have operated

manually in regular service at speeds of up to 130

mph. But some transit engineers and planners

believe that the combination of high speed and

short headway cannot be attained without the help

of ATO to eliminate the variability of manual

operation.

Data to support this contention are scarce

because there is only one transit system (PATCO)

where manual and automatic modes of operation

can be directly compared. The PATCO trains are

normally run under ATO, but full-speed manual

operation is possible as an alternate mode and is, in

fact, required of each train operator once a day as a

means of maintaining proficiency. The PATCO experience has been that the trips run under manual

control average about 20 seconds longer and are of

much greater variability than ATO runs, Since

these manual proficiency trips are not run during

peak periods, the impact of longer and more variable running time on headway is hard to assess, but

the effect might be to increase headway and so

lessen the overall throughput of the system. On the

other hand, the PATCO results may be misleading

because they were obtained while running with a

clear track ahead. Some transit engineers contend

that, when trains must follow closely or when track

and weather conditions are adverse, the manual

operator is superior to the automatic device; and

trains can be run more uniformly, at closer headways, and with shorter running times,

For the transit patron, the schedule of train service is only part of the equation. The patron also requires assurance that the schedule will be maintained with a high degree of consistency. That is,

the performance history of the system must lead the

patron to the conclusion that he can rely on the trip

being completed, on time, without skipping

scheduled stops, and

car space available.

with the customary amount of

94
FIGURE 55.—The Wait . . . . . . . . . . and the Rush to Leave

Schedule adherence of transit systems is not

strictly comparable because of differing definitions

of on-time performance and dissimilar methods of

keeping operational logs. For example, some

systems consider a train on time if it arrives at a terminal within the turnaround time, i.e., in time to

depart on schedule for the next run. Others use an

arbitrary definition, such as a delay not exceeding 5

minutes, either at a terminal or at checkpoints along

the route. Still others, such as BART, use a more

dynamic and detailed measure of schedule

adherence that takes into account the impact of individual delays on total system performance.

Schedule adherence is also influenced by

strategy employed in setting a schedule. One

the

approach is to base the schedule on maximum train

performance (maximum attainable speed, acceleration, and deceleration and minimum coasting time)

with the expectation that maximum throughput

will be” achieved except for a small fraction of the

time when complications arise. An alternative approach is to schedule trains at something less than

their maximum performance, thereby creating a

built-in reserve of performance that can be used to

make up delays en route. This approach sacrifices

some throughput but offers greater assurance that

the schedule can be met.

Because of these dissimilarities in setting

schedules and defining on-time performance, direct

comparisons across transit systems cannot be made,

95
The following data, therefore, should be regarded

only as individual examples of schedule adherence

for representative transit systems.

PATC O

A train is considered late in PATCO if it arrives

at a terminal more than 5 minutes behind schedule.

PATCO keeps a daily log of lateness and other

schedule anomalies such as trips annulled, station

stops missed, and trips made with less than the

scheduled number of cars (short consist). Table 16

shows the performance figures for 1974 and for an

average year in the period 1970– 74.

PATCO also computes an overall index of

schedule adherence:

where:

T s = trips scheduled

T a = trips annulled

CTA

CTA has a very stringent definition of lateness

and employs a complex strategy to compensate for

delays, A train is considered late if it is more than 30

seconds behind schedule at a terminal or intermediate checkpoint, When this occurs, preceding and

following trains are deliberately delayed also so as

to minimize irregularity in headways and balance

the service.

For the purpose of this report, a special study was

made of schedule adherence on one CTA line, the

West-South (Lake-Dan Ryan), which is one of the

newest lines and operates with cab signals. On-time

was defined to be arrival at a terminal with a delay

not exceeding the scheduled turnaround time, i.e.,

the actual time of arrival was not later than the next

scheduled departure of the train. Depending on the

time of day, turnaround time on this line is between

5 and 7 minutes-a standard roughly comparable to

that of PATCO. In addition to delay, the analysis

also considered the number of trips annulled,

scheduled station stops bypassed, and consist shortages, Table 17 is a summary of findings for the year

1974 and for the 5-year period 1970–74.

T I = trips late

TABLE 17.-Schedule Adherence on CTA Dan Ryan Line,

Sb = stations bypassed 1970–74

Applying this formula gives a figure of 98.71 percent schedule adherence in the 5-year period

1970–74 and a figure of 98.34 percent in 1974. It is

worth noting that in 1974, despite a derailment due

to traction motor failure and a subsequent schedule

disruption caused by replacement of motor bearings

for all cars in the fleet, PATCO was able to sustain a

level of performance nearly equal to that of the preceding 4 years—98.34 percent in 1974 versus 98.80

percent in 1970–73.

TABLE 16.-Schedule Adherence in PATCO, 1970–74

FIVE-YEAR

PERFORMANCE 1974 AVERAGE

(1970-74)

SCHEDULED TRIPS

Percent on time 98.36 98.75

Percent late 1.16 1.03

Percent annulled 0.48 0.23

SCHEDULED STOP S

BYPASSED (%) 0,18 0.40

TRIPS MADE WIT H

SCHEDULED

NUMBER OF CARS (%) 99.66 99.75

Five-Year

PERFORMANCE 1974 Average

(1970-74)

SCHEDULED TRIPS

Percent on time 96,26 97.37

Percent late 3.65 2.50

Percent annulled 0.09 0.13

SCHEDULED STOPS

BYPASSED (%) 0.34 0.26

TRIPS MADE WIT H

SCHEDULED

NUMBER OF CARS (%) 99.93 99.89

Despite certain basic differences between PATCO and the CTA Dan Ryan line in route complexity, track geometry, and station spacing, the

performance histories of the two systems are

roughly comparable when logged on essentially the

same basis. The on-time records of both are on the

order of 97-78 percent, and the percentage of stops

made and the percentage of trips run with a full

consist are nearly 100 percent. Thus, it would appear that a manual system with ATP (CTA) and an

96
automated system with ATP and ATO (PATCO)

can achieve equal levels of schedule adherence.

NYCTA

The rapid transit system operated by NYCTA is

the largest and most complex in the United States.

Automation is minimal, consisting of automatic

train protection by wayside signals with trip stops

and some automated dispatching. Train operation is

wholly manual.

In 1974, the on-time performance record of

NYCTA was 97.03 percent, where a train is considered on time if it arrives at a terminal within 10

minutes of the schedule. During 1974, there were

32,515 delays of unspecified length, or about 90 per

day or three per line,

AIRTRANS

AIRTRANS at the Dallas/Fort Worth Airport has

a fully automatic train control system. Automated

trains operate on 17 intermeshed routes over about

13 miles of one-way track. The system is still in the

process of shakedown and debugging, having

opened for operation in January 1974.58

Figure 56 is a plot of the availability of the

system on a weekly basis from May to October

1974, where availability is expressed as the ratio of

actual hours of operation to scheduled hours of

operation. The figure also shows the number of

service interruptions experienced each week.

It can be seen that, during the month of May, a

relatively few service interruptions caused long

delays. In June, the schedule of operation was increased from 105 to 168 hours per week, and the

number of service interruptions increased sharply

to over 160 per week, or about one per hour. As experience was gained and debugging of the system

continued, the length of delay per interruption

decreased. By October, system availability averaged

over 99 percent, while the number of service interruptions declined to about 40 per week. While servwIn November 1975 the system was shut down as a result of a

contract dispute between the airport management and the

manufacturer.

FIGURE 56.—AIRTRANS Availability and Service Interruptions

97
ice interruptions are

trips, it may provide

PATCO experienced

not truly equivalent to late

perspective to consider that

about 20 late trips per week

and the CTA Dan Ryan line about 54 per week during the first year of operation.

BART

BART has ATO and employs a computer-based

ATS system for maintaining trains on schedule,

The basic performance index is “total system

offset, ” an expression of the aggregate delay for all

trains operating in the system after application of

corrective scheduling algorithms. This measure is

more complex than that used by other transit

systems, not only because it incorporates more factors, but also because it considers the compensating

adjustments which have been applied to following

and leading trains, in addition to the late train itself,

Thus, a train that is 30 seconds late will result in

delays of 5 to 15 seconds for as many as three

following and two leading trains, producing a total

system offset of as much as 65 seconds while the

central control computer respaces the trains and

smooths out the traffic flow.

During the first 9 months of operation, under a

partial schedule with lo-minute headways, BART

experienced severe service disruptions. In the week

of 25–29 June, 1973, for example, total system offset

averaged about 12 minutes in the morning and increased to over 45 minutes by the evening rush

hour. Delays of over 10 minutes were experienced

five times during the week, and short consists were

run 16 times for periods ranging from 16 minutes to

3 hours.

Table 18 shows a larger sample of data, consisting of weekly performance summaries selected at

approximately 4-week intervals from August 1973

to August 1974. During this period, which covers

roughly the second year of operation, transbay service had not yet been inaugurated, and BART was

running what amounted to two separate systems:

Fremont/Richmond/Concord service in the East

Bay and San Francisco/Daly City service in the

West Bay. Service was limited to the hours of 6 a.m.

to 8 p.m., weekdays only.

Examination of the data for the period indicates a

slight improving trend with respect to delays, car

shortages, and total system offset. The opening of

the Transbay Tube in September 1974 caused a

sharp decline in the regularity of service for a few

weeks; but by the last week of 1974, total system

offset was running at an average of 3.6 minutes in

the morning and 20.4 minutes in the evening. These

figures are roughly comparable to those of August

1974, the month preceding inauguration of transbay

service, Still, it appears that the BART system has

not yet attained a level of service dependability

comparable to other rail rapid transit systems.

Other Transportation Modes

To assess the general quality of service provided

by rail rapid transit, it is useful to make some rough

TABLE 18.—Schedule Adherence in BART, August 1973–August 1974

TOTAL SYSTEM

WEEKLY TOTAL OFFSET (minutes)

Trains Delays Over Short Daily Average

WEEK Dispatched 10 min. Consist 7:00 a.m. 4:30 p.m.

20–24 Aug. 73

17–21 Sep. 73

15–19 Oct. 73

12–16 Nov. 7 3

1

IO– 14 Dec. 73

7 –II Jan, 74

18–22 Feb. 74

18–22 Mar. 74

8–12 Apr. 74

13–17 May 74

10–14 Jun. 74

8–12 Jul. 74

5–9 Aug. 74

—

AVERAGE

116

124

135

149

166

166

170

172

170

145

162

164

185

8

10

18

10

9

9

5

5

8

6

5

2

8

11

12

21

17

26

38

17

19

23

25

28

18

26

8.2

4.8

9.2

9.0

9.6

11.8

10.8

3.4

7.8

2.8

2.2

6.6

0.8

36.0

23.0

45.4

39.8

19.0

28.6

22.6

36.6

24.6

16.8

23.6

21.6

15.6

156 8 22 6.7 27.2

1West Bay service began on November 5 1973
comparisons with other modes of public transportation. The on-time performance records of the rail

rapid transit systems examined here range from 97

percent for an essentially manual system (NYCTA)

to almost 99 percent for a system with ATP and

ATO (PATCO). The on-time performance of more

highly automated systems such as BART and

AIRTRANS cannot be determined from the data

available, but it appears to be not lower than 90 percent.

The Metroliner operating between New York

and Washington is comparable to rail rapid transit

since it operates on a fixed guideway in an exclusive right-of-way and employs similar train control technology, The on-time record of the

Metroliner is currently running at about 53 percent,

where a train is counted late if it arrives more than

15 minutes behind schedule on a trip of 3 hours. Ontime performance for railroads in general exceeds

90 percent for many lines and in some cases reaches

95 percent (Reistrup, 1975).

Air carrier service is a more remote comparison,

but still generally valid if limited to flights of about

the same duration as a typical rail rapid transit run.

The on-time performance record in September 1974

is given below for air carrier service between three

pairs of cities about one flight-hour apart:

New York–Washington 79 percent

Los Angeles–San Francisco 84 percent

Los Angeles–Las Vegas 84 percent

(Air Transport World, 1975)

A flight is considered on time if it arrives within

15 minutes of schedule, a less stringent standard

than the 5–10 minutes used in the rail rapid transit

systems cited above,

ISSUE O-7: RELIABILITY

effect has ATC equipment reliability

had on the performance of transit systems?

ATC equipment poses reliability problems,

especially during the initial period of system

operation. However, in comparison with other

components of the transit system, ATC equipment does not cause a disproportionate share of

service disruptions. The problems do not seem to

stem from automation per se but from the increased complexity of all new transit system

equipment,

The general trip dependability, or schedule

adherence, of rail rapid transit systems employing

manual or automatic train control was examined in

the previous issue. It was found that the method of

train operation, either manual or automatic, did not

have a major influence. The principal cause of

schedule irregularity and service disruptions is not

how dependably the train is operated, but how serviceable is the transit equipment itself. Thus,

schedule adherence ultimately reduces to a question of whether the equipment can render service

when needed.

Technically, the ability of equipment to render

service when needed is known as availability and

embraces two separate concerns:

(1) Reliability—the ability of the equipment to

operate as required at any given

time,

(z) Maintainability—the ability of the equipment

to be restored to operating

condition after failure.

The two are closely related, but only the matter

of reliability will be examined here. Maintainability

is taken up as the next issue. To provide some

perspective for these issues, however, a brief

description of the general nature of reliability,

maintainability, and availability (RMA) is in order,

Reliability, maintainability, and availability are

linked in a relationship that can be expressed

mathematically as:

where A =

R =

M =

mean time to repair (or restore) to

serviceable condition (MTTR)

In effect, the entire expression reduces to a statement of the probability that the equipment will be

available in working condition, or that the

passenger will find the transit system fully operational at any given time,

99

72 .fi8’{ ( ) - 76 - f{
The general standard in transit systems is for the

reliability (MTBF) of major assemblies or subsystems to be on the order of 1,000 hours or more.

Repair time (MTTR) is typically 1 or 2 hours. Combining the separate MTBF and MTTR for all subsystems yields on expected availability of roughly

98 to 99 percent for the entire system. The issues to

be examined here are whether this expectation is,

in fact, realized and what part is played by ATC

equipment in the overall RMA picture.

Despite the recognition in the transit industry

that reliability is perhaps the single most pressing

technical problem, this study did not uncover a significant body of operational data on the performance of vehicle and wayside equipment components. Some transit agencies attempt to maintain a

systematic data bank of reliability information,

with computer analysis and calculation of component reliability rates (MTBF). Others have a less

formal system consisting of shop logs, summaries of

individual failure reports (“bad orders”), and other

such working records. The methods of recording

failures differ among transit systems. Some record

failures at the component level, others group these

failures in higher order assemblies, such as subsystems or replaceable modules. The definition of

what constitutes a failure also varies. Some count

reports of failure by train operators; others count

only failures confirmed by shop personnel and exclude the so-called “false bad order” or intermittent

failure. Still others count only those failures that

disable a train or cause it to be removed or withheld

from operation.

For those that calculate MTBF, some use a time

base that includes all the hours the equipment is actually in operation, counting the time in revenue

service as well as the time in yards or on storage

tracks when the equipment may be energized but

the train not running. Others count only revenue

service hours. This difference alone can have significant impact on the calculated failure rate. A t

BART, for example, it is estimated that yard time is

about twice the revenue hours.

As a result, a quantitative analysis of reliability

could not be performed in such a way to permit

detailed comparison of experience with ATC equipment among transit systems. The following summaries of equipment failure and reliability information for individual systems are therefore not to be

compared, except at the most general level and only

within the limits noted in the discussion.

FIGURE 57.--Carborne and Wayside ATC Equipment

PATCO

reliability and

produces sumPATCO has a computer-basedmaintenance record system that

maries of failure data at 4-week intervals. Table 19

is a sample of car component performance data for a

representative 16-week period from mid-July to the

end of November 1974. Only certain categories of

equipment failure have been selected—ATC equipment and a sample of other major components

generally considered reliable. Data on periodic inspection and preventive maintenance have also

been included to indicate the proportion of

scheduled to unscheduled maintenance events.

It can be seen that ATC equipment failure accounts for about 6 percent of all maintenance

events—roughly the same as the propulsion control

equipment (cam controller) and air brakes, two conventional items of car equipment that are generally

100
TABLE 19.—PATCO Car Component Performance, July-October 1974

NUMBER OF FAILURES PERCENTAGE

COMPONENT 13 JuL- 10 Aug.– 7 Sep.– 5 Oct. - TOTAL 4-WEEK OF ALL

9 Aug. 6 Sep. 4 Oct. 1 Nov. AVERAGE FAILURES

ATC

. Air Brake

Cam Controller

Communication

Controller

Coupler

Master Controller

Motor-Generator

All Other

66

74

47

26

20

60

5

34

1201

73

52

89

31

17

72

1

36

698

100

101

84

30

42

197

7

56

788

45

48

68

31

31

95

4

42

634

284

275

268

118

110

424

17

168

3321

71

69

72

30

28

106

4

42

830

5.7

5.5

5.8

2.4

2.2

8.5

0.3

3.4

66.3

Periodic Maintenance 219 270 449 275 1213 303

IHigh voltage switches.

Zoperator’s control unit in cab.

regarded as reliable elements. The incidence of

coupler failure is about one and one-half times as

high as that of ATC equipment. PATCO was experiencing a problem with couplers at that time,

necessitating a redesign and replacement of the

original equipment. The failure rate for couplers

was therefore unrepresentatively high during the

sample period. From these data, it can be concluded

that ATC equipment at PATCO, accounting for

about one failure in eighteen for the all carborne

components, is not a reliability problem of disproportionate magnitude.

A separate analysis, performed by Battelle Columbus Laboratory in support of this study, considered only disabling failures59 and covered a 1-

year period from August 1973 to July 1974. These

data, presented in table 20, indicate that ATC

failures accounted for about 10 percent of all train

removals during the year, but with considerable

variance. ATC failures, expressed as a percentage

of all disabling failures, ranged from as low as 7 percent to as high as 22 percent. Using these data, Battelle also calculated MTBF for vehicles as a whole

and for carborne ATC equipment. Vehicle MTBF

was found to be 23.9 hours, and the ATC MTBF

was about 227 hours, Since cars were operated an

average of 30 hours per week, each car had about

1.2 disabling failures per week.

WA disab]ing failure, as defined by PATCO, is one tha t

would require removal of a train or car from service or prevent

its return to service after leaving the line at the end of a

scheduled run.

ATC accounted for about one-tenth of the

removals, or roughly one removal per car every 8

weeks. Thus, ATC reliability accounted for 6 percent of all failures but about 10 percent of removals

from service, a reflection of the criticality of ATC to

train system performance. Still, the magnitude of

disabling failures due to ATC was not large—representing about one incident per ca r

every 8 weeks or, for the whole fleet of 75 cars, 488

removals due to ATC out of the 4,797 experienced

in a year,

BART

Like PATCO, BART has a computer-based

recordkeeping system for reliability and maintainability information. However, because of

differences in the definition of failure and the

equipment categories in which data are tabulated,

reliability data for the two systems cannot be

directly compared. Table 21 is a summary of

reported failures by major equipment categories for

the period January 1, 1974, to January 21, 1975. Two

major classes of equipment are included, carborne

equipment and wayside equipment, The latter class

includes a substantial amount of train control

equipment required for ATP (interlocking control),

ATO, and ATS.

The failure of BART carborne ATC equipment

accounts for about 11 percent of all carborne equipment failures, a proportion almost identical to that

of PATCO, if it is assumed that all the BART

101
TABLE 20,—Summary of Disabling Equipment Failures in PATCO, August 1973–July 1974

Disabling Failures2 ATC Failures3

Four-Week Total Percentage Percent of

Interval Ending Failuresl Number of total Number Disabling

8/10/73

9/7/73

10/5/73

11/2 /73

11130/73

12/28/73

1/25/74

2/22/74

3/22/74

4/19/74

5/17/74

6/14/74

7/12/74

Total

Average

755

1161

1339

1234

1197

1180

1193

1399

1298

962

1105

1197

1206

425

777

913

835

769

788

716

839

807

541

690

682

682

56.3

66.9

68.2

76,7

64.2

66.8

60.0

60.0

62.2

56.2

62.4

57.0

56.6

73

47

95

84

78

56

57

69

53

120

91

108

66

17.2

6.1

10.4

10.1

10.1

7.1

8.0

8.2

6.6

22.2

13.2

15.8

9.7

15,226 9,464 62.2 997 10.5

1,171 728 62.2 76.7 10.5

Battelle calculations, based on PATCO data)

IDoes not include preventive maintenance or cleaning.

ZDefined by pATCO to be critical fai]ums that would require removal of a train or would prevent its return to service after leaving the line at the end of its scheduled run.

3Does not include communications since PATC() does not consider this disabling.

TABLE 21.-Summary of Equipment Failure in BART, 1974–751

COMPONENT Number of Average Percent of Failures per car

failures per month total failures per month2

Carborne Equipment:

ATC

Air Conditioning

Auxiliary Electrical

Car Body

Communication

Doors

Friction Brake

Propulsion ●

Suspension

Truck

1,295

504

834

1,676

500

598

1,375

4,158

222

614

102

40

66

132

40

47

109

329

18

49

10.9

4.3

7.1

14.2

4.3

5.0

11.7

35.3

1.9

5.3

0.35

0.14

0.22

0.45

0.14

0.16

0.37

1.15

0.06

0.17

TOTAL CARBORNE 11,774 932 — 3

3.16

Wayside ATC Equipment:

ATO 339 27 21.3 N A

4

ATP

5

696 55 43.3 NA

ATS (Central) 41 3 2.4 NA

Power 31 2 1.6 NA

Switch & Lock 198 16 12.6 NA

Yard Control 299 24 18.9 NA

TOTAL WAYSIDE

ATC EQUIPMENT 1,604 127 — —

IThe period covered is from ]anllary 1, 1974 to January 21, 1975, 12,65 months. *

z~sed on an average fleet size of 295 (145 A-cars, 150 B-cars) during the period.

3Does not sum because of rounding in individual calculations.

qNot applicable.

SIncludes multiplex and interlocking control equipment.

102
failures should be counted as disabling. To this,

however, must be added the failures of wayside

equipment, which in BART accounts for a sizable

share of the train control system. BART wayside

ATC equipment, including central supervisory

(ATS) equipment, experiences about 127 failures

per month, the equivalent of 6 per day.60 In comparison with carborne equipment failures, wayside

failures tend to have more widespread consequences because all trains operating in the vicinity

(or, if a central control failure, all trains in the

system) are affected.

Reliability of equipment has been a major

problem in the BART system. For example, an

analysis of the operating logs for the period May

1974 to January 1975 shows that only slightly over

half of the car fleet was available for service at any

given time and that availability declined regularly

throughout the day and week. The problem was

particularly severe with the A-cars, which contain

the train control electronics. In an average week

during this period, only 71 of the 148 A-cars (48 percent) were in running condition. From Monday to

Friday, availability declined by an average of 8 cars,

often leaving fewer than 65 A-cars in service by Friday.

The extent to which ATC equipment reliability

contributes to the overall pattern of car problems

and service disruptions could not be determined

conclusively. The BART staff estimated that ATC

was initially cited as the reason for about 20 percent

of all train removals, but the actual figure may be

somewhat lower if “false bad orders” are discounted and only confirmed ATC failures are considered. Even so, ATC is not the single largest cause

of train removal. Propulsion motors, car body

defects, and brakes each account for a larger share

of car system failures than ATC.

CTA

Automatic train control equipment in CTA consists of wayside signals with trip stops on some

parts of the system and cab-signaled ATP on others.

Since the extent of train control automation is

lower than in PATCO or BART, it would be expected that the proportion of train removals due to

ATC failure would also be lower. This hypothesis

ISOBART operates only on weekdays, or about 20–21 days per

month.

cannot be conclusively affirmed because CTA does

not maintain a formal equipment reliability record

that would allow MTBF to be calculated directly.

However, a partial analysis, performed as part of

this study, sheds some light on the situation.

An analysis of carborne equipment reliability on

the West-South route for a representative 16-week

period in 1974 was performed by CTA personnel at

the request of the OTA staff, The results are shown

in table 22. Because two different types of cars are

operated on this line (180 2000-series cars and 78

2200-series cars) failures for each are tabulated

separately. Cab signal equipment, although listed as

a single entry, is of two types-one a rather simple

and conventional design and the other more complex and technologically advanced.

Cab signals are the largest failure category for

equipment on the West-South route, accounting for

44 percent of the sample of cases reported; but there

are several factors operating here that may have

distorted the results. First, this is only a partial listing of failures. When considered in the context of

all equipment failures, cab signal failures would

represent a lower proportion. CTA maintenance

personnel estimate that cab signal failures account

for no more than 20 percent of all “bad orders.”

Second, it should be noted that the total of 307 cab

signal failures listed in table 22 are reported failures.

Shop personnel confirmed only about 60 percent of

this number—the remainder being either erroneous

reports by motormen or intermittent failures that

could not be duplicated in shop tests. This illustrates the general problem of confidence in

reliability statistics, where the basic data may be

questionable because of incorrect initial diagnosis

or the inherent difficulty in troubleshooting

electronic equipment. Third, the cab signal failures

reported here are not all disabling failures. Some are

malfunctions of nonessential features, such as

burned-out indicator bulbs, that do not affect the

performance of the equipment for basic train protection functions. Fourth, the West-South route was

in the process of converting to cab signal operation

during the time period considered in this sample,

The general experience of CTA has been that

equipment reliability is particularly troublesome

during the initial installation and check-out period.

This is true not only of cab signals but any other

new and complex type of transit equipment introduced in an established system.

103
TABLE 22.—Car Component Performance on CTA West-South Route, July–October 1974

Number of Failures

Failures

COMPONENT 13 Jul. – 10 Aug.– 7 Sept.– 5 Oct.– TOTAL 4-WEEK per car

9 Aug. 6 Sept. 4 Oct. I Nov. AVERAGE per week

Cab Signals

Reported Defective

(Confirmed)

(Unconfirmed)

(:)

(34)

(:;)

(22)

(::)

(25)

(::)

(41)

307

(185)

(122)

(::)

(31)

0.08

(0.04)

(0.03)

Doors

2000 -Series1

2200 -Seriesl

All cars

(13)

(26)

39

(21)

(14)

35

(29)

(15)

44

(29)

(16)

45

( 92)

( 71)

163

(23)

(18)

41

(0.03)

(0.06)

0.04

Dynamic Brakes

2000-Series

2200-Series

All cars

(19)

( 4)

23

(12)

( 5)

17

(19)

( 5)

24

(19)

( 2)

21

( 71)

( 16)

87

(18)

( 4)

22

(0.03)

(0.01)

0.02

Friction Brakes

2000-Series

2200-Series

All cars

( 7)

(lo )

17

( 7)

(14)

21

(lo)

(25)

35

(19)

(22)

41

( 43)

( 71)

114

(11)

(18)

29

(0.02)

(0.06)

0.03

Traction Motors

2000-Series

2200-Series

All cars

( 3)

( 3)

6

( 5)

( 2)

7

( 8)

( o)

8

( 4)

( o)

4

(20)

( 5)

25

( 5)

( 1)

6

(0.01)

—

0.01

ITwo types of cars are opera ted: 180 200()-series cars (purchased 1964) and 78 2200-series cars (purchased 1969–70).

cars. The older equipment, despite having been in

service much longer, was five to ten times more

reliable than the newest equipment—the R–44

series cars. For example, the R–36 cars (purchased

in 1962) had 4,048 hours MTBF; and the R–38 cars

(dating from 1965), had 2,126 hours MTFB.62 In contrast, MTBF for the new R–44 cars was only 421

hours-or about half that of the fleet as a whole.63

Preliminary indications are that the newest equipment, the R–46 series now being delivered, have

even less low reliability.

This experience suggests that some of the

reliability problems experienced by new systems

such as PATCO and BART result not so much from

train control automation as from the general complexity of the newer transit vehicles, All types of

NYCTA

NYCTA has wayside signals and trip stops for

ATP and virtually no carborne ATC equipment except on the R–44 and R–46 cars.61 The experience

of NYCTA with equipment reliability is, therefore,

a useful baseline from which to estimate the

general performance of car components other than

ATC,

During 1974, there were 32,515 delays in service

in NYCTA, about 90 per day. Of these 16,872 (52

percent) were chargeable to car equipment failure.

During the same period, wayside signal failures accounted for only 1,435 delays, or 4.4 percent.

Using NYCTA data, Battelle Columbus

Laboratory estimated that the reliability of NYCTA

cars was about 842 hours MTBF. However, there

was great variability among the different models of

GIThe R–44 and R–46 cars are equipped with cab signa]s; but

since the wayside equipment associated with cab signaling has

not yet been installed, the cars are run with the cab signal units

cut out.

1 0 4

8ZThe R–36, R–38, and R–44 cars were all purchased from

the same manufacturer.

f33The average age of the NYCTA fleet is 17 years, with

almost one-sixth having been in service over 28 years. All of

these oldest models had an MTBF greater than that of the R–44

cars.
car equipment have grown more complex over the

years. Propulsion motors, suspension systems, door

operating mechanisms, air conditioning, and

couplers are but a few of the mechanisms that have

become more complicated and sophisticated. Thus,

ATC equipment may produce reliability problems,

not because of automation per se, but because it

represents the introduction of one more complex

piece of equipment in an already complex vehicle.

The general rule of reliability is that as the number

of interacting components increases, the overall

reliability of the system decreases, The experience

of NYCTA, which has no carborne ATC equipment, confirms this point.

ISSUE O–8: MAINTAINABILITY

To what extent does ATC equipment maintainability contribute to the general maintenance

problems of transit systems?

ATC equipment is considered by transit

managers to be a major maintenance problem,

but probably no more so than other types of complex and sophisticated transit equipment. T h e

problem of ATC maintenance is difficult to

assess quantitatively because of the scarcity of

detailed data and the variety of recordkeeping

methods employed by transit systems.

Maintenance of transit system equipment is a

never-ending battle. Weather conditions, hard daily

use, and the demands of meeting train schedules all

tax the ability of equipment to perform as required

and increase the pressure to restore equipment to

service when failures occur. The promptness with

which maintenance is performed and the effectiveness of the repair action play a role almost as important as equipment reliability itself in sustaining the

required level of service to transit system patrons,

The overall importance of maintenance in the

scheme of transit operations is illustrated by the

fact that in most systems the maintenance force is

equal to or larger than the force required to operate

the trains. Maintenance of ATC equipment,

because it is vital to the safety and efficiency of

train operations, is of special concern.

The influence of ATC equipment maintainability on the general maintenance picture is

hard to determine. Most transit systems do not keep

detailed and formal records that would allow the

maintenance problems of ATC (or any other

specific kind of equipment) to be analyzed and

evaluated in precise quantitative terms. Shop logs,

workmen’s time records, and repair tickets are

useful as working documents, but they do not lend

themselves to treatment as a data base for calculating maintainability statistics such as mean time to

restore (MTTR). The following observations,

therefore, are based primarily on interviews with

transit system maintenance personnel and constitute largely opinion and anecdotal evidence. This

is supplemented with a small amount of data obtained from BART and PATCO, where detailed and

quantitative maintenance records are kept.

The general feeling among transit system personnel is that ATC equipment poses especially

difficult maintenance problems. Because this view

is widely held by those intimately acquainted with

the maintenance situation, it must be accepted.

However, the data from PATCO, and perhaps

BART also, do not entirely bear this out. This is not

to deny that maintenance of ATC equipment requires substantial effort but simply to suggest that

the size of the effort is not disproportionate in relation to that required for other types of transit

system equipment of similar complexity and

reliability, An examination of the data from

PATCO will help to clarify this point.

Table 23 is a summary of maintenance time for

several types of equipment in PATCO during a recent 16-week period. Maintenance time is expressed in terms of mean time to restore or repair

(MTTR) and as a percentage of the total maintenance effort. For comparison, the frequency of

failure for each type of equipment is also shown,

expressed as the percentage of total failures,

In terms of both average repair time (MTTR) and

proportion of the maintenance effort, ATC equipment is not significantly different from other types

of equipment. MTTR is slightly over 3 hours for

ATC, the same as for the master controller and only

a few minutes longer than for the cam controller or

motor generator. It is also significant that the time

required for ATC repairs is in the same proportion

to the total maintenance effort as ATC failures are

to total equipment failures.

Interviews with maintenance personnel from

other transit systems suggest, however, that the

PATCO situation may not be typical, The experience in these other systems, notably older

105
TABLE 23.—Maintenance Time for Selected PATCO Car Components

COMPONENT

Average

Number of Total Repair Repair Time Percent of

Failures or Time (MTTR) All Maint- Percent of

Events (hours) (hours) enance All Failures

ATC

Air Brake

Cam Controller

Communication

Controller

Coupler

Master Controllers

Motor-Generator

All Corrective Maintenance

284

275

288

118

110

424

17

168

5,005

881

636

803

165

270

582

53

449

12,007

3.1

2.3

2.8

1.4

2.5

1.4

3.1

2.7

2.4

5.1

3.7

4.6

0.9

1.6

3.3

0.3

2.6

69.0

5.7

5.5

5.8

2.4

2.2

8.5

0.3

3.4

—

Periodic Maintenance 1,213 5,387 4.4 31.0 —

IData are for a 16-week period, July 1–November 1, 1974.

ZHigh vo]tage switches.

Soperator’s control unit in cab.
systems converting to

train control, indicates

more automated forms of

that ATC equipment takes

longer to repair than other kinds of equipment. This

is probably true if the comparison is made to conventional mechanical components. It could not be

established how ATC repair time compares to that

for other kinds of complex electronic equipment, in

part because there is relatively little such equipment in use, except for radios and some elements of

the propulsion control system.

Several reasons are cited by maintenance personnel to support this view that ATC equipment is

difficult to maintain. Troubleshooting and fault

isolation are more difficult procedures. It may take

a substantial amount of time to confirm the train

operator’s report of trouble. Some kinds of failure

are intermittent; others are difficult to reproduce

under shop conditions. Also, the description of the

malfunction reported by the operator may be erroneous or imprecise. Once the fault is diagnosed,

the repair process may be time-consuming, both

because of the type of work required and because of

the need to check out additional secondary

problems. A recurring problem in electronic maintenance in general, and ATC in particular, is the

difficulty in ascertaining the effectiveness of the

repair. This is the so-called repeating failure. In

BART, for example, it is estimated that about onethird of the cars account for over two-thirds of the

repairs; and a car delivered to the shop for a specific

repair may be returned one or more times on successive days for the same reason. This has led some

maintenance managers to the conclusion that

realistic work planning must be based on the

assumption that corrective maintenance for A T C

equipment will be from 1.25 to 2 times the equipment failure rate,

It is widely agreed that the maintenance of

electronic equipment, of which ATC equipment is a

prime example, calls for a different type of maintenance skill than conventional transit system equipment. The human factor aspects of this problem

will be treated later in a separate issue, but it should

be noted here that the qualifications and experience

of the shop force have a sizable influence on the

success of ATC maintenance operations. Related

problems are the shortage of qualified maintenance

technicians and the more extensive training required to bring in new personnel or reassign the existing shop force. These manpower problems are

especially keen in established transit systems going

through a process of installing a new ATC equipFIGURE 59.-Cab Signal Maintenance

ment or adding new lines. New systems tend to

recognize these problems in advance and make provision to solve them in the preparatory period

before inaugurating operations. Even so, this anticipatory action is not always successful, and new

systems such as BART have had trouble in acquiring and training a suitable shop staff for electronic

maintenance.

A related problem is that of facilities and shop

equipment. The work space and tools required to

maintain electronic equipment are very different

from that of the conventional car shop. Most transit

maintenance is dirty, heavy work that is largely

mechanical, Electronic maintenance calls for a

facility more like a laboratory or television repair

shop. Special tools and test equipment are needed,

and many transit systems have had to build such

items themselves because of a lack of a suitable version on the general market, Older systems like CTA

and MBTA have also had to build new maintenance

facilities or remodel existing ones in response to the

special needs arising from introduction of cab signals and related ATC equipment. But here again,

the problem is not peculiar to ATC but stems from

the more general trend in rail rapid transit to convert to a different form of technology.

107
As a final point, it should be noted that the

design of ATC equipment and its placement on

transit cars may aggravate the problems of maintenance. Access to equipment cases or individual

components within them may be difficult; and the

time to remove and replace an item may exceed

repair time itself. In some instances, the equipment

is not designed modularly so that defective elements can be quickly replaced and the car restored

to service.

Repair of electronic equipment while it is in

place on the vehicle is generally not an efficient

maintenance strategy; but in many cases, the

strategy of on-vehicle repair has been forced on

maintenance personnel by a lack of spare parts.

Nearly all transit maintenance and operating personnel interviewed during this study cited

availability of spare parts as a major problem.

Several factors seems to be at work here. First, there

is the generally low reliability of new equipment;

components are wearing out or becoming unserviceable at a much higher rate than anticipated.

Second, there has been some instances of inadequate provisioning of spare parts in the initial procurement order. The lead time for replenishing stocks is

often long, which tends to exacerbate the spare

parts problem once it is detected. Third, some suppliers do not find it profitable to keep a supply of

items that may be peculiar to a single transit system

or to only a single procurement order by that

system, Transit systems, old and new alike, have

found it increasingly difficult to locate alternative

sources of supply, The shortage of spare parts is not

restricted to ATC equipment. It is a general problem

in the transit industry, cited here to indicate all the

factors that influence the maintainability of train

control equipment,

The car availability problems that have plagued

the BART system have received widespread attention in the transit industry and in the public at large.

Equipment reliability, and often ATC system

reliability, is cited as the major cause. Upon closer

108
examination, it appears that maintenance may also

be an important part of the problem. A recent

management audit of BART (Cresap et al., 1975)

stated that maintenance was the prime problem to

be solved by BART and recommended that approval for a full 20-hour, 7-day operating schedule

be withheld until the maintenance backlog is

cleared up and continued operation of the full 450-

car fleet could be assured, Fig. 61 is a summary of

the maintenance situation that existed in BART

from May 1974 to January 1975, roughly the period

during which the management audit was conducted. These findings are offered not in order to

single out the BART system for special criticism but

only to illustrate the impact that maintenance can

have on car availability and transit system performance, In this regard, the categories of “Backlogged for Corrective Maintenance” and “Awaiting

Parts” are particularly noteworthy, Estimates by

BART officials indicate that ATC equipment maintenance makes up 10 to 20 percent of the total maintenance burden, a proportion roughly equivalent to

the ratio of ATC failures to all equipment failures.

Average Fleet Size:

A-Cars 148

B-Cars 174

Total 322

FIGURE 61.—Influence of

COST

The costs of automatic train control, both the

initial capital cost to design and install ATC equipment and the cost to operate a transit system with

ATC, raise several important issues,

1n the area of capital cost, there is a need to examine the expense of acquiring an ATC system, in

absolute terms and relative to the cost of the whole

transit system. It is also important to examine the

incremental capital costs associated with increasing

the level of automation from a simple ATP system

to one including ATO and ATS as well,

With regard to operational cost, the general issue

is the comparative expenses of transit systems

employing different levels of automation. Within

this issue are specific questions relating to manpower and labor cost savings that may be derived

from automation. There is also the question of

energy savings that may be achieved by the more

efficient train operation claimed to result from

ATO and ATS,

Maintenance on Car Availability in BART, May 1974–January 1975

109
Ultimately, the matter of cost reduces the question of whether the greater expense required to acquire an ATC system can be recovered by operational savings over the life of the equipment, This

matter is important, not just because of the public

funds involved in capital grants and operating subsidies, but also because advocates of automation

claim that ATC more than pays for itself in the long

run,

System Size and Configuration—miles of track,

number of interlocking, number of stations and

terminals, the number of trains or vehicles operated, and the nature of the train consist (i. e., A and

B cars, married pairs, single-car trains, etc.),

Condition of Installation—installation as part

of the original construction of the system or as an

add-on to a system already in service. (The latter is

generally more difficult and expensive.)

Customized Design s—the degree to which a

specific ATC installation differs from other ATC

designs in use within the system or elsewhere and

the degree of custom engineering required to meet

local requirements.64

ISSUE O–9: CAPITAL COSTS

What are the capital costs of automatic train

control ?

ATC equipment costs are roughly 3 to 5 percent of the total capital costs for a rail rapid transit system. Ninety percent or more of the ATC

cost is for wayside equipment.

Table 24 is a summary of capital costs on transit

systems recently built or now under construction,

Because of the factors cited above and the effects of

inflation, the costs of these systems cannot be

directly compared, However, the data do indicate

the general range of costs incurred in recent years

by transit agencies building completely new

systems with advanced levels of ATC.

The capital costs of an ATC system are influenced by a number of factors, primarily:

Level of Automation—the number of ATP,

ATO, and ATS functions which are automated and

the degree of operational sophistication (the number of running speeds, degree of supervisory control, or station stopping accuracy).

64One supplier of ATC equipment estimated that special

engineering of just the speed regulation and station stopping

equipment for a new installation can cost between $100,000 and

$200,000.

TABLE 24.-Capital Costs in New Transit Systems

●

PATCO BART WMATA MARTA MTA

(Baltimore)

INITIAL SERVICE

TOTAL SYSTEM

Cost ($ million)

Miles

Cost/Mi. ($ million)

VEHICLES

Cost ($ million)

Number

Cost/Vehicle ($)

TRAIN CONTROL

Automation Level6

Cost ($ million)

1969 1972 1976 1979 1981

1135

14

9.6

1,586

71

22.3

24,650

98

47.4

2

2,10 0

50

42

3450

31 5

330

15

75

200,000

143

450

318,000

199

556

358,000

N A

4

338

NA4

N A

4

N A

4

N A

4

ATP, ATO, ATS

2

100

ATP, ATO

4.5

ATP, ATO, ATS

5

40.5

ATP, ATO, ATS

N A

4

ATP, ATO, ATS

3

2 5

I ] n{:] I I{ifIS t:,] 1) i I il I c;{}st (If n[It\ ( ;on~ I rl It: t i on i] nd (’[] I I i preen t. N’ no ~’,] t ion, iI n(l IISI i m i] t(’(1 v, I I I I (I () f [)rII~I x i st i n~ ri~ h t -of-~v,l \ ,1 n(l

st rl I(:t I I r[)s

~Cllrrent estimate, cost Ily Comp]etlon date will probab]y be higher.

:) Estimate for phase I, I ~-mile partial system (1970 dollars).

aNot available,

sInc]lldes a(](i itional work; original bid was $26,2 million.

GATS here means computer-aided Central control.

110
Since there are so many local and temporal factors at work, and because so few new systems have

been built, historical data on procurements in such

systems as PATCO, BART, and WMATA and projections for MARTA and MTA do not provide a

meaningful picture of the capital cost of ATC. A

different perspective is provided by Table 25, which

contains estimated capital costs based on interviews

with manufacturers and consultants concerning the

current prices (1975 dollars) of major ATC system

components.

Table 25 separates ATC equipment into two

categories: carborne equipment and wayside equipment (including central control and ATS equipment). Within each category, successive levels of

automation are identified and priced. The prevailing view in the transit industry today is that cab signals, overspeed protection, route interlocking, a

modest supervisory system, and the associated communications equipment represent the minimum

ATC system that will be installed. Thus, the first

entries in the vehicle and wayside categories of table 25 should be considered a baseline system. Additional features incur additional costs as indicated.

To obtain an estimate of the total cost of a typical

ATC installation, consider the example of a hypothetical transit system consisting of 50 miles of

double track (100 single-track miles) and zOO carborne controlled units (400 cars operating as married pairs with one ATC package per pair). The

total cost of a baseline ATC installation (ATP only)

in such a transit system would be approximately

$59.5 million ($57.5 million for wayside and $2

million for carborne equipment) .65 This would be a

system with a level of automation roughly

equivalent to the MBTA Red Line or the CTA

West-South Line. The addition of ATO (the second

entry in the wayside and carborne categories of table 25) would raise the cost to almost $70 million

($65 million wayside, $4.5 million carborne), This

would be a system resembling PATCO. The addition of ATS, to build a system with a level of

automation similar to BART, would raise the

capital cost to $87 million ($82.5 million wayside,

$4.5 million carborne). Note that the addition of

ATS does not increase the cost of carborne ATC

equipment since virtually all the additional equipment needed for ATS is in the central control

facility.

While the absolute cost of an ATC system may

be large, ranging up to $100 million or more for a

large system with a high level of automation, its

sSTheSe estimates assume vaiues for carborne and wayside

equipment costs in the middle of the ranges given in table 25.

TABLE 25.—Cost Estimates for ATC Equipment

UNIT OF MEASURE APPROXIMATE UNIT

COS T

Single-Track Mile 500.000-650,000

CARBORNE EQUIPMENT

Cab signaling and overspeed protec - Controlled Unit2

$ 9,000-11,000

tion

Above, plus speed maintaining, pre- Controlled Unit2

18,000-25,000

cision stopping, performance

level adjustment, and train

identification

WAYSIDE EQUIPMENT

Cab signaling, overspeed protection,

route interlocking, dat a

transmission, modest supervisory system

Above, plus precision stopping, per- Single-Track Mile 550,000 -750! 000

formance level adjustment,

and train identification

Above, plus sophisticated ATS with Single-Track Mile 750,000-900,000

computerized control

11975 dollars

2A c~ntr~lled \lnit may be more than one vehicle. e.g., a married pair of cars typically has only one set of ATC eq~lipment,

(SOIJRCE: FX]ttellf’ from man~lfacturer and consultant interviews.)

‘11 1
cost relative to the total capital cost of the system is

low. A rail rapid transit system typically costs $30

million to $45 million per double-track mile to

build. Transit vehicles cost in the range of $200,000

to $350,000 each, depending upon their size and

complexity. On this basis, wayside ATC equipment

represents something on the order to 3 to 6 percent

of the cost per track mile. Carborne ATC accounts

for 5 to 12 percent of vehicle cost.

Returning to the example of the hypothetical

system, the total cost would be about $2 billion.66

The ATC system, depending upon the level of

automation selected, would run between $60

million and $87 million, or 3 to 5 percent of the total

capital cost, Note that the cost increment associated

o6(50 doub]e-track miles X $35 mi]]ion per mile) + (400 cars,

i.e., 200 married pairs, x $300,000) = $1.88 billion + $0.lz billion

= $2 billion.

BART Elevated Guideway

Section of BART Transbay Tube

WMATA Pentagon Station

FIGURE 62.—Transit System

WMATA Judiciary Square Station

Construction

112
with selection of an ATC system with a high level

of automation instead of a baseline system with

ATP alone, would amount to only 2 percent or so of

the total capital cost of the transit system. Note also

that the bulk of the expense, either for a baseline or

a highly automated ATC system, lies in wayside

equipment—90 percent or more.

ISSUE 0–10: OPERATIONAL COST

How do the operating costs of systems with

automatic train operation compare to those of

systems where trains are run manually?

The costs of operating trains are somewhat

lower in systems with ATO, but the maintenance costs are higher. In general, ATO reduces

the proportion of personnel-related costs in

operating a transit system.

One of the purported advantages of automatic

train control (particularly automatic train operation) is that it can reduce the operating costs of a

transit system. This reduction would be brought

about primarily by decreasing the number of personnel needed to operate the system. The question

of workforce reduction is thus a pivotal issue that

needs to be examined from several aspects. The

purpose here is to look at operating cost in general

terms to provide a background for the specific discussions of workforce reduction in the two follow -

ing issues.

Table 26 is an analysis of operating costs for the

most recent year in five transit systems, Since these

systems vary greatly in size and service level, the

data are normalized by expressing cost in terms of

dollars per revenue car mile and as percentages of

total operating expenses for each system. Costs are

allocated to three categories: transportation, maintenance, and administration, The transportation

category includes all costs incurred in providing

passenger service. Payroll and fringe benefits for

train crews, central control personnel, station

attendants, and supervisors are the largest components; but the category also includes electric power

costs and all other expenses associated with transit

operations. 67 Maintenance includes all personnelrelated costs for vehicle, track, signal, and structures maintenance as well as the cost of material

and supplies. Administration is made up of all expenses associated with management, support, and

administrative services and all general expenses not

directly attributable to either transit operations or

maintenance ,

The five systems are arrayed in an order that

represents an increasing level of automation, from

left to right, but the principal distinction is between

NYCTA, CTA, and MBTA with conductors on the

trains and PATCO and BART without. Note,

however, that technology is not the only factor

determining the size of the train crew, Local labor

67Transit police expenses have been excluded since not all

systems have an internal police force.

TABLE 26.—Summary of Rail Rapid Transit Operating Costs

NYCTA CTA MBTA PATCO BART

(1973/74) (1974) (1974) (1974) (1974/75)

OPERATING COST ($/revenue car mile)

Transportation 1.05 0.95 2.15 0.72 0.89

Maintenance 0.62 0.44 1.45 0.59 11.33

Administration 0.26 0.15 1.22 0.16 0.30

Total 1.93 1.54 4.82 1.47 12,52

PERCENT OF OPERATING COST

Transportation 55 62 45 49 36

Maintenance 32 29 30 40 52

Administration 13 9 25 11 12

RATIO OF MAINTENANCE COST TO

TRANSPORTATION COST 0.59 0.44 0.68 0.82 1.48

SALARIES. WAGES & BENEFITS AS PERCENTAGE OF OPERATING COST 82 82 80 64 74

I For stable year operation, BART forecasts a maintenance cost of about $0,83 per revenue car mile, with transportation and administrative expenses remaining a t present levels, If the reduction of maintenan(;e is achieved, the total cost per revenue car mile

would be $Z. OZ and the maintenance-transportation cost ratio would he 0,93.

113
agreements and operating philosophy also play

strong roles. Thus, any cost differences among

these systems are not purely the result of train control automation.

Examination of the revenue costs per car mile

reveals a wide variation among the five systems,”

with no clear-cut pattern. PATCO, a system with

ATO and a single train operator, has the lowest

overall operating cost;

68 but BART, which is

equally automated in the area of ATO, has costs

substantially higher than any system except MBTA.

B~The pATcO figures are somewhat deflated in the area of

transportation and administration. PATCO stations are largely

unattended, while all the other systems have station attendants.

Many administrative functions normally carried out by a transit

agency are, in the case of PATCO, accomplished by its parent

organization, the Delaware River Port Authority. If allowance is

made for these factors, the transportation-related costs of

PATCO might be on the order of 80 to 85 cents per revenue car

mile and the administrative costs 20 to 25 cents per revenue car

mile.

Nevertheless, it does appear that transportation

costs are lowest in the two systems with ATO. It

also appears that maintenance costs are somewhat

higher than in systems with manually operated

trains. In the case of BART, this is probably a reflection of the general maintenance problems that have

plagued the system and not a specific effect of

ATO.

The reciprocal relationship of maintenance and

transportation costs appears most pronounced

when they are expressed as percentages of the total

operating cost of the respective systems. As the proportion of transportation costs goes down, the maintenance proportion rises; and the sum of the two is a

roughly constant 80–90 percent of the whole.69 The

tendency of the relative cost of maintenance to in-

~gThis generalization does not hold true for MBTA, where

the percentage of administrative costs is unusually high and

where absolute costs are about double those of any other system,

+’

.

FIGURE 63.—Winter on the Skokie Swift Line

114
crease as a function of automation also appears

when maintenance cost is expressed as a ratio of

transportation cost.

Another apparent, and logically expected, effect

of automatic train operation is the lower proportion

of payroll-related costs in PATCO and BART.

Labor accounts for 80 to 82 percent of operating cost

in the systems with manually operated trains and

two- or three-man crews. In PATCO, labor costs are

only about two-thirds of total cost—partly due to

one-man operation and partly due to the absence of

station attendants. In BART, the percentage is higher, although still lower than NYCTA, CTA, and

MBTA. BART officials forecast that the labor component will drop to something like 65 to 70 percent

when the debugging period is passed and the maintenance situation becomes more normal.

While some of these observed differences u n -

doubtedly arise from causes not related to automation, it does appear that ATO (insofar as it leads to a

reduction of train-crew size) has the effect of

lowering labor cost and, perhaps, overall operating

expense, This conclusion must remain tentative at

this point because the data are limited to such a few

cases. However, it deserves further examination in

the following issues, which deal more specifically

with the manpower effects of ATO,

ISSUE 0–11: WORKFORCE REDUCTION

Does automatic train controJ lead to a reduction of the workforce?

Automation of train operation functions, permitting reduction to a one-man train crew, leads

to small but significant workforce savings.

Further automation, but short of total automation, has little effect.

As a concept, automation implies the replacement of human labor with machines. In some cases,

automation results simply in lessening th e

workload for operating personnel without changing

the manning level of the system. In other cases, it

may be possible to replace a human operato r

altogether--either by assigning all functions to

machines or by consolidating several partially automated functions into a smaller number of operator

positions. The potential economic advantages of

automation are large, Rapid transit is a labor-intensive system, in which personnel costs (salaries and

benefits) typically account for 65 to 85 cents of every dollar of operating expense. Clearly, even a

small manpower reduction of 10–15 percent would

have enormous leverage and might make the

difference between an operating deficit and breaking even,

Historically, rail rapid transit has pursued a

course of consolidation by successively reducing

the number of conductors in the train crew, In the

early days, conductors were assigned to each car or

pair of cars to collect fares and operate the doors. As

fare collection was transferred to stations and as

semiautomatic and power-assisted door mechanisms were introduced, the conductor workforce

was reduced to one per train, with even greater

relative reductions brought about by running longer

trains. In newer systems such as PATCO and

BART, the conductor has been eliminated

altogether, and the door operation function has

been transferred to the train operator (PATCO) or

automated entirely (BART). The ultimate step is a

fully automated system like AIRTRANS, which

operates unmanned vehicles.

Table 27 shows the general effect on the

workforce produced by various levels of ATC.

Representative transit systems are listed by increasing level of automation. Because these transit

systems vary greatly in size and organizational

structure, the data have been normalized by expressing workforce as the ratio of operations and

maintenance personnel to vehicles. Personnel

responsible for administrative, support, planning,

developmental engineering, station operation, station maintenance and police activities are excluded

in order to confine the comparison to the area most

directly affected by ATC.

For MBTA, NYCTA, and CTA, where automation is the least and the train crew is two or three,

the employee/vehicle ratio is between 3.1 and 2.4.

In PATCO, where ATO has permitted reduction of

the train crew to one, the ratio is lower than in

MBTA and NYCTA but higher than in CTA, The

PATCO ratio might be lower if PATCO were more

nearly the same size as the others. There are undoubtedly economies of scale in a large organization that cannot be obtained in a transit property

with only 75 vehicles and 203 operations and maintenance employees.

The more advanced level of automation represented by BART does not result in a manpower

1 1 5

72-6 H:i ( ) - 7’ (1 - ‘1
TABLE 27.—Effect of Automation on Size of Workforce

TRAIN O&M TRANSIT EMPLOYEES

SYSTEM I CREW EMPLOYEES VEHICLES PER VEHICLE

MBTA 3

2 – 3 1,063 354 3.0

NYCTA 2 21,045 6,681 3.1

CTA 2 2,594 1,094 2.4

PATCO 1 203 75 2.7

HART (1974/75) 1 1,000 350 2.9

BART (Stable Year)4

1 1,192 450 2.6

AIRTRANS (1974) o 142 68 241

AIRTRANS (Stable Year) 4

o 122 68 1.8

1 All {]ata are for the most r(’cently (;ompleted opt?rationa] yt?ar.

~lnclll{hw only personnt’1 to opc’rate an(l maintain trains, with immmiiate sllpervisors.

ITra in crew consists of motorman and one train gllarti for each pair of cars,

~Aft[~r (iel}(l~g ing anti transition to fill] operat iona] statlls.

reduction , BART at present has a n

employee/vehicle ratio about equal to MBTA or

NYCTA. In projected stable-year operation, the

ratio will decline to a level comparable to that of

PATCO, The reason for the rather high rate in

BART at present is apparently connected to the

problem of equipment reliability, which necessitates a large maintenance force. Further examination of this point will be deferred to the next issue,

where the composition of the workforce in BART

and other systems will be analyzed,

The employee/vehicle ratio for AIRTRANS, a

fully automated system with unmanned vehicles, is

about the same as PATCO, where there is a oneman train crew, AIRTRANS is, however, a new

system still undergoing operational shakedown.

The present operating force includes 36 passengerservice employees required to help patrons find

their way around the airport. It is anticipated that

the need for such employees will decrease once better signing has been installed. It is also expected

that the maintenance force will be reduced a s

debugging and break-in of the equipment is completed and more operating experience is gained, It is

anticipated that the total of O&M employees would

go down to about 122 in a stable year, producing an

employee/vehicle ratio of 1.8, a figure substantially

lower than that of any manned system,

From these data it appears that ATO, insofar as it

allows consolidation

functions in a single

of conductor and motorman

train operator position, will

produce a small but significant manpower saving.70

Automation to levels beyond the minimum required for such consolidation, but short of full

automation, does not seem to lead to further manpower savings because of offsetting increases in the

required maintenance force,

ISSUE 0-12: WORKFORCE DISTRIBUTION

What effect does automatic train control have

on the composition and distribution of the

workforce ?

As the degree of automation increases, the

number of operation employees goes down, but

the number of maintenance employees goes up.

The net result is a shift in the balance of the

workforce without a substantial decrease in the

total O&M force.

ToTransit system professionals point out that automation is

only one factor influencing the size of the train crew. Union

agreements and work rules, especially in established transit

systems, may play a part in keeping the conductor on the train

even though the train could be satisfactorily operated by one

person at the existing level of automation. In some circumstances, transit system management officials may also conclude

that the conductor position should be retained for reason of

passenger safety in emergencies or as a way of offering information and other assistance to patrons on long trains.

1 1 6
CTA Train With Conductor

BART Train Without Conductor

FIGURE 64.—Reduction of Train Crew

In the discussion of the preceding issue, it was

concluded that automatic train operation (ATO),

insofar as it permits reducing the train crew 10 one,

produces a small decrease in the total O&M

workforce. This decrease, however, is not commensurate with the number of conductor positions

eliminated, It is therefore necessary to examine the

composition and distribution of the workforce at

various levels of automation to see what countervailing effects are at work.

Figure 65 shows the relative size of the operations and maintenance forces in five transit

systems. To illustrate the effect of full automation

(i.e., elimination of all on-board personnel), similar

figures are also given for AIRTRANS, even though

it is not a true rail rapid transit system. Operations

employees are all those necessary to operate

trains-dispatchers, trainmasters, stationrnasters,

towermen, central controllers, and yard motormen

as well as the train crew itself. Maintenance personnel include the employees in car shops, and those

needed to maintain way, power, and signals. The

size of the operations and maintenance forces is expressed as a percentage of all employees for the

respective transit systemsoTl

While there is considerable variation in the data,

there does appear to be a discernible trend. Reading

from top to bottom, as train operation generally

becomes more automated, the proportion of operations employees declines while the proportion of

maintenance employees shows a corresponding increase. It appears that ATO results primarily in a

shift of the balance of the O&M workforce but

without significantly changing its size in relation to

the total workforce. More specifically, as conductors and finally the operator are taken off the train,

almost equal numbers of new jobs are created in the

car shops and wayside maintenance crews.

A more detailed analysis is presented in table 28,

where the workforce in the operations and maintenance departments is expressed in terms of the

number of employees per car. The number of operations employees per car generally declines from

1.2–1.4 for systems with manual train operation

and a crew of two (NYCTA, CTA, and MBTA) to

0.3 for a fully automated system (AIRTRANS).

PATCO and BART, with a train crew of one, fall

about midway between. At the same time, the

maintenance force increases from 0.8 per car in

CTA to 1.8–2.0 for BART and AIRTRANS in the

current year.TZ The same trend shows up even more

clearly in the ratio of maintenance to operations

employees, wherr thrr(] is {i thr[v~ ft)lt I to {[’n felt I

difference between manned systems without ATO

(NYCTA and CTA) and the unmanned AIRTRANS

system, with PATCO and BART falling at roughly

proportional intermediate points.

plTransit police and construction personnel are excluded.

TZEstimates of stable year operations for both systems project

a decrease in the ratio of maintenance employees per car to

1.5–1.7, a figure comparable to PATCO,

1 1 7
NYCTA (1974/75)

CTA (1974)

MBTA (1974)

PATCO (1 974)

BART (stable yr.) 2

AIRTRANS (Stable yr.) 2

1.

2

Excludes transt police and construction personnel

Estimated staffing when debugging IS completed and the system becomes fully operational

FIGURE 65.—Proportion of Operations and Maintenance Employees in Total Workforce

TABLE 28.-Analysis of Operations and Maintenance Workforce

BART AIRTRANS NYCTA CTA MBTA PATCO

(1974/75) (1974) (1974) (1974) 74/75 S.Y. l74 S.Y. 1

Total Cars in Fleet 6,681 1,094 354 75 350 450 68 68

O&M Employees 21,045 2,370 1,063 203 1,000 1,192 142 122

Operations Employees 8,350 1,540 482 75 315 415 22 22

Maintenance Employees 12,695 830 581 128 684 777 120 100

O&M Empl./Car 3.1 2.2 3.0 2.7 2.9 2.6 2.1 1.8

Ops. Empl/Car 1.2 1.4 1.4 1.0 0.9 0.9 0.3 0.3

Maint. Empl/Car 1.9 0.8 1.6 1.7 2.0 1.7 1.8 1.5

Maint. Empl./Opr. Empl. 1.5 0.5 1.2 1.7 2.2 1.9 5.5 4.5

IEstimated stable year operation.

ZTrain crew, dispatche~, towermen, central control, and yard motormen.

sMaintenance of vehicles, way, power, and signals.

The differences among these systems are not

solely attributable to ATC. A large share of the

maintenance force (67–93 percent) is not concerned

with ATC equipment but with other carborne and

wayside components, which also tend to need more

maintenance as the transit system becomes more

complex or equipment and structures grow older.

Still, the percentage of maintenance employees involved in ATC-related activities shows a general

increase proportionate to the level of automation.

In NYCTA, with no carborne ATO equipment

and all ATP in the wayside, it is estimated that 1 0

percent of the maintenance force performs ATCrelated work (primarily signal maintenance). The

estimated figure for CTA is about 5 percent, about

half for wayside equipment and half for cab signals.

For MBTA the figure is now 7 percent, but expected

to increase as cab signals are installed on other

lines. PATCO, with cabs-signaled ATP and ATO,

has about 15 percent of the maintenance force dedi118
cated to ATC (9 percent wayside, 6 percent cars),

For BART, the ATC position of the maintenance

force is now about 31 percent (18 percent for

wayside and central ATS equipment, 13 percent for

cars)--a distribution that is expected to remain essentially the same when stable-year operation is attained. From these data, it appears that the progression from ATP (either wayside or cab signals) to

ATP and ATO results in a doubling of the percentage of the maintenance force assigned to ATC activities. The increase to a system with ATP, ATO,

and ATS (if BART is typical) causes the percentage

to double again.

If the PATCO and BART cases are assumed to be

representative of the manpower shifts that result

from automation of the train control system, it is

possible to draw some tentative conclusions about

cost savings attributable to ATC. For PATCO, the

incorporation of ATO made it possible to run the

trains with a single operator, resulting in the

elimination of about 45 conductor positions. At the

same time, about 15 additional shop and wayside

NYCTA

(ATP, wayside signals)

ATC CAR O%

personnel were required to maintain ATC equipment. This is a net of 30 fewer employees.

However, the pay rate for personnel skilled in ATC

maintenance is generally higher than that for conductors. Assuming a pay differential of 20 percent

for ATC maintenance workers, the effective saving

in payroll costs reduces to about 25 positions, or

roughly 9 percent of the annual payroll. Following a

similar line of reasoning, the BART ATC system

eliminated the need for about 315 conductors, but

added about 200 to the maintenance force, a net of

115 fewer positions. 73 Adjusting for maintenance

pay differential, this is equivalent to a saving of

about 75 positions, or roughly 4 percent of the annual payroll. Since labor costs are about three-quarters of all system operating costs, ’these calculations

suggest that automatic train operation with a crew

of one offers the potential to reduce operating costs

somewhere between 3 and 6 percent per year.

73The BART estimate assumes stable-year staffing levels.

FIGURE 66.—Distribution of Maintenance Force as a Function of Automation

1 1 9
One of the arguments often advanced f o r

automatic train control is that ATO and ATS can

lead to a more efficient mode of train operation and,

hence, lower energy consumption. It is asserted

that, in an automatic system, trains can be run at

more uniform headways and at predetermined

speed-distance patterns, which provide lower maximum speeds and more uniform accelerating and

braking rates. This yields a lower power consumption per car mile as a direct effect. The more

uniform spacing of trains brought about by operating at optimum conditions also has an equalizing

effect on the passenger load of trains, and in turn

produces more energy savings as a secondary

benefit. More uniform headways also shorten

layover times at terminals, permitting a reduction in

the number of trains operated and still further

energy savings. (Irvin and Asmus, 1968)

Theoretically, this argument is sound; but it is

difficult to test its practical validity and to assess the

magnitude of energy savings that might actually be

achieved in revenue operations with various forms

of ATC. Table 29 is a summary of the energy consumption in the five transit systems considered in

this study. Energy usage is expressed in terms of

kilowatt-hours per revenue car mile and per

passenger mile. The latter figure is perhaps the better index for comparing energy consumption among

the five systems because it is independent of vehicle seating capacity and load factor.

Note that the power consumption figures are

systemwide totals, including traction power and all

other uses such as vehicle lighting and air conditioning, station operation (lighting, escalators, etc.),

parking lots, and maintenance facilities. A purer

form of comparison would be the energy required

for traction power alone, but such figures could not

be accurately derived from the records of some

systems. Thus, there is some distortion of the data

due to factors other than train operation, but their

influence is probably not large since traction power

represents the dominant share of all energy use

(typically three-quarters or more) .74

The data in table 29 do not indicate differences

among transit systems that appear to be related to

ATC. With the exception of CTA, the energy consumption per passenger mile is about the same for

all systems, regardless of the level of automation. In

short, there is no conclusive evidence that ATC

saves energy, at least when energy use is measured

at the overall system level.

TQ1n BART, for example, traction power amounts to about 75

percent of all power use. 1n PATCO, traction power is 85 to 90

percent of the total.

TABLE 29.—Rail Rapid Transit Energy Consumption

ENERGY CONSUMPTION NYCTA CTA MBTA PATCO BART2

(1973/74) (1974) (1974) (1974) (1974/75)

ANNUAL KILOWATT-HOURS 2055.0 256.2 102.4 39.3 197.9

(million)

ANNUAL REVENUE CAR MILES 320.6 46.8 10.3 4.3 21.6

(million)

ANNUAL PASSENGER MILES 35480,() 775.2 4

263. 2 95.0 446.4

(million)

KWH/REV. CAR MILE 6.4 5.2 9.9 9.2 9.2

KWH/PASSENGER MILE 0.38 0.33 0.39 0.41 0.44

lpower consumed for all purposes (traction, station operation, shops, etc.).

2Estimate based on operating data for July 1974 to January 1975.

:jEst i matr hawi on average trip I cng th of 5 m i 1(:s

QEstimate bawd on average trip length of 3,1 mi]es.

120
There may indeed be energy savings due to ATC,

but they cannot be discerned by the methods

employed here. In all probability they are small and

masked by several other factors which account for

most of the observed differences among the five

systems. For example, these transit systems differ

greatly in their maximum operating speed and

average line speed. The two systems with ATO

(PATCO and BART) also happen to run trains at

higher speeds. Since power consumption varies

directly as a function of speed. the possible energy

savings due to ATC in PATCO and BART are probably offset by the increased energy required to run

trains at 70–75 mph.

The weight of the vehicle has a profound effect

on the amount of traction power required to move

trains. There is great variation among transit

systems in the weight of vehicles, and this factor

alone probably accounts for most of the difference

in power consumption. In this regard, it is significant that CTA (with 20- to 24-ton cars) has the

lowest level of energy use and PATCO (39-ton cars)

has one of the highest.

It should also be noted that several other factors

influence power consumption. Among these are the

aerodynamic properties of vehicles75, route charac75The amount of aerodynamic resistance to be overcome

varies according to whether the train is operating in a tunnel, on

elevated structure, at grade, or in a cut.

FIGURE 67.—State-of-the-Art Car

121
tained by man, he becomes less an operational element of the system and more a monitor, overseer,

and back-up for automatic elements, which themselves carry out the direct functions of train control.

Up to this point in the discussion of operational

experience with ATC, automation has been treated

primarily in terms of machine performance and

engineering concerns. To complete the picture, it is

now necessary to examine the inverse subjects of

the role of man and the effects that automation produces upon the humans who, perforce, remain an

integral part of the train control system. There are

two major questions here. First, there is the need to

examine whether man is used effectively and prudently in systems with various levels of ATC. What

use is made of man’s performance capabilities? Is

adequate attention given to human needs as operator and supervisor? Is man well integrated into the

system? The second major concern is the consequences that have resulted from the application of

automation in transit systems. Specific matters of

interest are changes in working conditions and job

qualifications for transit system employees and the

secondary effects that ATC may produce for the

riding public using the transit system,

ISSUE O–14: THE HUMAN ROLE

Is effective use made of man in systems with

ATC?

In some cases, new transit systems with ATC

do not make effective use of the human operator

to back up or enhance automatic system

performance, and human involvement in normally automatic processes tends to degrade

performance, primarily in terms of speed, headway, and level of service. In systems now under

development, there seems to be a greater concern

for the role of man and for making the ATC

system more amenable to human intervention.

In considering the role of humans in systems

with automatic train control, it is necessary to distinguish among the parts played by man in each of

the major functional categories: train protection,

train operation, train supervision, and communication.

In train protection (ATP), the motormen (and

conductors, if there are any) customarily perform

very few functions, except in a back-up or emergency capacity. Nearly all transit systems have either

wayside or cab signal equipment that automatically

assures train separation and prevents overspeed,

The human operator’s tasks are track surveillance

(for detecting persons and obstacles on the right-ofway or as a back-up to track circuits for detecting

other trains) and emergency braking in unusual circumstances that the ATP system is not designed to

detect. The operator also acts to restore the system

to operation in the event of ATP system failure,

performing such tasks as emergency brake release,

key-by, or manual route request. Since the operator

is backing up a highly reliable system, there are significant problems in maintaining proper vigilance

and alertness, There is also considerable risk of

human error in cases where the ATP system is not

functioning properly or has been deliberately

bypassed (as when closing in on a disabled train).

FIGURE 68.—Student Conductors Training

on the Job

In the area of train operation (ATO) there is wide

variation among transit systems in the tasks

assigned to the on-board operator, In NYCTA,

CTA, and MBTA (except the Red line) all train

operation functions are performed manually. In

PATCO, only door operation and train starting are

manual in normal circumstances. In BART, all train

operation is automatic. The role of the on-board

operator in systems with ATO is mainly limited to

122
monitoring automatic equipment performance, acting as a back-up in the event of malfunction or

emergency, and—in some cases—adjusting the performance level of the ATO system (e.g., by modifying speed-acceleration profiles or by ordering the

train to run by a station without stopping). The major human performance problems that have been

encountered in regard to ATO are the effectiveness

(and safety) of manual intervention in normally

automated processes and the adequacy of the controls and displays provided to the operator for purposes of monitoring or manual takeover.

Train supervision embraces a number of diverse

functions, mostly carried out at a remote, centrally

located facility. Here, too, there is wide variation

among transit systems in the degree of automation.

At one extreme virtually all functions except train

dispatching are manual operations. At the other extreme, scheduling, dispatching, route selection,

traffic regulation, and documentation of events are

carried out by automatic devices either wholly or

primarily. Because the supervisory facility is the

nerve center of the transit system, there can be significant workload problems for supervisory personnel, particularly during rush hours or emergency

situations. These problems may be aggravated in

systems with ATS if there is a breakdown of

automatic equipment or the need for extensive

human intervention in response to unusual conditions to which the computers are not programed to

respond. The major difficulties that have been encountered in systems with ATS are the quality and

timeliness of information available to central control personnel, the flexibility of automatic system

response in abnormal or emergency conditions, and

the ability of humans to assume the burden of making and implementing decisions in areas normally

assigned to machines.

While there has been some automation of the

communication process in the newer transit

systems, primarily in the area of data transmission,

the major thrust of technological innovation has

FIGURE 69.—Motorman at Work been to-provide train crews and central supervisors

FIGURE 70.—Line Supervisors

123
with

tion.

how

communicating with remotely located transit

system employees.

Table 30 is a summary of the allocation of tasks

to men and machines in several operating and

developmental transit systems. The table also indicates man-machine allocations in AIRTRANS

which, although not a true rail rapid transit system,

may be considered representative of the extent that

present technology can go in achieving a fully automated train control system. The systems have been

arrayed in a generally increasing order of automamore extensive means of voice communicaThe major problems encountered have been

to manage communication networks of increased size and complexity, how to limit unnecessary or excessive exchanges (chatter), and how to

implement various modes of selective and general

address. There has also been a general concern

about the ability of improved communication

systems to compensate for the fewer number of onboard personnel in providing information and instructions to passengers in special or emergency

situations and in affording passengers a way of

TABLE 30.—Man and Machine Roles in Rail Rapid Transit Systems

KEY: A = Automated

M = Manual

— = Not provided

TRANSIT SITUATION

SYSTEM

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

—

—

M

A

A

M

A

A

M

A

A

M

A

A

M

A

A

M

A

A

M

A

A

M

A

A

M

A

A

AIM

A

A

AIM

A

A

AIM

A

A

A/M

A

A

AIM

A

A

A/M

A

A

AIM

A

A

AIM

A

A

AIM

A

A

AIM

A

A

AIM

A

A

A/M

A

A

AIM

A

A

AIM

A

A

AIM

A

A

AIM

A

A

AIM

A

A

A/M

A

A

A/M

M

M

M

M

M

M

A

A

M

A

M

M

A

A/M

M

A

AIM

M

A

A

M

A

A

M

A

A

M

M

M

M

M

M

M

M

M

M

A

M

M

A

AIM

M

A

AIM

M

A

A

M

A ,

A

M

A

A

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

M

A

AIM

M

A

M

M

A

AIM

M

A

—

M

M

M

—

M

M

—

M

M

—

M

M

—

M

M

—

A

A

—

A

AIM

—

A

A

—

A

A

—

M

M

M

M

M

M

M

M

M

M

M

M

A

M

M

A

A

M

A

AIM

M

A

A

M

A

A

M

Normal

Abnormal 1

Emergency 2

Normal

Abnormal

Emergency

Normal

Abnormal

Emergency

Normal

Abnormal

Emergency

Normal

Abnormal

Emergency

Normal

Abnormal

Emergency

Normal

Abnormal

Emergency

Normal

Abnormal

Emergency

Normal

Abnormal

Emergency

NYCTA

CTA

MBTA3

PATCO

MTA4

(Baltimore)

WMATA4

MARTA4

BART

AIRTRANS

IModerate delays, bad weather, unusually heavy demand

zMajor delays, accidents, failure of critical equipment.

:] Red Line only.

dl.Jnder development, not yet operational.

124
tion to facilitate seeing the overall pattern of

replacement of the human operator by automated

devices,

It can be seen that the general effect of increased

automation is for machines to assume a greater and

greater share of operational functions in normal

situations and in certain off-normal conditions, but

not in emergency conditions. At every level of

automation, man remains the primary means of

sustaining system operations under extreme conditions and the back-up element in the event of

equipment failure. On board the train, the result of

automation is diminished importance of operating

skills for the train crewman and increased emphasis

on the ability to monitor automatic equipment

functions. Man’s primary job is not running the

train but overseeing train operation and intervening

when necessary. At central control facilities,

automation results in more routine decisionmaking

being allocated to machines, which monitor traffic

flow, adjust schedules to compensate for irregularities, and alert supervisory personnel when

special action outside the bounds of computer

programs is required.

The conversion of train control from a manual to

an automated process has produced problems on

both sides of the man-machine interface. These

problems arise not from any inherent inadequacy of

automation technology as such; almost any level of

automation is a technically viable solution. Instead,

the problems stem from within the design of particular systems and from the way in which the manmachine interface is engineered. The following are

specific examples of successful and unsuccessful

aspects of automated equipment design drawn from

the experience of transit systems with operational

ATC systems.

Train Protection

ATP equipment has proven to be highly reliable;

but, in a way, this reliability has also created

problems, Train operators tend to take ATP for

granted. ATP equipment operates so well so much

of the time that the operator is inclined to neglect

his responsibilities as a monitor and back-up and to

forget what he must do to safeguard the train when

ATP equipment is inoperative or when it has been

purposely bypassed. The general experience of

transit systems is that accidents tend to occur when

train operators revert to visual observation and

rules of the road because the normal automatic

methods of train protection are inoperative.76

A related problem arising from ATP (and from

highly automated forms of train operation) is that of

vigilance. At first glance, it would appear that

relieving the train operator of most routine and burdensome tasks would produce a near-ideal situation, in which he would be free to concentrate on a

few surveillance and monitoring tasks and perform

excellently in that role, Unfortunately, the result is

almost always the contrary. Given too little to do,

one tends to lose vigilance and to exhibit problems

of motivation. For a person to remain vigilant, the

events to be observed must occur with reasonable

frequency. To keep a person motivated, the

assigned tasks must be demanding enough to prevent boredom and meaningful enough to engage attention. “Make-work” tasks, or those perceived as

such, are not satisfactory. The individual must feel

that he has a useful and important role to play.

Duties should not appear to be vestigial to machines

or compensatory for their inadequacies. (TSC, 1974)

Train Operation

One of the operator’s primary duties in systems

with ATO is to intervene whenever either equipment performance or operational conditions fall

outside prescribed limits. In some cases, however,

the act of manual intervention results in a further

degradation of system performance. For example,

in BART where trains are normally operated

automatically, the design of the system effectively

precludes the operator from assuming manual control without causing a delay in service. Train speed

in a manual mode of operation is limited to so percent of the speed allowable under ATO. Thus,

manual takeover inevitably results in a slowing of

the train and, as a consequence, following trains

also. Furthermore, taking over manual control requires that the train first be brought to a full stop,

thus compounding the delay. There is no technological or human impediment to operating transit

vehicles manually at high speed or to changing from

an automatic to a manual mode while the train is in

TOThe collision of MBTA trains in August 1975 occurred in

just such a circumstance. A train operating under line-of-sight

rules entered a tunnel and struck a leading train waiting to be

keyed by a defective trip stop, A third train, also operating

under line-of-sight rules, struck the rear of the second train

about 2 minutes later.

125
motion. The PATCO ATO system permits a man to

operate the train at full speed, and the WMATA

system will also, because it was recognized during

the design process that such was a desirable way for

man to augment the performance of an automated

system.

The PATCO system also incorporates other

features that promote effective cooperation between man and machine in maintaining the desired

level of service. One of the train operator’s responsibilities is to help complete the trip on time in case

the ATO equipment should fail. Because failure of

this sort is not expected to occur often, it is necessary to devise a means for the human operator to

maintain his manual skills so as to be able to perform at his best when needed. In PATCO this is

assured by an operating rule that requires each

operator to make one trip per day in the manual

running mode. The skill thus maintained also helps

in other circumstances, such as when rails are slippery. ATO system performance is not as good as in

manual operation in this condition. Thus, a combination of equipment design and procedures permits the system to make effective use of the human

operator as a means of enhancing the performance

of automated equipment. This lesson is being applied in the design of new systems such as

WMATA and MTA.

The display of information to the train operator

is an aspect of design that has been somewhat

neglected in transit systems. Speed regulation is an

important operator duty on manually operated

trains, and yet there is no speedometer in the cab to

tell the operator his actual speed, except in systems

that have cab signals or ATO. Even with cab signals, the human factors of information display are

not always given proper attention. For example, the

BART operator’s console originally contained only

an indicator of actual speed. The command speed,

with which actual speed is to be compared, was not

displayed, A command speed indication was later

added, but as a digital readout.77 This form of display does not facilitate the operator’s speed

monitoring task since it requires making comparisons between two digital indicators, each of

which may be changing rapidly. There is a considerable body of human factor research that indippThe WMATA operator’s console has indicators of command and actual speed, but also in digital form-an example of

learning part, but not all, of the lesson to be gained from the experience of others.

1 2 6

cates

trend

digital displays are difficult to interpret for

and rate of change, factors which are as important as speed itself in monitoring the relation of

command and actual speed, An analog indicator,

such as a conventional automobile speedometer, is

generally a much more effective and informative

display for such purposes.

Train Supervision

Train supervision is an area where, historically,

there has been very little automation, except for

train dispatching. All operating transit systems, except BART, supervise train movement by largely

manual methods. In BART, the central computer

handles tasks such as traffic regulation (schedule

adjustment) and performance level modification.

The train control systems under development in

Washington, Atlanta, and Baltimore will incorporate similarly automated forms of train supervision,

ATS poses several design problems relating to

human factors. One important concern is what to do

when the computer fails, An abrupt change from

automatic to manual supervision can cause major

disruption of service and may even affect the safety

of transit operations. Attention is being given to this

problem in the design of the new systems

(WMATA, MARTA, and MTA) and in planning for

the addition of ATS to NYCTA, One solution is to

design ATS equipment so that it does not fail

abruptly and absolutely, but gracefully (i.e., in slow

stages) and with sufficient coast time for human

supervisors to assess the situation and decide on an

appropriate course of action, New systems are also

providing for intermediate levels of operation between manual and automatic. These modes allow

the ATS system to operate under manual inputs or

to serve as an information processing aid to human

decisionmaking. The ATS system for MARTA

is being implemented in two stages — semiautomated first and fully automatic later. After the second stage is implemented, the first will be retained

as a back-up mode, a training device, and a means

for central control personnel to retain manual skills,

Central supervisory systems, both manual and

automated, also exhibit the deficiencies of display

design noted earlier in connection with operator’s

cab equipment. Some systems do not have any form

of central display board (model board) to allow

supervisors to monitor the progress of trains. Personnel are required to form a mental picture of the
situation on the line by monitoring verbal reports

from trainmen, towermen, or station dispatchers

and by reading pengraphs or other such nonpictorial

indicators. In systems that do have model boards,

the supervisor’s task is somewhat easier since there

is a large diagrammatic representation of the track

layout with lighted indicators to show train location. Sometimes, however, the model board does

not indicate track occupancy block-by-block but for

longer sections of track. If there is a stalled train, for

example, the supervisor may know from looking at

the board only that it is between one station and

another but not precisely where. If a following train

is ordered to close up and push the stalled train to a

station or siding, the central supervisor cannot

follow the progress of this operation by means of

the display board. The central control facilities

being designed for WMATA and MARTA will incorporate special displays that allow supervisors to

“zoom in” on selected sections of track or to call up

display modes of differing levels of detail to suit the

task in hand.

This brief review of human factors problems

associated with existing ATC installations is not intended to be exhaustive nor to single out particular

systems for praise or criticism. The purpose is only

to indicate the general range of problems encountered and to illustrate the need for more attention to

human factors in the design of ATC systems.

Neither the recently built systems with ATC

(PATCO and BART) nor those now under development have had a formal human factors program.

This is not to suggest that the role of man was not

considered by the planners and engineers, but there

is no evidence that an explicit and systematic

analysis of human factors was made a part of the

design process. An exception to this general finding

is MARTA, where periodic design reviews are

being conducted by a team from DOT Transportation Systems Center. This team includes human

factors specialists, and their examination of proposed MARTA designs has led to several suggestions for integrating man more effectively into the

system.

Proper attention to the role of the individual in

ATC systems can have substantial benefits for transit operations. If automation is approached not as a

question of how to replace the operator in the train

control system but as how to make best use of this

highly valuable human resource, the safety and

efficiency of ATC systems can be greatly improved.

Man is particularly valuable as an element of a realtime control system because of his versatility, flexibility of response, and ability to deal with the

unexpected or the unusual. To attain these advantages, however, man must be made a partner in the

system. His job must not be treated as an

afterthought or as the residue of functions that

equipment engineers have found technically or

economically impractical to automate.

ISSUE 0-15: EFFECTS OF AUTOMATION

ON EMPLOYEES AND PASSENGERS

What impacts does train control automation

have on transit system employees and on

passengers?

For employees, especially maintenance

workers, ATC results in higher job qualifications, more extensive training, and more demanding performance requirements. For

passengers, the effects are negligible except insofar as ATC influences the quality of service.

There have been no studies of the specific effects

of automation in rail rapid transit systems either for

employees or passengers, despite the obvious importance of these topics in the overall assessment of

the social impacts of new technology. What follows,

therefore, is based on anecdotal evidence and interviews with transit system managers. The applicability of these observations to transit systems

as a whole is hard to determine. The experience of

each operating agency is somewhat unique in that

labor conditions, workforce makeup, personnel

policies, and operating history vary from site to site.

New transit systems, like PATCO and BART, have

no previous experience with nonautomated operation against which to judge the effects of ATC. The

installation of ATC equipment in older systems,

such as MBTA or CTA, is both limited in scope and

relatively recent. For these reasons, comparisons

among systems or within systems for before-andafter effects cannot be made. The comments offered

here are therefore general in nature and confined to

those effects most frequently cited by system operators and managers.

Operations Employees

A primary result of the automation of train

operation functions is a general shift in the skill re127
quirements for trainmen. The motor skills, coordination, and knowledge of signals and rules

needed to operate a train manually are still important qualifications, but they are no longer the sole

concerns. The role of ATO system monitoring and

back-up places additional requirements on the

operator—knowledge of how the system operates,

ability to interpret failure indices, skill in diagnostic

techniques, and an understanding of how aid

automatic system operation without necessarily

assuming full manual control. Thus, the repertory

of operator performance tends to be larger in

systems with ATO, and the modes of response more

varied.

The selection criteria for train operators do not

appear to differ substantially for systems with or

without ATO, and they are about the same for bus

operators in those systems that operate both modes

of transit.78 The general requirements are physical

fitness and the common standards of employability

(checks of police record, retail credit, and previous

employment). Educational background (above a

certain minimum level of schooling) and aptitude

tests do not figure in the selection process, either for

manual or automatic systems. Thus, ATC does not

appear to alter the basic level of qualification for

initial employment as a train operator.

While employment qualifications are unaffected

by automation, there does seem to be a longer training program for operators in systems with ATC.

The longer program results not so much from a

need for more intensive training as from a need to

cover a greater range of subjects. This is probably a

direct consequence of the wider repertory of job

skills required of operators in systems with ATO.

Since manual train operation is not a regular part

of the job, systems with ATO have found it necessary to provide opportunities for practice and to test

operators periodically to determine if manual skills

have been retained. There is no evidence that train

operator performance standards are more exacting

at one level of automation than at any other, except

insofar as systems with ATO call for a wider

variety of job knowledge.

Train supervisory personnel appear to be very

little affected by ATS. Selection criteria, training requirements, and job performance for dispatchers

713VVMATA, which now Opemtes a bus system and is preparing to start rapid tmnsit operations, is =king to recruit train

operatora from its bus driver force.

and line supervisors are about the same for all the

rapid transit systems surveyed. The BART train

control room, because of the use of computers for

supervisory functions, has employees versed in

computer operation and maintenance-a class of

employee not found in other transit systems. For

these employees the skill, training, and performance requirements are, of course, unique and,

because of their special expertise, somewhat higher

than other types of supervisory employees.

Maintenance Employees

The major impact of ATC upon transit system

employees is for maintenance workers, Traditionally, the signal maintainer was a person who

had good mechanical skills and a basic understanding of the theory and operation of electromechanical devices (especially relays). This worker tended

to be a generalist, in the sense that he was capable

of dealing with all types of signal system failure and

repair, The installation of more advanced forms of

ATC and the technological shift to solid-state logic

and printed circuit boards has brought about a

change in the type of maintenance employee

needed and in the organization of the maintenance

force. New and more specialized skills are required,

and the organization has become more hierarchical

and segregated into specialty occupations. Transit

vehicle maintenance has come to be more and more

like aircraft maintenance.

The electronic nature of ATC equipment has

made the diagnosis and repair of malfunctions a

more complex and demanding task. Typically, this

task is divided among maintenance specialists, with

the first-line maintenance worker responsible only

for identification of the fault and replacement of the

defective module as a whole. Isolation of the fault

to the component level may not be the responsibility of the first-line worker. This part of the

maintenance task may be assigned to a second level

of worker, who may repair or replace the failed

component or who may isolate the fault further and

pass a particular element along to a third level of

maintenance worker specializing in that type of

repair.

An additional task assigned to maintenance personnel in systems with ATC is that of configuration

control. During the period following the introduction of new equipment or the opening of a new

system, equipment modifications are made frequently. Because of the strong interdependency of

1 2 8
Track Gang Electronic Repairmen

Cab Signal Maintainer Wayside Equipment Maintainer

FIGURE 71.—Transit System Maintenance Workers

129
components that characterizes most new and

sophisticated transit system equipment (of which

ATC equipment is only an example), it is becoming

more and more necessary to maintain extensive and

accurate records of exactly what equipment is installed on a given car at a given time. The maintainer must spend more time with service bulletins

and maintenance documents in order to keep

abreast of configuration changes.

In the area of maintenance, new transit systems

have some special human factors problems that are

not shared by established systems. In an established

transit system there is already a maintenance force

in being and procedures and techniques for maintaining the equipment are familiar to all. The introduction of a new item, such as cab signals, disrupts the pattern somewhat but only for a small part

of the maintenance force since the rest of the equipment is unchanged. In a new transit system, everything is new. The equipment itself may be a new

design or, at least, new in its specific application.

Workmen and supervisors are likely to be inexperienced in maintaining transit equipment-of all

types, not just ATC. Procedures are untested and

unrefined by experience. The facilities themselves

are usually sized to handle normal workloads rather

than the huge influx of failures and repairs that may

occur during start-up. Manufacturers’ representatives may be working alongside the maintenance

staff making equipment modifications or assisting

in debugging. The training system for preparing

new maintenance workers may not yet be functioning smoothly. These conditions may result in an impairment of worker efficiency, quality control

problems, and—if they persist--a lowering of

worker morale.

There are also long-term effects on the maintenance force produced by ATC. The size and

organization of the workforce, as noted earlier, are

different. Generally more workers are needed, with

special skills, and with a more elaborate division of

responsibilities. The qualifications for employment

as an ATC technician are usually higher and more

specialized than for other types of transit maintenance workers. The period of training, both in

classrooms and on the job, is often longer. The performance requirements on the job may also be more

stringent, Existing transit systems that are converting to some form of ATC have had difficulty in

finding qualified personnel, and efforts to recruit

trainees within the existing transportation or maintenance forces have not always been successful.

Bringing in new personnel from the outside is an

alternative, but the training period may be longer

since they are unfamiliar with transit equipment-a

disadvantage that may be partly offset by the better

basic skills typically found in personnel already

familiar with electronic maintenance and

specifically recruited for that purpose. New transit

systems, of course, have little choice but to recruit

and train an entirely new maintenance force since

there is no existing labor surplus of ATC technicians, either locally or nationally, to draw on.

It should be noted that ATC generally leads to an

upgrading of the maintenance force. Since ATC is

an addition to all the other types of transit equipment, it increases, not decreases, the number of jobs

available, The pay levels for this kind of work tend

to be higher than for other types of transit maintenance; and, to the extent that ATC technicians are

recruited from within an existing workforce, it

offers employees opportunities for advancement.

Passengers

The transit passenger typically has very little interest in the technical details of the system—ATC

or otherwise. One transit system manager expressed it thus:

People use a mass transit system to get from a

point of origin to a point of destination, and they

want to do it quickly, reliably, comfortably and

economically. The train is nothing more than a

people box, The system designers’ job is to create

a system which will enable that people box to

traverse the transit corridor rapidly and reliably,

day after day after day. The passenger doesn’t

care—has no interest in knowing—whether the

train is controlled by a master centralized computer, or localized control—whether it is

powered by AC or DC motors or by little squirrels running around cages-whether it operates

on standard gauge rails or extra wide rails—

whether those rails are supported on timber cross

ties or concrete cross ties. The passenger does

care about being able to board his train every day

at a preestablished time, riding in a clean and

comfortable environment, arriving at his destination without being ruffled either physically or

emotionally, completing the trip as quickly as is

reasonably possible, and accomplishing it all at a

fare which he considers to be reasonable.

(Johnston, 1974)

130
The impact of ATC on passenger acceptance of

the system would thus appear to be minimal, unless

the ATC system is the specific cause of service

delays-and publicly identified as such, Some transit system managers expressed the view that public

confidence in a highly automated system might be

lower than for a conventional system, especially

during the start-up period or following some other

period of operational difficulty, However, it was

also believed that, once the public becomes accustomed to the system and if performance is

reasonably reliable, apprehension about automation

would subside. It is very difficult to gauge public

opinion in this matter for there have been no

studies directed to the topic of automation in transit

operations. Furthermore, public comment on new

systems, such as BART, tends to be in response to

specific events and often does not grasp the essential technical issues.

There is a widely held view in the transit industry that a completely automated train control

system without an on-board operator is not a viable

proposition. Passenger safety in emergency conditions demands the presence of a transit system

employee to control the situation, to evacuate the

train, and to lead passengers to safety. The

AIRTRANS system has experienced problems in

this regard. Passengers in unattended vehicles

become apprehensive when the train stops somewhere other than at a station, even though there is

no real or apparent emergency. There have been

cases of passengers leaving the train and walking on

the tracks, causing a shutdown of the system until

they can be reboarded or led to a station. It is also

believed that passengers derive a sense of security

from the presence of an on-board operator, both as a

source of aid in emergencies and as a protection

against personal attack or crime. Unmanned vehicles are also considered to present operational

problems. Without an operator to control car door

closure, the passengers may adversely affect headways and capacity because of the variability in

dwell time introduced by passenger-actuated doors,

Systems with unmanned vehicles (and, to some extent, those with one-man trains) have also found

that passengers have difficulty in obtaining information about train routes and schedules. To accommodate passengers, it has been necessary to install

more extensive” signing and public announcement

devices and, in the case of AIRTRANS, to hire additional station employees to provide passenger information and assistance. The human factors of

system design and operation in relation to

passengers is a matter that acquires increased importance as the level of train control automation increases and the level of vehicle manning declines,

7’2 -fif13 O - 7(1 - 1 rl 131
Chapter 6

THE PLANNING AND

DEVELOPMENT PROCESS

133
INTRODUCTION

The main purpose of a rail rapid transit system is

to transport passengers with speed, safety, and dependability. The train control system provides the

protection (ATP), operational control (ATO),

supervision (ATS), and communications necessary

to accomplish this purpose.

The older rapid transit systems, such as CTA,

MBTA, and NYCTA, were designed to perform

many train control functions manually. Until recently, the major uses of automation have been for

train protection functions (ATP) and certain supervisory functions, such as dispatching. The development of new technology within the last decade or so

has made it possible to automate other train control

functions, and so the older rapid transit systems are

now in the process of converting to higher levels of

automation, especially in the areas of train operation and supervision.

Rail rapid transit systems built in recent years

(PATCO and BART) and those now under construction are tending to make use of more extensive

automation and more sophisticated train control

than the older existing systems. Various forms of

advanced ATC technology seem to figure in the

plans of system designers from the very outset.

Thus, it appears that the general trend in both existing and future rail rapid transit is toward increased

automation. In light of this, the process by which

train control systems are conceived, planned, procured, and tested assumes great significance; and it

is important to investigate the way in which the

ATC design evolves within the context of overall

rapid transit system development.

The evolutionary cycle of ATC, like the total

transit system of which it is part, has three major

phases: planning, development, and testing. These

phases are generally sequential but there are

numerous interactions and iterative steps. For

simplicity of discussion, however, the features and

issues of each phase will be treated separately. At

the end of this chapter is an examination of the subject of research activities that support the overall

planning, development, and testing process.

The evolution of an ATC system can be lengthy,

often as long as the evolution of the transit system

itself. Table 31 identifies the significant dates for 16

systems—the five existing and three developmental

systems considered in detail in this report and eight

other systems for general reference. The CTA,

MBTA, CTS (Cleveland), and NYCTA programs involve addition of new ATC equipment or extension

of an existing line. For the others, the program

spans the conception and development of the entire

system. The times listed include the evolution of

general train control system concepts and the

detailed engineering development.

The major issues associated with planning and

development are examined in the order in which

they generally occur in the system evolution process.

Planning (Concept Formulation and Preliminary

Design)

The concept of the ATC system is usually formulated early in the overall transit system planning

process, The major issues are concerned with the

origin of the ATC concept, the influences which

shape it, the selection of a desired level of automation, and the criteria and techniques used to evaluate the concept and translate it into a preliminary

engineering design.

Development (Final Design and Procurement)

The final engineering design and procurement

process may cover several years, during which the

original concept may undergo substantial change,

The most significant issues relate to how the

engineering design specifications are written, how

contractors are selected, how the development

process is supervised and managed, and how

emerging differences between concept and implemental ion are dealt with in the development

process.

Testing

Testing is a continual process that begins as soon

as specific items of ATC equipment are engineered

and, manufactured and ends when the entire system

is ready for revenue service. The issues in this area

have to do with the types of tests conducted, the

timing of the tests in relation to the development

cycle, and the methods by which the ATC system is

evaluated for serviceability and conformance to

specifications.

Research and Development (R&D)

R&D is a supportive activity that runs concurrently with planning, development, and testing. The

issues to be examined include the types of R&D

being conducted, its application to the design of

135
TABLE 31.—Significant Dates in the Engineering Planning, Procurement, and Testing of ATC for Various Transit Systems

CTA CTS

(Lake (Airport

St Exten.

Line) sion)

NYCTA

(System

MBT A Im -

(Red prove.

Dade Co. D/FW MARTA Line) NFTA ments)

Twin

Cities

SEA. Area

PAA C PATCO RTD T A C MTC WMAT A

————

1959 1958 1969 1967 1967 1960

Balti -

more BART

1962 Before

1965

1964 1965 1962 Before 1967 (f-l

1966

Planning b 1962

1967

1951

ATC 1953

Preliminary

Design

Started

ATC

Preliminary

Design

Completed

ATC Procurement

Specifications

Issued

ATC Procurement

Contract

Awarded

ATC

Bebugging

Started

ATC First

Used

In

Passenger

Service

Initial Planing

(Years)

ATC Evolution

( Years)

Total Time

Span

(Years)

1962 1969 1969 1966 1966 1973 Before 1963 1970 1967 1969 1962

1963

1973 1966 1965 (1975) 1970 1974 1970 1973 1972 1967

(d) (1977) 1966 1966 (1978) 1971 1974 1966 1969 1971

1967 1966 1971 (1976) (1975) 1966 1969 1971

1973 1971 (1978) 1968 1972

(1981) 1972 1967 1966 (1984) 1974 (1977) 1971 (1981) (1978) 1969 1973 (1981) 1976

5 4 4 1 6

(f) 4 5

5 3+ (15) 5 (11) 5 (8) (f) (14+) 6

5

(14)

(19)

2

19

21

1 1 2

2

5+ (12) 14

5 3+ (20) 9 (15) 5+ (14) 6 (14) 16

(f)

(18) 11

a Unless otherwise noterf, the dates Ilstwi are for the start of the actlvltv Dates enclosed In parenthtws ( ) are planned (iates All act]vltws are fnr new svstems except as notecf

b ATC plannlng IS generally Influenced by a numlwr of system IIeclslons w this date IS the start of the nverall syswm planning

“ Prellm\nary d~slgn IS cons] cierwi to In[.lu[ie snme conceptual work as well as ciemonstratlnn protects where applicable

{i Act]v)t y IS cllrrently In progress

e Most transit systems are [.onstructwi In phdses The program duration listed IS for a single phasr or the first phdse of the programs Becauw early planrrlng of mult~ple prngrams IS usIIally comprehenmve

the t~me requlrwi for such planning WI]] generally Iw longer than required for d ~maller single-phase effOrt

f At NYCTA the process of equipment replacement and updat!ng 1$ vmtually continuous
new systems, the use of test tracks, and

needs in the area of ATC technology.

major R&D

ISSUE D–1: DESIGN CONCEPTS

How do ATC design concepts originate, and

by what criteria is the level of automation

selected?

For new systems, ATC design concepts

emerge from policy and planning decisions about

the general transit system concept. Initial selection of the level of automation tends to be influenced more by social, economic, and political

considerations than by engineering concerns. In

already operating systems, where ATC is installed to upgrade or extend service, engineering

concerns–especially evolutionary compatibility

with existing equipment-are predominant. For

both new and old systems, the experience of

others (particularly their mistakes) has an important influence.

Some preliminary notion of the type of train control system desired is usually included in the statement of the basic transit system concept prepared

by the policymaking body responsible for planning

the system. For all of the transit agencies investigated in this study, the policy and planning

authority is a commission or board of directors created by legislative act. The size and composition

vary. Some are elected; others are appointed. The

members are usually not engineers and seldom

have technological backgrounds in the area of transit operation and train control, but there is always

either a technical staff or an engineering consultant

firm to assist the board in planning activities. Some,

particularly transit systems already in operation,

have staffs of considerable technical competence.

For example, the CTA and NYCTA staffs do all the

engineering planning for new developments and

oversee procurement and testing. In general,

however, the local policy and planning agency augments the technical capability of its staff by hiring

consultants who conduct studies to support planning decisions and flesh out the basic design concept. In some cases, the consultant firm may also be

responsible for the subsequent engineering

development of the system.

The activities of the planning agency are influenced by many factors: State and Federal legislation, regulatory agency rules and decisions, UMTA

policy, economics, public opinion, local social concerns, labor relations, and political interests, to

name a few. Technical, considerations often play

only a small part and may be overridden by these

other concerns. Specific examples from among the

systems investigated will help to illustrate the

nature and diversity of the ways in which ATC

design first takes shape.

The PATCO Lindenwold Line was planned and

constructed over an n-year period. It is not clear

when the basic ATC design concept was formulated; but an engineering consultant report

published in 1963, about midway between the time

of the initial decision to build the system and the

time the line was opened for service, recommended

the use of ATP and ATO. The tone of the report

makes it plain that the nature of the train control

system was still an open question 5 years after the

planning process started. The primary justification

advanced by the consultant for ATP was safety, and

for ATO efficiency of operation.

In contrast, an ATC design concept for BART

was established very early in the planning process

and took over 20 years to evolve. Original planning

studies conducted by engineering consultants to

BART in 1953 to 1956 advanced the general concept

of completely automatic operation at high speed

and short headways. An onboard “attendant” was

envisaged, not as an operator but as an aide to

passengers, much like an airline stewardess. The

idea of building a glamorous “space age” system

employing the most advanced technology seems to

have been a dominant concern in BART from the

very beginning, This approach was clearly

manifested in the ATC concept. The justification

most often given was that advanced train control

technology was necessary for the, high-speed, shortheadway operation needed to attract patrons,

CTA, in planning the conversion to cab signaling, appears to have been most strongly influenced

by operational and engineering factors, Cab signals

were seen by CTA as an improved method of assuring train separation and preventing overspeed, i.e.,

as a way of enhancing safety. Compatibility with

existing signal equipment and other elements of the

system was also a factor (as it is in MBTA where

cab signal conversion is now being implemented

and in NYCTA where it is in the planning stage).

Engineering and equipment concerns are also a

dominant concern in the planned expansion of

PATCO, where the existing ATC system dictates

that the new lines have the same operational

137
characteristics and

be integrated with

level of automation in order to

the present line.

Operational transit systems for airports (such as

Sea-Tac and AIRTRANS) feature automatic, crewless train operation. These systems were planned

and built in a rather short time span (6 years for

Sea-Tac, 9 for AIRTRANS). The concept of unmanned vehicles was inherent in the nature of

these systems from the beginning. It was felt by the

planning agencies and their consultants that fully

automatic operation offered significant savings in

labor costs and was the only way to make the

system economically viable.

There are sometimes general engineering decisions made during the planning process that may

limit the technology that can be employed for ATC

equipment. For example, a number of transit planning agencies have decided to employ only equipment already proven in use by other operating transit systems. For WMATA, the schedule set by the

policy makers did not permit extensive R&D and

engineering studies before selecting a train control

concept. Therefore, WMATA engineers decided to

specify an ATC system that could be realized with

proven, existing hardware.

The formulation of the ATC system concept is

also strongly influenced by events in other transit

systems. The community of rail rapid transit agencies, consultants, and suppliers is a small fraternity.

There is a continual exchange of information

among the members and a high degree of mutual

awareness of plans, problems, and operation experience. Because the supply of qualified transit

consultants and engineers is limited, there also

tends to be a steady interchange of personnel

among transit properties, consultant firms, and

equipment manufacturers. These forms of interaction assure that the experience of others will be

reviewed during concept selection and preliminary

design,

However, the review of others’ experience is

often rather narrowly focused. There is a tendency

to be swayed more by specific problems and incidents than by overall statistics and the general pattern of operations. “Avoiding others’ mistakes”

seems to be a more dominant concern than emulating their success. For instance, the problems encountered by BART were in part responsible for the

more conservative approach adopted by WMATA

and Baltimore MTA. Atlanta’s planners also have

chosen a train control system less sophisticated

than that originally proposed by their consultants

(PBTB, who were responsible for BART), partly as

a reaction to the experience in San Francisco. Caution is a prudent course, but the rapid transit industry could also benefit if there were a more comprehensive body of comparative performance data

to help make decisions on an analytical, rather than

a reactive, basis.

The salient points that emerge from an examination of the initial planning process are that ATC

design concepts originate (sometimes early, sometimes late) in policy-level decisions about the

general nature of the system. The methodology

employed to arrive at concept definition is often informal and influenced strongly by engineering consultant firms engaged to assist in planning the

system. Except in the case of modernizing an existing system, technical considerations of train control

system design seldom predominate. Route structure, service characteristics, vehicle design, rightof-way acquisition, cost, and local sociopolitical

concerns tend to be given greater importance at the

early stage of planning. The engineering aspects of

train control are most often deferred to a latter stage

of planning, when design specifications are to be

written, As a result, the embryonic ATC design is

usually not defined in detail until other parts of the

system have taken shape, The preliminary ATC

concept thus tends to develop a life and permanence without being subjected to engineering

scrutiny and cost-benefit analysis to determine its

appropriateness for, and compatibility with, the rest

of the system,

There seems to be a crucial difference between

existing and new systems. The former give greater

weight to engineering concerns and specific operational needs in defining an ATC concept. New

systems tend to take a broader, more informal, and

less technical approach, The engineering-oriented

approach offers the advantage of assuring a workable ATC system tailored, although perhaps not

optimally, to specific local needs. But there is a disadvantage. The scope of the ATC concept in

upgrading an existing system tends to be limited

and constrained by what already exists. The bolder,

“clean sheet of paper” approach employed by many

new systems results in a more technologically advanced concept and greater coherence between

ATC and the system as a whole, but the practical

problems of development and engineering may not

always be given sufficient attention,

138
ISSUED–2: SYSTEM DEVELOPMENT

How is the ATC system concept translated

into preliminary and final functional design ?

Most system development work is done by

engineering consultants, except for large

established rapid transit systems where it is done

by the in-house staff. The methodology varies,

but there is a trend toward a more systematic and

sophisticated approach using simulation, system

analysis, system assurance studies, and test

tracks.

The first step in the development process for

ATC systems is preparation of a preliminary functional design, expressing the basic concept and its

underlying policy decisions in engineering terms.

The preliminary design defines performance requirements and organizes the ATC system with

respect to functional relationships among system

components. At this stage, the ATC system is separated into its major subsystems (ATP, ATO, ATS,

and communications), and the functions required of

each are specified. Further analysis may separate

the system into carborne and wayside elements.

The preliminary design also defines the interfaces

between ATC and other parts of the transit system.

For most of the transit agencies investigated, the

technical staff plays some role as engineering planner in preliminary design. However, the extent of

staff involvement varies widely. In established

operating agencies, such as CTA, CTS, and

NYCTA, the engineering staff does almost all of the

preliminary design work. In new systems, where

the technical staff may be quite small, especially in

the early planning phases, engineering consultants

are generally and extensively used. Heavy participation by consultants is also characteristic in

established systems undergoing a major program of

new construction or modernization. While the proportion of staff to consultant participation varies,

there appears to be wide agreement among transit

system managers that staff involvement should not

fall below a certain minimum level, roughly 15 to 20

percent of the design work. In this way, the

authority can maintain technical involvement in

the preliminary design process and exercise proper

control over system evolution.

Several kinds of methodology may be employed

in preliminary design. The specific methods differ

widely from authority to authority, and it is difficult

to discern any common thread, beyond the general

belief that technical studies are needed to gather

and analyze information about the performance expected of the system. In the new systems now under

development, there seems to be an increasing

reliance on the so-called “systems approach”79 and

the use of techniques such as simulation, ridership

analysis, function/task analysis, and cost/benefit

studies. Several agencies (BART, CTA, NYCTA,

Sea-Tac, and PAAC) have also conducted studies at

test tracks on their properties to gather information

needed for preliminary design.

The application of system analysis techniques

does not appear, however, to extend very deeply

into the design of the ATC system itself. There is a

tendency, for instance in cost/benefit studies, to

treat ATC as a whole, without examining the

choices that may exist within the train control

system as to degree of automation or alternative

methods of achieving a given level of automation.

One reason is the general lack of empirical data on

the performance of ATC systems, which precludes

a precise formulation of potential benefits, A second reason is the overriding nature of the safety

factor which strongly influences designers to automate the train protection function, without regard

for the cost/benefit relationship of ATP to other

functional elements of ATO or ATS. Also, since the

entire ATC package typically amounts to only 5

percent or less of the total capital cost of the transit

system, there is a belief that cost/benefit analysis

should be concentrated in areas where the payoff

will be greater.

Thus, the process of developing a preliminary

functional design of the ATC system still tends to

be more art than science, but there is a trend toward

use of more objective, quantitative, and systematic

techniques. This is particularly evident at the points

7~he “sy.sterns approach, ” which derives mainly from aerospace technology, is a collective designation for techniques used

to solve complex problems in a methodical, objective, and often

quantitative way. The systems approach involves a logical and

reiterative analysis of the system into its constituent parts, each

repetition leading to a greater degree of specificity, Other

characteristics of the system approach include measurability of

parameters, constant recognition of subsystem interdependence,

and parallel analysis of elements. The heart of the systems approach is the *’System Engineering Cycle” which involves four

steps: (1) convert system requirements to functional requirements, (2) convert functional requirements to specific detail requirements, (3) conduct analysis to optimize parameters, and (4)

convert specific detail requirements into end products, (Grose,

1970)

139
of interface between ATC and other subsystems,

where mutual influence and interdependence can

be reduced to quantitative expression and the

parameters of performance can be manipulated.

Even here, however, ATC system characteristics

tend to be treated as dependent variables, i.e., the

driving concerns are other system characteristics, to

which the ATC system design must be accommodated.

System design is a continual and reiterative

process, preliminary functional design merging into

final engineering design without any clear line of

demarcation, The process culminates in the statement of specific equipment and performance requirements, suitable for incorporation in procurement specifications. Often, final design coincides

with the preparation of procurement specifications,

and it is difficult to separate the two activities.

However, for the purpose of this discussion, final

design is considered to include all activities needed

to define the detailed technical requirements of the

ATC system, up to but not including the actual

writing of procurement specifications.

As in preliminary design, the final design is executed either by the technical staff of the transit

agency or by engineering consultants. Here, too, the

older and established agencies tend to rely more on

their own personnel, and new agencies more on

consultants. Usually, a single consultant is hired for

final design of the complete ATC system –carborne,

wayside, and central control elements. This

consultant is often, but not always, the same firm

that carried out the preliminary functional design of

the ATC system. Once reason for selecting a single

consultant for the entire process is to assure continuity and coherence of the ATC design as it

develops, It is also considered advisable to have a

single consultant for all parts of the ATC system to

ensure integration of the design of vehicle and

wayside equipment and their all-important interface.

Many of the factors that shape the preliminary

design of the ATC system continue to have significant influence during the final design process. Nontechnical factors still play a strong, but perhaps

diminishing, role as the system moves from planning to engineering. The continuing influence of

nontechnical factors is not surprising since they are

usually built into the design criteria and guidelines

that emerge from preliminary design and are applied to the final design. Still, as the system approaches the hardware stage, it is to be expected

that purely engineering considerations should come

to the fore. Generally speaking, however, the

process of generating detailed engineering requirements from preliminary design criteria is basically

an interpretive effort, with the experience and judgment of the designer playing the dominant part.

However, there are two more formal design

methods that are being used increasingly in new

transit systems. They are system safet y

methodology and quantitative reliability, maintainability, and availability analysis.

Most of the systems now being planned are including a formal system safety study, involving

definition of safety criteria, analysis of potential

safety problems, and identification of ways to eliminate or minimize hazards, Some designers consider

this approach to safety superior to the traditional

methods of “fail-safe” design. Others disagree

sharply.

80 It appears, however, that much of the

controversy over the “fail-safe” and “system

safety” methods is semantic; and it is premature to

determine whether the results of the two approaches will differ, The important point is that

designers are turning, at least in the area of safety,

to more systematic and quantitative methods of

analysis,

Until recently, it has not been the practice in the

transit industry to specify safety requirements in

quantitative form, i.e., as a numerical statement of

risk or probability of occurrence. Many believe that

the levels of safety which must be achieved are so

high that it is difficult, if not impossible, to state

meaningful quantitative standards and to devise an

acceptable and practical method of verifying that

they have been met. This view is not universally

held, and the topic is highly controversial.

However, it does appear that future ATC specifications will place strong emphasis on formal procedures by which potential safety hazards can be

identified, evaluated, and reduced to “acceptable”

levels. An effort is being made to put hazard

analysis on a quantitative basis, but much of the

work is likely to remain qualitative and judgmental.

(Again, this view is not shared by all in the transit

industry, ) Along with the emphasis on quantitative

methods, there is also a trend to define safety in a

sense that is broader than just train protection and

to deal with the safety aspects of the total system.

1111%111 chapt(~r !I. p~igr tlh for (i (1 is(:llssion of this topi(; .

140
The second formal design method that is coming

into wider use in the transit industry is quantitative

reliability, maintainability, and availability (RMA)

analysis. A discussion of this design technique is

postponed to Issue D–4, where it is considered as

part of the general question of how these aspects of

system performance are written into procurement

specifications.

ISSUE D—3: PROCUREMENT

SPECIFICATIONS

How are ATC design requirements specified,

and is there a “best” way to write such specifications ?

There are two basic approaches to writing

specifications— the design (equipment-specific)

approach and the functional (performance) approach. Each has advantages and disadvantages.

The only generalization to be made about the

“best” way is that, whichever approach is used, it

is of crucial importance to specify equipment

performance standards and to define explicitly

the means of testing.

The final design of the ATC system is documented in procurement specifications in terms of

required performance for ATC functions and/or

equipment components. However, the procurement

specifications have a much broader scope than just

a listing of required ATC system performance. Requirements for documentation, scheduling, installation, management visibility and control, and

various types of testing may be specified together

with numerous contractual and legal provisions.

The procurement specifications include all of the

detailed information required for a prospective supplier to prepare a bid.

As a general rule, the organization that does the

final design of the ATC system also prepares the

technical portions of the procurement specification

for that system. At times, another consultant writes

the procurement specifications in cooperation with

the final designers. In this way some additional expert knowledge is incorporated into the specifications.

The most common method of preparing procurement specifications is by drawing on available

specifications for similar equipment, from preliminary proposals submitted by equipment suppliers,

or from experience gained through testing or use of

similar equipment. Often, a general incorporation

of test and use experience is achieved by requiring

the use of “proven technology,” which means that

the same or similar equipment must have been used

or tested successfully on an operating transit

property in the United States.

There are two basic approaches to writing procurement specifications. Requirements can be

stated in functional terms (performance specifications) or in equipment-specific terms (design

specifications). The two are not mutually exclusive,

and in practice something of each approach is used.

Thus, implicit in even the most design-oriented

specification is the expectation that the equipment

should perform in a certain way,

The design type of specification indicates, to a

greater or lesser degree, the equipment or system

components needed to perform individual functions. In the extreme case, design specifications call

for particular items, for which only a narrow range

of substitutes, or none at all, are acceptable. Such

specifications are often issued by transit agencies

that have similar, satisfactory systems in operation

and wish to assure compatibility of the new equipment with that already in place. Recent procurements of cab signaling equipment by CTA typify

this approach. Somewhat less restrictive is the

design specification that calls for a type of equipment with stated characteristics but leaves the supplier some room for choice. The WMATA train

control system specification is an example of the

modified design-oriented approach, which has

some of the features of a functional specification.

Functional (or performance) specifications

define what functions are to be accomplished but

not the way in which they are to be accomplished.

For ATC systems, the BART specification comes

closest to the purely functional approach, The

Diablo test track was operated for the purpose of

determining the feasibility of new ATC concepts

(not to select a system). At the end of the testing

period a functional specification was written to accommodate any of the concepts successfully

demonstrated (and many others). For example, the

basic train separation system could have used radar,

track circuits, or any other device that met the

stated functional requirements,

Table 32 below is a rough classification of the

type of specification used by seven transit systems

in recent procurements. The development of the six

newest systems (Baltimore, Dade County, MARTA,

141
NFTA, RTD, and Twin Cities) has not yet advanced

to the point where ATC system specifications have

been written.

TABLE 32.—Type of Specification Used in Recent ATC Procurements

TYPE OF SPECIFICATION

SYSTEM Design Functional Combined

AIRTRANS x

BART x

CTA x

NYCTA x

PATCO x

SEA-TAC x

WMATA x

The use of a design specification permits the

buyer to exercise a high degree of control over the

equipment purchased. At the same time, however,

it requires considerable experience and technical

competence on the part of the buyer to be sure that

what he specifies will perform as intended. There is

always the risk that individually procured subsystems will not prove compatible, with the buyer

having no recourse but to go through a process of

redesign or retrofit. If a testing procedure has been

established in the specification, product evaluation

and acceptance is usually easier for the buyer who

has followed the design approach. To the extent

that design specifications are equipment-specific,

they lock the buyer into a given technology and do

not allow taking advantage of innovation, economy,

or other improvements that the seller might otherwise be able to effect.

One of the major advantages of a functional

specification is its independence from particular

means of implementation. It gives the supplier great

latitude when innovation is desired or when a wide

range of hardware is acceptable. This approach is

most compatible with a new system being built

from the ground up or with an independent part of

an existing system. In effect, the functional

specifications transfer some of the responsibility for

system design from the procuring agency to the

equipment supplier.

Functional specifications, because they are less

detailed, may be somewhat easier to prepare than

design specifications. On the other hand, it is somewhat harder to define the desired end product with

precision. The functional specification allows the

supplier to be creative, but it can also provide the

opportunity for cutting corners. Litigation, as in the

case of the BART train control system contract, is

always a possibility if differing interpretations are

taken or if the method of testing system performance is not well defineed. From the buyer’s standpoint, one difficulty with functional specifications

is that it may not be possible to determine if the product will meet performance requirements until the

complete system is assembled,

There is no universal agreement on the

superiority of either type of specification, Either

can be employed successfully so long as the buyer

recognizes the shortcomings of the selected approach and so long as the standards for an acceptable . product are clearly and fully defined. The

results of the WMATA specifications, which combine a functional and a design approach, will be

awaited with great interest to see if they offer a

compromise solution to the problem of specifying

equipment requirements and characteristics.

It is of crucial importance that both the criteria

and methods of testing the equipment be made explicit in the procurement specification, From a practical standpoint, the design type of specification

may offer some advantages over the functional

specification in terms of the ability to define and

measure reliability and maintainability-a problem

that lies at the heart of the difficulties encountered

by most new systems. Because of its importance,

the topic of how RMA requirements are specified is

treated as a separate issue immediately following.

ISSUE D--4: SPECIFICATION OF

RELIABILITY, MAINTAINABILITY, AND

AVAILABILITY

Are the methods of specifying reliability,

maintainability, and availability (RMA) adequate to assure that ATC systems will give good

service ?

This has been one of the most troublesome

areas of ATC system design and development.

Transit agencies are becoming increasingly concerned with RMA problems, and an effort is

being made to write specifications in more precise and quantitative terms. In their present state,

however, RMA specifications still fall short of

what the transit industry (both buyers and

manufacturers) consider satisfactory.

142
RMA specifications can be divided into two

classes—those that state quantitative requirements

and those that do not. Before issuance of the BART

specifications, most transit agencies followed a

nonquantitative approach to RMA specifications,

and some still do. The BART specifications were a

pioneering effort to introduce in the transit industry

the quantitative methods used in the aerospace industry for specifying RMA. This was a major innovation at the time and, like nearly everything else

associated with BART, controversial. However, all

the agencies planning new systems are now incorporating some form of quantitative RMA requirements in their specifications.

Historically, reliability and maintainability have

been treated only in general terms in procurement

specifications by transit agencies. Some form of

warranty was called for, but specific requirements

as to reliability (mean time between failure, or

MTBF) or ease of repair (mean time to restore, or

MTTR) were not stated. Certain transit agencies

continue to follow this practice for a number of

reasons. In some cases, the procurement consists of

additional equipment similar or identical to past

purchases. Thus, the expected performance of the

equipment is understood by buyer and seller to be

like that already in use. Another reason has to do

with the size and nature of the transit industry.

There are only a few buyers and even fewer sellers,

all of whom have been in business for many years.

Hence, the needs of the former and the capability

and reputation of the latter are well known. In such

circumstances, it is considered unnecessary to draw

up elaborate and detailed statements of RMA requirements. The seller is familiar with the kind of

equipment now in use by a transit system, and the

transit agency knows that the seller must stand

behind the product in order to remain in consideration as a source of supply. A third reason for taking

the nonquantitative approach, especially in small

transit systems, is that the managing authority may

not feel it is cost-effective (or they may not be able

to get the funds) to prepare specifications that involve extensive engineering analysis, and perhaps

testing.

The quantitative method of specifying RMA has

found increasing favor in the transit industry for

two basic reasons. First, the type of equipment now

being purchased, especially for ATC systems, is

much more complex and technologically sophisticated, creating a need for the document that

governs the purchase of the equipment to become

increasingly detailed and precise. Second, the number of suppliers has increased and now includes

firms without a long and established record in the

area of train control equipment manufacture and

installation. Starting with BART and continuing

with WMATA, MBTA, and a number of new

systems being planned, transit agencies are turning

to a quantitative approach.81 Still, a decade after the

BART initiative, the specification of RMA requirements remains a developing art,

There are significant differences in how quantitative RMA requirements are written, depending

upon whether the procurement document is a

design or a functional specification. In a functional

specification, the buyer defines generic types of

failures, their consequences, and required system

performance. The seller is (in theory) free to configure the system in any way seen fit so long as the

functional requirements are met and the system

performs as expected. In a design specification, the

buyer develops a specific equipment configuration,

evaluates the consequences of failure of each component (equipment items not functions), and

defines the component performance requirements.

The seller must then meet the performance requirements on an item-by-item basis. Thus, the seller

may well have no responsibility for the performance of the total system, but only for the parts as set

forth in the procurement specification. In effect, the

functional specification transfers much of the

responsibility for detailed system design to the

equipment supplier, whereas with a design

specification this responsibility is retained by the

purchaser.

With regard to RMA, the difference between

design and functional specifications centers around

the definition of failure. In design specifications the

definition is reasonably clear-cut and precise.

Failure means that a given component does not respond to a given input or fails to make a particular

output within stated tolerances. In a functional

specification, failure is defined not in terms of

specific equipment performance, but mor e

generally as the inability of the system (or subsystem) to perform certain functions. Some functional specifications (such as those prepared for

BART and Sea-Tac) also identify the consequences

of failure that are of concern.

MMARTA, Dade County, Denver RTD, NFTA, PAAC, and

Twin Cities are all contemplating the use of quantitative RMA

specifications.

143
A problem of interpretation can thus arise in

evaluating equipment procured under a functional

specification. Some failures and their consequences

are defined; but others are not, even though the

same piece of equipment may be involved. What

then is a failure? And what particular equipment

malfunctions are to be counted in determining the

reliability of the purchased equipment? There is a

disagreement, and litigation in progress, between

BART and the ATC equipment supplie r

(Westinghouse Electric Corporation) as to the intent of the specification on these very points.

The WMATA train control system procurement

specification, written with the BART experience in

mind, attempts to deal more clearly with the definition of failure. In the WMATA specification, failure

is defined as “any malfunction or fault within an

equipment which prevents that equipment from

performing its function in accordance with the

specification. ” Thus, it appears that WMATA RMA

requirements pertain to all equipment failures

without regard to the effect on train operation.

However, the specification does not clearly indicate

what modes of operation are to be counted and how

equipment operating time is to be reckoned in

calculating MTBF, In some systems, ATC units are

located at each end of the train and actually control

only half the time. If a failure occurs in a unit not

involved in train operation at the time of malfunction, is this to be counted as failure? And if so, how

many hours has it been operating? All the time that

the car has been in revenue service, or only that part

of the time that the ATC unit has been used to control the train?

Without belaboring the example, it is clear that

the transit industry still has not reached a full and

universally accepted understanding of how to

specify and test equipment reliability. A recent

statement by a representative of an equipment

manufacturer (King, 1975) highlights the continuing

problem.

Success and failure of transit equipment and

systems must be defined in relation to their mission. Indeed, the term “mission” itself probably

requires redefinition. Many industry specifications in recent years have not agreed on such

points as whether a transit vehicle completes its

mission at the end of one trip or the end of a full

day, or when that day ends, or whether the vehicle must be available during all peak service

periods. If the function of transit equipment is

carrying passengers, has a mission failed if an

equipment outage occurs during nonrevenue

service? These are some of the fundamental

questions which must be answered to define traditiona1 reliabi1ity in a manner acceptable to

transit industry application.

One of the significant problems affecting the

ability of the transit industry to draw up meaningful

RMA specifications is the lack of a data base

describing the performance now being achieved in

the industry. Individual manufacturers have some

information, as do individual transit systems, but

there is no uniform method of reporting and no

available industry-wide data base.

This need has been recognized by transit agencies and equipment manufacturers; and, through

their industry organization (the American Public

Transit Association), an effort is underway to deal

with the problem. APTA task group, known as

RAM (for Reliability, Availability, and Maintainability), has been assigned the responsibility of

developing recommendations for a standardized

data collection and reporting procedure. The

problem of making these data generally available,

free from local transit system bias and manufacturers’ proprietary concern, is still unsolved,

ISSUE D–5: ‘ EQUIPMENT SUPPLIERS

What firms supply ATC equipment? Is there

transfer of ATC technology between automated

small vehicles and rail rapid transit systems?

Historically, two U.S. firms—GRS and

US&S--have supplied most of the ATC equipment to the rapid transit industry. In recent

years, several new firms, supplying either special

product lines or control equipment for small

vehicle sytems, have entered the market. The

major transfer of ATC technology is from rail

rapid transit to small vehicle systems, but not the

reverse.

The suppliers of ATC equipment to the rail rapid

transit industry fall into two distinct groups: those

that provide a broad line of services and equipment

and those that have limited lines or specialty

products. There are many firms in the latter category, but the former includes four companies, General

Railway Signal Company (GRS) and Union Switch

and Signal Division of the Westinghouse Air Brake

144
Company (US&S) 82 are old, established firms that

have a long history in the signals and communication business and have dominated the market. Recently, two new suppliers have entered the competition. Westinghouse Electric Corporation

(WELCO) supplied the ATC system for BART,

where they were low bidder against GRS and US&S.

Transcontrol is furnishing the ATC system for the

San Francisco MUNI light rail system and for the

Toronto Transit Commission in Canada,

There are many more suppliers of ATC equipment for small, automated-vehicle, fixed-guideway

systems. In addition to GRS, US&S, WELCO, and

TransControl, the list includes Philco-Ford, TTI

(now TTD) and Varo Monocab.

The number of firms supplying small-vehicle

ATC systems, and the organizational relationships

among them, change from year to year. Some drop

out of the market, new ones enter, and others form

joint ventures or acquire each other. It is a market

where there are many more companies offering

systems than have actually received contracts for

installations, Further, the resulting contracts are

usually rather small. The complete “Satellite Transit System” installation (guideway, vehicles, and

controls) at the Seattle-Tacoma airport was about

$7 million, while the AIRTRANS system at the

Dallas-Fort Worth airport was about $3 I million.

The ATC portions of these systems were about 7 to

12 percent of the total contract prices.83

To date, transfer of technology between conventional rapid transit systems and the new small vehicle systems has been in one direction—from the

conventional to the new systems. Reverse transfer,

and entry of small vehicle system developers into

the conventional rail rapid transit market, has not

occurred, perhaps due to the much larger size of the

contracts and capital commitments required to

compete in the conventional rail rapid transit

market, or perhaps due to the failure of AGT suppliers to develop workable systems for rail rapid

transit application.

While some foreign-made ATC equipment is

utilized in the United States, the market is not really

8ZUnlon Switch and Signal is also referred to by the acronym

of its parent firm, WABCO.

@aIn relative terms, this proportion is somewhat greater than

the 3 to 5 percent of total contract price that is typical for rail

rapid transit systems. The absolute dollar amounts, however, are

quite small.

receptive to foreign incursions. There are several

reasons. Some procurement specifications exclude

foreign suppliers by requiring prior transit service

in the United States or by including restrictions on

foreign-made components. Also, U.S. transit agencies tend to doubt that foreign suppliers would be

able to provide continuous long-term service.

Finally, there are some major differences between

U.S. and foreign ATC technology

techniques.

ISSUE D–6: CONTRACTOR

and engineering

SELECTION

How ore contractors for ATC design and

engineering selected?

The lowest technically qualified bidder is

usually selected. Competitive bidding and award

to the low bidder is required by law in many

States.

Usually, two or more suppliers will compete for

the opportunity to design, build, and install ATC

system hardware and software in response to the

technical specifications describing required system

characteristics. Ultimately, responsibility for selection of the supplier rests with the directors of the

transit authority. Most frequently, the directors rely

on their technical staff for evaluation of the proposals and for monitoring the work of the selected

contractor. This procedure was followed at CTA,

CTS, MBTA, NYCTA, and PATCO. However, at

BART, the general engineering consultant (Parsons,

Brinckerhoff-Tudor-Bechtel) was delegated

authority for some of the contractor selection and

management. Interviews with personnel at new

systems in the planning or early construction

phases (MARTA, RTD, WMATA, Baltimore,

NFTA, and the Twin Cities) indicate that these

agencies will also utilize consultants to assist in

contractor selection and management,

The increasing involvement of consultants in

contractor selection and management for new rail

rapid and small vehicle systems reflects the increasing complexity of new rail rapid and small vehicle

systems. The design and development of such

systems is often beyond the capability of the limited

staff maintained by most transit agencies. It should

be noted, however, that consultants may have

somewhat different motivation and may use somewhat different evaluation criteria than the transit

authority,

145
Contractor selec tion is relatively simple when The opportun

“off-the-shelf” equipment is to be used and the

competition reduces to a matter of price among

prospective suppliers, all of proven capability.

Often, however, the available equipment does not

satisfy all of the specifications and requirements.

Contractor selection then involves identifying

qualified suppliers, publishing an invitation for bid,

evaluating the bids received from the prospective

suppliers, and awarding a contract. Table 33 summarizes the contractor selection approaches used by

transit authorities in several recent procurements.

Several of the transit authorities require that a

prospective ATC system supplier be a manufacturer of equipment proven in use on operating transit systems in the United States. If the ATC system

at BART is considered to be proven, this restricts the

list of qualified ATC equipment suppliers to just

three companies: GRS, US&S, and WELCO.

However, technical personnel at some authorities

do not accept the BART ATC system as proven.

Thus, only GRS and US&S are presently considered

qualified by these authorities. The list could be

enlarged by including Transcontrol if Canadian installations were accepted.

ity for a new company to become

qualified as a supplier of ATC equipment is offered

by several authorities, who will permit the company to install and demonstrate ATC equipment at

a test track location on the authority’s property. If

testing proves that the equipment has desirable performance features together with acceptable safety,

quality, reliability, and maintainability, the

authority’s technical staff may approve this company’s qualifications to bid for the next ATC equipment procurement. The prospective supplier must

bear the expense of the demonstration equipment,

installation, maintenance, and testing in this prequalification program.

Prior to 1969, the Dallas/Fort Worth Airport

Board conducted an investigation of possible suppliers of an automated system. As a result of this investigation a Varo/LTV/GRS team and Dashaveyor

were selected as the two (and only) qualified candidates. These two submitted preliminary engineering reports in October 1969. In 1970, Varo/LTV/GRS

and Dashaveyor received technical study grants for

demonstration of their systems at the plant. Initial

bidding for AIRTRANS took place in March 1971,

with Varo/LTV/GRS and Dashaveyor being the

TABLE 33.—Contractor Selection Approaches

Transit Bidder Evaluation Contract

System Qualification Process Award

BART (d) (b, c) WELCO

CTA (b) GRS, US&S

CTS (d) (b) GRS

D/FW (e) (b, c) GRS

MARTA (d) (b, c)

MBTA (d) (b) GRS, US&S

NYCTS (a, d) (b) GRS, US&S[f)

PATCO (d) (b, c) us&s

SEA-TAC (b, c) WELCO

WMATA (g) (b) GRS

Demonstration at test track.

Low bid.

Proposed performance.

Manufacturer of proven equipment.

Demonstration at plant was an original requirement.

At a second bidding there was no such prequalification.

R-44 and R-46 procurements.

Preliminary proposals.

146
only bidders allowed. One bid was rejected as too

high, and the other was rejected as not responsive to

the specifications. In May 1971, a second bidding

took place with four bidders: Bendix/Dashaveyor,

VSD-LTV, WABCO Monorail Division, and

WELCO. VSD-LTV was selected as the supplier.

The subcontract for the train control system was

awarded to GRS by VSD-LTV.

The “invitation to bid” requests a cost quotation

for supplying the ATC system and services defined

in the procurement specifications. The solicitation

may also require submission of a technical proposal

that describes how the bidder intends to satisfy the

requirements of the procurement specifications. In

addition to the technical requirements, provisions

for documentation, program planning, management

visibility and control, quality control, acceptance

and systems assurance testing, and the many other

factors specified as important to the procurement

must be taken into account by the prospective supplier in preparing his bid. Experience shows that it

is very difficult to add or increase a requirement

once an “invitation for bid” has been published and

the prospective suppliers’ responses have been

received.

As a general rule, competitive bidding is

employed by the transit authorities; and, in most

cases, competitive bidding is required by State law

or local ordinance. Usually, however, the

authorities reserve the right to reject all bids and

have a new solicitation. This study has disclosed no

instances where a sole-source solicitation had been

employed.

The established transit agencies select an ATC

equipment contractor from previously qualified

suppliers on the basis of the lowest price. Other

agencies employ a single-step process where technical capability and cost are weighed together.

WMATA was unique in that they used a two-step

process in which the responsiveness of prospective

contractors’ proposals to the procurement specifications in a prebid solicitation was used to make a

selection of qualified bidders. Subsequent selection

of the winning contractor from the two qualified

bidders was based solely on cost.

To date, cost estimates and award to the low bidder have been based solely upon the capital costs of

system development and construction. Life-cycle

costing, which would require cost competition

based upon both the capital and operating costs, is

an alternative costing method that has not been

used but may find increasing favor as energy and

economic conditions cause a shift in values.

Once a contract has been awarded, data on

program status and control over program direction

available to the transit authority management are

limited to that specified by the contract. Therefore,

it is important that the contract provide the means

for monitoring the contractor’s progress and for exerting some directive control over contractor activities.

Management control is achieved in many ways

ranging from a resident engineer at the contractor’s

plant to formal design status reviews, RMA predictions, progress reports, and other such techniques.

Traditionally, management control of an ATC

system contract has been achieved by assigning signal engineers from the authority’s staff the task of

monitoring the work of the ATC contractor. These

engineers are expected to know the status of the

contractor’s program at all times throughout the

contract, and, in particular, to be aware of any

problems and the work being done to solve them.

They also direct contractor progress by exercising

approval of designs proposed by the contractor,

Maintaining management control has become increasingly difficult as ATC systems have grown

more complex. BART, PAAC, and WMATA ATC

system procurement specifications included provisions for system assurance programs, periodic

design reviews, and other modern management

techniques. Several transit authorities expect to hire

separate consultants to plan, specify, and monitor

the system assurance programs for their ATC pro147

72-683 0- 76 - 11
curements. These consultants will report directly to

the transit authority technical staff.

One important method for achieving management control is independent review of the ATC

manufacturer’s design. This review may be conducted by the transit authority engineering staff or

by engineering consultants. The manufacturer is required to correct all the deficiencies identified.

Besides providing an independent evaluation of the

manufacturer’s design, this procedure also educates

the reviewer on the details of the design. This particularly is important in new systems where the

staff may not have lengthy transit experience. A

variation of this approach is being used at MARTA.

Periodic reviews of the MARTA train control

system design are being held under the auspices of

UMTA, with the DOT Transportation Systems

Center serving as a technical consultant.

Established transit properties such as CTA and

NYCTA have traditionally required the manufacturer to continue to correct equipment deficiencies

until the equipment performance is acceptable to

the chief engineer. Management control by these

authorities succeeds, in part, because of the limited

market for ATC equipment. If an ATC equipment

manufacturer wishes to remain in business, he must

necessarily satisfy his customers, and these two are

the largest in the country. The major change in

methods of management control for the new ATC

system procurements is the introduction of requirements for detailed program planning by the contractor. The increased management involvement permits control action to be taken immediately when a

deviation from the program plan is noted. This

makes it possible for management to avoid potential

problems rather than waiting until they occur and

require drastic action to correct.

Upon completion of the manufacturing process,

the ATC equipment is delivered to the transit

authority, installed, and tested. Test procedures are

described in the next issue.

ISSUE D-8: TESTING

How are ATC systems tested? What kinds of

tests are conducted, for what purposes, and

when in the development cycle?

There are three categories of ATC system

testing,

system

148

each beginning ata different stage in the

life cycle and satisfying different needs.

Engineering testing occurs early in the development cycle and provides data for detailed system

design and modification Assurance testing is performed to evaluate how well the equipment

meets procurement specifications. Acceptance

testiing is performed when the whole ATC

system has been installed and debugged and may

be performed on significant subsystems before

their ‘integration into the total system. Acceptance testing is the final demonstration that the

system meets specification. There is room for improvement in several areas-test planning, documentation, and dissemination of results.

Testing serves a number of important functions

in the development process. It provides the data

necessary to support ATC design. It serves to identify actual or potential problems during manufacture and installation. It is the means to verify that

the resulting system meets specified requirements.

There are three basic types of testing: (1)

engineering testing, (z) assurance testing, and (3)

acceptance testing. Each is initiated at different

times in the system life cycle, and each satisfies

different needs, but they are not mutually exclusive. They frequently overlap in time, and data

obtained in one type of testing may be useful for the

purposes of another. Although all three types of

tests are initiated prior to opening of the system,

they may extend well into the period of revenue

service.

The results of testing are of primary interest to

the transit agency installing or modifying an ATC

system and to its system contractors. The test

results may also be of value to other authorities

who are planning a similar system. Careful planning of tests, description of test procedures, and

documentation of results is essential to maximize

the value of testing.

Of particular interest for this report is the adequacy of the testing process in terms of planning,

procedures, and documentation of results. Also of

interest is responsibility for testing and evaluation

of test results. Finally, the degree to which test

results for one system are utilized at others planning similar systems deserves exploration.

Engineering Testing

Engineering testing begins early in system

development and includes tests of components and
subsystems to verify that they perform as expected.

There are also tests undertaken to diagnose the

cause of a problem and assist in its solution. This

second category of tests is called “debugging.”

Engineering tests are generally performed by the

ATC system contractor to support equipment

design and manufacture. Results are not always

documented and are generally not submitted formally to the transit authority, A representative of

the authority may be in residence at the supplier’s

plant and may monitor engineering test results.

NYCTA, for example, follows this procedure.

Because engineering testing occurs early in

system development and there is higher order testing later on, it is probably not necessary to have

more formal documentation and wider dissemination of engineering test results than is presently the

custom. Furthermore, manufacturers frequently

consider the results of these tests to be proprietary.

Assurance Testing

Assurance testing includes inspection and

quality control during production and tests to ensure that the equipment meets procurement

specifications.

In general, the procurement specifications include provisions for the quality control program.

Unfortunately, quality control programs are not always adequate, For example, the BART ATC

system procurement specifications provided for

such a program, but strong and effective quality

control was really not achieved. An effective

quality control test program must include not only a

good inspection and test program but management

procedures to follow up and correct deficiencies.

Besides quality control, tests are conducted to

demonstrate that equipment meets specifications

for performance, safety, reliability, maintainability,

and availability. Such tests are performed on individual components at the factory or as they are installed, then on subsystems, and eventually on the

whole ATC system. Failure of the equipment to

perform according to specifications leads to diagnostic testing to isolate faults and correct them—

another type of debugging. Ideally, these tests

would be completed and all deficiencies corrected

before revenue operation. However, the length of

time required for some kinds of assurance tests

(notably reliability) and pressures to begin

passenger service often dictate that operations start

before the tests are completed. Some transit

authorities recognize this necessity by indicating in

the procurement specifications those assurance

tests that must be completed before revenue service

and those that will be accomplished during revenue

operation.

It is important to note that statistically significant

tests to demonstrate ATP safety probably cannot be

conducted, The required levels of safety are so high

that a valid quantitative test for safety would take

years or even decades to complete, even if accelerated testing methods were employed. As a result,

assurance of ATC safety is accomplished by a combination of analysis and testing. The analytical

work is done to identify possible design or engineering defects that could produce an unsafe condition.

Testing then concentrates on these areas. While it

may not be able to produce statistically significant

results, test data of this sort can lend credibility to

engineering judgments made about safety.

Acceptance Testing

Acceptance testing is the final set of tests on the

completed ATC system to demonstrate that the

system meets all procurement specifications, Acceptance testing is specified in detail as part of the

ATC system contract and usually consists of an’ integrated series of tests which take place over

months or years. Acceptance testing tends to concentrate first on safety features, then on performance, and finally reliability and maintainability,

Formal tests of the personnel subsystem and manmachine integration are seldom, if ever, conducted.

Problems in this area are detected and corrected as

they arise in the course of other testing or operations. The ATC system is accepted by the procuring

agency when it has been demonstrated that

specification requirements and contractual acceptance provisions in the contract have been met.

The planning, conduct, and communication of

test results are basic to all three categories of testing, The adequacy of documentation of plans, test

procedures, and results was reviewed during this

study in order to evaluate the testing process. The

general conclusion is that documentation of test

plans has been less than adequate,

From interviews with representatives of transit

systems now being planned, and from examination

of procurement specifications, it is apparent that

there will be increased emphasis on formal documentation of test plans in the future, For example,

149
the PAAC ATC system procurement specifications

require the contractor to prepare and submit

various test plans appropriate to the different

categories of testing. As another example, MTA

Rapid Transit Development Division (Baltimore)

expects to hire a reliability, maintainability, and

system safety consultant who will be required to

plan a comprehensive and integrated program for

the entire transit system, including the various

system assurance tests pertinent to RMA and

safety. This consultant will work with both the

general engineering consultant and the ATC system

design subcontractor.

Confidence in test results is determined to a large

degree by the detail to which testing procedures are

documented. Careful attention to details such as accuracy, precision of measurement, and control of

the test environment is important. In some cases, it

is difficult to assess the quality of testing that has

been conducted in existing transit systems because

documentation is lacking or inadequate.

For testing to be of maximum value, the results

must be communicated to interested parties. Within

a single organization, this may be accomplished informally by oral report or internal memoranda.

However, in an integrated test program, more formal reporting procedures are necessary to assure

that the test results are properly disseminated. As in

test planning and performance, there is room for

improvement in the dissemination of results, particularly outside of the transit agency.

R&D may be defined as discovery of new

knowledge and its development for use in practical

application. R&D must be distinguished from applications engineering which refers to the solution

of specific technical problems. With this distinction

in mind, the following summarizes the organizations which might be expected to perform R&D in

ATC and their involvement in such activity.

R&D Programs

Operating transit agencies perform very little

ATC R&D. Fiscal realities of the operating environment do not support such activity. Operating agencies do conduct ATC applications engineering.

Agencies planning new rail rapid systems and

their subcontractors perform R&D in the course of

system development--chiefly design and development of new hardware, test track demonstrations of

new concepts, and basic analytical work. Funds

may be provided for such purposes by the Federal

Government as part of technical study programs

and capital grants. Transit agencies sometimes use

their own funds to support such work.

The American Public Transit Association

(APTA) is the principal rail rapid transit industry

association. Some of its committees are active in

areas related to ATC, principally safety and

reliability. Such work is paper-and-pencil studies

and is supported by member organizations. The

Transit Development Corporation is an industryorganized R & D corporation. No programs

specifically related to ATC have been undertaken,

Some R&D in ATC reliability and small vehicle

systems is done by manufacturers. This work is

supported primarily by private investment, There

has been some private investment in test track

demonstration programs. (See Issue D-10, p. 151.)

Most industry work in ATC for rail rapid transit is

applications engineering.

Educational research organizations, such as the

University of Minnesota, Northwestern University,

Aerospace Corporation, and Applied Physics

Laboratory, have funded contributions to the

literature for small-vehicle, fixed-guideway

systems. They have not made substantial private

contributions to rail rapid transit R&D for ATC.

The Federal Government is the principal source

of R&D funds. Major Federal support to assist testing and demonstration of ATC equipment for conventional rail rapid systems was given in the

mid-1960’s in conjunction with the BART and

Transit Expressway test tracks. (See Issue D-10, p.

151.)

Recent Federal programs have generally been

associated with support of major vehicle or system

150
concept development rather than ATC as such.

These programs include the State-of-the-Art Car

(SOAC), the current Advanced Concept Train

(ACT I), the TRANSPO ’72 demonstrations, the

Standard Light Rail Vehicle, PRT activities at

Morgantown, West Virginia, and the now-canceled

Dual-Mode Program,

In small vehicle technology, a new project

directed toward the development of a high performance PRT (HPPRT) system has major ATC elements. Also, the Applied Physics Laboratory (APL)

of Johns Hopkins University has been providing

more or less continuous support to UMTA in PRT

technology. Most of the APL work has focused on

analytical studies of operational and reliability

problems associated with PRT systems. APL has

also provided general technical support to UMTA,

notably as a technical monitor (with MITRE) of the

TRANSPO ’72 PRT demonstrations.

Recent and current work in system assurance has

been closely allied with ATC technology and the

question of manned versus unmanned vehicles. An

UMTA-funded ongoing program in these areas is

being conducted by the Transportation Systems

Center (TSC). One product of this work was a

report entitled “Safety and Automatic Train Control for Rail Rapid Transit Systems, ” published in

July 1974. It is expected that the results of the TSC

investigation of system assurance and the question

of manned/unmanned systems will be available in

1976.

Except for the APL work, there has been little

support for the development of analytical tools

needed to evaluate ATC (and other) problems

associated with advanced technology systems. This

situation now appears to be changing. A part of the

now-canceled Dual-Mode project was to have involved development of the analytical tools necessary to evaluate such general concerns as operational strategies and reliability. Such a requirement

is included in the later phases of the recently initiated HPPRT program.

There are indications that a more programmatic

approach to ATC technology for small vehicles will

be initiated. UMTA is currently developing an

Automated Guideway Technology (AGT) program

which will deal with many system and subsystem

problems on a generic rather than project-specific

basis. If there are any significant contributions to

rail rapid transit system of these programs, they are

likely to fall in the area of the development of

methodology and analytical tools. Equipment requirements for AGT and rail rapid transit are so

different that contributions to rail rapid transit

hardware technology are unlikely. However, better

analytical tools would be an important contribution.

Application of R&D

The application of the results of R&D varies according to the sponsoring organization, Privately

supported R&D, such as is done by manufacturers,

is generally proprietary and not fully available to

the industry. Unfortunately, this is where most of

the expertise resides,

The results of federally supported research and

that conducted by educational institutions generally

finds its way into the literature, Much of this work

is more theoretical then practical in outlook.

Further, such work is often concerned with automated small-vehicle technology rather than more

conventional rapid transit. The increasing involvement of the Federal Government in rail rapid transit

may change the situation.

Transit agencies planning new systems or

modifying old ones generally exchange information, on a personal basis, with their counterparts at

other transit agencies, This helps to compensate for

the lack of research literature and the withholding

of proprietary data held by manufacturers.

ISSUE D-10: TEST TRACKS

What role do test tracks play in ATC R&D?

Who operates and funds test tracks?

Test tracks are not built solely for ATC studies

but to serve several objectives, and their value

should be judged accordingly. For development

of ATC, test tracks are used for R&D, demonstration of conceptual feasibility, and hardware test

and evaluation. By permitting scientific and

engineering work in the absence of constraints

imposed by revenue service, test tracks are vital

to advances in transit technology. Some test

tracks have short life spans. Others are more or

less perrnanent facilities. They are operated and

funded by the transit agencies, manufacturers,

and the Federal Government.

As used here, a test track is a facility built expressly for the purpose of engineering and scientific

151
studies, and not revenue trackage that may be used

for test purposes. Thus, the Morgantown project is

not a test track. The TRANSPO ’72 exhibition,

while perhaps better classed as a demonstration, is

included because of the post-TRANSPO test

program. Test track programs discussed below are

categorized by the three types of organizations

which operate them: transit agencies, manufacturers. and the Federal Government.

Transit Agencies

BART Diablo Test Track.—The purpose of this

track was to demonstrate the conceptual feasibility

of alternative subsystems for BART—not, as commonly thought, to select hardware to be procured.

The results of the program were used as a basis for

writing functional specifications for BART equipment.

The 41/2-mile test track was located between

Concord and Walnut Creek, California. It was operated in the mid- to late- 1960’s, at a total program

cost of about $12 million. The Federal Government

supplied about two-thirds of the funds, and BART

the remainder. Most suppliers participating in the

program are believed to have invested substantial

funds of their own.

ATC was 1 of 11 different system elements

studied at the track. Because the purpose was concept demonstration using prototype hardware,

reliability and maintainability studies were not part

of the ATC test program. Four ATC systems were

demonstrated, Suppliers were General Electric,

General Railway Signal, Westinghouse Air Brake,

and Westinghouse Electric.84 The results of the formal tests were that all four systems met the general

requirements for BART ATC, with no one system

significantly better.

After final ATC specifications were prepared by

BART, the winning contractor, Westinghouse

Electric, was selected on the basis of low bid.

Because the WELCO system was developed in

response to new specifications and designed to be

price-competitive, it is not surprising that it differed

from any demonstrated. This system was not subsequently tested on the Diablo track before final

systemwide installation. Whether such testing

would have avoided some of the later ATC

problems encountered in BART depends upon the

BqThe Philco Corporation also tested portions of an ATC

system later, after the completion of the formal test program.

type of tests which might have been performed and

the criticality of the analysis of results, rather than

the particular track used.

PAAC Transit Expressway Program Transit Expressway.—This program, conducted by the Port

Authority of Allegheny County, ran from June 1963

to November 1971 at South Park, 11 miles from

downtown Pittsburgh. The objective was to design

and develop a new technology—namely a fully

automated system of medium-size, light weight,

self-propelled vehicles which could be operated

singly or in trains of 10 or more vehicles. The work

was done in two phases at a cost of $7.4 million.

Two-thirds of the funds were provided by the

Federal Government; and the remainder was provided by Allegheny County, the State of Pennsylvania, and Westinghouse Electric.

As the first fully automated transit system, significant development work was done on ATC. The

ATC system underwent major changes between the

first and second phases of the program. The final

system is comparable to BART, with the exception

of the train detection equipment which was

specifically designed to detect the rubber-tired

vehicles planned for the system.

The importance and value of this program lies in

the many innovations demonstrated there and later

incorporated into systems now operationa l

elsewhere. The ATC technology has been used by

Westinghouse Electric for the Seattle-Tacoma and

Tampa airport systems, for BART, and for the Sao

Paulo METRO in Brazil. PAAC used the project to

develop procurement specifications for TERL, a

program recently defeated by the voters.

Manufacturers’ Test Tracks

Manufacturers’ test tracks have been built primarily for work on automated small-vehicle

systems. These tracks are used either to develop

new systems, to check equipment prior to delivery,

or both. Federal funds may be used, as was the case

of the Dashaveyor and Varo test tracks which were

used for feasibility studies conducted by these companies for AIRTRANS at the Dallas-Fort Worth airport. Some company test tracks that have been used

for ATC development or checkout are:

● Dashaveyor, Pomona, Calif.

● Varo Monocab, Garland, Tex.

● WABCO Monorail Division, Cape May, N.J.

152
. TTD, Denver, Colo.

● Bendix, Ann Arbor, Mich.

● Alden, Milford, Mass.

Federal Government

TRANSPO ‘72.—Four automated small-vehicle

systems were demonstrated at TRANSPO ’72 and

later evaluated in a test program conducted between August and November 1972. Federal funds

amounting to about $7 million were provided for

the demonstration and test program. There was also

substantial private investment. The exact amount is

unknown, but it is thought to be of the same order

as the Federal contribution. The systems demonstrated and their manufacturers were:

. Dashaveyor System—Bendix Corporation

. ACT System —Ford Motor Company

● Monocab System—Rohr Industries

. TTI System-Otis

The systems were developed under tight time

constraints with limited funds. This led to some

compromises in the ATC system design. The postTRANSPO test program showed that some of the

ATC equipment had undesirable control characteristics, including long delay times and speed

oscillation. It was concluded that the basic cause of

these problems was the prototype nature of the

equipment.

Apart from its value as a public demonstration of

new technology , the major benefit of the

TRANSPO ’72 program was the increased

capability in small-vehicle technology gained by the

four participating manufacturers, Because of basic

differences in philosophy and operating characteristics between automated small-vehicle systems

and rail rapid transit and because of the less

stringent demands placed on a system in an exhibition (in comparison to a revenue operation), the

TRANSPO ’72 program had limited value in improving ATC systems for general transit industry

application.

Pueblo Colorado Test Facility.—DOT’s High

Speed Ground Transportation Center at Pueblo,

Colo,, became operational in 1973, Managed by the

FRA, the Center can test several types of ground

transportation systems. Both advanced systems and

rail technology programs are conducted, The

former programs include the Tracked Levitated

Research Vehicle (TLRV), the Tracked Air Cushion

Research Vehicle (TACRV), and the Linear Induction Motor Research Vehicle (LIMRV), For rail

technology programs, the Center includes 20 miles

of conventional railroad trackage, used for studying

train dynamics under a variety of track and grade

configurations, a 9.1-mile oval rail transit track

with a third rail for testing electrically powered rolling stock, and a Rail Dynamics Laboratory for

simulator testing of full-scale railroad and rail transit vehicles. As a part of the now-canceled DualMode Program, it was planned to build two guideway loops at the site, each 2 miles in circumference.

Probably the most significant rail transit activity

at Pueblo was the testing of the State-of-the-Art

Car (SOAC) in 1973. There was little ATC related

work associated with this R&D activity, and the

ATC provisions at Pueblo are all but nonexistent.

There are several reasons for this. DOT has been

using the facility for other purposes. Limited

facilities are available. (For example, there are no

provisions for inserting signals into the rails,) The

site is very remote from both operating properties

and equipment suppliers. Most transit agencies feel

it is essential to conduct final ATC development

work in the actual operating environment (atmospheric, electrical, etc.) where the equipment

will be run. Unless there are specific federally

funded programs requiring that the work be conducted at Pueblo, it seems unlikely that significant

amounts of ATC research for rail rapid transit will

be conducted there.

The MITRE Corporation (1971) conducted a

survey of rail rapid transit agencies and equipment

manufacturers to identify problems that should be

addressed in a federally funded research program.

Of the 11 top priority areas indicated by this survey,

none had any direct relationship to ATC. The

results must be accepted with some caution because

153
.: .’ - t

FIGURE 72 DOT Test Track, Pueblo, Colorado

154
none of the industrial firms surveyed were ATC

equipment manufacturers and because the intent of

the study was to identify problems for investigation

at the DOT Pueblo test site. (As indicated earlier in

Issue D-10, p. 151, the Pueblo test facility is not

suited for investigation of ATC problems.) Still, the

survey does suggest that ATC is not viewed as a

major R&D problem by a significant part of the transit industry.

During visits to transit agencies made by Battelle

Columbus Laboratories as technical consultants in

this assessment, comments and suggestions were

solicited on R&D needs in rail rapid transit technology, particularly those associated with ATC.

Here again, the results indicate that ATC is clearly

not a major concern.

Operating transit agencies felt that the major

R&D needs were:

● Improvement of chopper control, multiplexing

of train lines,85 and a.c. traction motors;

● Documentation of slip-slide tests for use in

official and expert testimony in damage and

injury suits;

● Clarification of the trade-off values associated

with such technical matters as analog vs.

digital signals, control signal frequencies and

modulation rates, types of station stops, choppers vs. cam controllers, and the use of p-wire;

● Review of the availability and allocation of

radio frequencies for both voice and data

transmission by transit systems;

● Development of a data base an d

clearinghouse for reliability and maintainability information for the benefit of transit systems and manufacturers.

Transit systems in the planning and construction

stages had a differing set of priorities:

● Investigation of electromagnetic interference

problems;

● Improvement in the reliability of ATC

systems and related equipment;

. Study of techniques for, and the value of,

regenerative braking;

. Establishment of a data bank on the safety,

●

●

reliability, and maintainability experience of

operating transit systems;

Maintenance training programs to ensure that

new and sophisticated transit equipment (including but not limited to ATC) can be properly cared for;

Studies of collisions and crash resistance, particularly for small-vehicle systems.

Since one of the main purposes of this technology assessment was to weigh the need for R&D

in the area of automatic train control, this topic was

given special attention. In addition to review of the

literature and collection of opinion within the transit industry through the interviews cited above, the

matter of research needs and priorities was made

the subject of a separate investigation by the OTA

Transportation Program staff and the OTA Urban

Mass Transit Advisory Panel. This investigation

drew especially on the experience of individual

panel members and of various transit system

managers, equipment manufacturers, technical

consultants, and DOT officials. The findings of this

investigation, as they apply to rail rapid transit, are

presented below.86

At the outset, it should be noted that there is no

need for a significant R&D effort to make major advances or innovations in ATC technology for rail

rapid transit systems. The basic technology is sufficiently developed for present and near-term future

purposes. What is needed now is research and

development to refine the existing technology and

to improve performance at reduced cost. The major

elements of such a program are discussed below.

Figure 73 is a matrix, categorizing the importance of

these R&D efforts against the estimated relative

cost to carry them out.

Reliability and Maintainability

There are several aspects of reliability and maintainability in which further work is needed.

Equipment Reliability and Maintainability

There is a major need to develop more reliable

and maintainable equipment. This applies not

just to ATC but other types of rail rapid transit

equipment.

aSThe underlined items are those directly or indirectly related to ATC.

aeR&D needs for automated small-vehicle systems are explored in a separate OTA report, Automated Guideway Transit:

An Assessment of PRT and Other New Systems, June 1975.

155
RESEARCH AREAS

RMA Analytic Techniques

Equipment RMA

RMA Data Bank

RMA Standards

Safety Methodology

Technology Transfer

Handicapped Requirements

Standardization

●

FIGURE 73. ATC Research and Development Priorities and Relative Cost

Techniques for RMA Analysis

Improved and more quantitative methods are

needed to evaluate total system performance in

terms of reliability, maintainability, and

availability. Component performance measures

exist. Total system performance measures do

not. Total system measures would permit better

allocation of reliability requirements among subsystems, better understanding

trade-offs, and better utilization

nance work force.

RMA Standards and Guidelines

An effort is needed to establish

ment standards and to clarify

of reliability

of the mainterealistic equipmanufacturers’

responsibilities in the area of RMA. The standards must be high enough to assure reasonable

availability of equipment but not so high as to

make the equipment unnecessarily costly.

156

Reliability and Maintainability Data

A pool of data from testing and operational experience pertaining to equipment reliability and

maintainability y would be of great value to transit

system planners, research groups, and manufacturers. At present, there is no uniform way of

recording and reporting such information, and no

clearinghouse for collecting and disseminating it

within the transit industry.

Safety

The safety levels of the rail rapid transit industry

are high and exceed nearly all other forms of public

and private transportation. Still, there is a need for

research in two aspects of safety.

Train Detection

The much publicized train detection problems of

BART (which are probably no more severe than
those experienced in other transit systems) have

underscored the need for clarification of the

standard for train detection and the need for a

uniform method to test the performance of train

detection systems.

Safety Methodology

Controversy over system safety versus fail-safe

principles abounds in the transit industry, There

is also debate over how safety is to be measured

and how safe is safe enough. Research is needed

to develop an objective and quantified method

for evaluating the safety aspects of rail rapid

transit system performance.

Man-Machine Relationships

Function Allocation

There is great variability among transit systems

in the duties assigned to the human operator. Significant errors were made in the original design

of the BART system because of the highly

passive role assigned to the train attendant. The

man-machine interface needs to be carefully

studied to determine the optimum role of the

human operator in automated systems and to ensure that provision is made for the operator to interact effectively with the system in abnormal or

emergency situations. The role of personnel

assigned in a supervisory capacity needs to be

similarly examined.

Cost-Benefit of Automation

Research is needed to determine the relative advantages of manual and automated methods of

operation with respect to energy savings,

variability of trip time, equipment utilization,

system capacity, and manpower costs. Such data

would be of value not only in the design of new

systems but also in the .modernization of old

ones.

Application of Technology

Even though ATC is a rather mature and well

developed technology, there remain some problems

of practical application. Three areas are in need of

special attention.

Standardization

There are a number of technical and economic

benefits to be gained from reducing the diversity

of ATC equipment now in use or planned for installation in rail rapid systems. These advantages

must be scrutinized and evaluated against the

disadvantages of inhibiting innovation and impeding improvement that standardization might

bring.

Technology Transfer Within the Industry

There is a general shortage of persons with experience in ATC system design, manufacture,

and operation at all levels in the industry. This

shortage is most keenly felt by agencies planning

and building’ new systems. Research is needed to

devise more effective methods for sharing information, exchange of experienced personnel, and

training of new personnel.

Requirements for the Handicapped

Under the stimulus of the Federal Government,

there is an increasing concern in the transit industry with the transportation needs of the handicapped. As a part of the investigation of the

general social costs and benefits of providing rail

rapid transit service for the physically, visually,

and auditorily impaired, there is a need to consider the specific influence of ATC. Among the

matters of interest are acceleration and deceleration limits and their effects on system capacity

and trip time, passenger assistance on trains or in

stations with a low level of manning, and the

safety of the handicapped and others in emergency situations.

157
Chapter 7

POLICY AND

INSTITUTIONAL FACTORS

t

,..
INTRODUCTION

Rail rapid transit is a public entity. Transit

systems are built with public funds to serve public

transportation needs. The public is involved in the

conception and planning of the system-both in

public referenda to approve the building of the

system and in citizen participation programs during

the planning process. The planning and operating

agencies, themselves, are quasi-public bodies,

whose directors are responsible to a State or

municipal government or to a local electorate. The

operation of the transit system, especially in recent

years, may be subsidized with some combination of

Federal, State, and local funds. As a consequence,

the form and operation of a rail rapid transit system

are strongly influenced by public policy and institutional factors,

Three forms of influence can be distinguished:

legislative, regulatory, and institutional

Legislative influence is manifested through the

content, authority, and impact of laws enacted at

the Federal, State, and local levels of government.

Generally, such laws serve one of two purposes:

regulation or promotion. In the earliest days of

public transit, and continuing somewhat after

World War II, the intent was primarily regulatory.

Laws were enacted to control the private firms that

provided public transportation and to ensure that

the public interest was protected.

Since the middle of this century, the purpose of

legislation pertaining to public transit has shifted to

that of promotion and subsidy. This shift was coincident with, and occasioned by, the precipitous

decline of the transit industry to the point that it

was threatened with extinction. As a result, most of

the recent legislation has been aimed at promoting a

resurgence of public transportation. These laws

authorize the expenditure of public funds (often in

large amounts) to design, build, and operate transit

systems. These laws also establish and support

research programs to advance the state of technology and to broaden its application. While none

of this legislation has dealt specifically with

automatic train control technology, this aspect of

transit system design and operation has benefited

from the general increase of financial support for

rail rapid transit.

Regulation, although no longer the predominant

purpose of legislation, is still a major concern at all

levels of government. The oversight and control of

transit systems is an important function of Federal

and State agencies, especially in the area of safety.

Local governments tend to place more emphasis on

the regulation of fares and levels of service. The

pattern of regulatory legislation is far from static;

and, like promotional legislation, it appears to be

extending--especially at the Federal level—more

widely and deeply into the area of system operation.

Institutional factors are manifested primarily

through actions of the transit industry, labor unions,

and—to some extent—the public at large. While not

so clearly defined or so easy to isolate as legislation

and regulation, these institutional factors also serve

to shape the course of transit system development

and operation.

The purpose of this chapter is to examine the

issues raised by ATC in the area of public policy

and institutions. In some cases, these ATC issues

are not wholly distinguishable from the general

context of rail rapid transit system development

and operation. These larger, systemwide topics will

not be treated, however, except as background to

the particular aspects of ATC or the reciprocal

effects that policy and institutions have on train

control system technology and its application.87

SUMMARY OF EXISTING

LEGISLATION

Most of the legislation relating to rail rapid transit is of recent origin, and none contains specific

provisions for the promotion and regulation of ATC

per se. Nevertheless, this legislation (especially

Federal laws) does have an indirect effect upon

ATC design and development through the general

support provided to rail rapid transit technology.

The following is a summary of the Federal laws

with sections germane to ATC.

Urban Mass Transportation Act of 1964 (PL

88-365)

In general terms, the Act of 1964 provided three

forms of financial support:

87For an examination of the more genera] policy issues pertaining to transit system planning and development, see the

OTA report, An Assessment of Community Planning jor Mass

Transit, November 1975 (Report Nos. OTA-T-16 through OTAT-27).

161
●

●

●

Grants or loans to assist State or local agencies

in acquisition, construction, or improvement

of transit facilities and equipment88

Grants to State or local agencies for planning,

engineering, and design studies related to

mass transit;

Grants for research (including new technology) and training.

Funds in all three categories have been used for

development and acquisition of ATC systems.

Capital grants have been made both for the purpose

of upgrading existing ATC equipment (e.g., the recent cab signal installation programs in CTA and

MBTA) and for planning and constructing new

systems with advanced forms of train control (e.g.,

WMATA and MARTA). Funds available under the

1964 Act have also been used to support several

ATC-related research and development activities,

both within DOT and by outside R&D organizations.

The 1964 Act also contains two specific sections

that have an influence on decisions related to train

control system automation:

●

●

Transit employees adversely affected by any

federally assisted project must receive special

consideration, including protection of rights

and benefits;

Transit systems must afford accommodation

to the special needs of the elderly and handicapped.

Protection of individual workers (not specific

jobs) is contained in section 13(c) of the Act. which

also requires that clearance for a grant be obtained

from the Department of Labor. The Act allows the

elimination of jobs, but only as workers presently

holding those jobs retire or vacate the positions for

other reasons. Thus, economic benefits of workforce reduction through automation of an existing

transit system may be deferred for a number of

years until retraining, transfer, or attrition can account for the displaced workers. Alternatively,

direct compensation can be paid to affected

workers, eliminating the jobs earlier but at an

earlier cost. As noted previously, however, it appears that few employees are actually put out of

880rigina11y, the 1964 Act provided for two-thirds Federal

funding, with one-third State and local matching. In 1973, the

Act was amended to increase the Federal share to 80 percent.

162

work by increased automation of existing systems,

New systems do, in fact, have smaller train crews,

but this work force reduction is largely offset by the

increased need for more and higher skilled workers

to maintain the more sophisticated and complex

ATC equipment89

.

The Urban Mass Transportation Act of 1964, and

its amendments, directs that consideration be given

to the means of providing service to, and assuring

the safety of, the elderly and handicapped. This has

raised problems that are not yet fully resolved within the transit industry. The chief concerns related to

ATC are control of door operation and emergency

evacuation of vehicles in automated systems without an onboard operator. There is also uncertainty

about how accommodation of the elderly and handicapped will affect the service offered to other

passengers in normal operations and their safety in

emergencies.

Department of Transportation Act of 1966 (PL

89-670)

This Act created administrative and supervisory

bodies of the Federal Government that now have a

major influence on transit system development and

operation as a whole, and ATC in particular. The

Act established both the Urban Mass Transportation Administration (UMTA) and the National

Transportation Safety Board (NTSB), UMTA is the

principal DOT organization by which grants and

Federal assistance to transit development are administered. NTSB is charged, inter alia, with overseeing the safety of transit systems and with accident investigation.90

Federal Railroad Safety Act of 1970 (PL 91-458)

This Act placed the safety of rail rapid transit

systems within the purview of the Federal Railroad

Administration (FRA). To date, however, FRA has

not actively pursued this interest, apparently

because of preoccupation with problems of intercity

and commuter railroads, As discussed below in

Issue P-z, there is evidence within recent months of

W)st;(> ]ssl If, [).1 Z, l)f>g i n n i ng on pilg(~ I I ~, for a fl I rth[~ r tr(~a t -

ment of this point.

wThe NTSB investigation of the BART Fremont accident,

entitled “Safety Methodology in Rail Rapid Transit System

Development,” August 1973, and an earlier report, “Special

Study of Rail Rapid Transit Safety,” June 1971, raised several

important questions about the advantages and disadvantages of

ATC.
more active involvement of FRA in rail rapid transit.

National Mass Transportation Assistance Act of

1974 (PL 93-503)

This law is, in effect, a significant amendment

and extension of the Urban Mass Transportation

Act of 1964. Its major provisions include allocation

of additional funds for urban mass transportation

programs and—for the first time—makes Federal

funds available on a fifty-fifty basis for operating

expenses. Under the 1964 Act, Federal support was

available only for capital expenditures.

Some of the sections of the 1974 Act specifically

relate to ATC are:

● Section 5 (n) The provisions of section 13(c)

of the Act of 1964 are made applicable to all

assistance under the formula grant program.

● Section 107 The Secretary must investigate

unsafe conditions in facilities, equipment, and

operations funded under the Act of 1974,

which result in serious safety hazards. If unsafe conditions are found, he may withhold

assistance until appropriate actions are taken.

It is still somewhat early to assess the general

effects of this Act on transit system development or

its specific impact on ATC. Opinion on these subjects is mixed within the transit industry and in the

Federal Government, and evidence from transit

system operation is still too fragmentary to indicate

trends.

State, Regional, and Local Legislation

Before 1964, when the Federal Government

became involved in capital grants to mass transit, financial support was almost exclusively the concern

of State and local governments. Such support, when

given, was usually for publicly owned systems. Private transit operators, while subject to various

forms of State and local regulation, typically

received no support from public funds and were

almost wholly dependent upon the fare box for

revenues.

As transit ridership declined and operations

became less and less profitable, private operators

often severely curtailed services. Eventually, many

found it impossible to continue. It became necessary for public bodies to assume control in order to

prevent the total loss of these transit systems to the

community.

At the State, regional, and local levels, and occasionally by interstate agreement, legislation has

been enacted to set up various public or quasipublic agencies for operation of public transit

systems. These organizations take a variety of

forms. Some are purely operating authorities.

Others also have planning responsibilities. Most

control all modes of transit in their area of jurisdiction. A few (such as BART and PATCO) operate

only a rail rapid transit system.

Many States have formed Departments of

Transportation for the purpose of coordinating

mass transit activities on a statewide basis, In large

part, State DOT efforts are concentrated on obtaining a larger share of Federal funds or increasing the

eligibility of local agencies to participate in Federal

programs. There has also been considerable support

for mass transit at the State level in the form of

direct subsidies, special taxing plans, and public

assistance programs such as transportation of

schoolchildren and the elderly,

It is difficult to generalize about these State and

local legislative structures except to indicate that

the concern is primarily on the public service

aspects of the system as a whole. Technological

characteristics, chiefly as they relate to safety, do

receive attention in those States which have a

public utilities commission established to regulate

transit system operation, In some States, however,

the transit agency itself is charged with regulating

its operation.

ISSUE P—1: IMPACT OF EXISTING

. ‘ LEGISLATION

The Urban Mass Transportation Act of 1964 and

its amendments has been of enormous help to the

rail rapid transit industry for the planning and con163
struction of new systems and for the modernization

of equipment and facilities in existing systems. The

benefits of this law stem not only from the large

amount of money made available by the Federal

Government for capital grants but also from the-incentives offered to State and local governments to

participate in capital acquisition and improvement

programs by providing matching funds. During the

decade since enactment of the 1964 law, major improvements have been made in the New York,

Boston, and Chicago rail rapid transit systems, and

work on new systems has been started i n

Washington, D.C., Atlanta, and Baltimore.

The recently enacted National Mass Transportation Assistance Act of 1974 continues the policy of

Federal support for mass transit and, for the first

time, extends Federal assistance for operating costs.

Under the 1964 Act Federal support was provided

only for capital improvements and acquisition

(two-thirds Federal funds, one-third matching State

and local funds). The 1974 Act authorizes UMTA to

provide capital grants (on an 80-20 basis) and

operating aid (on a 50-50 basis). Table 34, a summary of the UMTA budget for Fiscal Year 1976, indicates the magnitude and distribution of the

Federal Government’s assistance program for mass

transit.

TABLE 34. UMTA Budget for Fiscal Year 1976

AMOUNT

UMTA PROGRAMS (millions of dollars)

Capital Grants 1,100.0

Operating Aid 500.0

(Carryover) 150.0

Technical Studies 38.7

system improvement and growth fostered by

Federal Government assistance,

There is a widely held view in the transit industry that the 1964 Act may have had the effect of encouraging the development and use of automated

train control systems. Because the Act provided

grants only for capital improvements or acquisition

and not for operating assistance, planners may have

been induced to concentrate their resources on

capital-intensive features such as automatic train

control (which would be eligible for Federal assistance) in the hope of thereby reducing later operating costs (for which Federal assistance funds were

not available).

The argument is plausible, but it does not seem

to be supported by events. First, the amount of

money for train control systems provided by the

1964 Act has been relatively small, probably not

. more than 2 to 5 percent of the total capital assistance program, and it is doubtful that such an

amount could have had the imputed effect, Second,

the ATC projects that have been undertaken in this

period and supported by Federal funding have been

justified on grounds other than potential manpower

savings through automation, At CTA and MBTA,

for example, the justification for cab signal installation was safety of operation not labor saving, It

should also be noted that the two most automated

systems placed in service during the time the 1964

Act was in force (PATCO in 1969, and BART in

1972) were planned and built without expectation

of Federal assistance.91 Further, the new systems in

Atlanta and Baltimore, for which preliminary planning and design took place between 1964 and 1974,

employ lower levels of automation than the BART

R&D and Demonstration Grants 53.4 system. If the 1964 Act had had the influence purManagerial Training 0.6 ported by some persons in the transit industry, just

University Research 2.0 the opposite would have been expected, i.e., Administrative Expenses 12.5 MARTA and Baltimore MTA would have a degree

Total 1,857.2 of train control automation equal to or surpassing

that of BART. Thus, it seems unlikely that Federal

Government policy, as expressed in the 1964 Act,

There is no evidence that either the 1964 Act or has tended to foster automation.

the 1974 Act has had a specific impact on ATC techFederal Railroad Administration (FRA).—The nology or its application in existing and planned

transit systems. The provisions of these laws are FRA, which has long had jurisdiction over the

quite general, and there is no explicit or implied safety of interstate and commuter railways, has interpreted the Federal Railroad Safety Act of 1970 to support provided for ATC in particular. While there

have been ATC programs undertaken with funds 91BART did receive some Federal assistance in the latter made available under the 1964 Act, and some pro- stages of development and construction, but this was long after

posed with funds from the 1974 Act, they represent the commitment had been made to a highly automated form of

no more than a part of the general pattern of transit train control.

164
confer upon it (through delegation by the Secretary

of Transportation) authority for safety regulation of

all transit systems using rail technology. To date,

however, FRA has not actually exercised this

authority over urban transit systems except to institute a standardized procedure for accident reporting and to announce proposed rulemaking with

regard to train protection systems and the safety of

door operation.

With regard to train protection, FRA is considering the possibility that cab signals and onboard

automatic stopping devices should be required for

all rail rapid transit systems. This requirement

would apply only to new systems, and some exceptions would be granted to existing systems that

have a heavy investment in wayside signals and trip

stops. The concern of the FRA with door operation

centers on how to prevent accidents in which

passengers are caught or struck by doors. Preliminary hearings on door safety have been held and the

views of the transit industry have been solicited.

FRA has not yet decided the approach to be taken,

but their stated intention is to regulate the force and

manner of door closure and the safety interlocks

between door operation and train motion.92

FRA’s sphere of authority is confined to the

safety of equipment already in use. They are not

able to exert direct control over the design process

for new systems, However, the FRA can wield indirect control since they could shut down-or prevent the startup of—any new system not meeting

the safety regulations in force for operating

systems.

Urban Mass Transportation Administration

(UMTA).—At the present time UMTA does not

perform a regulatory function, in the commonly accepted sense of the term. However, some form of

regulatory authority does appear to be implicit

within the general responsibility of UMTA to oversee and administer funding for the development of

new systems. Certain of UMTA’s requirements for

transit system development programs verge on

regulation—for example, the requirement that transit districts requesting capital grants for new system

conduct studies of transportation system alternag21n passing, it should be noted that the FRA’s concern with

the safety of door closure did not arise from rail rapid transit incidents but from operating experience on commuter railroads

regulated by the FRA.

tives and trade-offs. Also, the Safety Division of the

UMTA Office of Transit Management has proposed

initiation of a comprehensive “system safety”

program, which might later be broadened to cover

“system assurance, ” Under a system assurance

program, the concerns of safety would be integrated

with those of reliability and maintainability. If this

is done, the domain of regulation would be expanded to include all aspects that contribute to safe,

efficient, and reliable transit system operation.

While local transit agencies might not be required

to conduct such programs by UMTA regulation, the

control of grant funds exercised by UMTA would

have considerable mandatory force. In fact, several

transit agencies have already instituted system

assurance programs in anticipation that it might

become a future requirement for obtaining UMTA

grants.

UMTA may soon begin investigating transit accidents as a regular activity. Section 107 of the Act of

1974 requires the Secretary of Transportation to investigate serious safety hazards in systems whose

construction or operation is financed with Federal

Government funds, and UMTA is a logical choice

within DOT as the agency to carry this out.

However, it is intended that such investigations

would be conducted only after a serious accident or

incident had occurred and not as a routine beforethe-fact activity.

In the past 2 years, UMTA has made use of the

DOT Transportation Systems Center (TSC) to carry

out in-depth investigations of ATC in two new

transit systems—BART and the PAAC skybus. The

former was an investigation of a newly opened

system which was in the midst of controversy over

the safety of the ATC system. The latter was an investigation of the proposed ATC system for a transit system still in the preliminary design stage. Of

particular interest there was PAAC’s intent to operate rubber-tired vehicles with no onboard personnel. At the present time, TSC is also assisting

UMTA in design reviews of the MARTA transit

system now being built in Atlanta. Among the areas

of concern to the TSC participants are the safety

aspects of the ATC system design and the effectiveness of the integration of man and machine functions.

Some members of the transit industry have expressed concern about these TSC activities. They

fear that TSC might gradually assume a regulatory

165
function for rail rapid transit--especially by setting

down rules, standards, and guidelines that might

become the basis for a de facto form of regulation.

UMTA’s position is that, while TSC may continue

to provide technical assistance, there is no intent to

assign any sort of regulatory role to TSC.

National Transportation Safety Boar d

(NTSB).—The Department of Transportation Act

of 1966 created the NTSB which, while not precisely a regulatory body, has had influence on transit system safety in general and ATC in particular.

The NTSB is empowered to investigate rail rapid

transit system accidents (as well as accidents in

other types of transportation) and to make recommendations to the Secretary of Transportation concerning procedures and equipment that affect the

safety of operation. NTSB has made a number of accident investigations and special studies and has

produced several significant recommendations.

One report, entitled “Safety Methodology in Rail

Rapid Transit System Development” (August 1973)

has engendered strong controversy because it included a recommendation for “abandonment of the

fail-safe concept.” The NTSB view, which is

diametrically opposed to traditional railroad and

rapid transit practice, has brought adverse comment

from all segments of the transit industry. The report

went on to recommend that, as a replacement (or

perhaps more correctly a supplement) for fail-safe,

the industry adopt “an organized approach to accomplishing rapid transit system safety through the

application of current safety management and

engineering concepts. ” Without entering into the

merits of the NTSB argument, this report can be

cited as a major impetus for the system safety and

system assurance programs now being considered

by UMTA.

The role of NTSB appears to be expanding. The

Transportation Safety Act of 1974 contains provisions which require NTSB to conduct a much

broader program of accident investigations than

that set forth in the Department of Transportation

Act of 1966 that established NTSB. It is estimated

that this will involve over 700 additional accident

investigations per year in rail transportation alone.

While rail rapid transit is not mentioned

specifically, NTSB will be expected to investigate

all fatal railroad accidents, all accidents involving

passenger trains, and all rail transportation accidents resulting in substantial property damage.

Regulation of rail rapid transit systems is carried

out at three levels of government: Federal, State,

and local. In some cases, the transit system operating authority may also be self-regulatory, Until recently the concern of regulatory bodies at all levels

has been essentially limited to the area of safety.

Since, in the traditional view, safety involves prevention of collisions and derailments, regulatory interest has centered almost exclusively on ATP subsystems and equipment, Now that automation has

been extended into train operation and supervision,

the scope of regulatory agency concern is broadening to include all aspects of safety and to deal with

safety on a system-wide basis. Aside from safety,

other aspects of system operation (with possible exception of fare structure and level of service) have

received little or no attention from regulatory agencies.

Federal Regulation

Three Federal Government agencies have partial

jurisdiction over safety matters. These agencies and

their areas of responsibility are described briefly on

the following pages.

Under the 1974 Act, NTSB still is not vested with

any rule-making authority or power to establish requirements that specific safety-related actions or

remedies be effected, As before, the primary role of

NTSB will be to investigate and make recommendations to the Secretary of Transportation, who will

retain the authority to accept and enforce the

recommendations as seen fit,

An important point with regard to NTSB recommendations, which is not always recognized by the

166
public, is that NTSB does not attempt to evaluate

the economic or technical aspects of its recommendations. The sole concern of NTSB is to maximize

the safety of a transportation system, The responsibility for evaluating feasibility and cost-benefit is

left to the appropriate regulatory agency and the

local authorities who must ultimately decide on a

course of action.

State Regulation

In many States, regulatory bodies were created in

the 1900-10 period to oversee transit operation and

protect the public from the monopoly power of private owners. As such, these State agencies were

almost exclusively concerned with economic

regulation. With the shift of local transit systems to

public or quasi-public ownership and operation in

the 1940 and 1950 decades, these agencies were left

with vestigial responsibilities, and some ceased to

exist. Few of these State agencies, then or now,

have been active in safety regulation. As a practical

matter, then, most local transit authorities are selfregulated in the areas of both economics and safety,

During this study it was found that many transit

authorities considered themselves to be essentially

self-regulated, but perhaps subject to requirements

imposed by such agencies as the State DOT or

Public Utilities Commission, the State legislature,

or even a regional planning commission of one sort

or another. Transit systems serving areas which include the State capital appear to receive substantial

attention from the State legislature, although not

necessarily in the form of regulation. An example is

the State of Georgia Legislature which created the

MARTA Technical Overview Committee. This

committee is empowered to Iook into any or all

aspects of the MARTA system. Also, the State of

Minnesota Legislature has taken an active interest

in the activities of the Twin Cities MTC and, in

1973, directed that a special study of PRT alternatives be performed because they were not completely satisfied with the results of previous studies.

In some States, the public utilities commission

(PUC) has had an active role in the regulation of rail

rapid safety, often with specific interest in the ATC

system. Two notable examples are in California and

Massachusetts.

In 1967, the California PUC issued specific requirements dealing with ATC. Their coverage was

somewhat general but they specifically addressed

the subject of ATC. These requirements, a result of

section 29047 of the California Public Utilities Code,

state that BART shall be subject to safety regulations of the PUC and that the commission shall inspect BART facilities for safety of operations and

shall enforce the provisions of the section.

The Massachusetts PUC has taken an active interest in the ATC system installed on the MBTA’s

South Shore extension, and has ordered that fully

automatic operations be restricted until such time

as the PUC is satisfied that no potentially unsafe

conditions exist.

Industry Self-Regulation

Regulation of a transit system by an external

agency is not an easy matter, It requires establishing

an organization, staffed by technically competent

and experienced personnel, to write standards,

review plans and designs, and conduct tests and inspections. Even if the necessary personnel could be

found, it might not be practical at the State or local

level to create such an agency. Typically, a State

contains only one rail rapid transit system; and to

establish a special authority to oversee a single

operating agency might be a governmental extravagance.

For this reason, most publicly owned transit

agencies are self-regulated, both for safety and

economic matters such as fares and level of service.

As public or quasi-public bodies, they respond to

the influences of the political system by which they

are created and to the economic constraints imposed by the use of public funds.

The opinion within the transit industry is that

self-regulation is a workable solution. The excellent

safety record of rail rapid transit is cited as proof

that a self-regulating body can manage its affairs in

a responsible manner, with the public interest as a

foremost concern. The opponents of self-regulation,

while not questioning the integrity and sense of

responsibility of the local transit system officials,

point out the inherent danger of vesting a single

agency with the authority to conduct transit operations and oversee the results. Both sides of the argument have merit, and one of the basic issues in the

area of public policy for rail rapid transit is to find a

proper balance between external regulation by a

State or Federal agency (or some combination

thereof) and responsible management by the local

operating authority.

167
ISSUE P-3: ACCEPTANCE TESTING AND

QUALIFICATION

What part is played by regulatory bodies in

the testing and qualification of ATC systems?

Except for the public utilities commissions in

certain States, regulatory agencies are seldom involved in testing and qualifying a syatem for initial service. Up to now, the Federal Government”

has not taken an active role in this area.

Before a transit system is placed in service, each

of its major components and finally the system as a

whole must be subjected to acceptance and

qualification tests. Customarily, this testing is carried out by the engineering staff of the operating

authority, often with the assistance of technical

consultants and manufacturers’ representatives.

The State regulatory agency (typically a public

utilities commission) may observe some part of the

tests and may receive the results for review, but the

State agency usually does not take an active role in

testing and rarely, if ever, conducts independent

tests to verify that the system performs according to

standards. Regulatory agencies of the Federal

Government (FRA, UMTA, and NTSB) are not involved at all in acceptance and qualification testing,

and they do not perceive that they have a legislative

or organizational mandate to do so.

Thus, with regard to testing and qualification,

local transit authorities tend to follow the pattern of

self-regulation. The reasons are primarily those of

practical necessity and not explicit Government

policy. Automatic train control equipment, like

most other components of a modern transit system,

is complex and technologically sophisticated. For a

local or State agency to conduct tests of this equipment would require a staff of technicians trained in

the use of sophisticated instrumentation and experienced in train control system operation. In view

of the general shortage of such qualified personnel

in the transit industry, State agencies find themselves in a position where they must compete with

the transit authority, manufacturers, and consulting

firms for the few persons available. Further, State

agencies may be at a competitive disadvantage

because they cannot offer the salaries, prestige, or

opportunities for advancement that are available in

an operating transit organization, a manufacturer,

or an engineering consultant firm.

Scarcity of technically qualified personnel is not

the only reason. The program of testing necessary

for a local or State agency to qualify a system for

service is virtually the same as the test program normally pursued by the operating authority itself in

assuring that the equipment performs according to

specification and manufacturers’ warranty. Because

of this, public agencies have been reluctant to

establish separate organizations to engage in efforts

that would largely duplicate those of the operating

system they are charged with regulating, especially

since there may be only one transit system within

the entire State. And even if the regulatory agency

were willing to do so, it might be difficult to convince the State government and legislature that

such would be an effective and necessary use of

public funds.

Most State agencies have found that the practical

course is to monitor the tests conducted by the local

operating agency and to review the findings to

assure conformance with established standards,

either those of the State agency or those of the transit industry generally, In some instances, the State

agency has entered into a cooperative arrangement

with the local transit authority, whereby certain

tests are conducted by the local authority on behalf

of the State or whereby State standards have been

adopted by the local agency.

In passing, it should be noted that the primary,

and almost sole, concern of State regulatory bodies

is the safety of the system, specifically the design

features that prevent collisions and derailments.

The broader aspects of passenger safety and operational concerns such as reliability and availability

are almost never matters of regulatory action,

The history of the transit industry has shown

that, because of their size and complexity, new

systems are almost never completed by their

scheduled opening date, As deadlines are missed,

public impatience and political and economic

pressure mount. Because acceptance and qualification testing is usually one of the last items on the

schedule, the local operating agency is strongly

tempted to shorten the test program or to defer a

part of it until after the system has opened for service. The State regulatory body, influenced by the

same pressures, may find it necessary to acquiesce,

To assure that acceptance and qualification testing is not slighted in these circumstances, some

have suggested that the Federal Government

(through either UMTA or FRA) should require a

168
certain amount of testing before a new system is put

into service, It is argued that only the Federal

Government has the authority and the resistance to

local pressure required to ensure that the interest of

public safety is not compromised by expediency,

There is also an economic justification advanced.

The Federal Government, having provided as much

as 80 percent of the funds for development and construction, has the major interest in the new system

and should assure that full value has been received

for the investment of public moneys, A third, and

purely practical, reason for Federal Government involvement is-that only at the national level would it

be feasible to assemble and maintain a technical

organization capable of carrying out such tests.

There are strong counterarguments. As a matter

of policy, it is debatable that the Federal Government should enter into an area where State agencies

and local self-regulation have traditionally ruled

and where the general adequacy of such regulation

has been demonstrated. Further, it may not be correct to view financial support of local transit system

development as an investment by the Federal

Government. Rather, it may be an instance of

revenue sharing without the Federal Government

acquiring proprietary interest. On practical grounds,

the imposition of Federal-level requirements for

testing may add unnecessary delay to the acceptance and qualification process because of the need

to submit test plans to a Federal Government agency for approval, to have the test results reviewed,

and to obtain additional authorizations to open the

system for service. There is also the possibility that,

if disputes arise between the local transit authority

and the Federal Government agency, the acceptance and qualification process might be even

further protracted.

The unresolved issue of responsibility for acceptance and qualification testing is part of the larger

question of how and by whom should regulation of

transit systems be accomplished, The question is

not, of course, confined to the subject of ATC; it applies to all aspects of transit systems development

and operation, Still, the matter of acceptance and

qualification come most sharply into focus in the

area of train control systems because of the vital

part played by ATC in passenger safety. There is a

clear and present need to assure, by some combination of local, State, and Federal regulation and

supervision, that technology is used wisely in the

public service.

ISSUE P-4: STANDARDIZATION

What effects would standardization have o n

ATC?

There would be both positive and negative

effects. The benefits of a uniform technology lie

in the areas of improved system assurance and

reduced research and development costs. The

major disadvantages are restrictions on innovation and limited freedom of choice in system

design.

Few fields of technological endeavor run the full

cycle from experimentation to mature development

without the introduction of standardization. At

some point, the establishment of design and performance standards becomes desirable to check

proliferation of design variations, to reduce

development costs, to limit technological risk, and

to assure that best use is made of existing technology. The real issue is not whether to standardize,

but when and to what degree. If standards are imposed too early or too rigidly, innovation and technological improvement may be stifled. If too late,

the variety of designs may be so great that the

standards become meaningless, and there may be

economic hardship for those who own or manufacture equipment that lies outside the prospective

standard.

At this time, the matter of standardization of

ATC is an open question. Some argue that it would

be healthy for the transit industry and the general

public whose tax moneys are used to support the

development and installation of new ATC systems.

Others contend that it would be unwise to standardize now at a time of great experimentation and innovation because many promising avenues of improvement might be cut off. The following is a brief

examination of three areas where standardization

might be most applicable,

Procurement Specifications

As ATC equipment has become more complex

and sophisticated, the specifications governing the

design and procurement of this equipment have

grown more detailed and explicit with regard to

system performance and contractor responsibiIities.

At the present time, however, each transit agency

procuring a new system or upgrading existing installations writes a more or less unique specifica169
tion, tailored to local needs and conditioned by their

individual experience with ATC,

There would be an advantage for all if there

were a uniform set of terms, conditions, and procedures for the transit industry. This might take the

form of a model specification, establishing a standard terminology and defining basic methods for

verifying compliance. A model of this sort need not

be a completely rigid document; there should be

room for variation to accommodate local needs and

concerns. Further, the specification would not

establish uniform performance requirements; these

would be left to local decision. But it would standardize the phrasing of these requirements and set

forth a universal method for acceptance. and

qualification testing.

This approach would offer several advantages. It

would assure that a well-thought-out document

was available to the planners and directors of new

systems for guidance in an area where they might

be lacking in experience, It would help assure that

the best of past experience and current practice is

incorporated in new systems. There would also be

advantages for ATC equipment manufacturers

since a standard set of requirements and procedures

would permit contractors to know exactly what is

expected of them and would provide continuity and

regularity from one procurement to the next. For

the public, standardization might lead to benefits

such as reduced engineering and development costs

and elimination of some subsequent operational

problems.

Against these advantages must be set three major

disadvantages. A detailed specification is of questionable value for simple procurements; it might

result in overly elaborate and unnecessarily expensive provisions without materially enhancing the

quality and performance of the equipment. It may

not be possible, at the present state of technology

and specification writing, to produce a document

with sufficient generality to cover all situations and

still exercise meaningful control over the details of

design and performance. Finally, there is some

question whether the methodology of system

assurance is sufficiently well developed and precise

to permit its application to ATC systems.

ATC Characteristics

There is a tendency for the planners and

developers of ATC systems (and transit systems

generally) to design to their unique goals and requirements. In some cases, this is justified; nonstandard solutions are needed to meet special local

problems and conditions. In other cases, however, it

is not clear that the additional benefits of a specialpurpose design justify the increased costs. Increased

standardization of ATC system equipment offers

the promise of substantial economic and operational benefits. On the other hand, there is the risk

that standardization could inhibit innovation and

technological progress. The major arguments for

and against standardization of ATC equipment

characteristics are enumerated below. 93

The standardization of ATC equipment characteristics could produce several positive effects. It

would tend to reduce the variety of designs and the

proliferation of special-purpose equipment. It

would help assure use of the best of proven technology in new systems. Commonality of equipment

would make it easier to obtain and stock spare parts

(an important consideration for small transit

systems), Standardization could lead to some savings in equipment engineering and acquisition

costs, and perhaps substantial reduction of debugging costs (which are higher for new designs than

for already proven equipment).

There are some possible negative effects of

standardization, There is such a wide range of technology now in use in existing systems that it would

be difficult to establish a common core of ATC

equipment characteristics, There is no one type of

design that is clearly superior to others or that is applicable to the broad range of conditions that exist

in transit systems, Freezing design characteristics at.

this time, when there are some promising innovations just coming on the scene, may minimize the

opportunity for technological progress. The decision to select a particular system or systems as

standard might work a hardship on those who use

or manufacture “nonstandard” equipment and

might adversely affect industry competition.

Test Procedures for Train Detection

The basic and proven method of train detection

is the electrical track circuit. While the track circuit

is highly effective and reliable in most circumstances, there is a long history of difficulty with

QaNOte that the area of standardization is ATC equipment

characteristics, not components or specific designs. Component

and subsystem design could be improved and refined (for example, to increase reliability) while still retaining the same fundamental characteristics.

170
electrical train detection on little used track where

rust and film may build up and inhibit rail-to-rail

shunting by the train wheels and axle. The experience in BART has brought this problem to the

forefront of attention in the transit industry, but it,

has existed in the background for years in other

transit systems. Many in the transit industry believe

that is a need for a redefinition of the performance

standards for train detection circuits and for improved testing methods.

Standardization of test criteria and procedures

would have the primary advantage of providing a

uniform and objective way to verify the performance of train detection circuits and would thereby

assure that effective train protection is achieved.

This would have also a secondary benefit, in that a

potential source of misunderstanding (and litigation) between the buyers and sellers of ATP equipment would be largely eliminated. However, there

are some offsetting disadvantages. The problem of

train detection is so complex and influenced by so

many extraneous variables that it may not be possible to develop a single, universally applicable standard and testing method. Even if such a standard and

test could be devised, it might prove to be overly

conservative and could lead to excessively

complex equipment or unnecessarily redundant

mechanisms.

ISSUE P-5: SAFETY ASSURANCE

Is action by the Federal Government needed to

ensure the safety of ATC design and operation?

Federal action may be required to establish

safety standards, methods of measurement, and

testing procedures. Many in the transit industry

believe, however, that such could be brought

about internally by the process of self-regulation.

As noted in the discussion of Issue P–z, Regulation, most transit systems (both operating and

planned) are essentially self-regulating in matters

of safety. While many members of the transit industry recognize the need for improvement in safety

standards and methodology, they believe that the

safety record of rail rapid transit demonstrates the

effectiveness of self-regulation and that direct action by the Federal Government is not required,

They also argue that local self-control, while

perhaps not an ideal method, is preferable to intervention by a Federal agency because the local

officials are much closer to the needs and problems

and more likely to be responsive to the concerns of

the public in the area served. This position is not

strictly a “hands-off” policy. Many local transit

agency officials feel that the Federal Government

could be of substantial help in the matter of safety

assurance, but primarily in a supportive and advisory capacity and not in the role of a direct regulator.

There are, of course, counterarguments. The increasing complexity of transit systems (and the

ATC equipment that controls train movement) has

greatly magnified the difficulty of insuring that all

elements are safe and reliable throughout the life of

the system. The task of safety assurance may thus

have grown beyond the capability of a local operating agency to deal with it systematically and effectively. Perhaps only an organization at the national

level could command the resources and have the

authority to cope with the problem. Perhaps also,

only a national organization could be expected to

develop a sufficiently uniform and impartial set of

standards to ensure that safety matters are handled

equitably and consistently throughout all the transit

systems in the country. If a transit system is considered not as a local public utility but as part of the

national transportation resources, then Federal

regulation can be further justified on the grounds

that the Federal Government is the only body capable of overseeing the service of national interests.

If external regulation of rail rapid transit safety is

deemed necessary, there are three principal matters

that need to be addressed: safety standards,

methods of measurement, and testing procedures.

Safety Standards

How are the elements of an ATC system to perform under normal and abnormal conditions? What

are the requisite fail-safe characteristics of ATC

systems? What level of protection must be provided

for passengers, train crew, and equipment in the

event of failure or malfunction? And finally, what

degree of risk must exist before a system or situation is considered unsafe?

Methods of Measurement

There is a need for common definitions and

methods of measurement. It would be of little value

to standardize ATC systems and to develop a

general ATC system specification without also

171
defining what characteristics are to be measured cisco area), but it was greatly out of proportion to

and how such measurement is to be accomplished. the degree of actual injury and damage. Since then

the public concern over safety seems to have subTest Procedures sided to an insignificant level and revives only moThe procedural aspects of testing need to be

given attention, Uniform procedures would help

assure that testing gives valid results and that no

important aspect of system performance is overlooked. Uniform procedures would also help

guarantee consistency of treatment and evaluation

for all transit systems in the country.

mentarily in response to some new safety incident

or publicity surrounding the ongoing engineering

tests of the BART system. Transit operating

officials in other cities such as New York, Chicago,

and Boston remarked during the course of this study

that the same pattern of public concern for safety is

manifested there in response to accidents and

mishaps.

Closely allied to safety in the public mind is the

matter of security from criminal acts while riding

trains or waiting in stations. Public concern does

There is almost no information available on the

attitudes of the riding public toward transit systems.

Judging from newspaper coverage and individual

expressions of public opinion through the news

media, the public tends to take a transit system for

granted until some specific problem occurs. When it

does, public reaction is likely to be negative and

narrow in focus, centering around the incident itself

and ways to prevent recurrence, Public concern is

seldom of long duration and recedes as the normal

pattern of transit operations is once mor e

established and memory of the incident is eclipsed

by other interests.

Transit system operators believe that the public

is primarily concerned about personal safety while

riding the trains and about security from robbery

and crimes upon their person, Again, however, the

level of safety (i.e., the number and frequency of accidents and injuries) is such that public concern

about personal risk comes to the fore only when a

mishap occurs. The case of BART is a classic example. Before the Fremont accident, there appeared to

bean unspoken acceptance of the safety of the ATC

system, The public reaction to the accident was

prompt and widespread (even outside the San Franof assistance when needed. That is, the public does

not take a stand against ATC because it would

reduce the level of manning of the trains (and

perhaps the stations). Rather, the concern is with

the measures that may be employed to compensate

for the absence of crewmembers.

An interesting demonstration of the public’s

views took place in Denver, where a system of

small unmanned vehicles was proposed, During

public hearings, numerous questions were raised

about how muggings and assaults could be prevented or discouraged, what form of monitoring

would be used, and what actions would be taken

after detection of a crime. The suggestion that vehicles could be monitored by central control “listening in” by two-way radio was considered by some

as a form of eavesdropping, and therefore unacceptable.

There seems to be a general feeling that transit

systems should be safer than the general urban environment. Crime rates in transit systems are

generally lower than in the city at large, and yet the

fear of criminal acts seems to be higher in subways

than on the streets. Paradoxically, efforts by transit

authorities to increase the security of patrons is

sometimes a two-edged sword, The presence of

transit police may be reassuring, but it may also

give the impression that the transit system property

is so dangerous that extensive policing is necessary.

NYCTA is a case in point, This system has a very

large transit police force that actively patrols trains

and stations, and yet public concern over “crime in

the subways” is perennially high.

172
With regard to the dependability of service, the

public does not usually distinguish the role of ATC

from that of other elements of the transit system.

Either the trains run on time or they don’t. If there

are delays or habitual disruptions of service, the

public is most likely to lay the blame on management in general rather than any particular component of the system. Also, it seems that the public

does not regard lack of dependability as so serious a

matter as safety. Nevertheless, the public does cast

its negative vote. With the instant dependability of

the automobile ever present, public dissatisfaction

with transit service usually takes the form of

patronage diversion from public to private transportation. Transit system managers, on the other hand,

regard dependability as virtually coequal to safety

as a way of attracting public patronage. It is perhaps

for this reason that transit system publicity tends to

stress the speed, convenience, and dependability of

mass transit in their advertising to attract riders.

The public attitude toward cost is most diffuse

and hard to isolate. If the individual citizen is a

member of the fraction of the population that

patronizes rail rapid transit, he pays the fare but

probably does not think about how the costs are distributed. For the rest of the public the costs of constructing or supporting a transit system (or any

specific part such as ATC) is indirect, ill-defined,

and probably unnoticed. Where there is public reaction to the cost of a transit system, it usually is in

general terms and in connection with a public

referendum on the issue of transit system development bonds or taxation. On such occasions, the cost

of ATC specifically is submerged in the total cost of

the system.

173
. . 

, ..

.

APPENDICES
Appendix A

TRAIN CONTROL SYSTEM FUNCTIONS94

Train control is the process by which the movement of rail rapid transit vehicles is regulated and

supervised to assure safety and efficient operation

of the system. Such control can be effected by

manual means, by automatic devices, or by some

combination thereof. The description of train control system operation presented below is cast in

functional terms that apply equally to manual or

automatic forms of control. Because automation is

the central issue of this report, the discussion also

includes an examination of the relative merits of

man and machine components. A discussion of the

technology of automatic train control is presented

later, in appendix B.

The train control system is comprised of elements that perform four major types of functions:

● Train protection

. Train Operation

● Train Supervision

● Communications

TRAIN PROTECTION

The sole purpose of the train protection system is

to assure the safety of vehicle movement by preventing collisions and derailments. Traditionally,

the train protection system is functionally separate

and distinct from other elements of the train control

system; and it is designed so as to protect not only

against failure of other system elements but against

failure of its own elements as well.

Before taking up specific train protection functions, it is necessary to consider the general concept

y~This appendix is based on material originally prepared by

Battelle Columbus Laboratories in support of the OTA study.

TfIe editors gratefully acknowledge the contribution of Battelle

Columbus Laboratories but accept full responsihilit y for the version presented here and for any alteration of content that may

have been introduced in condensing and editing the material for

publication,

of train protection and its role in the overall scheme

of system operation.

Figure A-1 is a conceptual representation of train

protection functions in a typical rail rapid transit

system. The indicated functions might be performed by men, machine, or both; and they might

be performed by elements in locations other than

those shown in the diagram, Since the purpose of

the illustration is simply to indicate functional relationships, these different forms of implementation

can be ignored for the moment.

The train supervision system may generate a request for the movement of trains or switches. Some

of the requested moves may be unsafe. It is the

responsibility of train protection system to insure

that only safe moves are carried out. In order to do

this, it is necessary to know the status of switches,

the location of trains, and the allowable speeds for

trains as affected by track limitations and the presence of other trains in the system.

Wayside logic typically performs the route interlocking function by processing information on

the desired action, the location of trains, the status

of switches, and the allowable speed of trains. Output of this logic consists of safe commands to move

switches and safe speed commands issued to trains.

Excluding certain track and train surveillance

functions, the primary concern of the onboard train

protection system is the restrictive control of the

propulsion and braking system. Essentially, train

protection enables or inhibits the performance of

certain propulsion or braking actions. Train protection determines actual train speed and compares it

to the commanded safe speed. If the train is exceeding the commanded speed by a predefine amount,

action to override all other less restrictive propulsion and braking functions is initiated. Similarly,

the status of critical elements on board the train as

well as certain conditions on the track are used to

determine what action should be taken regarding

the propulsion and braking system.

177
178
Train and Track Surveillance

Train and track surveillance involves monitoring

the train, the track, and areas immediately adjacent

to the track for safety-related conditions. It can also

involve monitoring adjacent tracks and trains

operating on them. passenger security, though

clearly a safety-related matter, is not usually considered a part of the train and track surveillance

function, Door monitoring and control, another

safety-related function, is considered here to be a

train operation function. 95 Train and track surveillance are essentially human roles in all operating rail transit systems today, but the amount of

human involvement varies widely.

Train surveillance is concerned with monitoring

the status of the train and its passengers. Onboard

operators (motormen and conductors) traditionally

perform this role. The primary advantage of the

human in such a role is his ability to comprehend

and interpret many diverse types of inputs. Except

at PATCO and on the MBTA Green Line, the operator of a train is typically confined in a space that is

physically removed from the passengers. His primary role in train surveillance is monitoring the

status of the equipment. Conductors, if present,

have more freedom of movement and can sometimes go to the scene of a possible problem to determine its nature and severity.

Passengers may provide some train surveillance

functions. In systems where they can communicate

with employees, they may report onboard conditions. Two-way communications systems are provided at Sea-Tac and AIRTRANS, where the vehicles are unmanned. It is likely that passengers could

become more involved in train surveillance in automated small-vehicle systems.

Onboard operators provide the track surveillance

function at all operating rail transit properties. In

the closed environment of Sea-Tac, essentially no

track surveillance is performed. At AIRTRANS,

another special environment, only minimal track

surveillance by roving employees is provided.

Under ideal conditions, little, if any, track surveillance would be required. Humans external to

the system cause most of the problems requiring

track surveillance. Trespassing, vandalism, and

suicide attempts are three of the most commonly

gssome transit engineers consider door control to be a train

protection function because of its relationship to safety.

cited factors which make some form of track surveillance necessary. Here again, the human is unsurpassed in the ability to identify and deal with a

very broad range of track surveillance problems.

While a human can act to prevent some accidents, he cannot prevent all of them, partly because

he simply cannot stop the train in time. If one were

to assure an instantaneous response and brake application along with a rather high braking rate of 3

mphps, it can be calculated that the minimum stopping distance from 60 mph for a typical train is 880

feet, and 220 feet at 30 mph. Clearly, there are many

situations in which the potential hazard is either not

visible at this distance or is created within the stopping distance of the train, (Suicide attempts are the

classic example here.)

Damage assessment is a track and train surveillance function which can be performed by

humans. When something has happened, a human

can assess the damage to track or train and determine if it is safe to proceed.

Train Separation

The function of train separation is to maintain

physical separation between following trains so

that they are not in danger of colliding with each

other. In the simplest manual system, train separation can be provided by the operator who drives the

train much as a person drives an automobile. He

must know the maximum safe speed with which he

can approach curves and other places of limited

visibility, and he relies upon seeing the train ahead

and taking appropriate action to prevent a rear-end

collision.

Figure A-2 illustrates the basic principles involved in automating the train separation function,

The dashed line indicates the theoretical speed-distance relationship that a following train could

maintain and still be able to come to a stop before

reaching the end of the train stopped ahead.

When a block-type detection and speed command system is used, the location of the train within a block is not known accurately, Therefore, the

train must be assumed to be in the most hazardous

location, i.e., at the rear of the block. In the exampIe

shown, the train is almost out of block BC but must

be assumed to be at the location shown in dotted

lines. The shift of the theoretical speed-distance

profile can be seen to be essentially one block long.

In general, the shorter the blocks, the closer the attainable spacing between trains.

179
FIGURE A–2,—Train Separation in a Conventional Block Signaling System

Many arrangements of speed commands are

possible. For example, if the commands were only

stop or go, all signals shown (except perhaps the

ones at A and E) would indicate stop. It is frequently desirable for operational reasons to have a

train approach closer than the safe stopping distance from full speed. In such a case, an intermediate speed command would be provided, as shown in

the block DE. A train traveling in this block would

receive an intermediate speed command followed

by a zero speed command from point D. One can

readily see that the shorter the length of blocks and

the greater the number of speed commands, the

more closely a train can follow the theoretical

speed-distance profile. Obviously, the system for

accomplishing this becomes more complex and expensive as block length is shortened.

It should be noted that a number of factors used

in the actual design of a system are not shown in

this simple illustration. There is some system

response time involved before braking is initiated.

Grades may reduce the actual effectiveness of the

brakes. No safety factors are included. Some

systems provide additional blocks between trains,

All these tend to further increase the spacing between trains.

The difference between intermittent and continuous speed command transmission can be seen

here. Suppose the train is moving and, in a brief increment of time clears block BC. Block CD will immediately indicate the intermediate speed and

block DE will go to full speed. If a following train

were just a few feet into block DE when the speed

command in that block changed, the operator would

have no way of knowing it if the speed command

were transmitted by a visual signal located at E. He

would have no indication of a change in signal

status until the signal at D became visible. By contrast, the continuous, or cab, signal would immediately indicate to the operator that he could increase his speed. An additional advantage of cab

signals is that a train can move into block DC to stop

whereas, with wayside signals and trip stops, the

train would stop at D, or even farther back.

All rail transit systems to date have been

designed on the assumption that a leading train is

either stopped or will stop instantaneously. It can be

seen that trains could follow one another much

more closely if a less stringent assumption could be

made about the stopping of a leading train. This is

precisely what is proposed in many short-headway

PRT systems where position, velocity, and acceleration of a lead vehicle would all be considered

in establishing headways. Some studies of PRT

headway have shown, however, that removing the

brick-wall concept reduces minimum achievable

headway by only a small amount.

So far as is known, there are no rail rapid transit

systems planning to abandon the traditional train

separation philosophy. The major differences in

180
train separation practice are associated with the

way in which train separation commands are enforced, Intermittent or wayside signaling systems

provide train separation by use of trip stops.96 Continuous or cab signaling systems enforce train

separation using onboard equipment. A safe speed

command is transmitted to the train and equipment

on board insures that the operator initiates action to

slow the train as appropriate.

Humans play a role in train separation under at

least some situations. In some locations, operators

are permitted to approach trains ahead of them

more closely than would be permitted by the signal

indication, This is always done under strict procedural controls. It maybe done at highly congested

stations or in emergency situations. Practically

speaking, the maneuver is identical in nature to

driving one bus up behind another bus which has

stopped.

Route Interlocking

Route interlocking is the process by which trains

are prevented from making conflicting moves, i.e.,

moves that would be unsafe. Typical conflicting

moves are those which would cause a train to collide with another train, to go off the end of the

track, or to run through an open draw bridge. Route

interlocking involves monitoring the presence and

position of the trains in a system and the positions

of the track switches. The information from the

monitors is processed by logic, usually the front

contacts of vital relays, and used to inhibit or permit

the movement of the trains. As an example, when a

train is dispatched from one location to another and

the trip involves passage of the train through one or

more track switches or crossovers, the route interlocking allows the train to proceed through the

switches and crossovers only when it is safe to do so

and prevents other trains from entering the route

until the first train has safely passed.

Information on the presence and location of the

trains is obtained from the train detection system,

96A trip stop IS a mechanical device which is located near Or

between the running rails; it is associated with a wayside signal.

When the wayside signal indicates that a train is to stop, the trip

stop is positioned so that it will apply the brakes of any train

which attempts to pass the wayside signaL When the wayside

signal indicates that a train can proceed, the trip stop is

mechanically positioned so that it does not affect the brakes of a

passing train. Thus, the trip stop enforces a stop command presented by the wayside signal.

as described earlier. Information on the status and

the position of the track switches is monitored by

the route interlocking. Before a route is alined for a

train, it must be determined that the proposed route

will not be in conflict with an existing route for

another train. If no conflict exists, then the appropriate track switches must be positioned and

their positions verified. Then each switch must be

immobilized and locked until the passage of the

train has been verified. These precautions are

necessary to insure that the switch positions are not

changed after the route has been alined and to insure that a switch is not moved under a train. Either

of these events would be unsafe.

Route interlocking is an essential part of the train

protection for all but the most simple transit

systems. As system complexity increases, route interlocking assumes greater importance. Early route

interlocking functions were often accomplished

through the use of complex mechanical devices

which prevented establishing potentially hazardous

switch positions. Some such equipment is still in

use. New installations are all equipped with electrical or electronic logic which, may also permit

remote actuation of switches and signals.

Overspeed Protection

Overspeed is the condition where the actual train

speed is greater than the intended or commanded

speed. Overspeed can be dangerous because the

train may derail if it goes too fast around a curve or

the train may have a collision because it is going too

fast to stop within the available distance. It is the

responsibility of other train protection system elements to determine the allowable safe speed and to

assure that the commanded speed does not exceed

the allowable safe speed.

Basically, overspeed protection has two inputs

and one output. The inputs are commanded speed

and actual speed. A signal enabling or inhibiting the

propulsion and braking system is the output. A

comparator, either a man or machine, compares actual speed with commanded speed and determines

if propulsion power can be applied or if a brake application is required. The overspeed protection

function can be accomplished on board the vehicle

or through the use of wayside equipment.

All transit systems that use cab signaling also

have automatic overspeed protection. In order to do

this, it is essential that the onboard speed measuring

and comparing device have a virtually zero prob181
ability of failure in an unsafe mode, Even though

single tachometers traditionally have been regarded

as “fail-safe,” redundant tachometers are sometimes used. The outputs are compared, and if disagreement exists, a failure is assumed to have occurred and the overspeed protection logic treats this

as an overspeed condition. A more frequently used

approach, though, is a fail-safe speed measurement

system not requiring redundancy that reduces

reliability y.

It is not uncommon for a cab signal display to fail

without failure of the overspeed protection system.

Under such conditions, the operator can run the

train safely but may have difficulty in maintaining

the desired speed without exceeding the overspeed

limit, The audible warning devices that are normally provided permit the operator to run without

cab signals without receiving a penalty brake application.

OverSpeed can be detected and controlled from

the wayside. Through the use of timing circuits and

known lengths of track, it is possible to determine if

the average speed of a train over a certain distance

is equal to or less than the allowable safe speed, If

the measuring distance is short, an essentially continuous overspeed protection can be provided, If the

measuring interval is long (say tens or hundreds of

feet), only an average measure can be obtained, so

the instantaneous value could exceed the intended

limit,

TRAIN OPERATION

Train operation consists of three major functions:

Velocity Regulation

Station Stopping

Door Control and Train Starting

In the traditional concept of signaling, train operation is not considered a safety-related aspect of train

control. However, there are some safety aspects of

train operation. If abrupt starts, stops, and changes

are made, passengers may be thrown down and injured. If door control is assumed to mean the

monitoring of the status of the train doors,

passenger safety is also involved,

There is some disagreement among train control

engineers concerning the functional relationships

among train operation, train protection, propulsion,

and braking systems, Some consider control of jerk,

slip-slide, and flare-out as train operation functions;

others consider them to be propulsion and braking

functions. Some consider door control a part of train

protection (because of its relation to safety); others

place door control within the province of train

operation. These subjects will be touched upon

briefly below.

Velocity Regulation

Overspeed protection is designed to prevent a

train from going too fast. Velocity regulation is concerned only with controlling the speed of the train

in response to operational needs. Velocity regulation systems are “nonvital,” that is, they are not essential to the safety of the system.

Velocity regulation may be accomplished by a

man or machine, When a man acts as the controller,

he simply compares the actual speed with desired

speed and tries to minimize the difference between

the two. The desired speed may be presented in the

form of wayside or onboard displays. Actual speed

is determined from speedometers on board the

vehicle, A human controller uses a handle of some

sort to control speed much as an auto driver uses an

accelerator pedal. In such a system, the hand on the

handle is the interface between the train control

and propulsion and braking systems.

A machine controller performs exactly the same

functions as a man, but the control signal is provided in the form of an electrical signal to a controller in the propulsion and braking equipment.

Most ATO systems to date have provided this signal

in a combined digital and analog form. The system

designed for WMATA uses a completely digital interface,

For operational reasons, it is sometimes desirable

to modify the speed of the train. This is usually

called performance level modification, Here, a command (verbal, visual, or electrical) is transmitted to

the train telling it to run at a selected fraction of the

commanded safe speed. Performance leve l

modification is not a safety-related function.

Performance level modification is normally accomplished on board the vehicle. In manual

systems, an operator may receive a verbal or visual

instruction to operate the train at reduced speed. In

some systems, notably NYCTA, performance level

modification is not normally used, Trains are held

at stations rather than operated at slower speeds

between stations, Both BART and WMATA pro182
vide transmitters in stations and at other critical

locations to send performance level requests to the

train. Performance level modification is thus accomplished automatically without operator intervention. Baltimore is considering a performance

level modification system in which a visual

wayside display is provided to an onboard operator

who then manually sets the desired performance

level for the next segment of the trip.

There is a general trend toward the use of automated velocity regulation. The two newest systems

in operation (BART and PATCO) employ automated speed regulation, NYCTA is planning to install it (and other features) over a long period of

time with the objective of eliminating the conductor, MBTA has installed velocity regulation on the

new portions of the Red Line. CTA, however, opted

not to use automated velocity regulation on its new

cab signaling installation.

Station Stopping

Station stopping involves bringing the train to

rest at a selected location along a station platform

under some form of programed control. It is not

technically a safety-related function. Both humans

and machines perform the station stopping function.

In manually operated systems, the operator normally uses some reference mark as an indicator of

the point where he should initiate braking. This

mark may be any wayside object, possibly a marker

placed for the specific purpose of braking reference,

A skilled human can ordinarily stop a train within

an accuracy of a few feet. Variability in train

weight, performance characteristics, and track conditions affect the human’s ability to stop a train precisely. The required deceleration rate also affects

his performance. The higher the average rate, the

greater the variability in result.

The degree of sophistication of automated

program stop equipment is a function of the accuracy required. PATCO utilizes two “triggers”

spaced some distance away from the station as

reference points for programed stopping, The first

trigger initiates maximum-rate deceleration. A second trigger, roughly at the end of the platform,

causes the ATO package to measure the train’s

speed and adjust the deceleration rate accordingly,

A manually set switch in the train cab is used to

define train length so that the braking action will

cause the train to be centered on the platform

regardless of its length. Under adverse weather conditions, the operator makes the stop manually, initiating deceleration at a point marked by a yellow

pole on the wayside.

Where both station and train doors are used, it is

necessary to aline the train with the doors within an

accuracy of a few inches. Both Sea-Tac and

AIRTRANS have such a system. Information on

train weight, instantaneous position, speed, and

deceleration may be processed by an onboard computer to achieve precision stopping. At BART, a

long wayside antenna provides the position signals

necessary for the onboard program stop computer.

Other needed information is derived and processed

on board.

Door Control and Starting

Some engineers do not consider door control and

starting to be train protection functions since the

opening and closing of doors present no hazards to

the train. Clearly, however, the safety of passengers

is affected by door operation, so it is common to interlock door functions with train protection, a practice that leads some engineers to regard door control

as a part of train protection.

Three basic pieces of information are required

for the control of door opening, It is necessary to

determine that the train is in a proper location for

doors to be opened. If there are doors on both sides

of the train, the proper side must be identified at

each station, Assurance that the train is stopped and

will not move is required. (Clearly some of these requirements must be overridden in emergency situations.)

On starting, four conditions should exist before a

train leaves a station. The doors should be closed

and locked. No passengers should be caught in the

doors. It should be time for the train to depart. The

train protection system should indicate that it is

safe to move the train.

In manual systems, most of the door control,

monitoring, and starting functions are performed by

humans. When a conductor is on board, control and

monitoring of doors is ordinarily his most important

assignment. Lights are usually provided to indicate

the status of all doors. (It is worth noting that a 10-

car train may have as many as 40 doors, each with

two leaves, on each side of the train. Thus, 160 door

leaves must be monitored during the movement of

183
the train through the system.) Because there is no

truly foolproof practical door, all U.S. rail rapid

transit systems have onboard personnel to act as a

back-up to insure that door closure is not initiated

when passengers are boarding and leaving and to

verify that no one is caught when the doors are

closed and locked.

Where trains are unmanned, a more complex

form of door control is required, In special environments such as the Sea-Tac and AIRTRANS

systems, door systems much like those of elevators

have been used. The platforms are enclosed and

doors on both train and platform must be closed and

locked before the train can move. Doors with

pressure-sensitive edges are used to prevent possible entrapment of passengers in a closing door. All

door functions are interlocked with the train protection system.

Jerk Limiting

Jerk is defined as the rate of change of acceleration. Control of jerk contributes to a smooth ride

and from a rider standpoint, a somewhat safer one.

Customarily, jerk limiting is a function of the propulsion not the train control system.

Jerk limiting applied during stopping is sometimes termed “flare-out control.” It is identical to

the maneuver that a skilled automobile driver performs just as the car is coming to a stop. By easing

off on the brake, the transition from deceleration to

full stop is smoothed out. Because there are safety

implications to releasing the brakes, flare-out control is usually designated to be either a part of the

train protection system or to be interlocked with it.

In a manually operated transit system the flareout function is performed by the operator much as it

is performed by an automobile driver. The smoothness with which the function is performed depends

to a great extent upon the skill of the operator. In an

automatic train control system, the flare-out function can be performed automatically by sensing the

speed of the time when the train velocity becomes

less than some predetermined amount. It is necesary that this reduction in braking effort be allowed

to persist only for a short period of time. Otherwise,

the braking system of the train could be disabled.

Accordingly, flare-out is controlled by a timer so

that the reduction of braking effort can persist only

for a few seconds. During normal operation these

few seconds are sufficient to bring the train to a

complete halt, and the brakes then are re-applied. It

is essential that the design and the implementation

of the flare-out system be such that a failure cannot

permanently withhold braking action. Figure A-3 is

a schematic diagram of a typical automatic flare-out

control system.

Slip-Slide

Slip refers to the slipping of wheels during the

application of power. Slide is concerned with

wheels sliding when brakes are applied. Slip or slide

occurs when the tractive effort of the train exceeds

the adhesion capability of the wheels and rails. Excessive slip, which occurs during acceleration, can

damage the propulsion equipment, wheels, and

rails, Slide, which occurs during deceleration, can

damage the wheels and rails; a wheel locked during

braking can be ground flat on the bottom if it is

dragged very far, with possible damage to the crown

of the rail as well. In addition, one or more sliding

wheels during braking can increase the distance

needed to stop a train because the coefficient of

friction between a sliding wheel and rail is lower

than that between a rolling wheel and rail.

Slip-slide control is traditionally considered part

of the propulsion and braking system, but it has important relationships with the train control system.

For example, correction of sliding during braking

can be obtained only by reducing the braking effort,

which has obvious safety implications. Either

through the design of the braking system or in conjunction with the train protection system,

assurances must be provided that operation (or malfunction) of the slip-slide control does not permanently prevent application of the brakes when a

brake application is required.

TRAIN SUPERVISION

In general terms, train operation functions are

concerned with the movement of individual trains.

Train protection acts as a restraint to prevent accidents for individual trains or between trains. By

nature, these two groups of train control functions

are tactical and localized, in that they deal with

short-range concerns for specific elements or places

in the transit system. In contrast, train supervision

comprises a group of functions concerned with the

overall regulation of traffic and the operation of the

transit system as a whole. Thus, train supervision

functions are strategic, systemwide, and more longrange.

184
The

FIGURE A–3.-Conceptual Diagram of Service Brake Flare-Out Control

functions of train supervision are:

Schedule Design and Implementation

Route Assignment and Control

Dispatching

Performance Monitoring

Performance Modification

Alarms and Malfunction Recording

Recordkeeping

Schedule Design and Implementation

In most rail rapid transit systems, the functions

of schedule design and implementation are not connected on a real-time basis. Train schedules are

evolved to meet the transit system’s objectives,

whether they be minimization of operating cost,

maximization of service, utilization of equipment,

or whatever. Most train scheduling in such situations is performed manually, with perhaps occasional assistance from a computer,

Train schedules do not change frequently. Once

a basic service pattern has been established, it may

remain unchanged for months or years. The primary changes may be the addition of special trains

to provide extra service to special events. This type

of extra service is usually provided in off peak hours

and presents no major train control problem. Providing special crews is likely to be the most difficult

problem here.

Where major changes of schedule or operational

procedure are contemplated, it may be necessary to

utilize computer simulations. NYCTA has been

using such simulations for about a decade for examining complex scheduling and routing problems.

Simulations may also be used in the planning of

systems. Where systems are computer controlled,

provision may be made to use the computer for

simulations of possible operational changes.

Operational implementation of the schedule is

generally focused in some central control facility.

This facility may be simple or elaborate. Hierarchical control structures may be utilized, The primary

185
functions of the control center are (1) receipt and

display of information on the status of the system,

(z) decisionmaking regarding action to be taken,

and (3) issuing commands for action. It should be

kept in mind that supervisory functions and decisions may affect the safety of passengers, but train

supervision cannot override train protection considerations.

Most control centers have functions beyond train

control alone. It is common to monitor and control

the electric power systems and other critical elements such as pumps and blowers in these facilities,

Monitoring of station platforms, fare collection

areas, or parking lots may also be carried out by

central control facility, Passenger service communications may be provided, as well as some service to the news media or the general public.

Route Assignment and Control

The supervisory system selects, assigns, and controls the routes to be followed by trains. Under normal circumstances, the routes of a conventional

transit system are fixed, Major delays must be involved before train rerouting is done. In a linear

two-track system, the most ordinary form of rerouting is concerned with operating the system over

only one track until a problem on the other track is

cleared. Except for the systems which use computers, alternating the direction of traffic flow is accomplished under the control of humans at a control center or tower. BART provides special computer programs which can generate the necessary

commands for single-track operation. WMATA

plans a similar approach, This approach presumably

can lead to more efficient operation, both in terms

of increased flow through the system and in the

freeing of the controllers to make other decisions

during such emergencies.

In a few transit systems, there are opportunities

to route conventional trains from one line to

another in case of major service disruptions,

NYCTA, for example, can reroute trains on some of

the main Manhattan lines. Additionally, the fourtrack (two local, two express) arrangement of portions of the system permits interchange of trains

between some tracks on the same route-always at

a loss in overall performance.

Dispatching

Train dispatching is concerned with the makeup

of train sets and the timing of their departure from

selected points in the system. In conventional rail

transit systems, a written schedule is used to indicate the anticipated system needs for the day, both

by train size and time of departure. Dispatching

usually takes place from terminals or yards.

Most train dispatching in conventional systems is

accomplished through the use of preprogrammed dispatch machines at terminals and entry points.

These machines simply provide a visual indication

that it is time for the train to depart. In a short

system such as PATCO, there is normally no

further supervisory control of the motion of the

train through the system. Operators are provided

with a timetable, and verbal communications are

used if any problem arises.

Modification of the dispatching routine may be

accomplished under computer control in systems

such as BART and WMATA. Manual or verbal

override is used at all operating transit properties

except BART. Modification of dispatching

schedules is required to compensate for various

delays on the line.

Performance Monitoring

Train performance monitoring is closely allied

with train dispatching and route assignment. Essentially, the purpose of this function is to smooth out

irregularities in the flow of traffic. Methods of performing this function range from the very simple to

the very sophisticated.

Basically, there are two approaches to performance monitoring and control, They may be accomplished on an intermittent or a continuous

basis. In all conventional systems in operation and

being planned, performance monitoring is done on

an intermittent basis, Train running times between

stations or terminals are measured and any control

actions deemed necessary are taken. There is no

continuous monitoring of the performance of the

train while it is running. (Verbal communications

can ordinarily be used to provide an indication of

serious performance problems as soon as they occur.)

If it is desirable to modify the performance

(speed, running time, acceleration) of a train, commands for the performance modification are usually

transmitted at selected wayside locations (typically

stations). Continuous performance modification

commands are not provided. Again, verbal com186
munications may be used to transmit a command at

any time.

Performance Modification

There are two basic ways of modifying train performance. Trains may be held at specific stations to

provide more uniform spacing. Either in conjunction with this or as an alternative, the actual running time of the train speed or acceleration rate can

be changed.

In the systems which have the least amount of

automation, performance monitoring and control is

essentially accomplished by humans. Supervisory

and onboard personnel monitor the state of the

system. Information on significant perturbations

may come in through model board displays or voice

communications. Required performance modifications may be indicated by voice transmission or

reductions in speed commands.

One step upward in automation is the addition of

dispatching lights at certain stations. By use of such

lights, trains can be held in these stations to attempt

to smooth out the flow of traffic.

At the highest levels of automation are the

systems which use computers to adjust performance requirements continually so as to provide

schedule adherence and/or uniform flow of trains

through the system. Both BART and WMATA have

facilities to monitor the performance of all trains in

the system and to compare the actual and desired

status of the system, Through rather elaborate control procedures, computers then issue commands to

modify individual train performance in a way such

that the system objectives are met.

Views vary on the value of automating the function of train performance modification. At BART

and WMATA not only are the desired performance

levels calculated automatically, they are transmitted and implemented automatically as well.

Baltimore is considering an evolutionary system

which could eventually incorporate a computer.

Initial thoughts are that performance level commands would be displayed in stations and onboard

operators would set switches to establish performance levels for the ATO equipment. NYCTA,

which plans eventual conversion to automatic train

operation, does not now contemplate the use of

performance level controls as such. It is planned to

control train spacing by dispatching at terminals

and selected stations as well as by verbal control.

Alarms and Malfunction Recording

Aside from the annunciation of delays in train

motion, supervisory systems can be used to indicate

other problems in carborne equipment. Fire, low air

pressure, lights out, air-conditioner failure, motor

failure, and many other things are potential candidates for malfunction alarm. In traditional manned

systems, information on the status of onboard

equipment is not transmitted to the wayside

automatically. Annunciation of malfunctions is

provided by displays in the operator’s cab. The information may be relayed immediately by voice

transmission if the problem is serious. Minor

problems may be reported at the end of a run or the

end of the day.

In unmanned systems, there is a greater need for

annunciation of malfunctions. Both the Sea-Tac

and AIRTRANS systems have malfunction annunciation systems with displays in the central control

facility. A hierarchy of malfunction conditions is

defined, and each group is treated in accordance

with the seriousness of the event involved.

It should be noted that the annunciation system

for train supervision may be a subset of a larger

system which deals with the status of many types of

equipment throughout the system. This may include pumps, blowers, electrical power distribution

equipment, and so forth.

Recordkeeping

Supervisory equipment or personnel keep

records for individual vehicles and the overall transit system. By means of train and car identification

equipment, information is provided on the accumulation of car miles and used to schedule maintenance activity. If computational capabilities are a

part of the supervisory system, additional functions

may be performed. The computer may be used to

generate work orders or schedules for routine maintenance. Spare parts ordering may be handled. Manpower utilization and payroll data may be processed. Reliability and maintainability data may be

derived. Special management reports also may be

generated.

Where malfunction communication equipment

is used, it speeds diagnosis of system faults. In

general, it appears that in-service diagnosis and

repair of individual failures is significantly less important than maintaining operation of the system as

a whole. Where practical, attempts are made to con187
tinue to operate trains w

enough to get them out

th failed equipment long

of service. If this is not

possible, pushing a train or modular replacement of

elements is attempted, The use of significant

amounts of diagnostic equipment appears more appropriate in maintenance shops than on in-service

equipment,

COMMUNICATIONS

Communication functions are implicit in all

other types of train control system activity, and

various forms of communications (both verbal and

data) have been mentioned in connection with the

description of train protection, operation, and

supervision functions. Table A–1 is a summary of

the major types of communication performed by

and within the train control system. Each is discussed below, with emphasis on those that have not

been treated previously.

Train Protection

Train protection communications are traditionally separate from all others. Special precautions are taken to insure that signals from other circuits or systems do not mix with train protection

signals.

It appears that future ATP systems will all rely

heavily on electrical or electronic transmission

systems. Voice communications are a part of ATP

but, in general, play a minor role. Voice communications are largely used to transmit information regarding visual verification of a safety situation or procedural instructions related to emergency

operation.

Operational Control and System Status

These two functions are discussed together

because system status provides the feedback information for operational control. Essentially, these

are the communications involved in the train supervision function. Most routine status information is

transmitted by electrical means and displayed

visually. In automated systems, much of the status

information is processed directly by computers.

Visual displays may be provided routinely or on a

call-up basis.

Status information

motion of vehicles. It

platforms, availability

ditions, and any of a

includes more than just the

also concerns conditions on

of trains in yards, track conhundred other things. Malfunction alarms transmitted from carborne or

wayside equipment provide status information on

certain equipment. The more highly automated the

system, the greater the need for equipment status

information, but this does not necessarily mean increased automation of the means for transmitting

equipment status information. If additional information is to be communicated, it can also be given

over a voice channel by the onboard attendant.

Operational commands may be transmitted by

almost any means, ranging from a printed timetable

to electronic devices. There is a trend toward use of

electrical or electronic devices for signal transmission in the new systems being planned, but there

are some specific exceptions. NYCTA, for example,

plans to operate a hierarchical supervisory system

in which major decisions will be made in a command center and relayed by voice or teletypewriter

to dispersed towers for execution, Baltimore is considering visual transmission of performance level

TABLE A–1.—Primary Means of Communicating Information Related to Train Control

Function Primary Means of Transmission (T’) and Display (D)

Visual Voice Electric Signal Written

Train Protection T, D — T, D —

Operational Control I D T T, D —

System Status I D T T, D —

Emergency Communication I — T — —

Passenger Service — T — —

Maintenance Information — T T T, D

Business Operations — — T T, D

188
adjustments using displays on the wayside in stations. Voice communication with all trains appears

to be an essential element in all new systems and in

upgrading old ones, Emergency operational commands may thus be relayed by voice communication.

Emergency Communications

Emergency communications are the only type

that may involve contact with outside agencies or

employees not on trains or reachable by telephone.

For this and other reasons, at least one space radio

system is provided in all transit systems to allow

communication with roving employees.

It is felt by most transit system managers that the

ability to communicate with passengers, preferably

two-way but at least one-way, is extremely important in controlling emergency situations. Assuring

the passenger that his plight is known and help is on

the way is believed to have considerable psychological value.

Emergency communications may also involve

dealing with police and fire departments as well as

other organizations of the civil government, These

communications may be handled either by radio or

telephone.

The human role in emergency communications

is very important for the simple reason that the

nature of emergencies is such that unexpected

events occur. Because humans respond to a very

wide range of situations, it seems unlikely that the

emergency communication role of the human can

be replaced.

Passenger Service

Train control equipment or personnel act to provide information to the passengers. In most

systems, onboard operators or station personnel

provide information on station identity and train

destination. ATS equipment is used to perform

some of these functions in highly automated

systems. At BART, for example, special destination

signs indicate the imminent arrival of trains, the approximate location at which the trains will stop, and

the destination of the trains. These particular signs

are also used to display commercial messages and

thereby produce revenue for the system, Both

AIRTRANS and Sea-Tac utilize prerecorded

messages in the trains to provide information to

passengers. AIRTRANS has both TV displays and

lighted signs to display route information at the stations,

Maintenance Information

Elements of the train control system maybe used

to provide information needed for scheduled or

unscheduled maintenance. Train and car identification systems can be used to provide information on

accumulated car miles. In highly automated

systems, malfunction detectors and annunciators

transmit malfunction information either directly to

the maintenance facility or through central control

to the maintenance facility. Voice communications

relating to maintenance problems may be channeled through central control or handled directly.

Communication of maintenance information related to inventory control may also be handled over

the ATC communication system, especially if a

central computer is used. This maybe accomplished

over commercial telephone lines, or special data

transmission links. Except for fully automated

systems, there does not appear to be a trend toward

significant increases in ATC communications for

maintenance information transmission.

Business Operations

Basic data available from the train control system

may be used in planning business operations

regarding workforce allocation, expansion plans,

procurement policies, vehicle utilization, and so on,

This information is generally presented in the form

of tabulated reports which may be computer printouts or periodic manual summaries of system performance parameters.

189
Appendix B

AUTOMATIC TRAIN CONTROL TECHNOLOGY”

train control

and engineerThe technology of automaticembraces many kinds of equipment

ing techniques. All aspects of this technology cannot be adequately presented in a brief appendix

such as this. Therefore, the discussion is confined to

two major elements of train control technology: the

track circuit and methods for speed command and

control. The technology forms the basis for almost

all automation of train protection, train operation,

and train supervision functions. Of the two, the

track circuit is the more basic. It was the first to be

developed, and it underlies the operation of speed

command and control systems. It is the fundamental method of train detection and, while there has

been experimentation with other methods over the

years, none has proven to be as effective and reliable as this electrical technique for determining the

presence and location of transit vehicles. From this

basic positional information, signal systems are

operated, train protection is accomplished, train

operation is controlled, and supervisory functions

are carried out.

TRACK CIRCUITS

The track circuit is an electrical circuit which includes a length of running rails (or special rails) and

permits detection of the presence of a train. A track

circuit may also be used to communicate commands, instructions, or indications between the

wayside and a train. Track circuits provide information on the location of the trains, and this information is used to command train speeds so that the

trains operate safely. For instance, if a train attempts to approach too close to the rear of another

train, information on the locations of the two trains,

provided by the track circuits, is used to command a

slowdown or stop of the following train before

there is danger of a rear-end collision.

The basic d.c. track circuit was invented by Dr.

William Robinson and first used in a railway application is 1872. Although the equipment and technology have changed considerably in their detail

since that time, the basic principle has remained the

same. An electrical signal of some kind is impressed

between the two running rails, and the presence of

a train is detected by the electrical connection between the two running rails provided by the wheels

and axles of the train (wheel-to-rail shunting).98

Before proceeding to a discussion of the various

types of track circuits, it must first be considered

how track circuits are used in the operation of a

transit system. A track circuit provides information

on whether a train occupies a given length of track

(a block). The occupancy information for a particular block and for contiguous upstream of blocks is

used to control the operation of all trains within the

given area, For instance, when a train is detected in

a block, that occupancy information is used to cause

a zero-speed command for the block immediately

behind the train. Depending upon the block lengths,

the line speeds involved, and the number of available speed commands, the second block behind the

train may have a command speed between zero and

full line speed. The third block behind the train may

have a commanded speed greater than or equal to

the second block, and so on. In all cases, the blocks

behind a train are signaled so that a train entering a

block has sufficient braking distance to leave the

block at a speed not greater than the commanded

speed. In the case of a zero-speed command, the

QTThiS appendix is based on material originally prepared by

Battelle Columbus Laboratories in support of the OTA study.

The editors gratefully acknowledge the contribution of Battelle

Columbus Laboratories but accept full responsibility for the version presented here and for any alteration of content that may

have been introduced in condensing and editing the material for

publication,

~In tran5it systems with rubber-tired vehicles, special rails

are mounted beside the guideway and brushes or shoes on the

vehicle contact these rails as the vehicle moves along. The

special rails replace the running rails of a conventional steelwheel, steel-rail system, and the brushes or shoes replace the

wheels and axles of a train in the operation of the track circuits,

This is only a difference in detail; the principle is the same as in

conventional track circuits.

191
train must be

of the block.

able to stop before it comes to the end

D.C. Track Circuits

In all track circuits an electrical signal of some

kind is impressed between the running rails, and

the presence of a train is detected by the electrical

connection that the wheels and axles of the train

make between the two running rails. In d.c. track

circuits, the electrical signal is direct current,

usually supplied by batteries, The detector for the

electrical signal is a relay.

Figure B-1 shows a simple d.c. track circuit. The

track circuit consists of a block or length of track

which is defined at each end by insulated joints in

the running rails. The insulated joints provide

electrical insulation between a given track circuit

and the abutting tracks which comprise other track

circuits. The signal source, in this case a battery, is

connected to the rails at one end of the track circuit

while the receiver (a relay) is connected to the other

end, When no train is present, the track circuit is

said to be unoccupied, and the direct current supplied by the battery is transmitted by the running

rails to the relay and energizes it or “picks it up. ”

When the relay is energized, the upper set of relay

contacts is connected causing the green signal light

to be turned on. When a train enters the track circuit its wheels and axles connect the two running

rails together, shorting the battery and thereby

reducing the current through the relay. This causes

the relay to “drop,” as shown by the dashed line in

the diagram. This action connects the bottom set of

relay contacts, turning off the green signal light and

turning on the red light to indicate that the block is

occupied by a train. The resistor in series with the

battery protects the battery by limiting the current

the battery must provide when a train is present,

The terms “pick up” and “drop” refer to the position of the special “fail-safe” relays used for train

detection. These relays are constructed from

specifications approved by the Association of

American Railroads and are designed so that their

normally open “front” contacts will be closed only

when sufficient electrical energy is being supplied

to the coil, One or both of the normally open contact

members are made of carbon or carbon impregnated

with silver, which cannot be welded. The relays use

gravity rather than spring return and are mounted

vertically so that the relay armature, to which the

contacts are attached, is returned to the dropped

position when the current through the coil is

reduced below some critical value. The failure rate

of these relays for the mode in which the normally

open contacts would be closed with no power applied to the relay coil is so low that for all practical

purposes it is considered to be zero.

The track circuit shown here has been simplified

for the purpose of illustration. In actual practice, the

relay would have several sets of contacts connected

in combination with the contacts from other relays

in nearby track circuits to form logic circuits for the

control of the signaling devices (the red and green

lights). Even in the simple form shown in Figure

B-1, however, it can be seen that the breaking of any

conductor or the loss of power in the circuit will

cause either a red signal or no signal at all to be displayed. A red or “dark” signal is always to be in1

192
terpreted as a command to stop. If, for instance, the

green light burned out or the relay coil open-circuited so that the relay could not be “picked up, ” it

would be impossible to have a “green” signal. In

that case a train would be required to stop when it

arrived at that signal. To put it another way, all signaling systems are designed so that a green signal

(meaning proceed) is presented only when the track

circuits provide positive information that it is safe

to do SO.

The double-rail

interference when

the return for d.c.

d.c. track circuit is susceptible to

the running rails are also used as

electric propulsion current. For

this reason, d.c. circuits are not used in rail rapid

transit. 99 Single-rail d.c. track circuits could be used,

but in fact all modern rail rapid transit systems use

some form of a.c. track circuit.

Power-Frequency A.C. Track Circuits

The power-frequency a.c. track circuit is

energized by an alternating electrical current with a

frequency in the range of 50 to 150 hertz.100 Except

for the type of current and apparatus used, the a.c.

track circuit is similar in operation to the d.c. track

circuit described above.

~he principal modern application of the double-rail d.c.

track circuit is in railroads with diesel-powered locomotives,

l~his type of circuit is often called simply an a.c. track circuit.

Figure B-2 shows a simple power-frequency a.c.

track circuit. As with the d.c. circuit, the a.c. track

circuit consists of a block or length of track which is

defined at each end by insulated joints in one or

both of the running rails. Figure B-2 shows a double

rail circuit with insulating joints in both rails. The

a.c. signal source (usually a transformer) is connected to the rails at one end of the track circuit

while the receiver (a relay) is connected to the other

end, In addition to the signal source and the

receiver, the a.c. track circuit contains a pair of impedance bonds at each pair of insulated joints. An

impedance bond is a center-tapped inductance

which is connected across the rails on both sides of

the insulated joints. The center taps of the pair of

impedance bonds are connected together as shown.

The purpose of the impedance bonds is to provide

continuity between the track circuits for the d.c.

propulsion power and to distribute the propulsion

current between the two running rails. The impedance bonds do this while still maintaining a

relatively high impedance at the signaling frequencies between the two rails and between adjacent

track circuits.

When no train is present, the alternating current

supplied by the transformer at the left side of the

diagram in Figure B-2 is transmitted by the running

rails to the relay and “picks it up. ” The energized

relay turns on the green signal light, exactly as in a

d.c. track circuit. The wheels and axles of a train enFIGURE B–2.—Simple Power-Frequency A.C. Track Circuit

193
tering the track circuit connect the two running

rails together; and the current through the relay is

reduced, causing the relay to “drop.” This connects

the bottom set or relay contacts, turning off the

green light and turning on the red light to show that

the block is occupied. The resistor in series with the

transformer (at the left in the diagram) protects the

transformer by limiting the current that the

transformer must provide when a train is present.

High-Frequency A.C. Track Circuits

Some a.c. track circuits use a current that alternates at a frequency in the range of hundreds or

thousands of hertz. Because this frequency range

corresponds roughly to the spectrum of audible

sound, such circuits are sometimes called audiofrequency track circuits.

High-frequency a.c. track circuits eliminate the

need for insulated joints in the running rails.

Because insulated joints are expensive to install and

to maintain, eliminating them leads to a significant

cost reduction. Eliminating insulated joints also

allows the track circuit to operate with the continuous welded rails being used in some newer installations.

Figure B-3 shows a simple high-frequency a.c.

track circuit. Since no insulated joints are used in

the running rails, the ends of the block established

by special transformers are connected to the rails.

The transformer winding attached to the rails is

usually a single turn of heavy copper bar stock. The

transformer core is often a toroid. The other

transformer winding is tuned to resonate at the

operating frequency by a capacitor. The transmitter

is the a.c. signal source and provides electrical

energy at the operating frequency in the audiofrequency range. The receiver in this case is not

simply a relay, as with the d.c. and power-frequency a.c. track circuits, but an electronic circuit which

responds to the electrical signal provided by the

transmitter. The receiver may be used to actuate a

relay which performs functions like those in the d.c.

or power-frequency a.c. track circuits. Thus, when

no train is present the high-frequency a.c. potential

supplied by the transmitter is connected to the running rails by the transformer and transmitted along

the running rails to the other transformer and its

associated receiver. When the receiver detects the

high-frequency a.c. signal, the relay is energized

and the green signal light is turned on. When a train

enters the block, the circuit behaves much as it

would with the a.c. or power-frequency a.c. track

circuits, That is, the train wheels and axles connect

the two running rails together, and the current to

the receiving transformer and its associated

receiver causes the track circuit relay to drop, turning off the green light and turning on the red light.

The circuit illustrated in Figure B-3 is highly

simplified. In practice, it is necessary to accommo194
date the adjacent

Rather than install

track circuits

two separate

on either side,

transformers for

each track circuit, a second resonant winding can be

included in each transformer or a heavy primary

winding can be passed through more than one

transformer core. Thus, a single transformer assembly is used at the boundary between adjacent track

circuits and serves each. Although part of the same

transformer assembly, the resonant windings are

effectively isolated from each other because they

are tuned to and operate on different frequencies.

Figure B-4 shows another type of high-frequency

a.c. track circuit. No insulated joints are used in the

running rails. The ends of the block or track circuit

are established by shunts which are heavy copper

cables or bars attached to the rails, The transmitter

is the a.c. signal source and supplies electrical

energy to a loop which is placed between the rails

as shown. The loop is the primary of a transformer

of which the rails and the shunts form the secondary, At the other end of the track circuit, a pickup

directs the high-frequency a.c. energy to the

receiver, which in turn actuates the track circuit

relay. When no train is in the track circuit, the highfrequency a.c. potential supplied by the transmitter

is directed into the loop and thence into the running

rails to the pickup associated with the track shunt

shown at the right portion of the diagram, When the

receiver detects the high-frequency a.c. signal, the

relay is energized and the green light is turned on.

When a train enters the track circuit, the wheels

and axles connect the two running rails together,

and the current to the receiver is reduced. The

reduced current to the receiver causes the track circuit relay to drop, turning off the green light and

turning on the red light, as in other types of track

circuits. The relay in a practical circuit would have

several sets of contacts which would be connected

in combination with the contacts from relays in

nearby track circuits to form logic circuits for the

control of the signaling devices.

In practice a transmitting loop and a pickup are

associated with each track shunt. Adjacent track

circuits are operated on different frequencies, and

the receivers have frequency selectivity so they

only respond to their intended frequencies. This is

the type of track circuit used in the BART system.

Check-In/Check-Out Circuits

All of the track circuits described up to this point

operate on the closed-circuit principle. Any disruption of the circuit by a train passing along the rails

or by power or component failure, “opens” the circuit and causes a red (stop) indication to be displayed by the signal system.

An alternate approach to track circuit design uses

“check-in/check-out” logic, Simply stated, this cirA.C. Track Circuit

195
cuit is based on the principle that once a train is

detected or “checked in” to a block, it is assumed to

be there until it is “checked out” by being detected

in an adjacent block. The presence of a train may be

detected only intermittently at the time when it enters a new block. This is in contrast to the conventional track circuits described above in which the

presence of a train is detected continuously. In

some check-in/check-out systems the first and the

last cars of a train are checked in and out of the

blocks as the train moves through the system, A

transmitter of some kind located on the train can be

used with a receiver at a fixed wayside location to

indicate that a train has entered the block associated

with the wayside receiver, In some cases, two

transmitters are used, one at the head end of a train

and the other at the rear. When the head-end

transmitter enters a new block and is checked in,

the block remains in the occupied condition until

the rear-end transmitter also indicates that the rear

end of the train has entered the new block, At that

time, the train is checked out of the block behind.

Check-in/check-out has some operational disadvantages, For instance, consider the effects of a

temporary loss of power to the signal system. With

conventional track circuits, the loss of signal power

will cause all track circuits to indicate occupancy,

but when the signal power is restored, the true occupancy situation is again indicated. With a checkin/check-out system, the loss of signal power may

destroy the “memory” circuits charged with

“remembering” that a train has entered a block. The

memory often consists of electrical relays which are

energized (or deenergized) to indicate the presence

of a train in a block. The loss of electrical power can

destroy the information stored in such a memory.

(A memory whose information can be lost by a loss

of electrical power is termed “volatile.”) Thus,

when the signal power is restored, the information

on track circuits which are occupied may have been

lost. In this case the identity and location of each

train in the affected portion of the system must be

established before the entire transit system can be

operated again safely. In a small transit system the

identification and location of each train may not be

difficult to establish. However, in a large, complex

system even a short-term interruption of a portion

of the system can create a bottleneck which makes

it very difficult to restore the system to full operation. Thus, check-in/check-out systems do not find

application as the primary train detection system in

rail rapid transit systems.

A special case of a check-in/check-out system is

the SOR (sequential occupancy release) system recently installed at BART, which uses the check-in/

check-out principle as a logical back-up to the primary train detection system which uses high-frequency a.c. track circuits. The purpose of SOR is to

protect against the loss of train detection in the

event the primary system fails and to prevent service interruptions due to false occupancy indications,

The SOR system provides a latch such that an occupied track circuit continues to indicate occupancy

until it is reset by the detected occupancy of the second downstream track circuit. Thus, with the loss of

shunt or failure to detect the presence of a train, the

latched-up track circuit still indicates occupancy

and prevents a following train from colliding with

the rear of the leading train. A series of computers

is used in the SOR system, and the logic is such that

the computers can recognize false occupancies, i.e.,

a track circuit which shows occupancy without a

prior occupancy of the preceding track circuit is

considered by the computer to be falsely occupied,

SPEED COMMAND AND CONTROL

In considering how the speed of transit vehicles

is controlled by automatic devices, it is important to

understand the principle of closed-loop control

before proceeding to a discussion of the means by

which speed commands are transmitted and

received, A closed-loop control system is one in

which some feedback of information on the status

of the system (or its response to command inputs) is

used to modify the control of the system. As a

minimum, feedback verifies that the command was

received, Feedback may also be used to modulate

subsequent command inputs so as to smooth out irregularities of response, to make increasingly more

precise adjustments of the state of the system, or to

compensate for external perturbations. Thus, the

basic purpose of closed-loop control is to assure

continuity of control by confirming that command

inputs have been received and that the commanded

state of the system has, in fact, been achieved.

The alternative to closed-loop control is openloop control, where commands are transmitted

from the controlling to the controlled element without any feedback or acknowledgment that the command signal has been received and interpreted properly. The traditional wayside signaling of rail rapid

196
transit is an open-loop system. So, too, is a manually

operated train with cab signals, although the

automatic overspeed and stop enforcing mechanisms of cab signals represent the beginning of a

closed-loop system. Systems with ATO are true

closed-loop systems. Feedback is used to monitor

the response to propulsion and braking commands

and to regulate the performance of the system on a

continuous, real-time basis. Thus, a closed-loop

system, in contrast to an open-loop system, is

characterized by continuous control and self-adjusting commands conditioned by observation of

system response.

The technology for controlling the speed of transit vehicles is based on the track circuit. The signals

used for train detection can also be used for the

transmission of speed commands to wayside signaling devices and to the trains. Two general methods

are used for the transmission of such commands. In

one method, the track circuit signal is turned on and

off at a specific rate, which is interpreted as a speed

command. This rate modulation scheme is called a

coded track circuit. The second method is called

binary message coding. With either method, equipment on the wayside or on the train senses the signals in the rails and decodes the speed command.

Coded Track Circuits

This technique is applicable to either d.c. or a.c.

track circuits. The track circuit signal is switched on

and off (modulated) at a rate which is related to the

speed command. The switching rates are in the

range from about 50 to 500 times per minute. In a

d.c. track circuit, the direct current applied to the

running rails at one end of the track circuit is simply

turned on and off at the desired rate. Wayside

equipment at the other end of the track circuit

receives and decodes the signals. A code-following

track relay is used in the track circuit and codes

continuously when the circuit is not occupied. The

relay is energized when the current is allowed to

flow and is deenergized or “drops” when the current stops. The decoding equipment is actuated by

the contacts of the code-following relay. When a

given code (rate of transmission) is received, a particular relay in the decoding equipment is energized

and remains energized as long as that code is being

received. The relay, in turn, controls the appropriate wayside signal. When another code is received,

another relay is energized as long as that code is

being received. When a train enters the track circuit, the code-following relay is deenergized, and

this fact is used to indicate thee presence of a train.

Typical interruption rates for these circuits are 75,

120, and 180 times per minute,

In a.c. track circuits, either power-frequency or

audiofrequency, the a.c. signal is turned on and off

at a selected rate. Since the switching rates for the

coded signals are so much slower (I-3 per second)

than the frequencies of the a.c. signals applied to

the track circuit (50-150 per second), many cycles of

the a.c. signal occur during the time that the code

signal is switched on. The coded track signal can be

received by wayside equipment at the far end of the

track circuit and used to control wayside signals or

it can be received on board a train and used to control the speed of the train. The presence of a train

stops the operation of the code-following relay and

indicates occupancy of the track circuit. The coded

track signals are received on board a train by a pair

of coils mounted near the front of the leading car

just a few inches above each of the two running

rails and in front of the first set of wheels and axle,

The magnetic field from the electric current carried

in the rails produces a signal in these coils (sometimes called antennas), and this signal is processed

or decoded to determine the switching rate and

hence the speed command. The decoded speed

command is used in an automatic system to control

the speed of the train. In a semiautomatic system,

the decoded speed command is displayed to the

train operator who then regulates train speed

manually.

Binary Coded Track Circuits

This technique is sometimes used with audiofrequency a.c. track circuits. It could also be used

with power-frequency a.c. circuits, but customarily

it is not. Instead of turning the track circuit signal on

and off (rate modulation), the frequency of the

track signal is changed from one to the other of two

discrete frequencies. This technique is particularly

adaptable to digital systems in which one frequency

corresponds to the transmission of a “l” and the

other frequency corresponds to the transmission of

a “0.” The track circuit receiver responds to both of

the signaling frequencies that are used. When a

train enters the track circuit, the amplitude of the

signals at the track circuit receiver is reduced below

some threshold and this information is used as an

indication of the presence of the train. On board the

train two antennas or coils are mounted near the

197
front of the lead car close to the running rails and in mine the speed command. In an automatic system,

front of the first set of wheels and axle. As with the the decoded speed command is used to control the

coded track circuits, the magnetic field from the train speed, In a semiautomatic system, the decoded

electric current carried in the rails produces a signal speed code information is displayed to the train

in these coils, and this signal is decoded to deter- operator who controls train speed manually,

198
Appendix C

DESIGN CHARACTERISTICS

OF SELECTED RAIL RAPID TRANSIT SYSTEMS

This appendix is a tabulation of the ATC design

characteristics and engineering features of five

operating rail rapid transit systems:

Bay Area Rapid Transit (BART)

Chicago Transit Authority (CTA)

Massachusetts Bay Transportation Authority

(MBTA)

New York City Transit

Port Authority Transit

Authority (NYCTA)

Corporation (PATCO)

Listed vertically at the left of the tables are the

generic functions which must be accomplished to

provide train protection, train operation, train

supervision, and system communications. 101 A rrayed beside these functions are descriptions of the

equipment and techniques employed in the five

transit systems. The major distinction is between

manual and automated techniques, with supplementary material to indicate specific engineering

and operational features.

None of the rail rapid transit systems described

here is completely manual or completely automatic.

Iolsee appendix A for a definition and description of these

functions.

All represent various combinations of manual and

automatic train control—the particular mixture

being determined by local needs and conditions, the

history of engineering development in each locale,

and (for the newer systems, at least) the fundamental design philosophy. Generally speaking, NYCTA

and CTA are the least automated of the five transit

systems, although both have a considerable amount

of automation of train protection functions. The

Red Line of MBTA represents a higher level of

automation, incorporating some automatic train

operation features in addition to basic automatic

train protection. The other MBTA lines are

equivalent to NYCTA or CTA in the extent of

automation, PATCO is still more automated, with

virtually all train protection and operation functions assigned to machine components. On the

other hand, PATCO has almost completely manual

means of train supervision. BART is the most highly automated of the five systems. Train protection

and operation are fully automatic, but monitored by

an onboard operator. Train supervision is also

largely automated, with extensive use made of

central computers to accomplish functions that are

performed by dispatchers and towermen in other

transit systems. The order of listing in the table indicates progressive increase in the general level of

train control system automation.

199
TRAIN CONTROL SYSTEM CHARACTERISTICS

TRAIN PROTECTION FUNCTIONS NYCTA CTA

Train Detection

Monitoring of track occupancy

Train Separation

Collision prevention, primarily by

blocks to ensure safe separation

and speed limits to ensure safe

stopping distance

Movement Commands

Speed and stopping commands to

trains

Overspeed Protection

Comparison of command and

actual speed to ensure that civil

speed limits are not violated

Speed Determination

Sensing and display of actual

train speed

Interlocking

Prevention of conflicting train

movement through switches and

along routes

Train and Track Surveillance

Monitoring the right-of-way for

obstructions, persons on track,

broken rails, etc.

Monitoring condition of train

systems.

Conventional voltage level track

circuits of two types:

single rail, power frequency,

hardwired

double rail, power frequency,

hardwired

Fixed blocks (length: 40-1200 ft.)

Relay logic

Minimum design headway: 11/2 min.

Conventional voltage level track

circuit of three types:

single rail, power frequency,

hardwired

double rail, power frequency,

hardwired

double rail, audio frequency,

hardwired

Fixed blocks (length: 300-2000 ft.)

Relay logic

Minimum design headway: 11/2 min.

Wayside signals Mixture of wayside and cab signals

Three-aspect block signal system Three-aspect block signal system

(Proposed cab signal system will Five cab signal speed commands

have 70,50, 35, 25, 15, and 3 (70, 35,25, 15,0 mph)

mph speed commands and a cab

signal cutout. Absence of a

positive command is interpreted

as O mph.)

Wayside signals with timers and Mixture of cab signals with

trip stops automatic overspeed protection

and wayside signals with timers and

trip stops

Estimated by motorman, no speed- Tachometer, with speedometer in

ometer in cab except on new R 44 cab

and R-46 cars.

Mixture of electro-mechanical and Mixture of mechanical, electro -

all-relay mechanical, electro-pneumatic,

and all-relay

Visual track surveillance (primarily Visual track surveillance (primarily

by motorman with some assistance by motorman with some assistance

from conductor) from conductor); cab signal for

broken rail protection

Status of some carborne systems is Status of some carborne systems is

monitored automatically and monitored automatically and disdisplayed by annunciator placards in played by annunciator placards in

the cab. the cab.

200
MBTA PATCO BART

Conventional voltage level track

circuits of three types:

single rail, power frequency,

hardwired 

double rail, power frequency,

hardwired

double rail, audio frequency,

hardwired

Fixed blocks (length: 425-2100 ft.)

Relay logic

Minimum design headway: 11/2 min.

Mixture of wayside and cab signals

Three-aspect block signal system

Eight cab signal speed commands

(70, 65,50,40,25, 10,0 mph and

yard speed)

Conventional voltage level track

circuits of two types:

single rail, power frequency,

hardwired (yard only)

double rail, power frequency,

hardwired (revenue tracks)

Fixed blocks (length: 295-3400 ft.)

Relay logic

Minimum design headway: 2 min.

Cab signals

Five speed commands (75, 40,30,

20, 0 mph) to ATO system which

controls speed

Mixture of cab signals with automatic Cab signals with automatic

overspeed protection and wayside overspeed protection

signals with timers and trip stops

Low voltage level track circuits:

double rail, audio frequency,

multiplex one rail; power

frequency track circuits in yards

Fixed blocks (length 75-1100 ft.)

Solid-state logic

Minimum design headway: 11/2 min.

(With sequential Occupancy Release

system, headways are restricted to

2 min.)

Cab signals

Eight speed commands (80, 70,50,

36, 27, 18,6, 0 mph) to ATO system

which controls speed

Cab signals with automatic

overspeed protection

Estimated by motorman, no speed- Tachometer, with speedometer in Tachometer, with speedometer in

ometer in cab except for Silverbird cab cab

cars on Red Line

Mixture of electro-mechanical and All-relay

all-relay

All -relay

Visual surveillance (primarily by Visual surveillance by train operator Visual surveillance by train operator

motorman with some assistance cab signal for broken rail protection cab signal for broken rail protection

from train guards); cab signal for

broken rail protection (Red Line

only)

Status of some carborne systems is Status of some carborne systems is Status of some carborne systems is

monitored automatically and dis- monitored automatically and dis- monitored automatically and displayed by annunciator placards in played by annunciator placards in played by annunciator lights in the

the cab. the cab. cab.

201
TRAIN CONTROL SYSTEM CHARACTERISTICS–Continued

TRAIN SUPERVISION FUNCTIONS NYCTA CTA

Schedule Design and Implementation

Planning of service in light of

anticipated demand, available

equipment, and environmental

conditions (includes orders to

execute the plan)

Train Identification

Manual Manual

Determination of the route and

destination of a train

Mixture of manual and automatic

(Automatic only on R-44 and R-46

cars, where passive unit on train

resonates when excited by wayside

equipment )

Mixture of manual (by train

operator or towerman) and

automatic (passive unit on

train resonates when excited

by wayside equipment or optical

scanning of identity panel on

train by wayside equipment)

Train Dispatching

Control of train departures from

terminals (or waypoints) in

accordance with schedule

Route Assignment and Control

Mixture of manual and automatic

(electro-mechanical clock)

Mixture of manual and automatic

(electro-mechanical clock)

Selection and assignment of routes

to be followed by trains, including

periodic update reports by trains

as to identity, location, and

destination

Mixture of manual control by local

towerman and automatic control

based on train identity information or

track circuit occupancy

Mixture of manual methods (by

central control remotely or by

towerman locally) and automatic

control based on train identity

information or track circuit

occupancy

Performance Monitoring

Following the progress of trains

against the schedule

Visual observation (model boards

in towers and central control)

Also manual check-off at towers

Visual observation (model boards

in towers and pen graph recorders

at central control)

Performance Modification

Adjustment of movement commands or revision of schedule

in response to traffic conditions

Verbal instructions to adjust running

speed or station stops; remotely

controlled starting signals to delay

departure from terminals and control

points

Verbal instructions to adjust running

speed or station stops; remotely

controlled starting signals to delay

departure from terminals and control

points

Alarms and Malfunctions Recording

Alerting to malfunctions and

problems and recording of time,

location, and nature

Yard Train Control

Manually activated electrical alarming and manual recording based on

verbal reports

Manual alarming and recording based

on verbal reports

Train assembly, routing, and

movement with in yards and to

and from revenue tracks

Manual train operation and a mixture of manual and automated

switching

Manual

202
MBTA PATCO BART

Manual Manual Schedule prepared manually and fed

into central computer

Mixture of manual and automatic Automatic (passive unit on train Automatic (active unit on train

(optical scanning of identity panel resonates when excited by wayside transmits identity to wayside

on train by wayside equipment) equipment) transceiver for relay to terminals,

stations, and central control)

Mixture of manual and automatic Automatic (electro-mechanical clock) Automatic (computer controlled)

(electro-mechanical clock)

Mixture of manual methods (by

central control remotely or by

towerman locally) and automatic

control based on train identity

information or track circuit

occupancy.

Visual observation (model boards

in towers and central control)

Mixture of manual control by Automatic (trainborne destination

central control remotely and information transmitted to wayside

automatic control based on train equipment which automatically sets

identity information or track route); manual control (by central

circuit occupancy or local controllers) available as an

alternative or back-up mode

Visual observation (model board at Visual observation (model boards at

central control) central control and towers) with

computer-aided display and alerting

Verbal instructions to adjust running Verbal instructions to adjust running Automatic, station dwell time and

speed or station stops; remotely speed or station stops; remotely train performance mode (speed and/or

controlled starting signals to delay controlled starting signals to delay acceleration) controlled by central

departure from terminals and control departure from terminals and control computer (can be selected by computer

points points automatically or by manual input)

Manual alarming and recording based Manual alarming and recording based Automatic alarming and recording

on verbal reports on verbal reports for some events; manual inputs to

computer record also possible

Manual Manual Manual (special hostling control

panel)

203
TRAIN CONTROL SYSTEM CHARACTERISTICS–Continued

TRAIN OPERATION FUNCTIONS NYCTA CTA

Velocity Regulation

Control of actual speed in

relation to command (civil)

speed

Station Stopping

Stopping train in alignment

with station platform

Door Control

Opening and closing of doors

at stations

Train Starting

Departure from station

Manual

Manual

Manual

Manual

Manual, by conductor Manual, by conductor (or

operator on single-car trains)

Manual, by operation of propulsion Manual, by operation of propulsion

control control

COMMUNICATION SYSTEMS NYCTA CTA

Train – Central Radio

Train – Station No direct link, relayed through

central control

Train – Wayside Radio

Central - Station Telephone; also public address

system on platform at some stations

and automatic train departure

signs at some terminals

Central – Wayside Radio and dial telephone

Station – Wayside

Station – Station

Wayside - Wayside

Outside Emergency Assistance

*

Dial telephone

Dial telephone

Radio and dial telephone

Walkie-talkie radio net for police,

central control and key dispatchers,

other assistance summoned through

central control

Train phone

No direct link, relayed through

central control

No direct link, relayed through

central control

Telephone; also public address

system on platform at some stations

and automatic train departure

signs at some terminals

Dial telephone; also public address

to certain key towers and terminal

supervisors

Dial telephone

Dial telephone

Dial telephone

Dial or direct-line telephone

204
MBTA PATCO BART

Automatic on Red Line, with manual

operation (at full speed) available as

alternative mode.

Manual on other lines

Manual

Manual by train guard (conductor)

Manual, by operation of propulsion

control

Automatic, with manual operation

(at, full speed) available as alternative

mode.

Automatic

Stop command triggered when

train passes fixed wayside point;

braking effort to stop in required

distance reckoned from wheel

revolution

Manual by train guard (motorman)

Manual, by depressing start button

Automatic, with manual operation

(at reduced speed) available as a

back-up mode or if track conditions

dictate

Automatic

Continuous stop command generated

by wayside equipment; braking

effort to stop in required distance

reckoned from wayside measuring

points.

Automatic, with manual override

Automatic

MBTA PATCO BART

Radio

No direct link, relayed through

central control

Radio

Telephone and public address

system on station platforms; some

startees equipped with walkie-talkie

radios

Radio and dial telephone

Dial telephone

Dial telephone

Dial telephone

Police and fire each on separate

radio network; utilities contacted

by telephone

Train phone

No direct link, relayed through

central control

No direct link, relayed through

central control

Telephone, public address, closedcircuit TV, and call-for-aid phones

at automatic fare collection gates

Dial telephone, radio in trucks

and work trains, walkie-talkie

for trackside workers

Dial telephone

Dial telephone

Radio and dial telephone

PATCO police on system radio

network; outside police on separate

network or contacted by telephone;

fire and utilities contacted by

telephone

Radio

No direct link, relayed through

central control

Radio

Telephone and public address system;

automatic signs on station platforms

indicating train arrival and destination

Radio and dial telephone

Dial telephone

Dial telephone

Radio and dial telephone

BART police on system radio network; fire and utilities contacted by

phone

205
Appendix D

GLOSSARY OF TRAIN CONTROL TERMS

The language of rail rapid transit and train control technology contains many specialized terms

that may be unfamiliar to the general reader. This

glossary has been prepared as an aid to understanding the terminology used in the report. It is also contemplated that the glossary may be useful as a

reference for additional reading on the subject of

ATC and transit system engineering. For this

reason, the list of terms defined here has been expanded to include some background items not

needed for the immediate purpose of reading this

report.

The principal source of the definitions presented

here is the Lexicon of Rail Rapid Transit SafetyRelated Terminology, prepared by the Safety Technology Applied to Rapid Transit (START) Committee of the American Public Transit Association,

January 1975. The START Lexicon, in turn, draws

extensively on earlier work by the Association of

American Railroads and the U.S. Department of

Transportation. In addition to START, other

sources consulted include General Order No. 127 of

the Public Utilities Commission of the State of

California, August 1967, and several technical

specifications prepared by WMATA. In all cases,

however, the responsibility for interpretation and

for the accuracy and completeness of the definitions offered here rests with the authors of this

report.

ACKNOWLEDGING DEVICE—a manual device

used by the train operator to forestall automatic

brake application on a train equipped with

automatic train stop or to silence the sounding of

a cab indicator on a train equipped with cab signaling. (See Audible Cab Indicator.)

ASPECT—the visual indication presented to an approaching train by a wayside signal; also, the display presented by a cab signal to an operator in

the cab. The aspect is said to be “clear” (proceed

at civil speed) or varying degrees of “restrictive.”

False Clear Aspect—the aspect of a signal that

conveys an indication less restrictive than

intended.

False Restrictive Aspect—the aspect of a signal that conveys an indication more restrictive than intended.

ATTENDANT-a transit employee on board a

train in service whose principal duties are to

oversee safety, provide security, and assist in

emergency situations (as distinct from a train

operator, motorman, who is responsible for running the train).

AUDIBLE CAB INDICATOR-an alerting device,

on a train equipped with cab signals, designed to

sound when the cab signal changes and to continue sounding until acknowledged. (See

Acknowledging Device.)

AUDIO-FREQUENCY TRACK CIRCUIT—a track

circuit energized by an electrical current alternating in the audio-frequency range

(15,000-20,000 Hz); also called “high frequency”

or “overlay” track circuit.

AUTOMATIC BLOCK SIGNAL SYSTEM—a

series of consecutive blocks governed by block

signals, cab signals, or both, actuated by occupancy of the track or by certain conditions affecting

the use of a block; such as an open switch or a car

standing on a turnout and blocking the main

track. (See also Block and Manual Block Signal

System.)

AUTOMATIC CAR IDENTIFICATION—a

system that automatically provides positive

recognition and transmission of individual car

numbers as they pass a fixed wayside point.

AUTOMATIC TRAIN CONTROL—the method

(and, by extension, the specific system) for

automatically controlling train movement, enforcing train safety, and directing train operations. ATC includes four major functions:

Automatic Train Protection (ATP)--assuring

safe train movement by a combination of

train detection, separation of trains running

on the same track or over interlocked

routes, overspeed prevention, and route interlocking.

207
Automatic Train Operation (ATO)--controlling speed, programed station stopping, door

operation, performance level modification,

and other functions traditionally assigned

to the train operator and conductor.

Automatic Train Supervision (ATS)—

monitoring of system status and directing

traffic movement to maintain the schedule

or minimize the effect of delays.

Communication (CS)—interchanging information (voice, data, or video) between

system elements separated by distance.

AVAILABILITY—the portion of time that a

system is operating or ready for operation;

mathematically, the probability that a system or

system element will be operational when required, expressed as the ratio of mean time between failure to the sum of mean time between

failure plus mean time to restore. [A =

MTB F/(MTBF + MTT R)] (See also Mean Time

Between Failure and Mean Time to Restore.)

BASE PERIOD—the nonrush hour period of weekday transit system service. (See also Peak

Period,)

BERTH—the space assigned for a train of specified

length when stopped at a station platform or in a

terminal zone. (See Terminal Zone.)

BERTHING—the positioning of a train in its

assigned berth.

BLENDING—the automatic and simultaneous application of dynamic and friction braking, where

the effort of each is continuously proportioned to

achieve the required total braking effect.

BLOCK—a length of track of defined limits, the use

of which is governed by block signals, cab signals, or both.

Absolute Block-a block into which no train is

allowed to enter while it is occupied by

another train.

Permissive Block--a block into which a train

is allowed to enter even though occupied by

another train.

BLOCK SIGNAL-See Signal.

BRAKE ASSURANCE—the function provided by

a subsystem within the automatic train operation

system that will cause the emergency brakes of a

vehicle to be applied when the actual braking

rate of the vehicle is less than the braking rate requested by the automatic train control system.

BRAKING—the process of retarding or stopping

train movement by any of various devices:

Dynamic Braking—a system of electrical

braking in which the traction motors are

used as generators and convert the kinetic

energy of the vehicle into electrical energy,

which is consumed in resistors and, in so

doing, exert a retarding force on the vehicle.

Friction Braking—braking supplied by a

mechanical shoe or pad pressing against the

wheels or other rotating surface; also called

“mechanical braking. ”

Regenerative Braking-a form of electrical

braking in which the current generated by

the traction motor is returned to the traction power supply for use in propelling

other trains. (In ordinary dynamic braking

the generated power is dissipated in resistors.)

There are two methods of controlling

brake application:

Closed-Loop Braking-continuous modulation (by means of feedback) under the

direction of the automatic train operation

system or the human operator. (See ClosedLoop Principle,)

Open-Loop Braking—braking withou t

modulation through feedback from the

ATO system.

BRAKING EMERGENCY—irrevocable unmodulated (open-loop) braking to a stop usually at a

higher rate than that obtained with a full service

brake application.

BRAKING, FULL SERVICE-a nonemergency

brake application that obtains the maximum

brake rate consistent with the design of the primary brake system. Full service braking can be

released and reapplied.

BRAKING, SERVICE-braking produced by the

primary train braking system,

CAB SIGNAL SYSTEM—a signal system whereby

block condition and the prevailing civil speed

commands are transmitted and displayed directly

within the train cab. The cab signal system may

208
be operated in conjunction with a system of fixed

wayside signals or separately. (See also Signal.)

CATENARY—the wire or wires above the track

(including the messenger, supports, and insulation) that carry electric energy for the propulsion

of trains. (See also Contact Rail.)

CENTRAL CONTROL—the place from which

train supervision and direction is accomplished

for the entire transit system; the train command

center.

CIRCUIT, TRACK-an arrangement of electrical

equipment, including the rails of the track, that

forms a continuous electrical path used for the

purpose of detecting the presence of trains on the

rails; the track circuit may also be used to communicate commands or other information between the wayside and the train.

Check-In/Check-Out—a track circuit system

that detects the entrance of the front end of

a train into a block and the departure of the

rear end of a train from a block for the purpose of determining block occupancy.

Coded Track Circuit—a track circuit in which

the feed energy is varied or interrupted

periodically for the purpose of transmitting

commands or instructions to the train or

operating train detection apparatus.

Fail-Safe Circuit-a circuit designed to principles which will cause the actuated device to

assume its most restrictive position (or a

state generally known to be safe) when any

element of the circuit or system fails.

Vital Circuit--an electrical circuit that affects

the safety of train operation.

CIVIL SPEED-See Speed Limit.

CLOSED-CIRCUIT PRINCIPLE—the principle of

circuit design employing a circuit that is normally energized and, on being deenergized or interrupted, causes the controlled function to

assume its most restrictive condition.

CLOSED-LOOP” PRINCIPLE—the principle of

control system design in which the response of a

system (feedback) is continuously compared

with the controlling signal to generate an error

signal.

CLOSING IN—running a following train toward a

leading train that is either stopped or running

slower than the following train. (See also Closing

up.)

CLOSING UP—running a following train to a position that will allow it to couple with a stopped

leading train.

COAST—the moving condition of a car or train

where the propulsion is inactive and, usually, a

certain minimum braking is applied. (See also

Freewheeling.)

CONDUCTOR-an attendant whose main function is to operate train doors.

CONSIST (noun)—the number, type, and specific

identity of cars that compose a train.

CONTACT RAIL-a rail, mounted on insulators

alongside the running rails, that provides electric

energy for the propulsion of trains. (Also known

as “Third Rail.”)

CROSSOVER—two turnouts, arranged to form a

continous passage between two parallel tracks.

DEADMAN CONTROL-a safety device that requires continuous pressure or activity to remain

activated; used to detect the inattention or disability of a train operator.

DEPARTURE TEST-an operational test made in

a yard or on a transfer track before permitting the

unit to enter revenue service.

DISPATCH—to start a train into revenue service

from a terminal zone, transfer track, or designated intermediate point.

DISPATCHER-a person at central control whose

function is to dispatch trains, monitor train

operation, and to intervene in the event of

schedule disruption or when any change in service or routing is required. (Also called “Line

Supervisor” or “Central Supervisor.”)

DOWNSTREAM—for a given direction of travel,

locations that will be reached after passing a

given point (equivalent to the AAR term “in advance of”).

DWELL (or DWELL TIME)—the elapsed time

from the instant a train stops moving in a station

until the instant it resumes moving,

ENTRANCE—EXIT ROUTE CONTROL—a

system of interlocking control that automatically

alines switches and clears signals to form a train

route in response to manual inputs designating

209
the entrance and exit points of the desired route.

(Also called “N-X.”)

FACING MOVEMENT—the movement of a train

over points of a switch which face in the direction in which the train is moving. (See also Trailing Movement.)

FAIL-SAFE--a characteristic of a system which

ensures that a fault or malfunction of any element affecting safety will cause the system to

revert to a state that is known to be safe; alternatively, a system characteristic which ensures

that any fault or malfunction will not result in an

unsafe condition.

FALSE OCCUPANCY--an indication of track occupancy when no train is present.

FREEWHEELING-a mode of operation in which

the train is allowed to roll freely without tractive

or braking effort being applied. (See also Coast.)

FREQUENCY SHIFT KEYED (FSK)--a technique

used with high-frequency a.c. track circuits, in

which the frequency of the track signal is varied

between two or more discrete states to convey

information (used as an alternative to rate

modulation where the track circuit is turned on

and off as an information code).

FROG-a track structure, used at the intersection

of two running rails, to provide support for

wheels and passageway for their flanges, thus

permitting wheels on either rail to cross the

other. A frog may either be fixed or have movable points like a switch.

GATE—the limit of an interlocked route where entry to that route is governed by a signaling

device. 102

Fixed Gate--the limit of an interlocked route

beyond which automatic operation of trains

is never permitted.

HEADWAY—the time separation between two

trains traveling in the same direction on the same

track, measured from the instant the head end of

the leading train passes a given reference point

until the head end of the train immediately

following passes the same reference point.

HOSTLER-an employee assigned to operate cars

or trains manually within the yard or maintenance area.

Hz (HERTZ)—the unit of frequency equal to 1

cycle per second.

IMPEDANCE BOND-a device of low resistance

and relatively high reactance, used to provide a

continuous path for the return of propulsion current around insulated joints and to confine alternating current signaling energy within a track

circuit.

INDUCTIVELY COUPLED IMPEDANCE

BOND--an impedance bond in which transmitter energy and receivers are inductively coupled

into a track circuit,

INSULATED JOINT-a joint placed between abutting rail ends to insulate them from each other

electrically.

INTERLOCKING--an arrangement of signals and

control apparatus so interconnected that functions

must succeed each other in a predetermined sequence, thus permitting train movements along

routes only if safe conditions exist.

Automatic Interlocking-an interlocking controlled by logic circuits so that movements

succeed each other in proper sequence

without need for manual activation or control.

Manual Interlocking—an interlocking operated manually from an interlocking

machine, so interconnected (eithe r

mechanically or electrically) that movements succeed each other in proper sequency.

Relay Interlocking-an interlocking in which

locking is accomplished electrically by interconnection of relay circuits.

INTERLOCKING LIMITS—the length of track between the most remote opposing home signals of

an interlocking.

INTERLOCKING MACHINE-an assemblage of

manually operated levers or like devices for controlling the switches, signals, and other apparatus

of an interlocking. (Also called “Switch

Machine,”)

INTERLOCKING ROUTE-a route between two

opposing interlocking signals.

JERK—the rate of change of acceleration (the

second derivative of velocity), expressed in units

of miles per hour per second per second

(mphpsps, mph/see/see, or mph/sec 2

).

JUNCTION-a location where train routes converge or diverge. lo2Tht,sf, te

rms ;] rp pet; II 1 ia r to the BA RT s~st[’m. ,.

210
KEY-BY—the act of lowering a trip stop in order to

pass a signal displaying a stop indication; so

called because of the use at one time of a key by

the train operator to actuate the mechanism for

lowering the trip stop. Key-by today operates

automatically without a key,

LOCKING-establishing an electrical or mechanical condition for a switch, interlocked route,

speed limit, or automatic function such that its

state cannot be altered except by a prescribed

and inviolate sequence of actions.

Approach Locking-electric locking effective

while a train is approaching within a

specified distance a signal displaying an

aspect to proceed and which prevents, until

after the expiration of a predetermined

time interval after such signal has been

caused to display its most restrictive aspect,

the movement of any interlocked or

electrically locked switch, movable point

frog or derail in the route governed by the

signal and which prevents an aspect to proceed from being displayed for any conflicting route.

Electric Locking—an electrical circuit arrangement by means of which levers of an interlocking machine, switches, or other signal apparatus is secured against operation

under prescribed conditions.

Indication Locking-electric locking which

prevents actions that would result in an unsafe condition for a train movement if a signal, switch, or other operative unit fails to

make a movement corresponding to that of

its control.

Occupancy Detector Locking--electric locking

which prevents the movement of a track

switch while the track circuit or circuits

surrounding that switch are occupied by a

train.

Route Locking—electric locking, effective

when a train passes a signal displaying an

aspect for it to proceed, that prevents the

movement of any switch in the route

governed by the signal and prevents the

clearing of a signal for any conflicting

route.

Time Locking-electric locking that prevents

the operation of any switch in the route (or

for any conflicting route) until expiration of

a predetermined time interval after a signal

is restored to its most restrictive indication.

Traffic Locking--electric locking which prevents the actuation of devices for changing

the direction of traffic on a section of track

while that section is occupied or while a

signal displays an aspect for a movement to

proceed into that section,

Sectional Release Locking—a route locking so

arranged that, as a train clears a section of

the route, the locking affecting that section

is released. (Also called “Trailing Release

Locking.”)

MAINTAINABILITY—the property of a system

that allows it to be repaired and restored to

operating condition after a component malfunction or failure; maintainability is often expressed

as mean time to restore (or repair).

MANUAL BLOCK SIGNAL SYSTEM-a block

signal system operated manually, usually based

on information transmitted by telephone or

telegraph.

MARRIED PAIR—two semipermanently coupled

cars that share certain essential components and

are usually operated as a unit.

MASTER CONTROLLER-a carborne device that

generates control signals to the propulsion and

braking systems,

MEAN TIME BETWEEN FAILURES (MTBF)—

the average time that a system or component will

operate without fai1ure or ma1function;

mathematicaly , MTBF = (operatin g

time) /(number of failures). MTBF is the measure

of reliability.

MEAN TIME TO RESTORE (MTTR)—the

average time required to restore a system or component to operation after a failure; this time is

measured from the time troubleshooting and

repair work is begun until the system or component is again operable; mathematically,

MTTR = (cumulative corrective maintenance

time) /(number of failures). MTTR is the

measure of maintainability,

MODEL BOARD-a reproduction of the track

assemblage (not necessarily to scale) equipped

with lights and other indicators, used for the pur211

72-683 C) - 76 - 15
pose of train supervision and traffic control (Also

called “Train Board”).

MOTORMAN-See Operator.

MTBF-See Mean Time Between Failures.

MTTR-See Mean Time to Restore.

NORMAL DIRECTION—the prescribed direction

of train traffic as specified by the rules; usually,

the direction in which all regularly scheduled

revenue service operations are conducted.

N–X-See Entrance-Exit Route Control.

OPERATOR—the transit employee on board the

train having direct and immediate control over

the movement of the train. (Also called “Motorman.”)

OPPOSING TRAIN—a train moving in the direction opposite to another train on the same track.

OVERSPEED CONTROL—that onboard portion

of the carborne ATC system that enforces speed

limits in a fail-safe manner.

PABX—a designation used in the nationa l

telephone system to denote a privately owned

telephone system that operates by the use of dialing, such as that used in some transit systems for

communication between stations or wayside

locations and central control.

PEAK PERIOD—the period during a weekday

when system demand is highest; usually

7:30-9:30 a.m. and 4:30-6:30 p.m. (Also called

“Rush Hour.”) (See also Base Period)

POINT-See Switch Point.

PROPERTY—literally, the right-of-way, track,

structures, stations, and facilities owned or operated by a transit agency; but used generally as a

synonym for the operating agency itself. (See

also Territory.)

RAIL RAPID TRANSIT—a mode of transportation operating in a city or metropolitan area and

high-speed speed passenger cars run singly or in

trains on fixed guideways in separate rights-ofway from which all other vehicular and foot

traffic is excluded. Tracks may be located in underground tunnels, on elevated structures, in

open cut, or at surface level. There are very few,

if any, grade crossings; and rail traffic has the

right-of-way at such intersections. Cars are

driven electrically with power drawn from an

212

overhead electric line by means of pantograph or

from an electrified third rail. Rail rapid transit

may use steel wheels on steel rails or pneumatic

tires on wooden, steel, or concrete guideway.

RELAY-a device operated by variation in the condition of one electric circuit and used to effect

the operation of other devices in the same or

another circuit; commonly, an electromagnetic

device to achieve this function.

Track Relay--a relay receiving all or part of

its operating energy through conductors

having the track rails as an essential part.

Vital Relay—a relay, meeting certain

stringent specifications, designed so that

the probability of its failing to return to the

prescribed state after being deenergized is

so low as to be considered, for all practical

purposes, nonexistent.

RELIABILITY—the probability that a system or

component thereof will perform its specified

function without failure and within prescribed

limits; reliability is often expressed as a mean

failure rate (MTBF).

REVENUE SERVICE—transportation of farepaying passengers on main line routes.

REVERSE DIRECTION—train movement opposite to the normal direction. (See Normal

Direction.)

REVERSE RUNNING-operation of a train in the

reverse direction.

ROUTE-a succession of contiguous blocks between two controlled gates or interlocked signals.

Conflicting Routes—two or more routes (opposing, converging, or intersecting) over

which movements cannot be mad e

simultaneously without possibility of collision.

Normal Route--a prescribed route, a route in

the normal direction of train travel.

Reverse Route--a route opposite to the normal

route.

ROUTE REQUEST—registration at an interlocking

of a desired interlocked route.

RUNTHROUGH—intentionally passing a station

platform without making a scheduled stop.
.

SEMAPHORE-a wayside signal device by which

indications are given by the position of a movable arm in daylight hours and by the color of a

light in darkness.

SHUNT-a conductor joining two points in an

electrical circuit so as to form a parallel or alternate path through which a portion of the current

may pass.

SHUNTING SENSITIVITY-the maximum impedance that, when placed at the most adverse

shunting location, will cause the track circuit to

indicate the presence of a train.

SIDING—a track auxiliary to the main track, used

for meeting, passing, or storing trains.

SIGNAL-a means of communicating direction or

warning.

Block Signal-a fixed signal at the entrance of

a block governing trains entering and using

that block,

Cab Signal--a signal in the train operator’s

cab that governs the movement of that train

by conveying the automatic block aspects

and the prevailing speed command.

Clear Signal--a signal displaying the aspect

indicating to proceed.

Home Signal-a fixed signal at the entrance of

a route or block governing trains entering

and using that route or block.

Opposing Signals-wayside signals governing

train movements in opposite directions over

the same stretch of track.

Time Signal-a signal that controls train

speed by requiring that a certain time

elapse between entering and leaving a

block.

Wayside Signal-a signal of fixed location

along the track right-of-way.

SIGNAL ASPECT-See Aspect.

SLIDE (WHEEL)—the condition, during braking or

deceleration, where the surface speed of the

wheel is less than train speed,

SLIP (WHEEL)—the condition, during acceleration, where the surface speed of the wheel is

greater than train speed. (Also called “Spin.”)

SLIP-SLIDE SYSTEM-an onboard system for

automatically detecting and correcting slip and

slide by making compensating adjustments of

propulsion and braking to maintain optimum

traction (wheel-rail adhesion),

SPEED

Civil Speed (Limit)—the maximum speed

allowed in a specified section of track as

determined by physical limitations of the

track structure, train design, and passenger

comfort.

Safety Speed (Limit)—the maximum speed at

which a train can safely negotiate a given

section of track under the conditions prevailing at the time of passage. (Safety speed

may be less than or equal to civil speed,)

Schedule Speed-the speed at which a train

must operate to comply with the timetable;

mathematically, the distance from terminal

to terminal divided by the time scheduled

for the trip (including station stops),

SPEED PROFILE-a plot of speed against distance

traveled.

SPEED REGULATOR-an onboard subsystem,

usually part of the automatic train operation

(ATO) system, that controls acceleration and

braking to cause the train to reach and maintain a

desired speed within a given tolerance,

SPIN-See Slip.

STOP

Emergency Stop-stopping of a train by an application of the emergency brake, which—

after initiation-cannot be released until

the train has stopped.

Full Service Stop-a train stop achieved by a

brake application, other than emergency,

that develops the maximum brake rate.

Penalty Stop--irrevocable open-loop braking

initiated by an onboard automatic system

or by a wayside trip stop as a result of a

block violation or uncorrected overspeed.

Programed Stop-a train stop produced by

closed-loop braking such that the train is

stopped at a designated point according to a

predetermined speed-distance profile.

213
Stop Signal--a signal indication requiring a

train to stop and stay stopped and permitting no exceptions such as running at

reduced speed, movement within restricting limits, or similar alternatives.

Train Protection Stop-a train stop initiated

by the automatic train protection (ATP)

system.

SWITCH—a device that moves rails (switch

points) laterally to permit a train to transfer from

one track to another. (See also Frog,)

Facing Point Switch-a track switch with

points facing toward approaching traffic.

Trailing Point Switch-a track switch with

points facing away from approaching

traffic.

SWITCH POINT-a movable tapered track rail,

with the point designed to fit against the stock

rail.

TERMINAL ZONE-a length of track, within

which the prescribed running direction can be

reversed while it is occupied by a train,

TERRITORY—that portion of a route or route network characterized by a particular mode of

operation or type of equipment, e.g., cab signal

territory, multiple track territory,

THIRD RAIL-See Contact Rail.

TRACK

Double Track—two parallel tracks, usually

with each reserved for running in one

direction only.

Main Track-a track extending through yards

and between stations, upon which trains

are operated in revenue service or the use

of which is governed by signals.

Reversible Track--a section of track on which

the prescribed direction of running can be

reversed if it is unoccupied and the opposing home signals are at stop.

Single Track--a main track on which trains

are operated in both directions.

Transfer Track-a track in a yard area where

transfer between main track and yard

modes of operation takes place.

TRACK CIRCUIT—(See Circuit, Track,)

TRAFFIC REGULATION--a train supervisory

function making use of changes in dwell time,

performance level, acceleration rates, or other

train performance characteristics to maintain intended traffic patterns and system stability,

TRAIN-a consist of one or more cars combined

into an operating unit, (See also Consist.)

TRAIN BOARD—(See Model Board.)

TRAIN DETECTION EQUIPMENT—the track

circuits and associated apparatus used to detect

the presence of trains in blocks,

TRAIN IDENTIFICATION-a method of designating trains by means of such information as

train number, destination, or length; may be accomplished automatically for functions such as

routing or dispatching.

TRAIN ORDERS—instructions used to govern the

movement of trains manually, usually written

and hand-delivered,

TRANSFER ZONE-a zone where changeover

from manual to automatic operation, or vice versa, may be made. (See also Transfer Track, under

Track.)

TRIP STOP-a mechanical arm, located on the

wayside, that can initiate a penalty brake application on a train that passes it by engaging a

brake-triggering device (trip cock) on the train.

Trip stops may be fixed, i.e., permanently positioned in the tripping position; or they may be

raised and lowered in response to signal indications,

TURNBACK POINT-a point along the track, not

at a terminal, where a train may reverse direction

if allowed by the train control system, (See also

Terminal Zone,)

TURNOUT-an arrangement of switch points and

frog with closure rails that permits trains to be

diverted from one track to another,

UPSTREAM—track locations that, for a given

reference point and direction of travel, lie behind

the train and have been passed by it.

YARD-a network of tracks for making up trains

and storing cars.

214
Appendix E

CHRONOLOGY OF TRAIN CONTROL

DEVELOPMENT

The history of train control technology in rail

rapid transit is interwoven with railroad engineering. Most of the train control techniques applied in

rail rapid transit have their origin in railroading,

from which they are either borrowed directly or

adapted to the special circumstances of the urban

setting. For this reason, many train control

engineers consider ATC in rail rapid transit simply

an extension of the field of railroad signaling.

However, there are some distinct differences, both

in the technology and its application. The

similarities and differences are evident in the

chronology of train control development presented

here.

The development of signaling and train control

technology may be separated into two periods, with

1920 as the dividing point. Before 1920 the major

areas of technological advance were interlocking

control and block signaling (manual and automatic).

After 1920, the demand for moving heavier traffic

at higher speeds and with increased safety led to

major developments such as centralized traffic control, continuous cab signaling, coded track circuits,

and automatic train control. Generally, innovative

signaling and train control technology for rail rapid

transit was derived from railroads and lagged

behind railroad application by about 10 years. There

were some notable exceptions; the development of

automatic junction operation and automatic train

dispatching was pioneered in rail rapid transit. Very

recently, since roughly 1960, there has been some

experimentation with techniques and equipment

solely for rail rapid transit and small people-mover

systems.

The major source of this material is American

Railway Signaling Principles and Practices,

Chapter l—History and Development of Railway

Signaling, published by the Association of

American Railroads, Signal Section, 1954. Supplementary information, particularly on rail rapid transit technology in recent years, was assembled from

various sources, including manufacturer’s

brochures, local transit agency reports, and technical journals.

1832

1843

1851

1853

1853

1860

1863

1866

The first fixed signal system in America

was installed on the New Castle &

Frenchtown RR, The signals were ballshaped objects mounted on masts at 3-

mile intervals. The signals were raised

and lowered by a signalman to indicate

permissible speed—low meaning stop

and stay and high meaning proceed at

full speed, The latter indication gave rise

to the expression “highballing.”

The first mechanical interlocking was

installed at Bricklayer’s Arms Junction in

England. It was a simple machine operated by a signalman who worked the

switches with his hands and the signals

with his feet.

Morse code electric telegraph was first

used in train operation for sending train

orders on the New York & Erie RR.

The Philadelphia & Reading RR installed

signal towers for giving information to

approaching trains on the occupancy of

the track in advance.

Open-circuit manual block signaling was

first used in England.

Gate signals were initiated in America.

A stop indication was displayed by placing a red banner or disc on top of the gate

during the day. A red light was displayed

at night.

Closed-circuit (fail-safe) manual block

signaling, using the space interval

method of operation, was first employed

in America on the United New Jersey

Canal & RR Co. between Kensington, Pa.

(Philadelphia), and Trenton, N.J.

The first automatic electric block system

was installed on the New Haven System

at Meriden, Corm. Hall enclosed disc signals, open circuit, were operated by track

instruments.

215
1868

1870

1871

1872

1873

1876

1876

1880

1881

1885

216

The Pennsylvania RR used a type of

train order signal which was under the

control of the train dispatcher who could

set it in the stop-danger position at any

remote station by means of a selective

device operated over the regular Morse

telegraph circuit.

The first interlocking machine in

America was installed at Top-of-theHill, a junction at Trenton, N. J., on the

Camden and Amboy Division of the

Pennsylvania RR.

A system of automatic block signals,

comparable with presently used equipment, was installed on the New York &

Harlem RR and the Eastern RR.

The first installation of closed d.c. track

circuit, invented by Dr. William Robinson, was made at Kinzua, Pa., on the

Philadelphia & Erie RR.

The Robinson closed-circuit track block

for switch protection was first put into

use on the Philadelphia & Erie RR.

The first power interlocking of the Burn

pneumatic type was put in use on the

Pennsylvania RR at Mantua “Y,” West

Philadelphia, Pa.

The Boston & Lowell and the Boston &

Providence RRs introduced the Robinson electromechanical signal for

automatic blocking, controlled by direct

current track circuits.

The first automatic train stop was placed

in trial service on the Middle Division of

the Pennsylvania RR. A glass tube in the

train air line located on the locomotive

near the rails was designed to be broken

by a “track trip” set in operating position

when the signals were in the stop position.

The first interlocking of the hydraulic

type was installed by the Union Switch &

Signal Co. at Wellington, Ohio, for a

crossing of the Wheeling & Lake Erie Ry.

with the Cleveland, Cincinnati, Chicago

& St. Louis Ry.

The “Dutch Clock” device for establishing time intervals (headways) between

1885

1889

1893

1900

1900

1901

trains was in use on the New York, New

Haven & Hartford RR and the New York

Central & Hudson River RR. When operated automatically by a treadle device on

the rail, the passing train released a

pointer which started to move around a

dial divided into three segments each

representing 5 minutes. The pointer

movement was controlled by an escapement so that it moved across the dial in a

period of 15 minutes. Headway for the

train ahead was thus indicated up to 15

minutes.

The first electric detector locking for interlocked track switches was installed by

the Pennsylvania RR at the Pittsburgh,

Pa., terminal by using depression trips to

ground the indication circuit.

The first electric interlocking employing

dynamic indication, invented by John D.

Taylor, was installed at East Norwood,

Ohio, at the crossing of the Baltimore &

Ohio Southwestern RR and the Cincinnati and Northern RR.

The first low-voltage, direct-current,

motor-operated automatic semaphore

block signals were installed on the

Central RR of New Jersey in Black Dan’s

Cut, east of Phillipsburg, N.J. They were

two-position lower-quandrant signals

with the motor and driving chain outside

the mast.

The first three-block indication was installed on the Pennsylvania RR between

Altoona and Cresson, Pa. The signals

were two-position, lower-quadrant,

home and distant automatic semaphores,

In Acton Town, England, an illuminated

track diagram was first used in connection with resignaling on the District Ry.

due to electrification, It dispensed with

separate track indicators and brought

together all track occupancy information

on the plan of tracks and signals, thereby

facilitating the work of the signalman

handling traffic.

The Taylor Signal Co. put in service the

first electric interlocking embodying the

“dynamic indication” principle, at Eau
1901

1901

1903

1906

1907

1909

1911

1912

Claire, Wis., on the Chicago, St. Paul,

Minneapolis & Omaha Ry.

The Boston Elevated installed special

polarized d.c. track relays. This was the

first attempt to operate track circuits on a

railroad where propulsion power was

supplied by electricity and the rails were

used as the medium for current return.

The Boston Elevated made the first permanent installation of an automatic train

stop system, which consisted o f

mechanical wayside trips engaging brake

control apparatus on the moving car.

The North Shore RR of California made

the first installation of a.c. track circuits

for automatic block signals.

The first signal system with a.c. track

circuits on a road using a.c. propulsion

power was installed on the New York,

New Haven & Hartford RR, The track

circuits were the two-rail type, 60 Hz,

with impedance bonds. Propulsion current was 25 Hz.

The first automatic interlocking for the

protection of a railroad crossing was installed at Chester, Va., at a crossing of

the Tidewater & Western Ry. with the

Virginia Railway, Power & Light Co.

The Erie RR installed automatic signaling for train operation by signal indication on a two-track division, 139.7 miles

in length, which directed trains to: (1)

stop and hold main track, (2) take siding,

(3) proceed on main track regardless of

superior trains.

The absolute permissive block system

(APB), developed by the General Railway Signal Co., was first installed on the

Toronto, Hamilton & Buffalo RR between Kinnear and Vinemount, Ontario,

Canada, using direct-current semaphore

signals.

Train movements on the Chesapeake &

Ohio Ry. were directed for the first time

by signal indication without written

train orders.

1912

1914

1915

1919

1920

1923

1925

1926

Cab signals were first used on an electric

railway, the Indianapolis & Cincinnati

Traction Co. ●

The cam controller for control of power

application to d.c. propulsion motors was

first used in the Chicago Rapid Transit

co.

The American Railway Association

adopted rules which permitted train

operation on single track by controlled

manual block signal indications, superseding timetable and train orders.

The Buffalo, Rochester & Pittsburgh Ry.

made the first trial installation of the

General Railway Signal Co. intermittent

inductive train stop system. This system

used magnetic induction to transfer signals from wayside controls to train

equipment.

The first installation of automatic speed

control in the US. was that of the Regan

Safety Device Co. intermittent electrical

contact ramp-type train control system

on the Chicago, Rock Island & Pacific RR

between Blue Island and Joliet, Ill.

The Pennsylvania RR placed in service,

experimentally, the first installation

anywhere of the continuous inductive cab

signal and train control system coveting

43.5 miles of single track and 3.4 miles of

two-track, between Lewistown and Sunbury, Pa. It was the first instance where

vacuum tubes were used for purposes

other than in communication circuits.

This installation also was the first time

that cab signals were used in lieu of

wayside signals for operating trains by

signal indication.

The first permanent installation of cab

signals without wayside automatic block

signals was made on the Atchison,

Topeka & Santa Fe Ry., between

Chillicothe, Ill., and Ft. Madison, Iowa.

The equipment was a Union Switch &

Signal Co. three-speed continuous inductive-type train control device.

The Illinois Central RR was the first to

equip an operating division with

automatic train stop and two-indication

217
●

1927

1930

1931

1932

1933

1934

1937

continuous cab signals without wayside

automatic block signals,

The first General Railway Signal Co.

centralized traffic control system was installed on the New York Central RR between Stanley and Berwick, Ohio. The

first dual-control electric switch

machines, which provided for either

hand or electric operation, were introduced on this installation,

The first use of the all-relay interlocking

principle, as a substitute for indication

parts and magnets at the levers of a large

interlocking machine equipped with

mechanical locking, was at Cleveland

Union Terminal, Ohio,

The New York Central RR installed a

system of four~block indication signals

on a line equipped with automatic block

signals in heavy suburban traffic territory.

The Philadelphia subways installed a

modified type of the three-wire circuit

code scheme of centralized traffic control.

The Pennsylvania RR was granted permission by the ICC to convert all its

locomotives equipped with the coded

continuous train stop system to the

coded continuous cab signal system with

whistle and acknowledger. This was

done with the understanding that the

Pennsylvania RR would voluntarily extend cab signal territory to include most

of its main line trackage.

The first installation of coded track circuits on steam-operated territory was

made between Lewistone and Mt.

Union, Pa., on 20 miles of four-track

main line on the Pennsylvania RR, The

average length of track circuit was 5,201

feet. Energy was coded storage battery

for three and four-indication wayside

signals, with coded 100 Hz a.c. superimposed for continuous cab signals,

The first installation of a relay-type interlocking with push-button automatic

selection of routes and positioning of

switches and signals, General Railway

1939

1939

1940

1940

1940

1940

Signal Co. Type “N-X” (entrance-exit),

was made at Girard Junction, Ohio, on

the New York Central RR.

A four-indication, four-speed coded,

continuous train control system was installed on suburban cars of the Key

System, Southern Pacific and Sacramento Northern Railroads operating over the

San Francisco-Oakland Bay Bridge,

California, The system was designed to

handle 10-car multiple-unit trains

operating on a l-minute headway, The

installation included an N–X interlocking system with a train describer and

automatic operation of a single switch.

The first application of coded detector

track circuits in interlocking was made

by the Norfolk & Western Ry.

The first installation of coded track circuits for continuous cab signaling without wayside automatic signals in steam

territory, developed by the Union Switch

& Signal Co., was made between Conpit

and Kiskiminetas Junctions, Pa., on the

Pennsylvania RR,

The Pennsylvania RR installed a

centralized traffic control system between Harmony and Effingham, Ill.,

using the Union Switch & Signal Co,

two-wire, 35-station time code type for

the first time on a multiple-connected

line circuit in which the line wires were

continuous throughout the territory, and

which provided for the coordination of

the code circuit and communication circuits over the same line wires, This was

the first installation of a centralized

traffic control system to employ a twowire code line circuit in which all the

field locations were connected in multiple across the line wires,

The first installation of reversible coded

track circuits in single-track territory

with centralized traffic control was

made between Machias and Hubbard,

N.Y., on the Pennsylvania RR.

The first installation of absolute permissive block (APB) signaling with three

and four indications with coded track

218
1943

1944

1946

1948

1949

1951

1951

circuits was made on

Western Ry., between

Evergreen, Va.

The first installation of

the Norfolk &

Petersburg and

coded track circuits using polar reverse codes with

three-indication signaling for eitherdirection operation was made on the St.

Louis Southwestern Ry.

The first installation of normally

deenergized coded track circuits for

centralized traffic control on single track

was placed in service between Laredo

and Polo, Me., on the Chicago, Milwaukee, St. Paul & Pacific RR.

The Pennsylvania RR demonstrated the

feasibility of centralized traffic control

operation over commercial communication circuits, including beamed radio.

The test was made over approximately

1,130 miles of Western Union carrier

telegraph circuit including about 90

miles of beamed radio. This was the first

time beamed radio was used for this purpose.

The first use of automatic train dispatching in rail rapid transit was by the

Philadelphia Rapid Transit Co. (now

SEPTA). The device employed a perforated opaque tape driven by a clock

mechanism. A beam of light scanning

the tape triggered a photoelectric cell

that automatically activated starting

lights at terminals.

The Chicago Transit Authority initiated

experiments in the use of radar for train

detection and separation assurance.

The Pennsylvania RR installed a threespeed continuous inductive train control

system in which the limits were 20 miles

per hour with no code, 30 miles per hour

with 75 code, 45 miles per hour with 120

code, and no speed limit with 180 code.

CTA began the use of automatic train

dispatching with remote override

capability from

system, which

clock, pen graph

ment, and line

operation.

.

central locations. The

employs a mechanical

recorders of train movesupervision, is still in

1951

1952

1953

1953

1955

1959

1961

1962

1964

A portable radio, called “Dick Tracy,”

was first used by yard switchmen on the

Southern Ry. in connection with coupling cars in the classification yard and

transferring them to the departure yard.

The Erie RR placed in service at Waterboro, N, Y., in connection with the

establishment of a remotely controlled

interlocking, a system of automatic train

identification, This system automatically

identifies the direction and the number

of a train as it clears a manual block on a

branch line.

The first installation of cab signaling

using transistors in place of vacuum

tubes was placed in service on the New

York, New Haven & Hartford RR by the

General Railway Signal Co.

The first installation using transistors instead of vacuum tubes in safety-type

(vital circuit) carrier equipment was

made on the Pennsylvania RR. The

equipment was developed by the Union

Switch & Signal Division o f

Westinghouse Air Brake Co.

A crewless remote-controlled passenger

train was demonstrated on the New

York, New Haven & Hartford RR.

The inductive train phone was first used

in raiI rapid transit by the Chicago Transit Authority.

A completely automatic subway train

was placed in service on the shuttle run

between Times Square and Grand

Central Station in New York. A motorman was on board for emergencies, but

he was not involved in normal operation

of the train and often spent his time

reading the newspaper,

A crewless freight train operating

system was tested on the Canadian National RR.

Automatic train operation (ATO) equipment, intended for use in the BART

system, was operationally tested at

Thorndale on the Chicago Transit

Authority North-South route.

219
1966

1966

1967

1969

1971

Four automatic train control systems for

BART were demonstrated at the Diablo

test track--one using the moving block

concept, two using coded track circuits,

and the other using a “trackwire” communications link and wayside control

equipment.

Fully automated vehicle operation and

innovative methods of train control were

demonstrated for the Transit Expressway (Skybus) system at South Park, Pa.,

by the Port Authority of Allegheny

County (Pittsburgh).

Audio-frequency track circuits in a rail

rapid transit application were first

placed in regular service by the Chicago

Transit Authority.

Revenue service was begun on the

PATCO Lindenwold Line. After a

manually initiated start, train operation

is completely automatic until the doors

are opened at the next station.

An automatic people-mover system was

placed in operation at the Tampa Airport. This system incorporates some of

the ATC elements originally demonstrated at South Park,

1972

1972

1973

1974

1974

Four

were

automatic people-mover systems

demonstrated at TRANSPO ’72,

Washington, D. C., under the auspices of

the U.S. Department of Transportation.

Revenue service was initiated on the

Fremont-MacArthur portion of the

BART system, Train operation, including start, berthing, and door operation, is

entirely automatic but under the supervision of an onboard operator,

The Satellite Transit System, featuring

automatic crewless vehicle operation,

was placed in service for passengers at

the Seattle-Tacoma (Sea-Tac) Airport.

The AIRTRANS system at Dallas/Ft.

Worth Airport opened for service.

Operating on 17 interconnected routes,

AIRTRANS has automatic crewless

trains to carry passengers, baggage,

freight, and refuse within the airport

complex.

Demonstration of the Morgantown (W,

Va,) PRT system was conducted, Small

vehicles, operating on a fixed guideway,

circulate under automatic control and

without onboard operators,

220
Appendix F

PERSONS AND ORGANIZATIONS VISITED

During the course of this study, visits were made to each operating transit agency and to other organizations with an interest in the design and operation of rail rapid transit systems. The following is a list of the

persons interviewed and their organizational affiliation. Individual recognition of their contributions to the

study is not possible, except in a few cases where their observations are cited directly in the report. The

OTA staff and the Urban Mass Transit Advisory Panel are grateful for the cooperation of these people and

for the generous gift of their time and interest. Persons interviewed by the OTA staff are listed on the left.

Those interviewed by the technical consultants, Battelle Columbus Laboratories, are listed on the right.

OPERATING TRANSIT AGENCIES

Boston—Massachusetts Bay Transportation Authority (MBTA)

Jason B. Baker Larry Bulongie

Supt., Equipment Engineering Signals and Communications

Francis X. Capelle James A. Burns

Deputy Supt., Signals and Communications General Supt., Equipment Maintenance

Joseph P. Dyer Raymond M. Caddigan

General Supt., Power and Signals Supt. of Rail Lines

William Malone Francis X. Capelle

Safety Department Deputy Supt., Signals and Communications

David Marcham Frank Crowley

Transportation Department Deputy Supt., Maintenance

Col. Warren J. Higgins

Director of Operations

Larry Maddalena

Electrical Supervisor

Chicago-Chicago Transit Authority (CTA)

Joseph Bensen Kendrick Bisset

Librarian Supervisor, Signal Design .

James Blaa Paul Cleaver

Manager of Transportation Supt., Signals and Communications

Thomas Boyle Arthur Sandberg

Director of Safety Manager, Engineering

Albert Brandt James Stewart

Signal Maintainer, Lake-Harlem Shops Manager, Equipment Engineering

Daphne Christensen Ralph Tracy

Science Advisor to the Chairman of the Board Director of Transportation Services

221
Paul C. Cleaver

Supt., Signals and Communications

Adel El Dib

Management Systems

Judy Genneson

Librarian

Edward Henry

Public Safety

Harold Hirsch

Manager of Operations Planning

Paul Kole

General Manager, Finance

George Krambles

General Manager, Operations

Herbert Lowenstein

District Supervisor (North)

Katherine Moriarty

Supervisor, Collection Agents

Evan C. Olmstead

Manager of Maintenance

A. R. Sandberg

Manager of Engineering

Theodore Szewc

Supervisor, Signals Maintenance

Ralph Tracy

Director of Transportation Services

Joanne Vlecides

Development Planning

Thomas Wolgemuth

Director, Plant Maintenance

Chicago—Illinois Department of Transportation

B. G. Cunningham

Former Assistant Secretary of

Transportation (Illinois DOT)

Cleveland—Cleveland Transit System (CTS)

Elmer Corlett

Director of Personnel

Bernard Hamper

Employment Supervisor

Leonard Kraynik

Chief Research Analyst

222
Michael McKenna

Supt., Power and Plant

Philip Rockwood

Manager of Maintenance

Myron Silsby

Supt. of Rapid Transit

Bernard Wilchek

Supervisor of Management Development,

Training and Safety

Dear Williamson

Manager of Operations

Donald Yuratovac

Research Specialist, Research and Planning

New York—New York City Transit Authority (NYCTA)

Charles Kalkhof Louis Alessi

Assistant General Superintendent, Assistant Supervisor,

Maintenance of Way Car Maintenance

William O’Neill Frank T. Berry

Asst. Supervisor of Signals Executive Officer,

and Maintenance

Joseph Calderone

Irwin Cohen

Frank De Maria

Operations

Supt. of Rapid Transit

Seymour Dornfeld

Division Engineer, Signals and

Communications

Donald Gill

Chief Industrial Engineer

Charles Kalkhof

Assistant General Superintendent,

Maintenance of Way

Harold J. McLaughlin

Assistant General Supt., Rapid

Transit Transportation

Dennis Newman

Deputy Subdivision Engineer,

Maintenance of Way

Jack Rogg

Supt. of Engineering and Production

Control

223
Daniel T. Scannell

Senior Executive Officer, Operations

Management

Bart Sheehan

Railroad Signal Specialist,

Maintenance of Way

Ludwig Stanitsch

Senior Transit Management Analyst

Thomas Sullivan

Supt., Rapid Transit

Philadelphia, Camden—Port Authority Transit Corporation (PATCO)

David L. Andrus, Jr. James F. Elder

Supervisor of Traffic and Planning Supt. of Operations

Howard C. Conings Joe Fiori

Safety and Insurance Supervisor General Foreman,

Robert B. Johnston Robert B. Johnston

General Manager General Manager

Robert S. Korach Robert S. Korach

Signals and Communications

Assistant General Manager and Supt. of

Operations

John A. Lane J.

Administrative Assistant to the General

Manager

Assistant General Manager and

Supt. of Operations

William Vigrass

Supt. of Equipment

John J. McBride D. R. Wolfe

Captain of PATCO Police Supt. of Way and Power

Herbert McCreary

Statistician

J. William Vigrass

Supt. of Equipment

San

Clay Yost

Equipment Engineer

PATCO Consultants

Gibbs & Hill

Jack R. Shepard

Chief Systems Engineer (Ret.)

Francisco—Bay Area Rapid Transit (BART)

Malcolm Barrett

General Counsel

Ward D. Belding, Jr.

Senior Economic Analyst

Ray Carroll

Director of Maintenance

Krishna Hari

Train Control Systems Engineer

George Anas

William Briner

Supt. of Line Operations

Ray Carroll

Director of Maintenance

Marvin Denowitz

Manager of Quality Control

Krishna Hari

Train Control Systems Engineer

224
Fred Harmon

Transportation Division

William F. Hein

Director of Planning

Mary-Lou Mulhern

Librarian

Eugene P. Nunes

Safety Supervisor

Philip O. Ormsbee

Assistant to General Manager

William M, Reedy

Former Member, BART Board

William J. Rhine

Director of Engineers

Ronald E. Rypinski

Supervisor of Maintenance Planning

George M. Silliman

Former Member, BART Board

BART Consultants

Hewlett-Packard

David Cochran

Leonard Cutler

Lawrence Berkeley Laboratory

Don M. Evans

D. Theodore Scalise

Roy W. Harris, TRW

Manager, BART Safety Availability Project

Clarence Lovell

Member, Special Panel, Public Utilities

and Corporations Committee, California

Senate

Bernard M. Oliver

Member, Special Panel, Public Utilities

and Corporations Committee, California

Senate

William Wattenburg

Independent Consultant

San Francisco—State of California

William F. Hein

Director of Planning

Mary-Lou Mulhern

Librarian

William J. Rhine

Director of Engineering

R. Somerton

Training Supervisor

BART Consultants

Parsons-Brinckerhoff-Tudor-Bechtel

Walter Quintin of the Bechtel Corp.

TRW

Hal Buchanan

Roy Harris, Project Manager

Everett Welker

Alfred E. Alquist

Chairman, Public Utilities and

Corporations Committee,

California Senate

225
.

James Cooney

Office of the Legislative Analyst

Wayne Keithley

Office of the Legislative Analyst

James R. Mills

Member, Public Utilities and

Corporations Committee,

California Senate

A. Alan Post

Legislative Analyst

San Francisco—California Public Utilities Commissio n

James K. Gibson

Director, Transportation Division

Leo L. Lee

Senior Electrical Engineer

William L, Oliver

Transportation Division

Herman W. Privette

Senior Transportation Supervisor

Theodore E. Rogers

Chief, Railroad Operations and

Safety Branch

In addition to contacts with the preceding people and organizations who are involved in operating transit

agencies, OTA technical consultants from Battelle Columbus Laboratories interviewed the following persons.

AGENCIES IN PLANNING OR CONSTRUCTION ACTIVIT Y

Atlanta—Metropolitan Atlanta Rapid Transit Authority (MARTA)

Al Locke, System Safety Engineer

John J. Tucker, Equipment Design Manager

Ernest Young, Equipment Design Engineer

Consultants

Parsons-Brinckerhoff-Tudor-Bechtel

Dale H. Fencken, Supervising Engineer, ATC

Baltimore—Mass Transit Administration (Maryland)

Walter J. Addison, Administrator

Carl Buhlman, Manager, Equipment and Equipment Systems

Frank W, Hearne, Director, Rapid Transit Development Division

Bernard Walker, Senior Electrical Engineer

Consultants

Daniel, Mann, Johnson, and Mendenhall/Kaiser Engineers

P. Morris Burgess, Chief Systems Engineer

David Hammond, Project Manager

Lewis Sanders, Senior Systems Engineer

226
Buffalo—Niagara Frontier Transportation Authority (NFTA)

Kenneth Knight, Manager of Metro Construction

Eugene Lepp, Manager of Systems

Denver—Regional Transit District (RTD)

Dr. J. Edward Anderson, Advisor

George Billman, Manager, Technology Assessment

Aubrey J. Butts, System Design

Carlos DeMoraes, Assistant Executive Director, Development

R. J. Farrell, Command and Control Specialist

Ralph Jackson, Director of Planning

Paul Newcomb, Director, System Design

John Simpson, Executive Director

A. J. Weaver, Subsystem Requirements

W. Wild

Consultants

Systems Management Contractor (TRW Systems et al.)

E. Bagerstos, Reliability/Safety

R. K. Boyd, Assistant Program Manager, Controls

A. F. Ems, Reliability/Safety

Robert Johnson/Simulation

Herman Wells, Controls

Miami—Metropolitan Dade County Transit Authority

E. Randolph Preston, Asst. Coordinator for Transportation Development

Consultants

Kaiser Engineers

James Allis

Ralph Mason

Eugene Stann, Project Manager

Minneapolis-St. Paul—Twin Cities Area Metropolitan Transit Commission

Camille Andre, Executive Director

John Jamieson, Director of Transit Development

Douglas Kelm, Chairman, Metropolitan Transit Commission

William Marshall, Systems Engineer

Robert Pearson, Project Manager, Fixed-Guideway Systems

Consultants

De Leuw Cather

Frank Smith, Small Vehicle Study

Others

Dr. J. Edward Anderson, University of Minnesota

J. Kiedrowski, Staff Member, Minnesota Senate Metropolitan Urban

Affairs Committee

Pittsburgh—Port Authority of Allegheny County (PAAC)

72-683 0 - 76

John Mauro, Executive Director

James Maloney, Acting Manager, Early Action Program

Robert Sedlock, Systems Technology

16

227
Consultants

Kaiser Engineers

Thomas R. Gibson, Systems Engineering

Zoltan Stacho, Project Manager

Washington, D.C.—Washington Metropolitan Area Transit Authority (WMATA)

C. David Allen, Systems Maintenance Engineer

Howard W. Lyon

David Q. Gaul, Assistant Director, Office of Equipment Design

Warren Quenstedt, Deputy General Manager

William Randolph

Ralph Sheldon, Train Control Engineer

Consultants

Gibbs and Hill

Joseph Smith, Senior Transportation Engineer

Jack Shepard, Chief Systems Engineer (Retired)

AUTOMATED AIRPORT SYSTEMS

Dallas-Fort Worth Airport—Dallas-Fort Worth Regional Airport Board (AIRTRANS)

Dennis Elliott, Manager of Engineering

Dalton Leftwitch, Operations Supervisor, AIRTRANS

David Ochsner, Manager, AIRTRANS

David Slaboda, Maintenance Supervisor, AIRTRANS

Supplier

LTV

Richard Condrey, Manager, Ground Transportation

Austin Corbin, Project Manager

John Loutrel, Operations Research

Seattle-Tacoma International Airport—Port of Seattle (Sea-Tac)

Arthur Krause, Airport Maintenance Superintendent

Eugene Sagar, Operations Manager, Port of Seattle

Don Shay, Director of Aviation, Port of Seattle

Consultants

The Richardson Associates

Harry Linden, Assistant Administrative Director

Supplier

Westinghouse Electric Company

Joseph Borkowski, Maintenance Manager

SUPPLIERS

General Railway Signal Corp. (GRS), Rochester, N.Y.

Dr. John Freehafer, Manager of Advanced Engineering

Arthur Gebhardt, Vice President, Marketing

Mark Sluis, Vice President, Engineering

228
Westinghouse Air Brake Company (WABCO), Union Switch and Signal Division,

Swissvale, Pa.

Homer Hathaway, Senior Systems Consultant

Westinghouse Electric Company (WELCO) Transportation Division, Pittsburgh, Pa.

Philip Gillespie, Manager of Market Development

James H. King, Reliability Engineer

Dr. Robert Perry, Manager, Train Controls and Vehicle System Engineering

INSTITUTION S

Amalgamated Transit Union, Washington, D.C.

Walter Bierwagen, Member. General Executive Board and Director of

Public Affairs

Earle Putnam, General Counsel

American Public Transit Association (APTA), Washington, D.C.

Robert Coultas, Deputy Executive Director

Jack Hargett, Legislative Liaison

B. R. Stokes, Executive Director

FEDERA L

Transportation Systems Center (TSC),

Robert Casey, Systems Analyst

AGENCIES

Cambridge, Mass.

Harry Hill, Man-Systems Technology

Robert Pawlak, Project Manager, ATC Program

Chan Watt, Systems Safety/Reliability/Maintainability

Urban Mass Transportation Administration (UMTA), Washington, D.C.

Steven Barsony, Acting Director, Morgantown Division, Office of R&D

Edward J. Boyle, Manager, Safety Division, Office of Transit Management

Ray Brunson, Systems Development Branch, Office of R&D

Vincent DeMarco, Systems Development Branch, Office of R&D

Duncan MacKinnon, Chief, Advanced Development Branch, Office of R&D

Paul Spencer, Staff Engineer, Rail Branch, Office of R&D

Federal Railroad Administration (FRA), Washington, D.C.

C. M. Bishop, Chief, Signals Branch, Standards and Procedures Division

Rolf Mowatt-Laarsen, Chief, Standards and Procedures Division, Bureau of Safety

William Paxton, Chief, Maintenance of Way Branch, Standards and Procedures Division

National Transportation Safety Board (NTSB), Washington, D.C.

J. Emerson Harris

Robert Jewell

Thomas Styles, Chief, Railroad Safety Division

229
Appendix G

BIOGRAPHIES OF URBAN MASS TRANSIT

ADVISORY PANEL

George Krambles, Chairman

General Operations Manager

Chicago Transit Authority (CTA)

Chicago, Ill.

Mr. Krambles is responsible for the transportation, maintenance, and operations planning departments

which together include more than 11,000 of CTA’s 12,500 employees. Prior to assuming the position of

General Operations Manager, he served as operating manager in charge of the transportation and shops and

equipment departments from 1972 to 1973. He was superintendent of research and planning related to service and marketing from 1965 to 1972, and superintendent of operations for the transportation department

from 1961 to 1965. In addition, he was named manager in 1964 for the 2-year Skokie Swift mass transportation demonstration grant project.

Mr. Krambles is a graduate of the University of Illinois and a registered professional engineer in Illinois.

After a brief period with the Indiana Railroad, he joined the Chicago Rapid Transit Company, serving in the

mechanical and electrical departments. His work during this period included maintenance and construction

design as well as power system operation.

Walter J. Bierwagen

Vice President and Director of Public Affairs

Amalgamated Transit Union

AFL–CIO .

Mr. Bierwagen has spent most of his professional life in a leadership role in organized labor. From 1951 to

1964, Mr. Bierwagen was president and business agent of the Washington local of the Amalgamated Transit

Union representing Washington transit employees. In this role he was the primary officer who directed collective bargaining and legislative programs of interest to his union. Subsequently he became vice president

of the international union, engaging in legislative representation before Congress on behalf of the members

of the Amalgamated Transit Union, and conducting collective bargaining negotiations on behalf of many

ATU local unions in the Eastern section of the United States. In addition he has been involved in State activities for the labor movement by serving as vice president of the Maryland State Federation, AFL–CIO, as

well as a principal officer of the Washington Central Labor Council. His interests have gone beyond the

labor movement, including active leadership in Group Health Association, and the development of transit

health, welfare, and pension funds on the local level. As mentioned above, Mr. Bierwagen’s principal activity has been in the legislative arena. In that role, he played an important part in the development of the

Urban Mass Transportation Act of 1964 and its amendments, especially the requirements to protect

employees, and in the development of similar legislation at the State level.

231
Robert A. Burco

Deputy Director

Oregon Department of Transportation

Salem, Oreg.

Mr. Burco has been active in the field of urban transportation policy research since 1967, performing studies

for local and State governments and the Federal Government. Most recently he has headed his own consulting firm specializing in transportation and environment policy. Previously he was employed in a research

capacity at the Stanford Research Institute and at Bell Telephone Laboratories. Mr. Burco received a B.S. and

M.S. from Stanford University and a second master’s degree from the University of California at Berkeley.

He has been involved professionally in the activities of the Transportation Research Board and has lectured

widely on the subject of transportation. His clients have included a number of public interest groups, the

California State Legislature, Office of the Mayor of Los Angeles, and the California Department of

Transportation. He is familiar with transportation policy in Europe, Canada, and Japan, having worked on

international assignments with the Organization for Economic Cooperation and Development in Paris. In

September 1975, he joined the administration of Governor Straub as Deputy Director of the Oregon Department of Transportation.

Jeanne J. Fox

Associate Director, Research

Joint Center for Political Studies

Mrs. Fox has conducted research on transportation as a public policy issue since 1971. Prior to her present

position, she was a consultant at Mark Battle Associates, and before that she was employed at the United

States Information Agency.

She is a graduate of the University of Minnesota.

Mrs. Fox was the principal author of Urban Transportation: Minority Mobility in the 70’s (DC-RDG-12),

prepared for UMTA, Civil Rights Division. She was one of two principal investigators and co authors for

UMTA research which resulted in the following three reports:

Transportation for the Elderly and the Handicapped (DOT-UT-533), Marketing Techniques and the Mass

Transit System (DOT-UT-533),

(DOT-UT-533).

She also wrote the “Public Transit

Lawrence A. Goldmuntz

Marketing Techniques and the Mass Transit System—A Handbook

in the Spotlight, ” Focus, 1974.

President, Economics & Science Planning, Inc.

Washington, D.C.

Dr. Goldmuntz is a consultant and the present Visiting Professor of Engineering and Public Policy at Carnegie-Mellon University in Pittsburgh, Pa. Prior to his present positions, he worked in the Office of the

Assistant Secretary of Transportation for Research and Technology and chaired the Metroliner Steering

Committee, charged by the Secretary of Transportation to supervise the completion of the Northeast corridor Washington-New York high speed rail project. He also served as Executive Secretary of the Air Traffic’

Control Advisory Committee at DOT, as Assistant Director for Civilian Technology in the Office of Science

and Technology of the Executive Office of the President, and as chairman of a committee for the Office of

Science and Technology which reviewed the Cumulative Regulatory Effects on the Cost of Automotive

Transportation (RECAT). Previously in private industry, he served as President of TRG Inc., a research and

development organization involved in air traffic control and other electronic systems.

Dr. Goldmuntz is a graduate of Yale University where he received his B.E.E. (1947) and M.E.E. (1948)

degrees and h@ Ph.D. (1950) in Applied Science.

232
Dorn C. McGrath, Jr.

Chairman, Department of Urban and Regional Planning

The George Washington University

Washington, D.C.

Professor McGrath has served as an advisor or consultant to a variety of agencies concerned with transportation and urban growth policy, including the House Committee on Public Works, the House Committee on

Banking and Currency, the U.S. Commission on Population Growth and the American Future, the U.S.

Aviation Advisory Commission, the Port of Oakland, and the North Central Texas Council of Governments.

He is a member of the Environmental Studies Board of the National “Academy of Sciences and Chairman of

the Environmental Advisory Board for the Chief of Army Engineers.

Professor McGrath is a graduate of Dartmouth College where he received his B.A. degree. He received his

M.A. in City Planning from Harvard University.

He is a principal author of the National Academy of Sciences report, Jamaica Bay and Kennedy Airport,

published in 1970, and has written numerous articles on transportation and related community development

planning.

Bernard Oliver

Vice-President of Research and Member of the Board of Directors

Hewlett-Packard Company

Palo Alto, Calif.

Dr. Oliver previously worked on the development of automatic tracking radar, television transmission, information theory and efficient coding systems, as a member of the technical staff of the Bell Telephone

Laboratory (New York) from 1940 to 1952. He joined Hewlett-Packard in 1952 as director of research and

was appointed Vice-President of Research and Development in 1957. Presently, he is also a lecturer in

electrical engineering at Stanford University and a member of the Science and Technology Advisory Committee to the California State Assembly. He recently served on a State senate panel investigating the safety

aspects of the BART system.

Dr. Oliver is a 1935 graduate of Stanford University where he received his A.B. and M.S. degrees in electrical

engineering. In 1940 he received his Ph.D. degree in electrical engineering from Cal Tech.

He is the author of numerous technical articles and holds over 50 U.S. patents in the field of electronics. He

is a Fellow of the IRE and has served as vice president and later president of the IEEE.

Simon Reich

Supervising Engineer-Signals

Gibbs & Hill, Inc.

New York, New York

Mr. Reich took his present position in the Signals department, after serving in the Transportation and

Systems departments of Gibbs & Hill. He has an extensive background in automatic train control (ATC). He

has worked on the design of signaling and control systems and the technical coordination of the WMATA

rail rapid transit system, including the ATC and communication functions. Prior to association with Gibbs &

Hill, he was involved in the design of train control demonstration systems for the BART Concord test track,

the CTA Lake Street Line, the CTS Airport Extension, and the MBTA South Shore Project-all while working for the General. Railway Signal Company. Other activities of Mr. Reich at GRS include the engineering

for automatic train operation systems and train control research and development for rapid transit lines and

railroads. These included projects on automatic train operation for the NYCTA 42d Street Shuttle, and a cab

signaling system for the Netherlands State Railway, This work involved design of train-borne equipment

and instrumentation to measure train performance.

Mr. Reich is a 1959 graduate of the Polytechnic Institute of Brooklyn where he also received a B.S. in

Physics.

233
Frederick P. Salvucci

Secretary, Executive Office of Transportation and Construction

Commonwealth of Massachusetts

Boston, Mass.

Secretary Salvucci has been occupied, both professionally and personally, with the problems of urban planning and transportation in the Boston area since his formal training at the Massachusetts Institute of Technology. Prior to his appointment as Secretary, Mr. Salvucci held transportation and management jobs with

the Boston municipal government and worked as a transportation planner for the Boston Redevelopment

Authority,

Mr. Salvucci helped to organize and found Urban Planning Aid, an advocacy planning group established to

provide technical and planning assistance to low-income and other community groups. He has also been active in the Greater Boston Committee on the Transportation Crisis, a public transportation advocacy group,

the Massachusetts Air Pollution and Noise Abatement Committee, an organization concerned with promoting a shift from air to rail travel, and the East Boston Neighborhood Council,

Mr. Salvucci’s formal training at M.I.T. concluded in 1962 with an M.S. in civil engineering. He was named

Fulbright Scholar in the 1964-65 academic year.

Thomas Chapman Sutherland, Jr.

Assistant Dean, School of Architecture and Urban Planning

Princeton University

Princeton, N.J.

Dean Sutherland, prior to his present position, was Assistant Director, Office of Research and Project Administration at Princeton and before that, Assistant to the Chairman of Princeton’s Department of

Astrophysical Sciences, He has served as former Chairman of the South New Jersey Group of the Sierra

Club, a Trustee of the Stony Brook-Millstone Watersheds Association, Vice Chairman of the Princeton Conservation Commission, and recently a member of the New Jersey Solid Waste Advisory Council. Dean

Sutherland is presently Chairman of the University Environmental Advisory Committee and a member of

the Gateway Citizens Committee.

He is a graduate of the United States Naval Academy. While in the Navy, he served in the submarine service

and, as a staff member of the Navy’s Office of Special Projects, worked on the development of the Polaris

missile.

Dean Sutherland has authored numerous articles on conservation, ornithology, astronomy, and railroads.

He is co author of the book, The Way to Go: The Coming Revival of U.S. Rail Passenger Service (Simon &

Schuster), published in 1974. He is presently on the Board of Directors of the National Association of

Railroad Passengers (NARP).

Stewart F, Taylor

Vice President & Director Mass Transportation

Sanders & Thomas, Inc.

Pottstown, Pa.

Mr. Taylor has been a consultant on transportation projects for public agencies at the Federal, State, and

local level and for private corporations, Before becoming a consultant, he served with the former Pennsylvania Railroad in various staff and management positions, He was also Chairman of the 1975 National

Conference on Light Rail Transit, jointly sponsored by the Urban Mass Transportation Administration, the

National Research Council, the American Public Transit Association, and the University of Pennsylvania.

Mr. Taylor is a graduate of Yale University and Harvard Law School. He has authored numerous articles and

papers on transportation, The most recent is entitled, “Urban Transportation—Another Alternative,”

published by the Heritage Foundation of Washington, D.C. His work has appeared, on several occasions, in

the United States Congressional Record.

234
Appendix H

REFERENCES

American Transit Association, “Vandalism and

Passenger Security, ” September 1973.

Association of American Railroads, Signal Section,

American Railway Signaling Principles and Practices, Chapter 1: History and Development of Railway Signaling, Chicago, Ill., 1954.

Air Transport World, “Facts and Figures,” Vol. 12,

No. 1, January 1975.

Battelle Columbus Laboratories, Safety in Urban

Mass Transportation, Report No. UMTA RI-06-

0005-75-1, prepared for Urban Mass Transportation

Administration, Washington, D, C., April 1975,

Department of Transportation, Transportation

Systems Center, Safety and Automatic Train Control for Rail Rapid Transit Systems, Report No.

DOT-TSC-OST-74-4, prepared for the Office of the

Secretary, Washington, D, C., July 1974,

Grose, V. L., “Constraints on Application of

Systems Methodology to Socio-Economic Needs,”

presented to First Western Space Congress, Santa

Maria, Calif., October 1970.

Highway Research Board, Task Force on Urban

Mass Transportation Safety Standards, Safety in Urban Mass Transportation: the State of the Art, for

the National Research Council, Washington, D. C.,

September 1973.

Institute for Rapid Transit, Moving People Safely:

Safety Guidelines for Urban Rapid Transit Systems,

Washington, D. C., January 1974 (2d ed.).

King, J. H., “Making Transit Reliability a Reality,”

Westinghouse Transway News, October 1975.

MITRE Corp., Research Requirements of the Rapid

Rail Industry, Report No. UMTA-TRD-90-71, prepared for Urban Mass Transportation Administration, Washington, D. C., June 1971. (PB 204 438)

National Transportation Safety Board, Special

Study of Rail Rapid Transit Safety, Report No.

NTSB-RSS-71-1, Washington, D. C., June 1971.

National Transportation Safety Board, Safety

Methodology in Rail Rapid Transit System

Development t, Report No. NTSB-RSS-73-1,

Washington, D. C., August 1973.

Reistrup, P., President of the National Railroad

Passenger Corporation (Amtrak), Statement before

the Subcommittee on Transportation of the Committee on Appropriations, United States Senate,

April 7, 1975.

Transit Development Corporation, Safety Priorities

in Rail Rapid Transit, Report No. UMTA-DC-06-

0091-75-1, prepared for Urban Mass Transportation

Administration, Washington, D.C., March 1975 (2

Vols.),

United States Congress, Urban Mass Transportation

Act of 1964, P.L. 88-365, 78 Stat. 302. (49 U.S.C.

1601).

United States Congress, Department of Transportation Act (October 15, 1966), P.L. 89-670, 80 Stat. 931

(49 U.S.C. 1653).

United States Congress, Federal Railroad Safety Act

of 1970, P.L. 91-458, 84 Stat. 791 (45 U.S.C. 421).

United States Congress, National Mass Transportation Assistance Act of 1974, P.L. 93-503, Stat. 1565

(49 U.S.C. 1601).

235
Appendix I

CONGRESSIONAL LETTERS OF REQUEST

U NITED S TATES S ENAT E,

C OMMITTEE ON A PPROPRIATION S ,

Washington, D. C., February 25, 1974.

Hon. EDWARD M. KENNEDY,

Chairman, Technology Assessment Board,

House Annex, Washington, D.C.

DEAR MR. CHAIRMAN : On behalf of Senator Robert C. Byrd, Chairman

of the Transportation Subcommittee, and Senator Clifford P. Case, the

Subcommittee’s Ranking Minority Member, I am transmitting the attached technology assessment request to you.

With kindest personal regards, I am

Sincerely,

J OHN L. MC C LELLA N, Chairman .

Enclosure.

U NITED S TATES S ENAT E,

Washington, D. C., February 6, 1974.

Hon. JOHN L. MCC LELLA N,

Chairman, Senate Appropriations Committee, New Senate Office Building, Washington, D.C.

D EAR MR. CHAIRMA N : We would like to enlist your support for a

prompt and thorough study of automation in federally supported urban

rail transit projects.

This matter of increasing concern to our Subcommittee arises because

several large cities, including Baltimore and Atlanta, are planning automated train systems and are or will be seeking substantial federal funding

within the next two years.

At the same time, serious questions have arisen as to whether and to

what degree Automated Train Control (ATC) should be used in rail transit.

The recent experience with San Francisco’s new rail system, known as

BART, has helped focus attention on this problem.

Original plans for BART called for a fully automated system requiring

no on-board train operator. This has not worked out because of a series of

malfunctions in the ATC system. Costly patch-up work, with substantial

federal help, is underway, but complete automation of BART now appears out of the question.

In light of the BART experience we should be alert to see to it that the

same expensive mistakes are not made in other federally supported urban

rail transit projects involving Automated Train Control.

237
At present, there is no means of assuring that the mistakes made in the

BART project will not be repeated.

A draft study just completed by the Department of Transportation’s

Transportation Systems Center states that train control “typically

receives little priority and emphasis” even though—as the study emphasizes—this choice of system greatly affects revenue, safety, including, we

add, the serious matter of crime prevention, and operation and maintenance costs. The DOT study did not purport to deal with cost and cost savings in detail, but it did state that there seemed to be an “intuitive

conclusion that an automated system should be more economical than a

man-operated system in achieving or surpassing a given level of service or

safety. ”

The Congress and this Committee should not accept an “intuitive”

judgment on matters of such cost and complexity.

There are at least two questions that require particular study: (1) to

what extent should urban rail transit systems be automated? and (2) how

should these projects be planned and executed?

The appropriate body to carry out such an independent, in-depth study

for this Committee is Congress’ Office of Technology Assessment. Under

the provisions of the “Technology Assessment Act of 1972” (P.L. 92–482,

Sec. 3(d), (l)), we ask that you transmit to the Chairman of the Technology Assessment Board our request for a study that would:

1. Assess the state of automated train control technology and its

application to existing and planned rail transit systems.—What major research is underway and what is its objective? What train control systems are being considered for transit projects now in the

planning stage? What are the characteristics of these systems and

how are they similar to or different than those of BART and other

highly automated systems in use?

2. Assess the testing methods by which the workability of automated train projects is determined .—To what extent are prototypes

built and tested? What has been the lesson of BART and other recent projects concerning the necessity for system testing during

development? What provisions have been made for the testing of

train control systems now being planned?

3. Assess the process by which new rail transit systems or extensions of existing systems are planned and executed; evaluate the

adequacy and professionalism of cost, safety, including crime prevention, and other analyses used.—What criteria are used, particularly in determining degree of automation? To what extent are

economic tradeoffs (i.e., cost of partially manual vs. fully automated

system) explicitly considered? How and to what extent is public

oversight maintained throughout the project? What federal requirements, if any, apply to these federally assisted projects?

Your assistance in transmitting this request will be appreciated,

Sincerely,

R OBERT C. B Y R D,

Chairman, Transportation Appropriations Subcommittee.

C LIFFORD P. CA S E,

Ranking Minority Member,

Transportation Appropriations Subcommittee.

238

U. S. GOVERNMENT PRINTING OFFICE : 1976 0-72-683