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FHWA Safety Program

Recording Devices for 

Interconnected Grade Crossing and 

Intersection Signal Systems: 

An Informational Report
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FHWA-SA-12-020

Recording Devices for Interconnected Grade Crossing 

and Intersection Signal Systems: An Informational 

Report

Vanasse Hangen Brustlin, Inc.

8300 Boone Boulevard, Suite 700

Vienna, VA 22182-2626

Federal Highway Administration

Offi ce of Safety

1200 New Jersey Ave., SE

Washington, DC 20590

Kevin Moriarty, Joshua Bendyk, Hugh McGee, Joseph Herr, Terry Byrne, 

and Matthew Dixon

Unclassifi ed Unclassifi ed 131

October 2012

DTF61-05-D-00024

2. Government Accession No. 3. Recipient’s Catalog No.

Final Report 

September 2010-September 2012

This report was produced under the FHWA contract DTF61-10-D-00022-T-11003. The Contracting 

Offi cer’s Technical Manager (COTM) was Guan Xu, FHWA Offi ce of Safety. The USDOT Technical 

Panel members were Brian Gilleran, Joe Glinski, Jeff Shaw, Chris Webster, and Wei Zhang.

Over 15 years ago, the National Transportation Safety Board (NTSB) issued 29 recommendations 

to improve safety at active controlled highway-rail grade crossings following the school buscommuter train collision in Fox River Grove, Illinois. The objective of this task order was to 

develop technical information to assist highway agencies and railroads with integrating 

effective event recording devices within interconnected/preempted highway-rail grade crossing 

signal systems. This information is intended to be applicable to the installation of new systems 

as well as to retrofi tting existing systems. The objective also included developing technical 

information that could be used to establish periodic inspection of traffi c signals by State and 

local highway agencies as well as detailed joint annual inspections of interconnected highwayrail grade crossing signal systems. Specifi c emphasis was placed on highway agencies, as 

there are currently no national regulations to counterpart 49 CFR 234 and AREMA mandates 

for railroad agencies. The outcomes of this effort are focused to help the Federal Highway 

Administration (FHWA) and the Federal Railroad Administration (FRA) implement the two NTSB 

recommendations, supporting Safety Advisory 2010-02.

Railroad, Highway, Grade Crossing, Intersection, 

Event Recording, Signal Systems, Preemption

No restrictions.
iii

TABLE OF CONTENTS

CHAPTER 1. INTRODUCTION ...........................................................................................................1

CHAPTER 2. CONVEYING CHANGES IN HORIZONTAL ALIGNMENT ..............................................3

2.1 EVENT RECORDING TECHNOLOGY ............................................................................................ 3

2.1.1 Highway .............................................................................................................................. 3

2.1.2 Railroad .............................................................................................................................. 7

2.1.3 Summary ............................................................................................................................ 9

2.1.4 Market Product................................................................................................................... 9

2.2 STATE OF PRACTICE FOR INSPECTION, TESTING, AND REGULATION ......................................... 9

2.2.1 Highway.............................................................................................................................12

2.2.2 Railroad .............................................................................................................................13

2.3 STATE OF KNOWLEDGE FOR INSPECTION, TESTING, AND REGULATION ...................................15

2.3.1 Highway .............................................................................................................................15

2.3.2 Railroad .............................................................................................................................15

2.3.3 Highway Traffi c Signal Preemption ..................................................................................16

2.4 LIABILITY ......................................................................................................................................16

CHAPTER 3. TECHNICAL AND POLICY INFORMATION ................................................................. 17

3.1 TECHNICAL INFORMATION ........................................................................................................17

3.1.1 New Systems ......................................................................................................................17

3.1.2 Hybrid Systems ................................................................................................................. 35

3.1.3 Legacy Systems .................................................................................................................37

3.1.4 General Event Recording Device Functional Requirements ........................................ 45

3.1.5 Event Recorder Costs........................................................................................................47

3.2 POLICY INFORMATION .............................................................................................................. 48

3.2.1 Scope ............................................................................................................................... 48

3.2.2 Frequency of Inspection and Testing ............................................................................ 48

3.2.3 Scheduling....................................................................................................................... 48

3.2.4 Responsibilities of Personnel ........................................................................................... 49

3.2.5 Procedures ....................................................................................................................... 49

3.2.6 Documentation ............................................................................................................... 55

3.2.7 Reference Documentation ............................................................................................. 55

CHAPTER 4. MODEL STRATEGY FOR ESTABLISHING REGULAR JOINT INSPECTIONS OF 

INTERCONNECTED SYSTEMS .......................................................................................................... 57

4.1 PRE-INSPECTION ........................................................................................................................ 57

4.2 INSPECTION ............................................................................................................................... 57

4.3 POST- INSPECTION ..................................................................................................................... 59

4.3.1 Agreements...................................................................................................................... 60

4.4 FUNDING SOURCES ....................................................................................................................61
iv

REFERENCES ............................................................................................................................................... 62

APPENDIX A: IGOR INFORMATIONAL BROCHURE .................................................................................... 63

APPENDIX B: HIGHWAY AGENCY AND RAILROAD QUESTIONNAIRES ...................................................... 64

APPENDIX C: EXAMPLE BLOCK DIAGRAMS/WIRING DIAGRAMS ............................................................ 68

APPENDIX D: HIGHWAY SIGNAL PREVENTATIVE MAINTENANCE CHECKLIST ........................................... 71

APPENDIX E: RAILROAD 49 CFR TESTING AND INSPECTION REGULATION DETAILS ................................ 86

APPENDIX F: SAMPLE INSPECTION AND DIAGNOSTIC REVIEW FORMS ................................................... 89

APPENDIX G: SAMPLE AGREEMENTS ........................................................................................................111
v

LIST OF FIGURES

Figure 1: Field Examples of Highway Traffi c Signal Controller Assemblies and Data Transfer Set-ups .....4

Figure 2: Priority States .................................................................................................................................. 10

Figure 3: New System Confi guration Functional Block Diagram ............................................................... 19

Figure 4: HRI Interface ...................................................................................................................................21

Figure 5: Railroad Events to be Recorded for each Train Movement ....................................................... 31

Figure 6: Hybrid System Confi guration Functional Block Diagram ...........................................................36

Figure 7: Legacy System Confi guration Functional Block Diagram ..........................................................38

Figure 8: Example Warning Labels ..............................................................................................................50

Figure 9: Field Example of Warning Label ...................................................................................................50

LIST OF TABLES

Table 1: Highway Signal Control Manufacturers Reviewed by Device Type ..............................................5

Table 2: Sampling of Highway Signal Events (or Alarms) Recorded by Device Type ................................6

Table 3: Railroad Event Recorder Manufacturers Reviewed by Device Type .............................................7

Table 4: Sampling of Railroad Events (or Alarms) Recorded by Device Type ............................................8

Table 5: Railroads Initially Contacted .......................................................................................................... 11

Table 6: HRI Messages ..................................................................................................................................22

Table 7: Minimum Proposed Events/Circuits to be Monitored and Recorded ........................................59
vi

LIST OF ABBREVIATIONS

AHWS Automatic Highway Warning System

AREMA American Railway Engineering and Maintenance-of-Way Association

ATC Advanced Transportation Controller

CFR Code of Federal Regulations

DIR Direction of Train

FHWA Federal Highway Administration

FRA Federal Railroad Administration

HRI Highway Railroad Intersection

ICO Island Circuit Occupied

IEEE Institute of Electrical and Electronics Engineers

IMSA International Municipal Signal Association

LTI Long Term Obstacle Indicator

MUTCD Manual on Uniform Traffi c Control Devices

NEMA National Electrical Manufacturers Association

NGD Entrance Gate Down

NGP Entrance Gate Present

NGU Entrance Gate Up

NTSB National Transportation Safety Board

PEA Preemption Warning Active

PER Preemption Relay

PSP Product Safety Plan

RSO Roadway System Operational

RSPP Railroad Safety Program Plan

SO System Operational (railroad)

TPD Train Presence Detection

USDOT United States Department of Transportation

VAS Vehicle Arrestor Barrier Status

VP Vehicle Presence

WSA Warning System Active

XGD Exit Gate Down

XGP Exit Gate Present

XGU Exit Gate Up

XR Grade Crossing Relay
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

1

CHAPTER 1. INTRODUCTION

In 1996, the National Transportation Safety Board (NTSB) issued a fi nal investigative report on the 

school bus-commuter train collision that occurred at a highway-rail grade crossing in Fox River Grove, 

Illinois (1). In the report, 29 recommendations were made to improve safety at active controlled 

highway-rail grade crossings that are interconnected with adjacent signalized intersections. Two 

recommendations were classifi ed as “Open – Unacceptable Response” by NTSB for a number of 

years:

1. NTSB Recommendation I-96-010. NTSB recommends that DOT require the use and 

maintenance of railroad and highway/traffi c signal recording devices on all new and 

improved installations at railroad/highway grade crossings that have active warning train 

detection systems and are interconnected/preempted to highway signal systems. These 

devices record suffi cient parameters to allow railroad and highway personnel to readily 

determine that the highway signals and railroad-activated warning devices are coordinated 

and operating properly. NTSB recommends that DOT require that the information from these 

devices be used during comprehensive and periodic joint inspections.

2. NTSB Recommendation I-96-011. NTSB recommends that DOT requires that existing recording 

devices for railroad and highway signals systems at interconnected/preempted grade 

crossings be retained or upgraded as necessary; requires that these recording devices be 

maintained and that the information from these devices be used during the comprehensive 

and periodic joint inspections.

In September 2010, the Federal Railroad Administration (FRA) issued Safety Advisory 2010-02 to 

address these two recommendations (2). The advisory recommended that four actions be taken by 

highway agencies and railroads:

1. Each State and local highway authority and railroad should conduct comprehensive joint 

inspections of highway traffi c signal pre-emption interconnections when the highway-rail grade 

crossing active warning system is placed in service, whenever any portion of the system which 

may affect the proper function of the interconnection is modifi ed or disarranged, and at least 

once every 12 months, during which observation of the actual pre-emption function and its 

effect on the highway traffi c signal system can be made;

2. Each State and local highway authority and railroad should install railroad and highway traffi c 

signal recording devices at all new and improved highway-rail grade crossings that have 

active warning systems which are interconnected with highway traffi c signal systems;

3. Each State and local highway authority and railroad should maintain and upgrade existing 

railroad and highway traffi c signal recording devices at highway-rail grade crossings that have 

active warning systems which are interconnected with highway traffi c signal systems; and

4. Each State and local highway authority and railroad should use the data provided by 

railroad and highway traffi c signal recording devices during their comprehensive periodic 

joint inspections of interconnected highway-rail grade crossing active warning systems and 

highway traffi c signal systems to determine whether further investigation of any recorded 

operational anomalies may be warranted.

Following the issuance of the Safety Advisory, NTSB changed their classifi cation of the two 

recommendations to “Closed – Acceptable Alternate Action”.
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

2

The objective of this task order was to develop technical information that would assist highway 

agencies and railroads with integrating effective event recording devices within interconnected/

preempted highway-rail grade crossing signal systems. This technical information is intended to be 

applicable to the installation of new systems as well as to retrofi tting existing systems. The objective 

also included developing technical information that could be used by State and local highway 

agencies as they perform periodic inspection of traffi c signals as well as detailed joint annual 

inspections of interconnected highway-rail grade crossing signal systems. The outcomes of this effort 

are focused to help the Federal Highway Administration (FHWA) and the FRA implement the two NTSB 

recommendations, supporting Safety Advisory 2010-02.

The tasks completed to achieve the objective were as follows:

• Collect, Review, and Evaluate Available Technologies and Current State-of-Practice.

• Develop a Technical and Policy Information Document.

• Develop a Model Strategy for States to Establish Regular Joint Inspections of Interconnected 

Systems.

This report documents the fi ndings and outcomes of these individual tasks.
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

3

CHAPTER 2. EXISTING EVENT RECORDING TECHNOLOGY AND CURRENT 

PRACTICE

Currently, the technology being installed in highway traffi c signal controller cabinets and railroad 

grade crossing equipment bungalows includes some ability to record event data. The data 

recorded, however, are not always either easily retrieved or of much use for effective analysis. 

Additionally, communication and data transmission between the highway and railroad systems is 

relatively limited.

This chapter summarizes the collection and analysis of information related to existing recording 

capabilities of devices installed within highway traffi c signal controller cabinets and/or railroad grade 

crossing equipment bungalows. A brief description of a “market–available” event recording device is 

provided; no product endorsement is made or implied by its inclusion in this document. This chapter 

also documents current highway agency and railroad testing, inspection, and regulation practices 

pertaining to interconnected signal systems.

2.1 Event Recording Technology

2.1.1 HIGHWAY

There are many different types of devices used in highway traffi c signal controller cabinets that can 

record various types of events or information. These devices are manufactured according to several 

national standards for signal control assemblies, including NEMA TS-1, NEMA TS-2 Type 1, NEMA TS-2 

Type 2, Type 170, Type 179, Type 2070, and ATC. Some agencies use a hybrid approach to highway 

traffi c signal cabinet architecture and customize these standards to meet their unique individual 

requirements. Field examples of highway traffi c signal control assemblies and data transfer set-ups 

are shown in Figure 1.

Table 1 summarizes the various highway traffi c signal control device manufacturers, listed by device 

type. Based on the manufacturer listing, a sampling of events (or alarms) that can be recorded and 

stored as data in each highway traffi c signal control cabinet device is presented in Table 2. Please 

note that the information presented in Table 1 and Table 2 is for highway traffi c signal controller 

applications only. Additionally, the listing in Table 2 contains events (or alarms) related to highway 

traffi c signal control that may be relevant in maintaining highway-rail grade crossing operation; 

not every event (or alarm) would be recorded, but could be investigated as second- or third-tier 

information if an incident did occur. Most in-cabinet event recording systems are focused on system 

malfunction monitoring of such anomalies as signal confl icts, fi eld circuit failures, short interval 

occurrences, internal electrical levels out of range, and electrical noise. Traffi c fl ow information can 

also be logged, as well as a variety of user-defi ned functions such as cabinet door open, keyboard 

data change, and system coordination status. The event recording capability varies depending on 

cabinet architecture. The exact number and type of events (or alarms) recorded also vary greatly 

depending on the type, model, and manufacturer of the device. Additionally, each device typically 

requires manufacturer-specifi c software to record and/or access the desired information.
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

4

A. Type 170 Cabinet Assembly E. NEMA TS-2 Type 2 Cabinet with Field Master

B. Type 2070 Cabinet Assembly F. Field Laptop Data Transfer to Traffi c Signal Cabinet

C. NEMA TS-1 12-Channel Confl ict Monitor G. NEMA TS-2 Type 1 Cabinet with Field Master

D. NEMA TS-1 Cabinet Assembly

Figure 1: Field Examples of Highway Traffi c Signal Controller Assemblies and Data Transfer Set-ups
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

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Table 1: Highway Signal Control Manufacturers Reviewed by Device Type

DEVICE MANUFACTURERS

Confl ict Monitors / Malfunction 

Management Units

Econolite Peek

Eberle Design Inc. (EDI) Reno A & E

Naztec

Controllers

Eagle-Siemens Naztec

Econolite Northwest Signal

McCain Peek

Pre-emption Devices

EMTRAC Systems Tomar

Global Traffi c Technologies (GTT)

Vehicle Detection

Inductive Loops: Video:

Eberle Design Inc. (EDI) Econolite

Global Traffi c Technologies (GTT) Iteris

Reno A & E Naztec

Peek

Trafi con

Highway traffi c signal control assemblies, when located in the vicinity of a highway-rail grade 

crossing, typically have a single point connection from the railroad grade detection/control system 

– one per approach. Upon receipt of a valid preempt call from the rail system, the highway traffi c 

signal assembly will revert to a preempt state at the intersection. While standard highway traffi c 

signal control assemblies have various levels of event/data recording capability, only those cabinets 

containing specialized recording units designed for such an application have the capability to log 

more detail than a preempt call being activated, the time the call was received, and the time the 

signal reverted back to normal operation. Events/data such as time of event signal display status, 

vehicle/pedestrian call status, preempt call reports, and sequence time duration is available from 

various devices; however, recording capabilities are typically contained in manufacturer-specifi c 

devices and not consolidated in a single device within a highway traffi c signal control cabinet that 

is readily available for fi eld review purposes. Information that is being recorded can be accessed on 

a device-by-device basis either through a front panel display on the device itself or via connection 

to a laptop computer containing the appropriate fi rmware designed to interrogate the device and 

retrieve such data. Typically, the laptop fi rmware required for data retrieval is manufacturer-specifi c 

to the device being interrogated.
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

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Table 2: Sampling of Highway Signal Events (or Alarms) Recorded by Device Type

DEVICE EVENT (OR ALARM) RECORDED

Confl ict Monitors 

/ Malfunction 

Management Units

+24 VDC latch status Field check / dual indication switch status

AC line – brownout Field signal voltages

AC line – power down Flash delay time

AC line – short interrupt Graphical display of channel voltage levels

AC line – voltage value Log clear

Cabinet temperature Minimum yellow change channel disable 

jumper status

Confi guration change – jumper selection Per channel voltage levels

Confi guration change – program card Permissive channel jumper status

Confi guration change – switches Port 1 fail

Control signal voltages Signal sequence history (30 seconds prior 

to event)

CVM latch status Time line sequence log

CVM status Voltage limit faults

Dual indication enable status Voltage dropout

Entry to fl ash Voltage surge

Event monitoring trigger

Exit from fl ash

Controllers

Alarm log fault MMU confl ict

BIU frame error MMU fi eld check fault

Cabinet door open MMU minimum clear fault

Checksum failure MMU Port 1 failure

Communication log fault MMU red failure

Confl ict fl ash on/off No coordination – command free

Controller power on/off No system command – back up operation

Coordination / free switch active Preempt on / off

Coordination active Priority on / off

Coordination fault / cycle problem SDLC failure

Coordination fault / program problem Software clock adjust

Cycle zero phase fault System active

Data change – keypad System communications status

Data change – remote System off line – remote fl ash

I/O failure System off line – voltage monitor

Local fl ash on / off Time change – keypad

Low battery Watchdog failure

Manual control enable active Watchdog time-out

Pre-emption Devices

Active channel call Preempt call placed to controller

Duration of event Priority (high / low)

End of event Start time of event

Event green time Vehicle class

Final green phase Vehicle speed

Vehicle Detection Loop status
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

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2.1.2 RAILROAD

In general, event/data recording capability within a railroad grade crossing equipment bungalow 

in the vicinity of a highway-rail grade crossing is dependent on a standalone unit rather than as an 

integral part of another installed device. The use of standalone event recorders allows railroads to 

deploy the same technology at different types of signal locations and in conjunction with equipment 

of varying age and manufacturer. It assists in the isolation of non-vital functions – such as event 

recording – from vital functions, allowing the railroads to have signifi cant discretion as to what events/

data are recorded. Many devices can be expanded, daisy chained, or networked to increase 

the number of inputs that railroad event recorders can monitor. Some newer systems incorporate 

elements that were formerly distinct units (e.g., grade crossing predictor, grade crossing controller, 

and event recorder); however, among existing crossing systems, these are the exception rather than 

the rule.

Table 3 summarizes by manufacturer the various railroad event recorders reviewed for this task. Table 

4 presents a sampling of events (or alarms) that can be recorded. All of the devices listed Table 3 

can record the identifi ed events if the proper inputs are provided. Other events (e.g., temperature, 

train speed, gate up/down, etc.) require additional modules/sensors to provide the necessary inputs 

to the event recorder. The number and types of events actually recorded vary with each railroad’s 

standard practice; however, most railroads do not record as many events as shown in the table. 

Please note that the information presented in Table 3 is for railroad event recording applications only.

Table 3: Railroad Event Recorder Manufacturers Reviewed by Device Type

DEVICE MANUFACTURER

CWR-24E

MICRO-AIDE

CWR-72E

CWR-96E

CWR-264E

CWR-272E

CWR-264XC

• CWR-264P

• CWR-264S

VDL Microlok II (Data Logger)

VDL S7-300 (Data Logger)

Micro Data Analyzer I

North American Signal Micro Data Analyzer II

Universal Data Analyzer

Universal Recorder Module

Event Analyzer Progress Rail Hawk Recorder (GETS)

SEA/R

SAFETRAN

SEAR II

Argus

GCP-4000
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

8

Some devices employ more complex event recording functions and can monitor performance of the 

highway-rail grade crossing warning system. For example, if programmed correctly and provided 

with the proper inputs, an event recording device may be able to detect unsafe conditions such 

as gates not down within 5 seconds of a train occupying the island circuit or warning time of less 

than 20 seconds. Some devices can also assist in performing and recording monthly, quarterly, and 

yearly tests required by the FRA.

Device memory can typically store over 100,000 events, which can be retrieved through the device’s 

graphic interface or by downloading to a laptop in the fi eld using standard connections such as 

RS232 or USB. Data formats and communications capabilities vary by manufacturer. Devices may 

communicate by several methods, including dial-up modem, cellular modem, Ethernet modem, 

Base Communications Package (BCP), Mobile Communications Package (MCP) radio, VHF, UHF, 

and spread spectrum radio. The communication capabilities can be used to provide alarms to 

railroad control centers or to maintenance personnel in real time. Some devices also include GPS 

capabilities for location and time stamping.

Table 4: Sampling of Railroad Events (or Alarms) Recorded by Device Type

DEVICE EVENT (OR ALARM) RECORDED

CWR-24E AC and DC voltage levels

AC power on / off

Battery capacity

Bell operation

Crossing warning equipment activation / deactivation

False crossing activation

Flash rate

Gate level

Gate up / gate down

Ground faults

Interlocking logic operation

Lamp-out conditions

Low battery voltage

Preemption call

Stick circuit operation

Temperature

Track occupancy – approach circuits and island circuits

Train speed

Unauthorized facility entry

Warning time

CWR-72E

CWR-96E

CWR-264E

CWR-272E

CWR-264XC

CWR-264P

CWR-264S

VDL Microlok II (Data Logger)

VDL S7-300 (Data Logger)

Micro Data Analyzer I

Micro Data Analyzer II

Universal Data Analyzer

Universal Recorder Module

Event Analyzer

Hawk Recorder (GETS)

SEA/R

SEAR II

Argus

GCP-4000
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

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2.1.3 SUMMARY

As shown in Tables 1 through 4, there are several prominent manufacturers of highway and railroad 

signal control devices. Likewise, there are a number of devices that can be assembled within a 

cabinet or bungalow architecture, each of which has its own capability to record various events. 

Depending on the type, model, and manufacturer of the device or the agency’s standard practice, 

the number and type of events being recorded vary greatly. As such, one challenge is to determine 

which events can be recorded across different signal control architectures that will satisfy the two 

NTSB recommendations. A second challenge is to determine how to easily retrieve these events from 

the various devices being used. To date, the amount of data exchanged between highway and 

railroad signal control systems is limited; many times it is a single preemption call circuit. Much more 

data will need to be consolidated and supplied to the recording device, whether it is located in the 

highway traffi c signal controller cabinet or railroad grade crossing equipment bungalow. Another 

signifi cant challenge will be addressing the existing electrical isolation that exists between the two 

systems, as any data exchanged will require a common electrical reference. A proposed single 

recording device will have several technical challenges. These challenges will be addressed in 

subsequent sections pertaining to technical guidelines.

2.1.4 MARKET PRODUCT

One currently available device that does support the recording of events in both highway traffi c 

signal cabinets and railroad bungalows that may be of interest is “Interconnected Grade-Crossing 

Operations Recorder (IGOR)”. This event recording device was recently developed through a 

partnership between Campbell Technology Corporation (CTC) and Reno A&E. IGOR units are 

installed in both the highway traffi c signal controller cabinet and the railroad grade crossing 

equipment bungalow and can be integrated into various system architectures. The device records 

events such as traffi c signal state, right-of-way transfer time, track clearance green time, and gate 

and fl ashing warning light status. The device also has the ability to record high-defi nition video, if 

desired. An informational brochure for IGOR is provided in Appendix A.

2.2 State of Practice for Inspection, Testing, and Regulation

Highway agency and railroad personnel can be important sources of information when seeking 

to understand the technical capabilities of currently deployed event recording devices in highway 

and railroad signal control systems. Using the United States Department of Transportation (USDOT) 

FRA National Highway-Rail Grade Crossing Inventory database (3), the number of locations per 

State where interconnected highway-rail recording devices are currently deployed were identifi ed. 

Additionally, consideration was given to the FRA’s top 10 “worst” States for highway-rail grade crossing 

accidents/incidents on average during the time period 2006 through 2008.

From these sources, a prioritized list of 12 States was created to contact for further information. The 12 

States are listed below and highlighted in Figure 2:

• California • Minnesota

• Florida • New Jersey

• Georgia • North Carolina

• Illinois • Ohio

• Indiana • Texas

• Louisiana • Washington
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

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Figure 2: Priority States

State traffi c engineers from each of the 12 identifi ed States were contacted, as well as personnel at a 

number of Class I railroads and commuter rail/transit organizations. Table 5 summarizes the railroads 

contacted. The objective of these contacts was to gain further insight of the following:

• Technical capabilities and requirements of deployed recording devices to function in an 

interconnected system.

• Specifi c recording device deployment experiences.

• Current policy or practice for inspecting and maintaining signal control systems and recording 

devices.

• Financial perspective or installing, operating, and maintaining recording devices.

An initial email was sent to the various contacts requesting that the recipient forward contact 

information for personnel directly related to highway-rail grade crossing operation and maintenance; 

only a limited number of responses were received. From State highway agencies, direct contact 

information for related personnel was received from California, Georgia, Minnesota, and New Jersey. 

From the railroads, responses were received from three Class I railroads and one commuter railroad. 

As a follow up to the initial email, direct phone calls were made in an attempt to solidify further 

contacts for future questioning; however, these efforts did not produce additional State highway 

agency or railroad responses.
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

11

Table 5: Railroads Initially Contacted

RAILROAD TYPE RAILROAD

Class I

Burlington Northern Santa Fe 

Railway (BNSF)

Kansas City Southern (KCS)

Canadian National (CN) Norfolk Southern (NS)

Canadian Pacifi c (CP) Union Pacifi c (UP)

CSX

Commuter Rail / Transit

Amtrak NITCD

Capitol Metro NJ Transit

Dallas Area Rapid Transit (DART) San Francisco Bay Area Rapid Transit 

(BART)

Maryland Area Regional 

Commuter (MARC)

SCRRA – MetroLink

MBTA SFRTA – Tri-Rail

Metro Sound Transit – Seattle

MTA – Long Island Railroad (LIRR) Southeastern Pennsylvania 

Transportation Authority (SEPTA)

MTA – Metro North Utah Transit Authority (UTA) – Salt 

Lake City

Virginia Rail Express (VRE)

A questionnaire was sent to the respondents with regard to existing recording device deployment 

practices as well as testing and inspection policies and practices. The questionnaire sent to the 

respective highway agencies and railroads is included as Appendix B. In addition to existing 

technical and policy information that is vital to developing practical guidelines for interconnected 

highway-rail recording devices, the questionnaire also sought to gain insight on the fi nancial 

ramifi cations of such devices. This includes more than just the initial cost of the device, with 

consideration being given to associated costs such as installation, operation, service life, interfacing 

with existing infrastructure, maintenance (preventative and reactionary), and other indirect costs 

such as staff training relative to the device. With the limited number of responses from highway 

agency and railroad personnel, providing a comprehensive assessment of the fi nancial impacts of 

such devices proved to be diffi cult.

The following summarizes the state-of-practice based on the questionnaire responses received from 

the various State highway agencies and railroads.
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

12

2.2.1 HIGHWAY

Event Recording

Until recently, highway traffi c signal systems generally did not have recording devices that can be 

used to assist with preventive maintenance. The majority of States responded that, within the traffi c 

signal controller cabinet, the controller and the malfunction management unit (MMU) can record 

events related to preemption calls and similar types of events. It was noted that in-cabinet devices 

store a predetermined amount of system activity before overwriting fi les. One State responded that 

they have event recorders at two crossings equipped with “health” monitors that report directly to 

the railroad. Responses also indicated that the railroads will typically install event recording devices 

within new bungalows. Other than the use of a supervisory circuit, no other information or data was 

reported as being exchanged between highway and railroad traffi c signal control facilities in the 

fi eld.

Preemption Design

From the responses, two different design plans were indicated: two conductor, normally closed circuit 

activation and four conductor. With regard to the four conductor, the pairs reported were preempt 

relay, supervisory relay, gate down relay, and supervisory latch relay. One State noted that, while two 

conductor closed loop is acceptable, four conductor is normally used. Example block diagrams/

wiring diagrams of “typical” installations depicting interconnected highway-rail signal control systems 

already in place are shown in Appendix C.

Battery back-up systems (BBS) are available to support critical highway traffi c signal functions. One 

State responded that a few of their highway traffi c signals are equipped with BBS, but not at all 

highway-rail grade crossings. Another State indicated that installing BBS is a design standard for all 

of their new signals with railroad preemption. Overall, the provision of BBS at new and upgraded 

highway traffi c signal installations is becoming standard practice for several agencies. Railroad 

signal systems typically have their own BBS, which do not supply back up power to an adjacent 

highway traffi c signal control system.

The majority of the responses indicated that highway-rail grade crossing facilities are not remotely 

monitored. One State did respond that many of their highway traffi c signals at railroad crossings 

with preemption are structured with closed loop signal systems that have the capability of providing 

remote monitoring. These signals can be called up via telephone line, providing an agency with 

various levels of remote system monitoring and control capability. These types of systems can report 

back the number of railroad preemption calls and certain malfunctions.

At this time, responding highway agencies did not envision or anticipate future plans to modify how 

highway and railroad signal control systems are interconnected.

Testing

Highway agencies test the circuitry that interfaces the traffi c and rail signal controllers. This is typically 

done at the initial turn-on of new highway-rail interconnected signal system installations. The majority 

of the responses indicated that no approved inspection or testing checklists were available. Instead, 

technicians use checklists developed by the local or regional highway agency. As an example, one 

State responded that a technician will place the highway traffi c signal into fl ash mode by creating 
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

13

an open circuit and disconnect the highway-rail interconnect wire. Upon attempting to reset, the 

highway traffi c signal should not exit fl ash mode. Another State indicated that, if possible, a train will 

be present for testing or the team will wait for the arrival of a train to observe correct operation. Most 

responses noted that representatives from the responsible railroad are not required to be present 

at the initial testing and turn-on, but their presence is requested. Typically, personnel from both the 

highway agency and the railroad are present.

Preventive maintenance and testing practices varied across the responses received. Intervals range 

from monthly to quarterly to bi-annually to annually. One State responded that they do not engage 

in such practices. Similar to initial turn-on, respondents indicated that there is typically no written 

procedure or checklist for these activities. One State did, however, supply documentation of their 

preventive maintenance and testing practice protocols. Another State indicated that they are in 

the process of developing a standardized inspection and reporting method. Maintenance activities 

as well as periodic inspections and testing are often recorded and fi led for several years. Local or 

district highway operations offi ces typically initiate and lead the preventive maintenance and testing 

activities. Railroad personnel are typically not present during these activities unless requested by the 

local or district highway agency or if a problem is noted with rail equipment. However, railroads may 

be provided a copy of the work performed for their records.

2.2.2 RAILROAD

Event Recording

Railroads generally have event recorders installed at the majority of highway-rail grade crossings. 

Depending on the railroad, every new or updated crossing in the last 5 to 10 years has an event 

recorder installed. Event recorders identifi ed by respondents include: 

• Safetran SEA/R, SEAR II and SEAR IIi

• Progress Rail Event Analyzer, Hawk, and HCA

• Micro-Aide Recorders

• IDERS

• EPC

For the most part, the recorders installed are standalone devices; however the SEAR IIi is integrated 

into the railroad signal controller.

Not all railroads record the exact same inputs and alarms at highway-rail grade crossings. Generally, 

power off, gate down, island presence, and dropping of the preemption circuit are recorded by all 

railroads at locations with a device installed. Some railroads record more information such as alarms 

when lights are not fl ashing; when the gate is all the way up, starting to go down, and all the way 

down; and when the train reaches the approach, each side of the island circuit, and when it clears 

the opposite approach. A railroad may choose not to record more inputs or alarms if it has older 

equipment installed that cannot store as much information or data as the newer equipment.

Event recorders are generally not used by railroads to conduct testing and inspection of the crossing 

and are not regularly downloaded as part of any inspection procedure; however, some railroads 

may occasionally check the log history for short warning times. Railroads typically allow event 

recorders to store data in memory until it begins overwriting rather than transmitting the information 

to a central location. If a report is needed for a claim or an incident, it is downloaded on site.
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The coverage of crossings that are remotely monitored ranges from 5 to 40 percent, depending on 

the railroad. If an element of the crossing does not operate as it was set up or intended, an alarm 

is sent to a central offi ce. This can be done a number of different ways: through radio, a cellular 

modem, phone line, or even a third party, which then calls the railroad.

Preemption Design

Railroads typically have their own standard drawings for preemption circuit installation. These 

generally follow American Railway Engineering and Maintenance-of-Way Association (AREMA) 

standards for preemption circuits (at least functionally), but may differ slightly depending on the 

location or age of the crossing. Railroad acquisitions may inherit crossings with different preemption 

circuit layouts. Railroads are generally aware of new signal equipment capabilities that can pass 

additional information (other than the preemption request) between the railroad signal controller 

and the highway traffi c signal controller; however, they are not availing themselves of it.

Example block diagrams/wiring diagrams of “typical” installations depicting interconnected 

highway-rail signal control systems already in place are shown in Appendix C. Example preemption 

circuits are not provided due to concerns with confi dentiality.

Testing

For the initial inspection of newly installed or upgraded interconnected highway-rail grade crossings, 

railroads typically test the entire crossing following the Code of Federal Regulations (CFR), but do not 

have any special procedures that are required to be followed. The highway agencies are informed 

of the inspections by the railroads, but they often do not participate in the testing.

For the testing of highway traffi c signal preemption, railroads follow the federal regulations, which 

require that preemption interconnections are tested once per month for proper operation. This 

test requires verifi cation that the preemption circuit opens up when the crossing relay (XR) drops, 

but does not entail testing the actual preemption time provided at the highway traffi c signal. The 

railroads’ test procedures generally do not vary by State and do not contain any tests beyond what is 

required by the CFR.

Some States may require railroads to conduct a joint inspection of the highway traffi c signal 

preemption with the highway agency. Railroads would like to verify that the highway traffi c signal 

controller received the preemption indication as well as visually observe at what time the queue 

actually clears from the crossing. Typically, only the railroad is required to sign off on the inspection. 

If a joint inspection is conducted, railroads require that participating highway agency personnel are 

properly trained for safe access and working within railroad right-of-way.

Railroads have also expressed scheduling concerns, as maintainers currently have diffi culty meeting 

the existing requirements. At present, railroads would not generally use a device that can perform 

a self-test of preemption to replace the required monthly inspections. The railroads generally 

suggested that such devices would be used daily or weekly and probably at night, but only as an 

additional aid to the human tests each month. Once these devices are industry- and FRA-approved, 

they could be a huge time saver for the railroads.
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2.3 State of Knowledge for Inspection, Testing, and Regulation

This section addresses inspection and testing of highway and railroad signal systems as prescribed in 

various literature sources.

2.3.1 HIGHWAY

Currently, there is no national highway traffi c signal inspection policy that mandates what is to be 

inspected, how the inspection is to be conducted, and when the inspection should take place. 

Highway traffi c signal system testing and inspection processes are typically developed by State 

or local highway agencies. The 1989 edition of the ITE Traffi c Signal Installation and Maintenance 

Manual (4) states, “Maintenance problems can often be traced to inadequate inspection during 

signal equipment installation...A major contributing factor is often the lack of comprehensive 

inspection guidelines, including a fi nal acceptance “punch list” to ensure a thorough, systematic 

inspection by the fi eld inspector.”

The International Municipal Signal Association (IMSA) has created a Traffi c Signal Inspection 

Certifi cation Program to educate and certify fi eld technicians in the inspection of highway traffi c 

signal installations. Inspection topics include traffi c signal displays and supports, underground and 

overhead equipment, vehicular and pedestrian detection systems, controller assemblies, safety 

requirements, electrical grounding and bonding, and fi nal acceptance and turn-on. The knowledge 

is intended to ensure that specifi ed construction practices are properly followed during signal 

installation, resulting in correct operation.

The IMSA course and the 2010 ITE Traffi c Signal Maintenance Handbook (5) provide guidance for 

inspection and testing of highway traffi c signals through construction to acceptance; however, no 

guidance is provided for similar activities post-acceptance. In the 1989 edition of the ITE Traffi c Signal 

Installation and Maintenance Manual, the chapter on risk management provides a section specifi c 

to periodic inspections and reviews. This section states, “Review of court cases indicates that, in 

general, a 6-month interval for routine inspection is considered a reasonable exercise of due care. 

Thus, conduct of the routine preventative maintenance program as outlined in Chapter 4 should 

meet the basic requirements for routine inspection.” Chapter 4 states, “...preventative maintenance 

should be performed on detector equipment every 3 months; on signal controller cabinets, signals, 

and related equipment at 6- or 12-month intervals; on controller equipment generally on an annual 

basis.” The preventative maintenance checklist with recommended intervals is included in Appendix 

D. Again, it is noteworthy that this information does not appear in the more recent 2010 publication.

2.3.2 RAILROAD

Title 49 Part 234 Subpart D of the Code of Federal Regulations (49 CFR Part 234) (6) details all of the 

maintenance standards and requirements for inspecting and testing highway-rail grade crossing 

signal systems. Each railroad must comply with maintenance and testing procedures outlined in 

the CFR and is required to document these tests and provide them to the FRA. In addition to the test 

reports, railroads are required to document all incidents that occur within the railroad right-of-way 

and fi le these reports with the FRA. Railroad organizations that do not comply with 49 CFR are subject 

to fi nes imposed by the FRA.

Inspection and testing of highway-rail grade crossings are required at monthly, quarterly, and 

annual intervals. Most Class I railroads, Amtrak, and major commuter railroads have developed 

documented procedures to satisfy these requirements, some of which go beyond the 49 CFR 

requirements. Appendix E presents further information regarding the monthly, quarterly, and yearly 

testing requirements defi ned under various rules of 49 CFR, particularly warning system operation, 

warning time, and highway signal preemption.
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With regard to event recording devices, 49 CFR does not contain any laws mandating the 

maintenance or inspection of devices used to monitor highway-rail grade crossings. The railroads 

are under no regulatory requirement to install event recorders as part of their Automatic Highway 

Warning System (AHWS). However, for locations with an event recording device installed as part of 

the AHWS, the lack of maintenance and inspection regulation results in widely varying practices.

2.3.3 HIGHWAY TRAFFIC SIGNAL PREEMPTION

Currently in the United States, according to the FRA grade crossing inventory, there are a total of 

215,820 at-grade railroad crossings. Of these, highway traffi c signal preemption is used at 4,954 

(approximately 2%). As stated in Section 8C.09 of the Manual on Uniform Traffi c Control Devices 

(MUTCD) (7), “If a highway-rail grade crossing is equipped with a fl ashing-light signal system and is 

located within 200 feet of an intersection or midblock location controlled by a traffi c control signal, 

the traffi c control signal should be provided with preemption in accordance with Section 4D.27. 

Coordination with the fl ashing-light signal system, queue detection, or other alternatives should 

be considered for traffi c control signals located farther than 200 feet from the highway-rail grade 

crossing. Factors to be considered should include traffi c volumes, highway vehicle mix, highway 

vehicle and train approach speeds, frequency of trains, and queue lengths. The highway agency 

or authority with jurisdiction and the regulatory agency with statutory authority, if applicable, should 

jointly determine the preemption operation and timing of traffi c control signals interconnected with 

highway-rail grade crossings adjacent to signalized highway intersections.”

According to 49 CFR, highway-rail grade crossing warning systems must provide a minimum of 20 

seconds of warning. If preemption is necessary, the preemption time is added to the minimum 

warning time to determine the track detection point of the approaching train. Also, under Section 

8C.09 of the MUTCD, “If preemption is provided, the normal sequence of traffi c control signal 

indications shall be preempted upon the approach of trains to avoid entrapment of highway 

vehicles on the highway-rail grade crossing.”

At highway-rail grade crossings with preemption, the FRA regulates the railroad portion of the system; 

however, the FRA has no regulatory means to assure that the highway portion of the system is 

working as desired.

2.4 LIABILITY

The CFR regulates the railroads and requires them to conduct regular inspections of their equipment. 

The highway authorities are under no federal inspection regulations and are not required to inspect 

their equipment. The railroads generally feel that, until the highway authorities are required to 

regularly test their equipment, a joint inspection would be diffi cult to conduct.

A major concern for the railroads is liability. The highway agency does all of the traffi c signal design, 

calculates the necessary warning time to clear the intersection, and then informs the railroad how 

much warning time is needed. The railroad then provides the necessary time; however, the railroad 

personnel are not familiar with the highway traffi c signal equipment or the process of calculating 

the warning time. The overall opinion of the railroads is that it is not necessary or practical to have 

railroad personnel looking into whether or not the highway traffi c signal preemption is working 

beyond testing that the circuit is being dropped coming out of the railroad equipment box. The 

railroads maintain that they should not be responsible for inspecting anything on the highway side 

of the preemption and are not comfortable signing off on whether or not a highway traffi c signal is 

working properly.
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CHAPTER 3. TECHNICAL AND POLICY INFORMATION

This chapter offers technical information needed to address the design, installation, operation, 

maintenance, and inspection of event recording devices at locations with interconnected highwayrail grade crossing signal systems.

3.1 Technical Information

This section describes the functional requirements for event recording devices to be installed at 

highway-rail grade crossing locations with highway traffi c signal preemption. The intent of these 

devices is to provide operating and maintaining agencies with a tool to assist them in ensuring 

that interconnected signal systems are working as designed. These devices can be installed as 

standalone units or integrated with other devices installed in a highway traffi c signal controller 

cabinet or railroad grade crossing equipment bungalow. The functional requirements of three 

different potential interconnected system confi gurations are discussed in this section, and are 

classifi ed as “new”, “hybrid”, and “legacy” systems. The new confi guration refers to new or future 

systems with interfacing capabilities between highway and railroad signal controllers using IEEE 

Standard 1570 (8). A hybrid confi guration refers to existing systems having some level of event 

recording and/or processing capabilities. The legacy confi guration refers to existing systems having 

no event recording or processing capabilities. For the highway components of these systems, 

the minimum requirements should be supported by all types of highway traffi c signal control 

architectures and assembly types.

Minimum required events and alarms are proposed for each system confi guration. For each 

proposed event and alarm, there is a description of the event or alarm and an explanation of how 

it can be monitored and recorded. For new and hybrid system confi gurations utilizing IEEE Standard 

1570, these explanations include how the events and alarms can be generated from the information 

included in the defi ned IEEE Standard 1570 messages. For the hybrid and legacy systems that will 

not be utilizing the IEEE Standard 1570, the explanations include how the events and alarms can be 

generated from the various equipment and circuits input to the event recorder.

3.1.1 NEW SYSTEMS

“New” systems have the capability to interface between the highway traffi c signal controller and 

railroad grade crossing controller using IEEE Standard 1570. IEEE Standard 1570 uses a serial 

communication interface between the highway and railroad systems to communicate vital safetycritical system information such as preemption requests and health status, as well as additional 

information and data used to monitor each system. IEEE Standard 1570 is explained in further detail 

in a subsequent section (see “IEEE Standard 1570”).

There are currently only a few existing highway traffi c signal controllers that provide even a limited 

amount of support for IEEE Standard 1570. These controllers use IEEE Standard 1570 as another 

means of providing the preemption input and only support the two safety-critical IEEE Standard 

1570 messages, which are subsequently described in detail. At present, there are no highway traffi c 

signal controllers capable of using the additional IEEE Standard 1570 railroad messages (other 

than preemption information) to modify the preemption sequence in the traffi c controller. Highway 

agencies and/or traffi c signal equipment manufacturers will need to develop this functionality in the 

future. The additional information provided via the IEEE Standard 1570 messages will still be a useful 

maintenance tool for highway agencies and railroads through monitoring and event recording.

The supervisory component of the interconnected interface should be performed using the defi ned 

IEEE Standard 1570 messages over the serial communication interface. This system should meet the 

Federal requirements for processor-based signal and train control systems defi ned in 49 CFR 236 
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Subpart H (see “49 CFR 236 Subpart H Requirements”).

Figure 3 shows a functional block diagram of a typical new system confi guration.

IEEE Standard 1570

This section provides an explanation of the IEEE Standard 1570, the IEEE standard for the interface 

between the rail subsystem and the highway subsystem at a Highway Railroad Intersection (HRI). The 

following summarizes the content of the IEEE Standard 1570, including the necessary components 

and the messages the standard defi nes in detail.

The IEEE 1570 standard defi nes the Advanced Transportation Controller (ATC) as the platform 

that provides the digital data communication link at the highway traffi c signal control cabinet. 

The term “ATC” refers to a specifi c controller standard that is a product of a national standards 

development effort comprised of the Institute of Transportation Engineers (ITE), American Association 

of State Highway and Transportation Offi cials (AASHTO), and the National Electrical Manufacturers 

Association (NEMA). This standard is still being developed with the latest version 06.05, which is 

pending approval as of this writing. There are several other enhanced controller platforms currently 

available on the market that are in use by agencies and could support the IEEE 1570 standard. For 

this reason, the generic term “traffi c controller” is being used in this report so as to not preclude the 

use of alternative traffi c signal controller platforms that an agency may want to use to support the 

IEEE 1570 communications standard in a future deployment.

The primary purpose of an interconnection interface between the highway and railroad controllers 

at a HRI is to preempt highway traffi c signal operation in order to clear traffi c from the crossing as a 

train approaches. Existing standards defi ne analog interfaces, generally using an electrical cable to 

convey voltage between the two subsystems, where the absence of voltage on the wires results in the 

highway traffi c signal entering preemption operation. As required by Federal regulations, this existing 

interface is designed to meet both fail-safe and closed loop principles.

IEEE Standard 1570 specifi es a digital communications interface between the highway and 

railroad subsystems that provides equivalent functions and maintains the safety requirements of 

existing systems. In addition to providing the preemption functions currently carried out by an 

interconnection circuit, this interface specifi es digital data communications to provide for the sharing 

of additional information between the highway and railroad subsystems. This standard also supports 

future upgrades in equipment functionality on both sides of the system, but it does not mandate that 

functionality.
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Figure 3: New System Confi gureation Functional Block Diagram
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

20

The IEEE Standard 1570 interface uses a digital serial connection between the highway advanced 

transportation controller (ATC) and the railroad wayside equipment terminator. Both the ATC and the 

wayside equipment terminator handle numerous control functions, which typically reside in separate 

physical devices and communicate via an internal communications network. IEEE Standard 1570 

does not make assumptions about the technology used to implement those control functions. 

The standard only specifi es the interface between highway and railroad subsystems and not the 

interfaces internal to the highway or railroad subsystems. In other words, this interface provides a 

means for control functions in the ATC and the wayside equipment terminator to communicate with 

one another without specifying the internal communication structure in either system. This allows 

for fl exibility in the actual allocation of components and supports alternative equipment placement 

should it be necessary in the future.

The HRI interface consists of a virtual or logical component and a physical component. The virtual 

component is what provides the channel for communication between the ATCs and the wayside 

equipment terminator. It consists of the message formats and information content that fl ow between 

the two systems. The physical component of the interface is the physical connection that facilitates 

the transfer of data between the highway and railroad internal data networks, acting as a bridge 

between the two independent components.

The HRI interface architecture is made up of four functional components: ATC functions, ATC 

gateway, wayside functions, and wayside gateway. Figure 4 shows the HRI interface and the 

functional components of the HRI interface architecture, which are described following the fi gure.

The ATC functions are those functions internal to the ATC that obtain or generate the information to 

be transmitted to the railroad system across the HRI interface. They also process data received from 

the railroad system.

The ATC gateway acts as the internal router and interface bridge controller for the ATC. It is 

responsible for interfacing with the internal ATC functions and routing incoming or outgoing 

messages across the HRI interface to the wayside gateway or to the appropriate ATC function.

The wayside functions are those functions internal to the wayside equipment terminator that obtain 

or generate the information to be transmitted to the highway system across the HRI interface. They 

also process data received from the highway system.

The wayside gateway acts as the internal router and interface bridge controller; for the wayside 

equipment terminator. It is responsible for interfacing with the internal wayside functions and routing 

incoming or outgoing messages across the HRI interface to the ATC gateway or to the appropriate 

wayside function.

More than one type of protocol is specifi ed for the HRI interface. This gives equipment manufacturers 

fl exibility to implement the HRI interface to fi t an installation’s specifi c circumstances. The data link 

and physical layer protocols provide the physical infrastructure for the HRI physical interface. The 

protocols specifi ed for these layers include Ethernet, RS232, RS422, and RS485. These protocols 

should support the transfer of individual message packets of up to 128 bytes in length at a minimum 

of 19.2 kilobytes per second, meaning the protocols should be capable of transferring a 128 byte 

message packet across the HRI interface in less than 250 milliseconds.
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Figure 4: HRI Interface

HRI Messages

IEEE Standard 1570 defi nes a total of 12 messages for exchange over the HRI interfaces, which are 

listed in Table 6.

This section, which addresses the required minimum amount of information to be shared between 

the highway and railroad subsystems, describes how four of the eight defi ned messages should be 

used to transfer information to the event recorder in system confi gurations using the IEEE Standard 

1570 protocol for communication. A description of each of the four messages recommended for use 

is provided with an explanation of the standard information included in each message packet.

The same standard data format is used for all defi ned HRI messages. The information in this standard 

data format includes the message length, a time stamp (date and time, from the month down to 

the second), a message sequence number, a message label, and a message version number. Also 

included is information identifying the message as vital or non-vital and the actual message data.
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Table 6: HRI Messages

MESSAGE 

ID

MESSAGE NAME SOURCE DESTINATION SAFETYCRITICAL?

9.4.40 HRI Rail Crossing Operational State Railroad Highway Yes

9.4.41 HRI Approaching Train Information Railroad Highway No

9.1.41 HRI Approaching Train Information Request Railroad Highway No

9.4.42* HRI Wayside Equipment Status Railroad Highway No

9.1.42* HRI Wayside Equipment Status Request Highway Railroad No

9.4.43 HRI Roadway Obstacle Detection State Highway Railroad Yes

9.4.44* HRI ATC Equipment Status Highway Railroad No

9.1.44* HRI ATC Equipment Status Request Highway Railroad No

9.4.45 HRI User-Specifi c Wayside Message Railroad Highway No

9.1.45 HRI User-Specifi c Wayside Message Request Highway Railroad No

9.4.46 HRI User-Specifi c ATC Message Highway Railroad No

9.1.46 HRI User-Specifi c ATC Message Request Railroad Highway No

*Reserved for future use

HRI Rail Crossing Operational State (9.4.40)

This message is transmitted from the railroad system to the highway system and is defi ned as a 

safety-critical message. The message is sent at a frequency of once per second, and is called 

the vital heartbeat message from the wayside system. Byte 0 of the message data includes a fi eld 

named RHBA, for receiving vital heartbeat (9.4.43) from the ATC system. The status of this fi eld will 

be either ‘0’ for “Not Receiving Message 9.4.43” or ‘1’ for “Receiving Message 9.4.43”. The defi nition 

of receiving or not receiving is determined locally and should be defi ned by the equipment 

manufacturers or the highway agency and railroad. Receipt of the vital heartbeat message from the 

ATC system, as well as the highway system’s receipt of the wayside vital heartbeat message within the 

specifi ed allowable time, represents the vitality of the HRI interface.

Also included in byte 0 of the message data is the number of crossings. The standard is defi ned 

for 1 to 8 crossings, each of which may contain from 1 to 8 tracks and up to a maximum of 8 trains 

associated with each crossing. The overall message length is dependent on the number of crossings 

and the number of trains associated with each of those crossings. Bytes 1 through 7 are repeated 

for each crossing, and bytes 5 through 7 are repeated for each train associated with each of the 

crossings. Other fi elds defi ned in this message include:

• Crossing sequence number

• Number of trains associated with this crossing

• System Operational (SO)

• Train Presence Detection (TPD)

• Warning System Active (WSA)

• Preemption Warning Active (PEA)

• Exit Gate Present (XGP)

• Exit Gate Up (XGU)
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• Exit Gate Down (XGD)

• Entrance Gate Present (NGP)

• Entrance Gate Up (NGU)

• Entrance Gate Down (NGD)

• Preemption Design Time

• Train Sequence Number

• Direction (DIR) - Direction of the train

• Island Occupied (ICO)

• Warning System Activation Design Time

• Estimated Time to Warning System Activation

Note that not all of these fi elds are required for use as outlined in this section.

HRI Roadway Obstacle Detection State (9.4.43)

This message is transmitted from the roadway system to the railroad system and is defi ned as a 

safety-critical message. The message is sent at a frequency of once per second, and is called the 

vital heartbeat message from the ATC system. Byte 0 of the message data includes a fi eld named 

RHBW, for receiving vital heartbeat (9.4.40) from the wayside system. The status of this fi eld will be 

either ‘0’ for “Not Receiving Message 9.4.40” or ‘1’ for “Receiving Message 9.4.40”. The defi nition 

of receiving or not receiving is determined locally and should be defi ned by the equipment 

manufacturers or the highway agency and railroad. Receipt of the vital heartbeat message from the 

wayside system, as well as the railroad system’s receipt of the ATC vital heartbeat message within the 

specifi ed allowable time, represents the vitality of the HRI interface.

This message also provides safety-critical crossing obstacle information to the railroad system. The 

information fi elds defi ned in the message include:

• Vehicle present with gate down (VP)

• Long term obstacle indicator (LTI)

• Vehicle arrestor barrier status (VAS)

• Roadway system operational (RSO)

It is noted that the standard is not intended to defi ne the functionality of obstacle detection; it is only 

intended to provide a framework for transferring such information to the railroad system should any 

obstacle detection exist. The specifi c functionality should be agreed upon by the highway agency 

and railroad. Obstacle detection functionality is not required for event recording as defi ned in this 

section.

HRI User-Specifi c Wayside Message (9.4.45)

This message is transmitted from the railroad system to the highway system and can be defi ned as 

either an informational message or as a safety-critical message. The highway agency and railroad 

should jointly determine the message defi nition. Transmission of the message can be defi ned 

as either on request or on a periodic basis. Therefore, the message frequency should also be 

determined and agreed upon by the highway agency and railroad. If the message is sent upon 
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

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request, the defi ned HRI User-Specifi c Wayside Message Request (9.1.45) will be used. This is a one 

byte query message sent from the ATC system to the wayside system to request that the wayside 

system send the HRI User-Specifi c Wayside Message (9.4.45).

The data content and format of the user-specifi c message should be defi ned by the highway agency 

and railroad. Additionally, the highway agency and/or railroad should specify data fi elds in this 

message to include the following information:

• Lock out protection

• Power (On/Off)

• Entrance alarm (Open/Closed)

This message data is required in order to monitor and record several of the events described in 

“Events”. The highway and railroad equipment used to communicate these messages, as well as 

the event recording devices used to monitor these messages, should be programmed to support the 

user-specifi c message settings.

HRI User-Specifi c ATC Message (9.4.46)

This message is transmitted from the highway system to the railroad system and can be defi ned as 

either an informational message or as a safety-critical message. The highway agency and railroad 

should jointly determine the message defi nition. Transmission of the message can be defi ned 

as either on request or on a periodic basis. Therefore, the message frequency should also be 

determined and agreed upon by the highway agency and railroad. If the message is sent upon 

request, the defi ned HRI User-Specifi c ATC Message Request (9.1.46) will be used. This is a one byte 

query message sent from the wayside system to the ATC system to request that the ATC system send 

the HRI User-Specifi c ATC Message (9.4.46).

The data content and format of the user-specifi c message should be defi ned by the highway agency 

and railroad. Additionally, the highway agency and/or railroad should specify data fi elds in this 

message to include the following information:

• Preempt in (Field termination)

• Preempt in (Traffi c controller input)

• Vehicle and pedestrian signal circuits

• Signal/Flash

• Cabinet electrical service

• Main cabinet door status

This message data is required in order to monitor and record several of the events described in 

“Events”. The highway and railroad equipment used to communicate these messages, as well as 

the event recording devices used to monitor these messages, should be programmed to support the 

user-specifi c message settings.

49 CFR 236 Subpart H Requirements

The primary purpose of the safety-critical interconnection interface between the highway and 

railroad systems of a highway-rail grade crossing is to preempt highway traffi c signal operation in 

order to clear traffi c from the crossing as a train approaches. As required by Federal regulations, 

this existing interface is designed to meet both fail-safe and closed loop principles. Section 8C.09 
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of the MUTCD specifi es, “This preemption feature shall have an electrical circuit of the closed-circuit 

principle, or a supervised communication circuit between the control circuits of the highway-rail 

grade crossing warning system and the traffi c control signal controller.” Part 16.30.10 of the AREMA 

C&S Manual (9) states that, “The interconnection between the traffi c control signal and the railroad 

warning system shall be a double break relay circuit or serial data circuit in accordance with IEEE 

Standard 1570-2002.” New systems should also provide fail-safe supervision of the vital preemption 

functions to be carried out using the serial communication interface specifi ed in IEEE Standard 1570. 

49 CFR 234.275 states that, “Highway-rail grade crossing warning systems, subsystems, or components 

that are processor-based and that are fi rst placed into service after June 6, 2005, which contain 

new or novel technology, or which provide safety-critical data to a railroad signal or train control 

system that is governed by part 236, subpart H or I, of this chapter, shall also comply with those 

requirements. New or novel technology refers to a technology not previously recognized for use as of 

March 7, 2005.”

New systems using the IEEE Standard 1570 interconnection interface between the highway and 

railroad systems are subject to the requirements of 49 CFR 236 Subpart H. 49 CFR 236 Subpart 

H specifi es the minimum performance standards for safety-critical products. This includes the 

requirements railroads are subject to for development, installation, implementation, inspection, 

testing, operation, maintenance, repair, and modifi cation of safety-critical products. Additionally, 

49 CFR 236 Subpart H contains a detailed explanation of the required fi ling and approval processes 

for Railroad Safety Program Plans (RSPPs) and Product Safety Plans (PSPs). It also specifi es product 

implementation procedures, operation requirements, testing and records recording requirements 

for safety-critical products, and the requirements of training and qualifi cation programs for these 

products. Supervisory components and acceptable message frequencies of the IEEE Standard 1570 

communication interface should be specifi ed in the RSPP and PSP.

Each railroad subject to this subpart must submit a RSPP to the FRA for approval. The RSPP is the 

principal safety document for all safety-critical products and it must establish the minimum PSP 

requirements that will govern the development and implementations of the safety-critical products. 

These plans must include complete descriptions of the preliminary safety analysis, including the 

methods used to evaluate a system’s behavioral characteristics, the risk assessment procedures, 

the system safety precedence followed, and identifi cation of the safety assessment process. A RSPP 

also requires identifi cation of verifi cation and validation methods, including the standards to be 

used in this process. Finally, the RSPP requires a description of the process used to identify human 

factors issues and development of design requirements to address those issues, as well as to specify 

requirements for product confi guration management. Railroads should consult 49 CFR 236.905 for a 

complete description of the contents required in a RSPP.

Railroads must also submit a PSP for each new product subject to 49 CFR 236 Subpart H. The 

PSP must provide complete descriptions of the product and all of its components, the railroad 

operation(s) it is intended for, the product operational concepts, and safety requirements. The PSP 

also must include all safety assessment, verifi cation and validation processes and the associated 

results, a hazard mitigation analysis, a risk assessment, description of the safety assurance concepts, 

and a human factors analysis. Complete descriptions of the specifi c training for railroad employees 

and contractors and of the specifi c procedures and test equipment needed to ensure safe and 

proper installation, implementation, operation, maintenance, repair, inspection, testing, and 

modifi cation are also required to be included in a PSP. Among several other requirements, a PSP 

must also include, for each of the requirements of 49 CFR 234, an explanation of how the product 

meets the requirement, why the requirement is not applicable to the product design, or how the new 

product satisfi es the requirement using alternative methods. Railroads should consult 49 CFR 236.907 

for a complete description of the contents required in a PSP.
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26

As stated in 49 CFR 236.909, the minimum performance standard for products covered by this 

subpart is that, “The safety analysis included in the railroad’s PSP must establish with a high degree of 

confi dence that introduction of the product will not result in risk that exceeds the previous condition. 

The railroad shall determine, prior to fi ling its petition for approval or informational fi ling, that this 

standard has been met and shall make available the necessary analyses and documentation as 

provided in this subpart.” This section also explains the requirements for full and abbreviated risk 

assessments that must be completed to support the minimum performance standard.

Full risk assessments are required to address the safety factors associated with the introduction, 

modifi cation, replacement, or enhancement of safety-critical products. This includes any risks from 

the previous condition that are no longer present as a result of the new product or change, new risks 

associated with the changed or new product, and risks that are not affected. 49 CFR 236 Appendix 

B contains the specifi c requirements of a full risk assessment. An abbreviated risk assessment may 

be submitted instead of a full risk assessment if there are no new hazards introduced as result of the 

change, and there is not an increase in hazard severity or exposure from the previous condition. 

Railroads should consult 49 CFR 236.909 for specifi c requirements of an abbreviated risk assessment 

to support the minimum performance standard.

Event Recording

New system confi gurations should include an event recording device to monitor the communication 

between the highway and railroad systems. The recording device(s) should be connected to the 

communication interface between the ATC gateway in the highway traffi c signal controller cabinet 

and the wayside gateway in the railroad grade crossing equipment bungalow, and should monitor 

the messages sent between the two systems. Event recorders installed should be able to process the 

IEEE Standard 1570 messages in order to monitor the status of the various highway traffi c signal and 

railroad grade crossing subsystems and record the required events, as necessary. The proposed 

minimum required events to record are listed below with a general description and an explanation 

of the associated IEEE Standard 1570 message and message fi eld that contains the information 

required for a recorded event.

Highway Events

1. Roadway System Operational

The health of the highway traffi c signal system should be monitored using message 9.4.43. 

In this message, the Roadway System Operational (RSO) fi eld represents an overall health 

check to show that the highway system is operational. This message should be monitored 

for a change in status between “System Operational” and “System Not Operational”. In the 

occurrence that the highway system is not operational, an event record should be created 

and an alarm reported.

2. Preempt In

This should record the change in state of preemption controller input based on the MUTCD 

standard hierarchy (drawbridge, railroad, emergency, transit). Specifi c to rail operation, 

there should be one input for each rail preemption circuit entering the highway traffi c signal 

controller cabinet.

Field Termination should record the fi rst electrical termination in the highway traffi c signal 

controller cabinet from the rail control circuit. A change in status at the fi rst electrical 

termination in the highway traffi c signal controller cabinet should be recorded as an event. 

This will identify if an active preemption call was received by the highway traffi c signal 

controller cabinet assembly from the railroad control system. The status of the preemption fi eld 

termination should be included in message 9.4.46 as defi ned by the highway agency.
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Traffi c Controller Input should record the electrical termination in the highway traffi c signal 

controller cabinet as it provides the preemption input to the highway traffi c signal controller. 

A change in status of the preemption input into the highway traffi c signal controller should 

be recorded as an event. This will identify if an active preemption call was properly routed 

through interface circuitry to initiate a valid preemption sequence. The status of the 

preemption traffi c controller input should be included in message 9.4.46 as defi ned by the 

highway agency.

3. Vehicle/Pedestrian Signal

This should record phases, overlaps, and displays for vehicle and pedestrian signals. Circuit 

status should be provided at the termination point used for connecting the highway traffi c 

signal control system with vehicle and pedestrian signal displays (“green”, “walk”, etc.). This 

information should be logged for a time period of at least 60 seconds, but not less than the 

highway traffi c signal cycle length, prior to a rail preemption call and for an equal time period 

after the call for rail preemption is terminated. The status of the vehicle/pedestrian signals 

should be included in message 9.4.46 as defi ned by the highway agency.

4. Right-of-Way Transfer Time

This should record the status of the right-of-way transfer time in the highway traffi c signal 

preemption sequence. The right-of-way transfer time is the amount of time needed for the 

highway traffi c signal equipment to react to a preemption call plus any green, yellow, red, 

pedestrian walk, and pedestrian clearance time prior to the track clearance green interval. 

The status of the right-of-way transfer time (when it commences and terminates) should be 

included in message 9.4.46 as defi ned by the highway agency.

5. Track Clearance Green Interval

This should record the status of the track clearance green interval in the highway traffi c signal 

preemption sequence. The track clearance green interval is the portion of the highway 

traffi c signal sequence after completion of the right-of-way transfer time when the green 

signal indications are displayed to roadway users in order to vacate the highway-rail grade 

crossing based on the minimum track clearance distance. The status of the track clearance 

green interval (when it commences and terminates) should be included in message 9.4.46 as 

defi ned by the highway agency.

6. Flash Operation

This should distinguish between conditions upon which an intersection operates in fl ash 

mode: confl ict monitor trigger, manual switch trigger, or time of day programming trigger. In 

confl ict monitor or manual switch mode, the highway traffi c signal controller cannot initiate 

the preemption sequence. In time of day mode, the highway traffi c signal controller can 

initiate the preemption sequence. The input provided from the highway traffi c signal controller 

cabinet electrical bus connected to fl ash transfer relays should be monitored and a change 

in status should be recorded as an event. The status information for fl ash operation should be 

included in message 9.4.46 as defi ned by the highway agency.

7. Cabinet Electrical Service

This requires monitoring for deviations in electrical service voltages that would trigger the 

confl ict monitor/malfunction management unit. Any deviation in the electrical service 

triggering the confl ict monitor/malfunction management unit as defi ned by the highway 

agency should be recorded as an event. This serves to identify the stability of electrical 

service. This information for the highway traffi c signal controller cabinet electrical service 

should be included in message 9.4.46 as defi ned by the highway agency.
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8. Main Cabinet Door(Open/Closed)

This requires monitoring of highway traffi c signal controller cabinet access, prompting further 

examination of the various devices and data programming to determine if changes have 

been made. This is particularly benefi cial if the highway traffi c signal controller cabinet has 

been accessed in between inspections. The input should be provided through an appropriate 

electrical switch connected to the main cabinet door that detects a change in status between 

when the door is opened or closed. A change in status between “Open” and “Closed” should 

create an event record and an alarm reported. The status information for main cabinet door 

should be included in message 9.4.46 as defi ned by the highway agency.

Railroad Events

1. Supervisory Circuit

The vitality of the highway-rail grade crossing preemption circuit should be supervised by 

monitoring the status of the receiving vital heartbeat fi elds in messages 9.4.40 and 9.4.43, 

which are each sent once per second between the ATC and wayside systems.

The RHBA fi eld in the message 9.4.40 indicates if the wayside system is receiving the vital 

heartbeat (9.4.43) from the ATC system. This message should be monitored for a change in 

status between “Receiving Message 9.4.43” and “Not Receiving Message 9.4.43”.

The RHBW fi eld in message 9.4.43 indicates if the ATC system is receiving the vital heartbeat 

(9.4.40) from the wayside system. This message should be monitored for a change in status 

between “Receiving Message 9.4.40” and “Not Receiving Message 9.4.40”.

In the occurrence that one of these messages is not received within a certain time interval 

as determined by the highway agency and railroad and a change in status occurs, an 

event record should be created and an alarm reported. This supervisory component of the 

system should meet the requirements of 49 CFR 236 Subpart H (see “49 CFR 236 Subpart H 

Requirements”).

2. Railroad System Operational

The health of the railroad grade crossing warning system should be monitored using message 

(9.4.40). In this message, the System Operational (SO) fi eld represents an overall health 

check to show that the railroad system is operational. This message should be monitored 

for a change in status between “System Operational” and “System Not Operational”. In the 

occurrence that the railroad system is not operational, an event record should be created and 

an alarm reported.

3. Railroad Preemption Request

The preemption request from the wayside system to the ATC system is contained in message 

9.4.40. The Preemption Warning Active (PEA) fi eld(s) of the message should be monitored for 

a change in status between “Active” and “Not Active”. A change in status of this fi eld should 

be recorded as an event. This recorded event serves to identify when an active railroad 

preemption call was placed.

4. Approach Circuits

Train presence detection (TPD) information for each crossing track is contained in message 

9.4.40. The TPD fi eld(s) of the message should be monitored for each track crossing included 

in the message. A change in status between “Train Present” and “No Train Present” should be 

recorded as an event. This recorded event serves to identify when a train has been detected 

on an approach of any of the crossing tracks.
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5. Railroad Crossing Relay

The railroad crossing relay (XR) controls when the active grade crossing warning systems are 

operational. For newer systems, the grade crossing controller processors carry out the function 

of the railroad crossing relay by assigning variables in a logical expression to set the status 

of the grade crossing warning system. The status information of the grade crossing warning 

system is contained in message 9.4.40. The Warning System Active (WSA) fi eld(s) should be 

monitored for a change in status between “Activated” and “Not Activated”. This recorded 

event serves to identify when the railroad grade crossing warning system is in an operational 

state (e.g., lights fl ashing, bells ringing).

6. Entrance Gate Status

Entrance gate status information is contained in message 9.4.40. The Entrance Gate Present 

(NGP) fi eld of the message indicates if entrance gates are present at the crossing and can 

either have a status of “Entrance Gate(s) Present” or “Entrance Gate(s) Not Present”. In the 

occurrence that there is a change in status, an event record should be created and an alarm 

reported.

The Entrance Gate Up (NGU) and Entrance Gate Down (NGD) fi elds should be monitored 

for a change in status. For the NGU fi eld, a change in status between “Entrance Gate(s) Up” 

and “Entrance Gate(s) Not Up” should be recorded as an event. For the NGD fi eld, a change 

in status between “Entrance Gate(s) Down” and “Entrance Gate(s) Not Down” should be 

recorded as an event.

7. Exit Gate Status (if present)

Exit gate status information is contained in message 9.4.40. The Exit Gate Present (XGP) fi eld of 

the message indicates if exit gates are present at the crossing and can either have a status of 

“Exit Gate(s) Present” or “Exit Gate(s) Not Present”. In the occurrence that there is a change in 

status, an event record should be created and an alarm reported.

The Exit Gate Up (XGU) and Exit Gate Down (XGD) fi elds should be monitored for a change 

in status. For the XGU fi eld, a change in status between “Exit Gate(s) Up” and “Exit Gate(s) 

Not Up” should be recorded as an event. For the XGD fi eld, a change in status between “Exit 

Gate(s) Down” and “Exit Gate(s) Not Down” should be recorded as an event.

8. Island Circuit Occupancy

Island circuit occupancy information for each crossing track is contained in message 9.4.40. 

The Island Occupied (ICO) fi eld(s) of the message should be monitored for each track 

crossing included in the message. A change in status between “Island Circuit Occupied” and 

“Island Circuit Unoccupied” should be recorded as an event.

9. Train Direction

Traditionally, the direction of a train movement is determined by the status of the directional 

stick relays on each track. For newer systems, the railroad grade crossing controller processors 

carry out the function of the directional stick relays by assigning them as variables in a logical 

expression relating train presence detection on the approach and island circuits to the train’s 

direction. Once a train has been detected on an approach circuit and an island circuit 

consecutively, the train’s direction is determined and the appropriate directional stick variable 

is set to indicate the direction of the train’s movement.

The directional information of each train movement is contained in the Direction (DIR) fi eld(s) 

of message 9.4.40. A change in status between “Unknown”, “Heading East/North” and 

“Heading West/South” should be recorded as an event. A status of “Unknown” is the default 
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

30

when there is no current train movement. The directional designations do not indicate the 

geographical direction of movement, but refer to the directional designation for the track as 

defi ned on the railroad’s track plans.

10. Lock Out Protection

Lock out protection should be provided for each train movement through a highway-rail grade 

crossing. After a train movement has completed, if the trailing circuit does not clear after 

a preset time interval, an event should be created and an alarm reported. This information 

should be included in message 9.4.45 defi ned by the operating railroad.

11. Power(On/Off)

This requires the electrical power source for the railroad grade crossing equipment bungalow 

to be monitored. The power off relay (POR) switches the power source that feeds the 

bungalow. When there is a loss of power, the POR drops to switch to the battery power supply. 

A change in status of the power off relay (when it drops or picks up) should be recorded as an 

event and an alarm reported. Additionally, any changes in voltages that would result in an 

alarm being reported, as determined by the operating railroad, should create an event record. 

This information should be included in message 9.4.45 as defi ned by the operating railroad.

12. Entrance Alarm (Open/Closed)

This requires the bungalow door switch to be monitored for a change in status between 

“Open” and “Closed”. A change in status should create an event record and an alarm 

reported. This may require the installation of an electrical switch in existing railroad grade 

crossing equipment bungalows that changes state when the door is opened and closed. This 

event record would allow the railroad to determine when the bungalow has been accessed, 

fl agging the potential necessity for further examination of various devices and programming. 

The status of the bungalow door should be included in message 9.4.45 as defi ned by the 

operating railroad.

Figure 5 illustrates the sequence of railroad events to be recorded for each train movement through 

the highway-rail grade crossing.
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

31

Figure 5: Railroad Events to be Recorded for each Train Movement
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

32

Alarm Reporting

In addition to monitoring the IEEE Standard 1570 messages and recording the required events, the 

device should be able to process this information in order to fl ag recorded events and/or report 

alarms. Event recorders should use user-specifi c logical expressions to relate fi elds of various 

IEEE Standard 1570 messages to determine that the highway and railroad systems are working 

as designed. As defi ned by the highway agency and/or railroad, any recorded event or logical 

combination of events should be fl agged as an alarm. A list of situations that should result in the 

reporting of an alarm along with explanations of how they can be determined is provided below. 

At a minimum, fl agging event records will allow highway agency and/or railroad personnel to 

determine if a problem exists at a crossing during regular maintenance or inspections.

The following is a list of proposed situations for which an alarm should be reported. These alarms 

should be determined by monitoring the recorded events or IEEE Standard 1570 messages previously 

described. Event recorders should be capable of processing and relating the fi elds of each 

recorded event or IEEE Standard 1570 message described in order to trigger the alarm(s).

1. Event records indicate that the vital heartbeat message from the ATC system is not being 

received by the wayside system or the vital heartbeat message from the wayside system is not 

being received by the ATC system. This should be determined by monitoring the RHBA fi eld of 

message 9.4.40 and the RHBW fi eld of message 9.4.43. If the status of the RHBA or RHBW fi elds 

changes from ‘1’ to ‘0’, indicating one of the vital heartbeat messages has not been received 

by the opposite system, then an alarm should be reported.

2. Event records indicate that the highway or railroad system is not operational. This should be 

determined by monitoring the SO fi eld in message 9.4.40 and the RSO fi eld in message 9.4.43. 

If the status of the SO or RSO fi elds changes from ‘1’ to ‘0’, indicating one of the systems is not 

operational, then an alarm should be reported.

3. Event records indicate that the railroad preemption request is not being sent prior to the 

design preemption warning time. The preemption warning time provided for a particular train 

movement should be determined using the recorded time stamps of message 9.4.40 for when 

the status of the PEA fi eld(s) changes from ‘0’ to ‘1’ (preemption warning is active) and when 

the status of the ICO fi eld(s) changes from ‘0’ to ‘1’ (island circuit or the crossing is occupied). 

If the preemption warning time provided is less than the time specifi ed in the Preemption 

Design Time fi eld of message 9.4.40, then an alarm should be reported.

4. Event records indicate that a train is being detected on an approach circuit and the 

associated island circuit; however, there is no recorded event for a railroad preemption 

request. This is determined by comparing the TPD, ICO, and PEA fi elds of message 9.4.40. If 

the status of the TPD and ICO fi elds changes from ‘0’ to ‘1’ (train has been detected on an 

approach and associated island circuit) and the PEA fi eld remains at ‘0’ (preemption was not 

requested), then an alarm should be reported.

5. Event records indicate that the highway traffi c signal controller did not receive or did not act 

on the receipt of a preemption request. This is determined by comparing the PEA fi eld of 

message 9.4.40 and the Preempt In (Field Termination/Traffi c Controller Input) fi elds in message 

9.4.46. If the status of the PEA fi eld changes from ‘0’ to ‘1’ (railroad system has requested 

preemption), but the status of the Preempt In (Field Termination) fi eld does not indicate receipt 

of the preempt request or the status of the Preempt In (Traffi c Controller Input) does not 

indicate a valid preemption call into the highway traffi c signal controller, then an alarm should 

be reported.
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

33

6. Event records indicate that the grade crossing warning system is not being activated before 

the specifi ed warning time. The warning time provided for a particular train movement should 

be determined using the recorded time stamps of message 9.4.40 when the status of the WSA 

fi eld(s) changes from ‘0’ to ‘1’ (warning system is active) and when the status of the ICO fi eld(s) 

changes from ‘0’ to ‘1’ (island circuit or crossing is occupied). If the warning time provided 

is less than the time specifi ed in the Warning System Activation Design Time fi eld of message 

9.4.40, then an alarm should be reported. 49 CFR 234.225 requires activation of the grade 

crossing warning system to occur at least 20 seconds prior to a train occupying the highwayrail grade crossing.

7. Event records indicate that the entrance gate(s) begins to descend prior to the required 

minimum of three seconds after the grade crossing warning system is activated and the 

fl ashing lights begin to operate (49 CFR 234.223). This should be determined by comparing the 

recorded time stamps of message 9.4.40 when the status of the NGU and WSA fi elds change. 

If the status of the NGU fi eld changes from ‘1’ to ‘0’ (entrance gate(s) is no longer up) less than 

three seconds after the WSA fi eld changes from ‘0’ to ‘1’ (warning system is active), then an 

alarm should be reported.

8. Event records indicate that the entrance gate(s) reach horizontal position after the required 

minimum of fi ve seconds prior to a train arriving at the highway-rail grade crossing. This should 

be determined by comparing the recorded time stamps of message 9.4.40 when the status 

of the NGD and ICO fi elds change. If the status of the ICO fi eld changes from ‘0’ to ‘1’ (island 

circuit or crossing is occupied) less than fi ve seconds after the NGD fi eld changes from ‘0’ to ‘1’ 

(entrance gate(s) is down), then an alarm should be reported.

9. Event records indicate that the exit gate(s) begins to descend prior to the completion of the 

track clearance green interval, potentially trapping vehicles within the highway-rail grade 

crossing. This should be determined by comparing the XGU fi eld of message 9.4.40 and the 

track clearance green interval status in message 9.4.46. If the XGU fi eld changes from ‘1’ to ‘0’ 

(exit gate(s) is no longer up) before an indication that the track clearance green interval has 

terminated, then an alarm should be reported.

10. Event records indicate that an entrance or exit gates(s) has left the vertical position but there 

is no recorded event indicating the gate(s) has reached the horizontal position within a preset 

time interval. This should be determined by comparing the recorded time stamps of message 

9.4.40 when the status of the entrance or exit gate(s) up and down fi elds change. If the status 

of either the NGU or XGU fi elds change from ‘1’ to ‘0’ (entrance or exit gate(s) have left the 

vertical position) and there is no recorded event showing the status of the respective NGD or 

XGD fi elds changing from ‘0’ to ‘1’ before a present time interval, then an alarm should be 

reported.

Alternately, event records indicate that an entrance or exit gate(s) has left the horizontal 

position but there is no recorded event indicating the gate(s) has reached the vertical position 

within a preset time interval. If the status of either the NGD or XGD fi elds change from ‘1’ to 

‘0’(entrance or exit gate(s) have left the horizontal position) and there is no recorded event 

showing the status of the respective NGU or XGU fi elds changing from ‘0’ to ‘1’ before a present 

time interval, then an alarm should be reported. Part 3.3.30 of the AREMA Communications 

& Signals Manual of Recommended Practice (C&S Manual) states that gate arms should fully 

raise in no more than 12 seconds, or as instructed.
Recording Devices for Interconnected Grade Crossing and Intersection Signal Systems: An Informational Report

34

Finally, event records indicate that an entrance or exit gate(s) is in both the vertical and 

horizontal position in the same message. If the status of the NGU or XGU is ‘1’ (entrance or 

exit gate(s) is in the vertical position) and the status of the NGD or XGD is ‘1’ (entrance or exit 

gate(s) is also in the horizontal position), then an error has occurred and an alarm should be 

reported.

11. Event records indicate that the right-of-way transfer time is longer than the design right-of-way 

transfer time. This should be determined by comparing the recorded time stamps of message 

9.4.46 when the status of the right-of-way transfer time indicates it commences and terminates. 

If the right-of-way transfer time is longer that the design maximum right-of-way transfer time, 

then an error has occurred and alarm should be reported.

12. Event records indicate that the track clearance green interval is less than the design track 

clearance green interval. This should be determined by comparing the recorded time 

stamps of message 9.4.46 when the status of the track clearance green interval indicates it 

commences and terminates. If the track clearance green interval is less than the design track 

clearance green interval, then an error has occurred and an alarm should be reported.

13. Event records indicate that the amount of time from the start of the track clearance green 

interval to train presence detection on an island circuit is less than the design track clearance 

green interval. This should be determined by comparing the recorded time stamps of 

message 9.4.46 when the status of track clearance green interval indicates it commences and 

of message 9.4.40 when the status of the ICO fi eld changes to ‘1’ (island circuit is occupied). If 

the time between the start of track clearance green and island circuit occupancy is less than 

the design track clearance green interval, then an error has occurred and an alarm should be 

reported.

14. Event records indicate train presence detection on an island circuit, but there is no event 

record indicating the termination of the track clearance green interval. This should be 

determined by comparing the status of the ICO fi eld of message 9.4.40 and the status of 

the track clearance green interval fi eld of message 9.4.46. If the status of the ICO fi eld is ‘1’ 

(island circuit is occupied) before an indication that the track clearance green interval has 

terminated, then an error has occurred and an alarm should be reported.

15. Event records indicate train presence detection on an approach and an island circuit, but 

does not indicate the train direction; or event records indicate a train direction when no train 

was detected, signifying a possible electrical problem with the circuits or relays. This should be 

determined by comparing the status of the TPD, ICO, and DIR fi elds of message 9.4.40. If the 

status of the TPD fi eld is ‘1’ (train is present on an approach or island circuit), the status of the 

ICO fi eld is ‘1’ (respective island circuit is occupied), and the status of the DIR fi eld is ‘2’ (train 

direction is unknown), then an alarm should be reported. Alternatively, if the status of the DIR 

fi eld is a ‘0’ or ‘1’ (train direction), but the status of both the TPD and ICO fi elds are not ‘1’, then 

an alarm should be reported.

16. Event records indicate lock out protection is being provided on a particular track approach. 

If it is indicated that lock out protection is being provided in message 9.4.45, than an alarm 

should be reported.

17. Event records indicate a loss of primary power, a switch to battery power, or changes in 

voltages. This should be determined by monitoring the Power (On/Off) fi eld of message 9.4.45. 

If the status of the Power (On/Off) fi eld changes, then an alarm should be reported.
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18. Event records indicate that either the highway traffi c signal controller cabinet or railroad grade 

crossing equipment bungalow door has been opened, allowing access to the equipment and 

settings. This should be determined by monitoring the Main Cabinet Door (Open/Closed) fi eld 

of message 9.4.46 or the Entrance Alarm (Open/Closed) fi eld of message 9.4.45. If the status 

of either fi elds change, then an alarm should be reported.

3.1.1 HYBRID SYSTEMS

“Hybrid” systems are existing systems having some level of event recording and/or processing 

capabilities. This includes a wide variety of existing system confi gurations of varying age and 

technology capabilities of technology in both the highway and railroad systems.

Highway agencies and railroads should jointly determine if they will upgrade their respective systems 

to support the IEEE Standard 1570 serial communication interface. The upgrade would require 

updating various existing equipment executive software and programs to generate and process 

the defi ned ATC and wayside messages. In some instances, upgrades may require completely new 

installations. In either case, the requirements of 49 CFR 236 Subpart H will need to be met.

Existing event recording devices may also require updates to their executive software or programs 

to support IEEE Standard 1570. The event recording devices should be able to monitor the status 

of message fi elds being sent across the serial communication interface between the highway and 

railroad gateway devices. This allows events to be recorded and alarms to be reported. If necessary, 

the communications capabilities of the event recording devices may need upgrading to support the 

transfer of events associated with alarms to a central offi ce database.

If highway agencies and railroads do not jointly upgrade their respective equipment to support IEEE 

Standard 1570, then their systems should support a minimum level of monitoring, event recording, 

and alarm reporting required of legacy systems (see “Legacy Systems”). Highway agencies and 

railroads may consider future upgrades to support communication capabilities using IEEE Standard 

1570.

Figure 6 shows a functional block diagram of a typical hybrid system confi guration.
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Figure 6: Hybrid System Confi guration Functional Block Diagram
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3.1.2 LEGACY SYSTEMS

“Legacy” systems are existing systems having no event recording and/or processing capabilities. 

These systems will need to be modifi ed to include new event recording equipment capable of future 

communication via IEEE Standard 1570.

Figure 7 shows a functional block diagram of a typical legacy system confi guration.
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Figure 7: Legacy System Confi guration Functional Block Diagram
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Event Recording

Legacy system confi gurations should be equipped with an event recording device to monitor the 

highway and railroad systems. The recording device(s) should be capable of supporting IEEE 

Standard 1570 serial communication should the location receive future upgrades utilizing this 

interface. The recording device(s) should support the number of digital and analog inputs required 

to monitor the highway and railroad. Event recorders should be able to process the various digital 

and analog inputs to monitor the status of the highway traffi c signal and railroad grade crossing 

equipment and record the required events as necessary. The minimum events to record, along with 

explanations, is provided below. These events/circuits are intended for those existing systems that are 

currently incapable of and/or not utilizing the IEEE Standard 1570 communication protocol.

Highway Events

1. Preempt Active/Inactive

This should record the change in state of preemption controller input based on the MUTCD 

standard hierarchy (drawbridge, railroad, emergency, transit). Specifi c to rail operation, 

there should be one input for each rail preemption circuit entering the highway traffi c signal 

controller cabinet.

Field Termination should record the fi rst electrical termination in the highway traffi c signal 

controller cabinet from the rail control circuit. A change in status at the fi rst electrical 

termination in the highway traffi c signal controller cabinet should be recorded as an event. 

This will identify if an active preemption call was received by the highway traffi c signal 

controller cabinet assembly from the railroad control system.

Traffi c Controller Input should record the electrical termination in the highway traffi c signal 

controller cabinet as it provides the preemption input to the highway traffi c signal controller. 

A change in status of the preemption input into the highway traffi c signal controller should 

be recorded as an event. This will identify if an active preemption call was properly routed 

through interface circuitry to initiate a valid preemption sequence.

2. Vehicle/Pedestrian Signal

This should record phases, overlaps, and displays for vehicle and pedestrian signals. Circuit 

status should be provided at the termination point used for connecting the highway traffi c 

signal control system with vehicle and pedestrian signal displays (“green”, “walk”, etc.). This 

information should be logged for a time period of at least 60 seconds, but not less than the 

highway traffi c signal cycle length, prior to a rail preemption call and for an equal time period 

after the call for rail preemption is terminated.

3. Right-of-Way Transfer Time

This should record the status of the right-of-way transfer time in the highway traffi c signal 

preemption sequence (when it commences and terminates). The right-of-way transfer time is 

the amount of time needed for the highway traffi c signal equipment to react to a preemption 

call plus any green, yellow, red, pedestrian walk, or pedestrian clearance time prior to the 

track clearance green interval.

4. Track Clearance Green Interval

This should record the status of the track clearance green interval in the highway traffi c signal 

preemption sequence (when it commences and terminates). The track clearance green 

interval is the portion of the traffi c signal sequence after completion of the right-of-way transfer 

time when the green signal indications are displayed to roadway users in order to vacate the 

highway-rail grade crossing based on the minimum track clearance distance.
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5. Flash Operation

This should distinguish between conditions upon which an intersection operates in fl ash 

mode: confl ict monitor trigger, manual switch trigger, or time of day programming trigger. In 

confl ict monitor or manual switch mode, the highway traffi c signal controller cannot initiate 

the preemption sequence. In time of day mode, the highway traffi c signal controller can 

initiate the preemption sequence. The input provided from the highway traffi c signal controller 

cabinet electrical bus connected to fl ash transfer relays should be monitored and a change in 

status should be recorded as an event.

6. Cabinet Electrical Service

This requires monitoring for deviations in electrical service voltages that would trigger the 

confl ict monitor/malfunction management unit. Any deviation in the electrical service 

triggering the confl ict monitor/malfunction management unit, as defi ned by the highway 

agency, should be recorded as an event. This serves to identify the stability of electrical 

service.

7. Main Cabinet Door(Open/Closed)

This requires monitoring of highway traffi c signal controller cabinet access, prompting further 

examination of the various devices and data programming to determine if changes have 

been made. This is particularly benefi cial if the highway traffi c signal controller cabinet has 

been accessed in between inspections. The input should be provided through an appropriate 

electrical switch connected to the main highway traffi c signal controller cabinet door that 

detects change in status between when the door is opened or closed. A change in status 

between “Open” and “Closed” should create an event and an alarm reported.

Railroad Events

1. Railroad Preemption Request

This requires the railroad preemption relay (PER) to be monitored for a change in status (when 

the relay drops or picks up) and record it as an event. This recorded event serves to identify 

when an active railroad preemption call was placed.

Some highway-rail grade crossings may have a second preemption relay installed in order to 

send an additional preemption request to the highway traffi c signal controller. For example, 

a second preemption request may be sent when the gates reach horizontal, indicating that 

traffi c is no longer permitted to enter the crossing and the highway traffi c signal controller can 

terminate the track clearance green interval and hold the traffi c signal green in the parallel 

direction. The status of any additional preemption relays should be monitored and a change 

should also be recorded as an event.

2. Supervisory Circuit

This requires the supervisory circuit on the railroad interconnection preemption circuit to be 

monitored. A change in status of the supervisory relay (when it picks up or drops) should be 

recorded as an event.

3. Approach Circuits

This requires the approach circuit for each track in each direction to be monitored for train 

presence detection. A change in status of the approach circuit relay (when it drops or picks 

up) should be recorded as an event. This recorded event serves to identify when a train is 

detected entering or exiting an approach.
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4. Railroad Crossing Relay

This requires the status of the railroad crossing relay (XR) to be monitored and for a change in 

status (when the relay drops or picks up) to be recorded as an event. In some newer systems, 

there may no longer be a physical XR relay to monitor. At these locations, the internal logic 

in the processors of the railroad grade crossing controller or predictor carries out the function 

of the grade crossing relay by assigning variables in a logical expression to set the status of 

the grade crossing warning system. The status of these variables should be monitored and 

a change should be recorded as an event. This recorded event serves to identify when the 

railroad grade crossing warning system is activated.

5. Entrance Gate Status

Entrance gates at the highway-rail grade crossing should be monitored for a change in status. 

This requires the equipment and ability to monitor gate up and gate down contacts in either 

the interconnection circuits or the gate circuits. A change in status of the gate contacts 

between “Entrance Gate(s) Up” and “Entrance Gate(s) Not Up” or “Entrance Gate(s) Down” 

and “Entrance Gate(s) Not Down” should be recorded as an event.

6. Exit Gate Status (If present)

If exit gates are present at the highway-rail grade crossing, they should be monitored for a 

change in status. This requires the equipment and ability to monitor gate up and gate down 

contacts in either the interconnection circuits or the gate circuits. Any change in status of the 

gate contacts between “Exit Gate(s) Up” and “Exit Gate(s) Not Up” or “Exit Gate(s) Down” and 

“Exit Gate(s) Not Down” should be recorded as an event.

7. Island Circuit Occupancy

This requires the island circuits for each track to be monitored for train presence detection. 

A change in status of an island circuit relay (when the relay drops or picks up) should be 

recorded as an event.

8. Train Direction

The direction of a train movement is determined by the status of the directional stick relays 

on each track. In some newer systems, there may not be physical directional stick relays to 

indicate train direction. At these locations, the internal logic in the processors of the railroad 

grade crossing controller or predictor carries out the function of the directional stick relays by 

assigning them as variables in a logical expression relating train presence detection on the 

approach and island circuits to the train’s direction. Once a train has been detected on an 

approach circuit and an island circuit consecutively, the train’s direction is determined and 

the appropriate directional stick relay picks up or directional stick variable is set to indicate the 

direction of the train’s movement. The status of the directional stick relays or directional stick 

variables should be monitored and a change in status should be recorded as an event.

9. Lock Out Protection

If provided, lock out protection should be monitored for each train movement through a 

highway-rail grade crossing. After a train movement has completed, if the trailing circuit 

does not clear after a preset time interval, an event record should be created and an alarm 

reported.

10. Power (On/Off)

This requires the electrical power source for the railroad grade crossing equipment bungalow 

to be monitored for any loss of power and switch to battery power. The power off relay (POR) 

switches the power source that feeds the bungalow. When there is a loss of power, the POR 

drops to switch the bungalow to the battery power supply. A change in status of the power 
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off relay (when it drops or picks up) should be recorded as an event and an alarm reported. 

Additionally, any changes in voltages that would result in an alarm being reported, as 

determined by the operating railroad, should create an event record.

11. Entrance Alarm (Open/Closed)

This requires the bungalow door switch to be monitored for a change in status between 

“Open” and “Closed”. A change in status should create an event and an alarm reported. 

This may require the installation of an electrical switch in existing railroad grade crossing 

equipment bungalows that changes state when the door is opened and closed. This 

event record would allow the railroad to determine when someone has had access to the 

bungalow and the equipment and therefore, when further examination of various devices and 

programming may be necessary.

Alarm Reporting

In addition to monitoring the status of various highway and railroad equipment and recording the 

required events, the device should be able to process this information in order to fl ag recorded 

events and/or report alarms. Event recorders should use user-specifi c logical expressions to 

relate the status of equipment to determine that the highway and railroad systems are working 

as designed. As defi ned by the highway agency and/or railroad, any recorded event or logical 

combination of events should be fl agged as an alarm. A list of situations that should result in the 

reporting of an alarm along with explanations of how they can be determined is provided below. 

At a minimum, fl agging event records will allow highway and railroad maintenance personnel 

to determine if a problem exists at a highway-rail grade crossing during regular maintenance or 

inspections. The following is a list of proposed situations for which an alarm should be reported. 

These alarms should be determined by monitoring the circuits and recorded events previously 

described. Event recorders should be capable of processing and relating the recorded events 

described in order to trigger the alarm(s).

1. Event records indicate that the preemption circuit does not drop or a railroad preemption 

request was not sent prior to the design preemption warning time. This should be determined 

by comparing the time stamps of the events recorded when the preemption relay (PER) drops 

and when an island circuit relay drops, indicating train presence is detected on an island 

circuit. If the preemption warning time is less than the preemption design time, then an alarm 

should be reported.

2. Event records indicate that a train is present on an approach circuit and the associated island 

circuit; however, there is no recorded event for a railroad preemption request. This should be 

determined by comparing the time stamps of events recorded when a track’s approach circuit 

relay and island circuit relay drops, indicating train presence is detected on an approach and 

island circuit and when the PER drops. If a track’s approach circuit relay and island circuit 

relay drops and the PER has not dropped, then an alarm should be reported.

3. Event records indicate that the supervisory relay does not pick up after a preemption request, 

signifying that the traffi c controller did not confi rm receipt of the preempt message; or the 

supervisory relay picks up when there is no preemption request, signifying a possible electrical 

problem in the interconnection. This should be determined by comparing the status of the 

PER and supervisory relays. If the PER has dropped and there is no event indicating that the 

supervisory relay has dropped, or if the supervisory relay drops and there is no event indicating 

that the PER dropped, then an alarm should be reported.
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4. Event records indicate that the XR, which activates the grade crossing warning system, does 

not drop or activate the warning system before the specifi ed warning time. This should be 

determined by comparing the time stamps of the events recorded when the XR drops and 

when an island circuit relay drops, indicating a train is detected on an island circuit. If the 

warning time is less than the design warning time, then an alarm should be reported.

Alternatively, some newer systems may not have a physical XR to activate the warning system. 

At these locations, the internal logic in the processors of the railroad grade crossing controller 

or predictor carries out the function of the grade crossing relay by assigning variables in a 

logical expression to set the status of the grade crossing warning system. If recorded events 

indicate that the warning system is activated before the specifi ed warning time, then an alarm 

should be reported.

49 CFR 234.225 requires the activation of the grade crossing warning system at least 20 

seconds prior to the train occupying the crossing. Train occupancy of the crossing is 

determined by the train presence detection on the appropriate island circuit.

5. Event records indicate that the entrance gate(s) begins to descend prior to the 49 CFR 234.223 

required minimum of three seconds after the grade crossing warning system is activated and 

the fl ashing lights begin to operate. This should be determined by comparing the time stamps 

of the recorded events when the XR drops, indicating activation of the grade crossing warning 

system, and when the entrance gate(s) begins to descend. If the entrance gate(s) begin to 

descend less than three seconds after the XR drops, then an alarm should be reported.

6. Event records indicate that the entrance gate(s) reach horizontal position after the required 

minimum of fi ve seconds prior to a train arriving at the highway-rail grade crossing, or when 

a train is detected on the island circuit. This should be determined by comparing the time 

stamps of the recorded events when the gate(s) reach horizontal position and when an island 

circuit relay drops, indicating a train is detected on an island circuit. If the island relay drops 

less than fi ve seconds after the gate(s) reach horizontal position, then an alarm should be 

reported.

7. Event records indicate that the exit gate(s) begins to descend prior to the completion of the 

track clearance green interval, potentially trapping vehicles in the highway-rail grade crossing. 

This should be determined by comparing the time stamps of recorded events for when the 

exit gate(s) leaves the vertical position and when the track clearance green interval has 

terminated. If the exit gate(s) leave the vertical position before an indication that the track 

clearance green interval has terminated, then an alarm should be reported.

8. Event records indicate that an entrance or exit gates(s) has left the vertical position, but there 

is no recorded event indicating the gate(s) has reached the horizontal position within a preset 

time interval. This should be determined by comparing the time stamps of events recorded 

when the status of entrance or exit gate(s) change. If the entrance or exit gate(s) have left 

the vertical position, and there is no recorded event showing the entrance or exit gate(s) 

has reached the horizontal position before a present time interval, then an alarm should be 

reported.

Alternately, event records indicate an entrance or exit gate(s) has left the horizontal position, 

but there is no recorded event indicating the gate(s) has reached the vertical position within 

a preset time interval. If the entrance or exit gate(s) have left the horizontal position and there 

is no recorded event showing the entrance or exit gate(s) have reached the vertical position, 

then an alarm should be reported. Part 3.3.30 of the AREMA C&S Manual states that gate 

arms should fully raise in no more than 12 seconds, or as instructed.
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Finally, event records indicate that an entrance or exit gate(s) is in both the vertical and 

horizontal position. If the status of the entrance or exit gate(s) indicates they are in the vertical 

position and also that they are in the horizontal position, then an error has occurred and an 

alarm should be reported.

9. Event records indicate that the right-of-way transfer time is longer than the design right-of-way 

transfer time. This should be determined by comparing the time stamps of the events recorded 

when the status of the right-of-way transfer time indicates it commences and terminates. If the 

right-of-way transfer time is longer than the design maximum right-of-way transfer time, then an 

error has occurred and alarm should be reported.

10. Event records indicate that the track clearance green interval is less than the design track 

clearance green interval. This should be determined by comparing the time stamps of the 

events recorded when the status of the track clearance green interval indicates it commences 

and terminates. If the track clearance green interval is less than the design track clearance 

green interval, then an error has occurred and an alarm should be reported.

11. Event records indicate that the amount of time from the start of the track clearance green 

interval to train presence detection on an island circuit is less than the design track clearance 

green interval. This should be determined by comparing the time stamps of the events 

recorded, when the status of the track clearance green interval indicates it commences and 

when an island circuit drops to indicate an island circuit is occupied. If the time between 

the start of track clearance green and island circuit occupancy is less than the design track 

clearance green interval, then an error has occurred and an alarm should be reported.

12. Event records indicate train presence detection on an island circuit, but there is no event 

record indicating the termination of the track clearance green interval. This should be 

determined by comparing the status of the island circuit relays and the status of the track 

clearance green interval. If the status of an island circuit relay drops, indicating island circuit 

occupancy, before indication that the track clearance green interval has terminated, then an 

error has occurred and an alarm should be reported.

13. Event records indicate train presence detection on an approach and island circuit, but the 

appropriate directional stick relay did not pick up, or a directional stick relay picks up when 

no train was detected. This indicates there may be an electrical problem with the circuits or 

relays.

Alternatively, some newer systems may not have physical directional stick relays to indicate 

train direction. At these locations, the internal logic in the processors of the railroad grade 

crossing controller or predictor carries out the function of the directional stick relays by 

assigning them as variables in a logical expression relating train presence detection on 

approach and island circuits to the train’s direction. Once a train has been detected on an 

approach circuit and an island circuit consecutively, the train’s direction is determined and the 

appropriate directional stick variable is set to indicate the direction of the train’s movement. 

If recorded events indicate train presence detection on a crossing track’s approach and 

island circuits, but there is no recorded event indicating train direction, or if a recorded event 

indicates train direction when no train has been detected, then an alarm should be reported.

14. Event records indicate that lock out protection is being provided on a particular track 

approach. If it is indicated that lock out protection is being provided, than an alarm should be 

reported.
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15. Event records indicate a loss of primary power, a switch to battery power, or signifi cant 

changes in voltages. If an event record indicates a change in status of the power supply, then 

an alarm should be reported.

16. Event records indicate that either the highway traffi c signal controller cabinet or railroad grade 

crossing equipment bungalow door has been opened, allowing access to the equipment and 

settings. If an event record indicates the status of either door changes, then an alarm should 

be reported.

3.1.3 GENERAL EVENT RECORDING DEVICE FUNCTIONAL REQUIREMENTS

This section describes the general functional requirements for event recording devices to be installed 

at highway-rail grade crossing locations with highway traffi c signal preemption. These requirements 

are for event recording devices in any of the three system confi gurations (new, hybrid, and legacy).

The event recorder can be installed in the highway traffi c signal controller cabinet, railroad grade 

crossing equipment bungalow, or in both. Highway agencies and railroads should jointly determine 

the location of the event recording device(s). The recording device should support time and date 

stamping of events and have suffi cient capacity to record the required events from the highway 

and railroad for a period of one month prior to overwriting itself. The event recorder should have an 

internal battery backup to store data in the event of a power loss. For the required highway traffi c 

signal events, the event recorder should dynamically record all required events for a time period of at 

least 60 seconds, but not less than highway the traffi c signal cycle length, prior to a rail preemption 

call and for an equal time period after the call for rail preemption is terminated.

The event recording device should support two types of user interfaces. A visual display interface 

should dynamically indicate the status of each input, providing a valuable troubleshooting 

maintenance tool as well as supporting scheduled maintenance and inspection tasks. This 

requirement can be satisfi ed by a series of LED front panel indicators or an LCD alpha-numeric 

screen. A laptop computer or other portable device interface should provide for initial unit 

programming at the specifi c installation location as well as the ability to retrieve and display 

recorded event logs. If integrated as part of the highway traffi c signal controller and/or railroad 

grade crossing controller, the controller should also support the computer/portable device 

requirement.

It is recommended that the event recording device support communications with an internet 

database or back offi ce location to report alarms to the maintaining authorities as they occur. If an 

event recorder determines that alarm conditions have been met and fl ags an event record or several 

event records used to determine such conditions, it should report the alarm and send the associated 

event records to an internet database or back offi ce system. This allows the highway agency and 

railroad to act as quickly as possible to investigate the problem. To support these features, the event 

recording devices should support an Ethernet-based connection to the back offi ce system. This can 

be achieved by connecting through a high-speed communications link supplied to the equipment 

cabinet, or through wireless methods such as a cell modem connected to the event recorder. At 

remote locations, this communications link may not be achievable. The Ethernet connection should 

be shared by the maintaining agencies through a closed communications network. For new systems 

using IEEE Standard 1570 communication, the internet database or back offi ce system receiving the 

reported alarms should support IEEE Standard 1570 so that it can process the alarms and recorded 

event messages sent to the database. This helps to initiate the required action from the highway 

agency and/or railroad maintenance personnel, if necessary.
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Time Reference Requirements

The event recording device should maintain an accurate time reference. Traditionally, time 

referencing for highway traffi c signal control devices had been based on the 60 Hz AC frequency of 

the utility generated service. However, it should be noted that on June 14, 2011, the Federal Energy 

Regulatory Commission stated that it is proposing an experiment that would allow more frequency 

variation in the nation’s power grid. This may adversely impact time referencing systems that rely on 

electrical frequency for accuracy. Highway traffi c signal controllers connected as part of a larger 

control system architecture may rely on a central device (system fi eld master or remote computer 

station) to receive a time reference. In the event of power failure to the highway traffi c signal 

controller, an internal crystal-based oscillator backed up by an internal battery should serve to keep 

time. The accuracy of this backup system would vary based on controller type and manufacturer.

In recent years, a GPS-based time reference system has begun to be used to maintain accurate time 

in a highway traffi c signal controller. Typical installations consist of a small, round antenna installed 

on top of the highway traffi c signal controller cabinet. There are two methods of transmitting the 

GPS information into the controller. The fi rst method uses a contact closure as a single function input 

into the controller. (For example, this is typically a manufacturer-defi ned pin on the “D” connector 

for a NEMA TS-1 cabinet assembly.) The second method is for a serial connection into an unused 

communication port (RS232) on the controller.

For the event recorder, a GPS-based time reference should be used to maintain accurate time for 

both the highway traffi c signal and railroad grade crossing recording systems. This should include 

the existing highway traffi c signal controller and confl ict monitor/malfunction management unit 

installed in the cabinet. All devices installed in the highway traffi c signal controller cabinet and 

railroad grade crossing equipment bungalow should have the same time reference for event 

logging.

Electrical Requirements

The event recording device should be adaptable to accommodate variations in electrical data 

transmission based on signal cabinet/bungalow architecture. Each highway traffi c signal controller 

and railroad grade crossing architecture utilizes different electrical levels and protocols for in-cabinet 

communications. NEMA TS-1, for example, employs a single function to single conductor architecture 

for device-to-device data transmission. A full eight-phase NEMA TS-1 traffi c controller has 171 wires 

connected to it, allowing for +24 VDC (ground true) input/output to the unit. Type 170 and Type 179 

use a similar confi guration with a 102 conductor interconnection to the controller. NEMA TS2, type 1 

uses serial data transmission (SDLC) to interface with other cabinet devices and terminals. The 2070 

and other types of device cabinets have the user option to specify a variety of cabinet interface 

confi gurations including single function/single conductor or serial interface. For the event inputs 

identifi ed, the input electrical levels will vary on cabinet type.

Electrical interfacing should conform to NEMA TS-2 “Traffi c Controller Assemblies with NTCIP 

Requirements - Version 02.06” for NEMA-based cabinet assemblies; Caltrans “Transportation Electrical 

Equipment Specifi cation” for 170-, 179-, and 2070-based cabinet assemblies; and “Advanced 

Transportation Controller (ATC) Standard” (latest approved version) for ATC-based cabinet 

assemblies. It should be noted that ATC Version 06.05 was the latest proposed at the time of this 

writing.
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47

Environmental Requirements

The event recorder should be manufactured such that it meets the minimum environmental and 

test requirements as defi ned in NEMA TS-2 “Traffi c Controller Assemblies with NTCIP Requirements - 

Version 02.06” for NEMA-based cabinet assemblies; Caltrans “Transportation Electrical Equipment 

Specifi cation” for 170-, 179-, and 2070-based cabinet assemblies; and “Advanced Transportation 

Controller (ATC) Standard” (latest approved version) for ATC-based cabinet assemblies. The 

recording device should also meet the environmental requirements recommended in AREMA C&S 

Manual Part 11.5.1 “Recommended Environmental Requirements for Electrical and Electronic Railroad 

Signal System Equipment.”

Inspection & Testing

Event recording devices should conduct self-diagnostics and testing as recommended in AREMA 

C&S Manual Part 3.1.29. Upon start-up and after reset, the recorders should perform self-diagnostics 

and the results of self-diagnostic tests should be recorded with a date and time stamp. The recorders 

should also verify proper operation and perform self-diagnostics periodically, while continuing to 

monitor and respond to status changes. If the tests are successful, the recorder should locally 

indicate being operational and, if possible, report being online and operational. If the tests are not 

successful, the recorder should create an event record and report an alarm. The recording devices 

should also verify input states by providing multiple sampling or time integration when evaluating 

the status of each input. Finally, the recorders should include a timer that requires the continuous 

servicing by the self-diagnostics in order to keep operating. If the timer expires, the recorder should 

reset itself and perform self-diagnostics upon resetting. This should also create an event record 

indicating the system was reset.

The event recording device should be tested to determine that it functions as intended when it is 

installed or modifi ed and at least once a month, as required of grade crossing warning systems in 

49 CFR 234. During regular joint inspections, highway agency and/or railroad inspecting personnel 

should download the recorded data from the event recording device to compare with known train 

events, if the data is not already regularly uploaded to and monitored from a back offi ce database.

3.1.4 EVENT RECORDER COSTS

The cost of event recording devices varies based on the processing and reporting capabilities as 

well as storage capacity and recording needs of the highway-rail grade crossing. Larger highwayrail grade crossing locations or locations with more equipment that require additional monitoring 

and recording may require expanding the event recorder’s inputs and outputs. Depending on 

the amount of information being recorded, event recorders may also need expanded memory so 

that they can store events for the required one month period prior to overwriting the memory. The 

geographic location of the highway-rail grade crossing and the available communication options 

will also impact the cost of event recording devices. For example, remote locations may require 

additional equipment for effective monitoring and alarm reporting.

Current pricing for basic event recording devices, without expanded inputs and outputs or memory, 

is between $1,500 and $2,500. Additional analog and digital I/O modules can cost from $500 to 

$2,000 depending on the size, type, and manufacturer. Memory expansion cards or modules can 

cost up to $1,000. Optional communication modules or cards typically cost up to $1,500. Given that 

the proposed event recorder will be required to contain more functionality than existing systems, 

event recording devices could cost up to $10,000 depending on the size of the location and 

necessary equipment. Back offi ce systems needed for reporting alarms and remotely monitoring 

and testing highway-rail grade crossing equipment can cost from $10,000 to $150,000 based on the 

level of monitoring and automatic testing desired.
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The prices for event recording devices capable of supporting IEEE Standard 1570 and monitoring the 

communication messages will most likely be greater than the costs provided here. These recording 

devices will need new executive software and the necessary communication options and equipment 

to support IEEE Standard 1570. Manufacturers will incur expenses for product development, which 

will in turn increase the costs of the new recording systems. Event recorder manufacturers typically 

provide railroads with discounted prices for buying in bulk, which vary based on the price of the 

product and quantity purchased.

3.2 Policy Information

3.2.1 SCOPE

Railroad maintenance standards and requirements for testing and inspecting highway-rail grade 

crossing signal systems are mandated by the Code of Federal Regulations Title 49 Part 234 Subpart 

D and AREMA. However, there is no national traffi c signal counterpart to these standards and 

requirements. Traffi c signal system maintenance, testing, and inspection processes are typically 

developed by State and local highway agencies. The following presents information pertaining to 

minimum maintenance, testing, and inspection policies and practices to be followed by State and 

local highway agencies for highway-rail grade crossing locations. Relevant 49 CFR 234 sections 

are also presented. The ultimate goal is to encourage a working relationship between highway 

agencies and railroads through a joint testing and inspection procedure to ensure that highway-rail 

grade crossing signal systems and interconnected highway traffi c signal systems are communicating 

correctly and working properly. Achieving this goal will satisfy the four actions recommended in the 

Safety Advisory 2010-02 noted in Chapter 1.

3.2.2 FREQUENCY OF INSPECTION AND TESTING

Performing preventive inspections and maintenance activities at highway-rail grade crossing 

locations is considered proactive risk management by State and local highway agencies. The Traffi c 

Signal Installation and Maintenance Manual (4) recommends that these preventive inspections and 

maintenance activities be conducted at a 6-month intervals.

Railroads should perform inspections, testing, and maintenance activities at highway-rail grade 

crossing locations as required by 49 CFR 234.

Safety Advisory 2010-02 set forth requirements for State and local highway agencies to perform 

joint inspections in coordination with railroads at highway-rail grade crossing locations. The joint 

inspections should be performed at a maximum interval of twelve months.

3.2.3 SCHEDULING

It would be desirable for the 6-month preventive inspections and maintenance activities to be 

scheduled and initiated by the State (district) or local highway agency offi ce with jurisdiction over 

the highway-rail grade crossing. Ensuring that each highway-rail grade crossing with a jurisdiction is 

inspected and maintained within the specifi ed interval may be the responsibility of the State (district) 

or local traffi c engineer.

The monthly and quarterly inspections, testing, and maintenance activities conducted by the 

railroad should be scheduled and initiated as currently done in accordance with 49 CFR 234.

It is encouraged that the annual detailed joint inspections be scheduled and initiated by the State 

(district) or local highway agency offi ce with jurisdiction over the highway-rail grade crossing. The 
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State (district) or local traffi c engineer would be responsible to coordinate scheduling with the 

appropriate railroad. The State (district) or local traffi c engineer would also ensure that each 

highway-rail grade crossing location within his/her jurisdiction is jointly inspected within the specifi ed 

interval.

3.2.4 RESPONSIBILITIES OF PERSONNEL

At least one highway traffi c signal technician may conduct each 6-month preventive inspection 

and maintenance activity, verifying the elements identifi ed under “Procedures”. However, if 

deemed necessary, a traffi c engineer may also perform the 6-month preventive inspection and 

maintenance activity. When two traffi c personnel are present, the highway traffi c signal technician 

would be responsible for the functionality of the highway traffi c signal system whereas the traffi c 

engineer would be responsible for the signal operations, signs, pavement markings, and other safety 

concerns.

Each monthly and quarterly inspection, testing, and maintenance activity performed by the railroad 

should be conducted by at least one railroad inspection/testing personnel. The railroad inspection/

testing personnel should be responsible for the functionality of the railroad grade crossing warning 

system. The railroad inspection/testing personnel should be familiar with the requirements of 49 CFR 

234 to ensure that all aspects of the highway-rail grade crossing are reviewed as specifi ed.

Each detailed annual joint inspection may be conducted by at least one highway traffi c signal 

technician, one traffi c engineer, and one inspection/testing personnel from the railroad. The 

highway traffi c signal technician would be responsible for the functionality of the highway traffi c 

signal system whereas the traffi c engineer would be responsible for the signal operations, signs, 

pavement markings, and other safety concerns. The railroad inspection/testing personnel should 

be responsible for the functionality of the railroad grade crossing warning system. Coordination 

between the highway traffi c signal technician, the traffi c engineer, and the railroad inspector is 

important to ensure that all aspects of the interconnected highway-rail grade crossing signal system 

are properly working.

3.2.5 PROCEDURES

Identifi cation

Highway-rail grade crossings that have interconnection between the highway traffi c signal system 

and the railroad grade crossing warning system should be identifi ed as such. The warning labels 

shown in Figure 8 may be affi xed inside the main door of the highway traffi c signal controller cabinet 

and the railroad grade crossing equipment bungalow, respectively.
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Figure 8: Example Warning Labels

A fi eld example of a warning label is shown in Figure 9. In addition to the warning, the label also 

includes contact information for the responsible highway agency and railroad.

Figure 9: Field Example of Warning Label
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Plans

Signed and sealed plans required for proper testing and maintenance of the highway traffi c signal 

system may be kept at each highway-rail grade crossing location within the highway traffi c signal 

controller cabinet. This may also include signed and sealed plans for signing and pavement 

markings installed in advance of the highway-rail grade crossing on all roadway approaches. It is 

an effective practice to maintain legible and current plans that contain an accurate database of 

all programming resident in each of the various control devices. If modifi cations are made to the 

highway traffi c signal system or to signing and pavement markings, modifying or replacing the plans 

within the highway traffi c signal controller cabinet would be the duty of the highway agencies.

As required by 49 CFR 234.201, plans required for proper testing and maintenance of the railroad 

grade crossing warning system should be kept at each highway-rail grade crossing location in the 

railroad grade crossing equipment bungalow. It is the responsibility of the railroad to keep these 

plans legible and correct. If any modifi cations are made to the railroad grade crossing warning 

system, it is the responsibility of the railroad to modify or replace the plans contained in the railroad 

grade crossing equipment bungalow. Additionally, it should be the responsibility of the railroad to 

notify the appropriate highway agency of any changes made to the railroad grade crossing warning 

system that may have an impact on the operation of nearby highway traffi c signal systems.

Six-month Highway Preventive Inspections and Maintenance Activities

The 6-month preventive inspections and maintenance activities are intended to verify that basic 

highway traffi c signalization parameters are functioning properly, that appropriate signing and 

pavement markings are in place and in good condition, and that no other safety concerns are 

present. The items to be verifi ed by a highway traffi c signal technician (and traffi c engineer, if 

present) may include the following:

• Signalization (vehicular and pedestrian, if present) to ensure that indications on all roadway 

approaches and at all pedestrian crossings are properly aligned and illuminated, when 

applicable.

• Signing to ensure that appropriate advance warning signs on all roadway approaches are 

present, visible, and in good condition.

• Pavement markings to ensure that appropriate pavement markings on all roadway approaches 

are present and in good condition.

• Visibility to ensure that sight triangles on all roadway approaches are clear of obstructions, 

particularly vegetation growth.

• Pavement condition to ensure that the surface on all roadway approaches is free of signifi cant 

defects that would present a safety concern.

• Lighting to ensure that luminaires (if present) on all roadway approaches are functioning and 

providing suffi cient illumination.

• Controller cabinet condition to ensure that the internal area is free of debris or animal 

infestations that may cause system malfunctions.

The issues identifi ed through the 6-month preventive inspection process need to be brought to 

the attention of the appropriate responsible parties. Problems to be addressed immediately may 

include signalization, missing signing, and lighting outages. Additionally, seriously deteriorated 

pavement conditions should be given immediate attention while less signifi cant deteriorations may 

be addressed in the short-term. Signing and pavement markings in poor condition may be updated 

at a regularly scheduled interval. It is important that controller cabinet debris or animal infestations 

be cleared at the time of the inspection.
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Monthly and Quarterly Railroad Inspections and Maintenance Activities

The CFR regulations explain in detail the components of the railroad grade crossing warning system 

that should be inspected, tested, and maintained on a monthly and quarterly (3 month) basis. The 

purpose is to ensure that the warning system functions as designed, including being visible and 

audible to highway users approaching the crossing. At each of the specifi ed intervals, railroad 

inspection/testing personnel should verify the following:

Monthly

• 49 CFR 234.257 — Warning System Operation:

a. Each highway-rail crossing warning system shall be tested to determine that it functions 

as intended when it is placed in service. Thereafter, it shall be tested at least once each 

month and whenever modifi ed or disarranged.

b. Warning bells or other stationary audible warning devices shall be tested when installed 

to determine that they function as intended. Thereafter, they shall be tested at least once 

each month and whenever modifi ed or disarranged.

• 49 CFR 234.261 — Highway Traffi c Signal Preemption:

Highway traffi c signal preemption interconnections, for which a railroad has maintenance 

responsibility, shall be tested at least once each month.

The railroad having jurisdiction over the highway-rail grade crossing should be responsible for 

inspection, testing, and maintenance up to the point of interconnection with the highway traffi c 

signal control system. The State or local highway agency should be responsible for inspecting, 

testing, and maintaining all remaining circuitry and highway traffi c signal control devices. The 

test should ensure that an approaching train activates the railroad grade crossing warning 

system and initiates the highway traffi c signal clearance sequence. The railroad should check 

contacts and devices interconnected with the highway traffi c signals and advanced warning 

signs to ensure they perform as intended as defi ned in 49 CFR.

Inspection/testing personnel should also verify the proper operation of the interconnect 

circuit and observe that highway traffi c signal preemption is operating as intended. Ideally, 

preemption should be verifi ed with the actual passing of a train through the highway-rail grade 

crossing location; however, this is not always feasible. Under these circumstances, inspection/

testing personnel may simulate a train movement by de-energizing the interconnection circuit, 

thereby activating the preemption sequence. If the crossing is equipped with advanced 

preemption, inspection/testing personnel should observe a train movement to verify proper 

operation. Inspection/testing personnel should note any repairs or adjustments made. If 

the interconnection circuit is discovered to be not operational and/or any inconsistency is 

discovered, inspection/testing personnel should notify the State or local highway agency 

having jurisdiction over the highway-rail grade crossing as well as report the fi ndings to the 

appropriate railroad supervisor. If the railroad equipment is found to be operating properly and 

the highway traffi c signal system does not respond, inspection/testing personnel should notify 

the State or local highway agency having jurisdiction over the highway-rail grade crossing 

of the problem. The railroad may request the presence of State or local highway agency 

personnel during the monthly preemption testing.
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Quarterly

• 49 CFR 234.269 — Cut-out Circuits:

Each cut-out circuit shall be tested at least once every three months to determine that the 

circuit functions as intended. For purposes of this section, a cut-out circuit is any circuit which 

overrides the operation of automatic warning systems. This includes both switch cut-out circuits 

and devices which enable personnel to manually override the operation of automatic warning 

systems.

• 49 CFR 234.271 — Insulated Rail Joints, Bond Wires, and Track Connections:

Insulated rail joints, bond wires, and track connections shall be inspected at least once every 

three months.

These tests are used to assure that trains are being properly detected on each of the railroad 

approaches.

Detailed Annual Joint Inspections

The detailed annual joint inspections are intended to verify that all aspects of the interconnected 

highway-rail grade crossing signal system are properly working. It is desirable that the detailed 

annual joint inspections be conducted by highway agency and railroad personnel as described.

A highway traffi c signal technician and traffi c engineer may verify the following:

• Controller equipment to ensure that all installed units are in proper working order and that all 

connections are tight and secure. In particular, testing of the confl ict monitor/malfunction 

management unit ensures that the interconnected highway-rail system reverts to safe mode in 

the event of failure. This would include both fi eld testing and automated bench testing of the 

system.

• Vehicular and pedestrian timings to ensure that all traffi c controller settings match the current 

master timing sheet.

• Preemption to ensure that, upon activation by an approaching train, the highway traffi c signal 

system initiates and properly cycles the preemption sequence as specifi ed on the plans and 

master timing sheet. This includes ensuring that the minimum activation warning time provided 

is suffi cient to clear the highway-rail grade crossing of vehicular and pedestrian traffi c prior to 

train arrival. Ideally, preemption would be verifi ed with the actual passing of a train through 

the highway-rail grade crossing location; however, this is not always feasible. Under these 

circumstances, the railroad personnel may initiate the preemption sequence. Otherwise, the 

highway traffi c signal technician may remove one of the connectors provided from the railroad 

to the highway traffi c signal controller cabinet to activate preemption. This testing process needs 

to be conducted during coordinated operation, non-coordinated operation, and when other 

modes of signal operation are active, including emergency vehicle preemption and transit signal 

priority operation.

• Vehicle/pedestrian detection to ensure that detection systems installed on all approaches/

crossings are in proper working order, that all connections within the controller are tight and 

secure, and that all inputs are being received and processed. Any existing/historical fault 

indicators need to be noted as problems to be rectifi ed.
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Railroad inspection/testing personnel should verify the following:

• 49 CFR 234.225 — Activation of Warning System:

A highway-rail grade crossing warning system shall be maintained to activate in accordance 

with the design of the warning system, but in no event shall it provide less than 20 seconds 

warning time for the normal operation of through trains before the grade crossing is occupied by 

rail traffi c.

• 49 CFR 234.259 — Warning Time:

Each crossing warning system shall be tested for the prescribed warning time at least once 

every 12 months and when the warning system is modifi ed because of a change in train speeds. 

Electronic devices that accurately determine actual warning time may be used in performing 

such tests.

Railroads should ensure the grade crossing warning system activates as designed, and in no 

instance provides less than 20 seconds of warning time. Inspection/testing personnel should 

observe the crossing warning time and verify that it is in accordance with the designed warning 

system as shown on the circuit drawings. If an electronic device is installed at the highwayrail grade crossing location to accurately determine actual warning time, the warning time 

must be observed during a train movement or calculated by measuring the approach track 

circuits and using the highest timetable speed. If the warning time is found to be less than 20 

seconds, inspection/testing personnel should immediately take corrective action and provide 

appropriate documentation.

• 49 CFR 234.263 — Relays:

a. Except as stated in paragraph (b) of this section, each relay that affects the proper 

functioning of a crossing warning system shall be tested at least once every four years.

b. (1) Alternating current vane type relays, direct current polar type relays, and relays with 

soft iron magnetic structure shall be tested at least once every two years. (2) Alternating 

current centrifugal type relays shall be tested at least once every 12 months.

Railroad inspection/testing personnel should check relay operation for each track at the 

highway-rail grade crossing location and in each direction to ensure that the relays are deenergized after testing is complete. Railroads may provide specifi c instructions for inspection of 

each relay type and for testing with current and voltage.

• 49 CFR 234.265 — Timing Relays and Timing Devices:

Each timing relay and timing device shall be tested at least once every twelve months. The 

timing shall be maintained at not less than 90 percent nor more than 110 percent of the 41 

predetermined time interval. The predetermined time interval shall be shown on the plans or 

marked on the timing relay or timing device. Timing devices which perform internal functions 

associated with motion detectors, motion sensors, and grade crossing predictors are not 

subject to the requirements of this section.

During the detailed annual joint inspection process, it is desirable to maintain the normal operation 

of the highway-rail grade crossing. If normal operation is to be suspended, other provisions should 

be made prior to the inspection to ensure highway-rail grade crossing safety for all transportation 

modes at the location.
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3.2.6 DOCUMENTATION

For the 6-month preventive inspections and maintenance activities, a report completed by the 

highway traffi c signal technician (and traffi c engineer, if present) may include information such as 

the highway-rail grade crossing location, the technician’s name (and traffi c engineer, if present) and 

employee identifi cation number, the date and time, the tasks performed, and the problems noted. 

A minimum of two copies of the 6-month report may be required, both signed by the highway traffi c 

signal technician (and traffi c engineer, if present). One report may be kept within the highway traffi c 

signal controller cabinet and one may be fi led at the State (district) or local highway agency offi ce 

with jurisdiction over the highway-rail grade crossing. Upon the next inspection, the report within the 

highway traffi c signal controller cabinet would be replaced. The report fi led at the State (district) or 

local highway agency offi ce may be discarded after a period of fi ve years. If interim maintenance 

activities are required to the highway traffi c signal system, it is important that signed documentation 

be attached to the most current report on fi le.

For the detailed annual joint inspections, a report should be completed by the highway traffi c signal 

technician, traffi c engineer, and railroad inspector. The report may include information such as the 

highway-rail grade crossing location, the participants’ names and employee identifi cation numbers, 

the date and time, the tasks performed, and the problems noted. A minimum of four copies of 

the joint inspection report may be required, signed by the highway traffi c signal technician, traffi c 

engineer, and railroad inspector. One report may be kept within the highway traffi c signal controller 

cabinet, one may be fi led at the State (district) or local highway agency offi ce with jurisdiction over 

the highway-rail grade crossing, one should be kept within the railroad grade crossing equipment 

bungalow, and one should be fi led in the offi ce of a railroad supervisory offi cial having jurisdiction, 

as required by 49 CFR 234.273. The reports within the highway traffi c signal controller cabinet and the 

railroad grade crossing equipment bungalow would be replaced upon the next joint inspection. The 

report fi led at the State (district) or local highway agency offi ce may be discarded after a period of 

fi ve years. The report fi led with the railroad supervisory offi cial should be kept until the next report for 

that test is fi led and at least for one year, also as required by 49 CFR 234.273. If interim adjustments 

have been made to the highway traffi c signal control system or railroad grade crossing warning 

system, it is important that signed documentation be attached to the most current report on fi le.

Several example inspection and diagnostic forms are attached in Appendix F. These forms can be 

modifi ed by highway agencies and railroads for use during the 6-month preventive inspections and 

maintenance activities and the detailed annual joint inspection of highway-rail grade crossings.

3.2.7 REFERENCE DOCUMENTATION

The following reference documents may be consulted when performing inspections and 

maintenance activities:

• Manual on Uniform Traffi c Control Devices (MUTCD) (7)

» Part 8 – Traffi c Control for Railroad and Light Rail Transit Grade Crossings

• Traffi c Engineering Handbook (10)

• Traffi c Control Devices Handbook (11)

• Code of Federal Regulations (6)

» Title 49 – Transportation; Part 234 – Grade Crossing Signal System Safety and State Action 

Plans; Subpart D – Maintenance, Inspection, and Testing
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• AREMA Communications and Signals Manual (9)

» Section 3 – Highway-Rail Grade Crossing Warning Systems; Part 3.1.10 – Recommended 

Functional/Operating Guidelines for Interconnection Between Highway Traffi c Signals and 

Highway-Rail Grade Crossing Warning Systems

» Section 3 – Highway-Rail Grade Crossing Warning Systems; Part 3.3.1 – Recommended 

Instructions for the Maintenance and Test of Automatic Highway-Rail Grade Crossing Warning 

Systems

» Section 3 – Highway-Rail Grade Crossing Warning Systems; Part 3.3.30 – Recommended 

Instructions for Inspection and Test of Highway-Rail Grade Crossing Warning System Installation 

Before Placing In Service

• Railroad-Highway Grade Crossing Handbook (12)
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CHAPTER 4. MODEL STRATEGY FOR ESTABLISHING REGULAR JOINT 

INSPECTIONS OF INTERCONNECTED SYSTEMS

The following presents a model strategy to establish regular joint inspections of interconnected 

highway-rail grade crossing signal systems. “Regular” joint inspection is recommended on an 

annual (12 month) basis. The annual inspection cycle coincides with FRA-mandated 49 CFR 234 

inspection, testing, and maintenance procedures currently required of railroads. As previously 

stated, the ultimate goal is to encourage a working relationship between highway agencies and 

railroads to ensure that highway-rail grade crossing locations are being proactively maintained to 

minimize the occurrence of vehicle-train collisions. This generic model strategy is intended to assist 

with formulating and establishing more stringent processes and procedures than what is generally 

the current practice.

4.1 Pre–Inspection

Prior to the inspection taking place, the highway agency should coordinate with the railroad to 

schedule times and locations. Given that there is currently no national highway traffi c signal 

inspection program counterpart to the FRA regulations, it should be the responsibility of the highway 

agency to initiate the inspection. This will promote participation by both agencies having jurisdiction 

over a highway-rail grade crossing location.

It is important that personnel involved in the joint inspections be knowledgeable of preemption 

operation at highway-rail grade crossings. Limited personnel resources may preclude intraagency participation; therefore, agencies may be supported by additional resources including 

outside entities. For example, smaller jurisdictions such as counties or towns may work with the 

State Department of Transportation or with private contractors to perform inspection, testing, and 

maintenance tasks. In these instances, the jurisdictional highway agency should be responsible 

for coordinating with all outside parties involved to ensure participation. When scheduling, 

consideration may be given to railroad timetables such that the inspection is conducted 

simultaneously with an actual train movement through the highway-rail grade crossing under 

inspection.

As part of the pre-inspection preparation, participating highway agency and railroad personnel 

should meet and review documentation related to the crossing(s) being reviewed. Documentation 

that should be part of the inspectional process includes the most current signal as-built plan, signal 

timing and operations forms, and any previous inspection reports. Highway agency and railroad 

personnel (or representatives) should also identify and note any changes that have occurred since 

the last annual inspection or are planned to occur at a time after the upcoming annual inspection 

is to be conducted. This information should be brought to the inspection and shared with all 

participants.

4.2 Inspection

The recommended annual joint inspection of highway-rail grade crossings with interconnected 

signal systems is intended to verify that all aspects of the interconnection and of each individual 

system component are working properly. In order to make these verifi cations, there are a number 

of critical items that should be checked and tested during the inspection. The following are sample 

prompts for these items; however, additional items may be appropriate.
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 Does a preemption call from the railroad activate the highway traffi c signal and any other 

warning devices? Are signals, active advance warning signs, etc. functioning as intended?

 Does the grade crossing warning time provided match the time shown on the most current 

grade crossing plan? Are fl ashers, bells, gates, etc. functioning as intended?

 Does the preemption sequence match the most current signal plan?

 What is the required track clearance green time? Is the calculated time consistent with what is 

shown on the signal plan and programmed in the fi eld?

 What is the calculated required total preemption warning time? Is the actual total preemption 

warning time consistent with what is required by calculation?

 Does preemption override basic controller times?

 Does preemption work properly under free and coordinated operation? Does the preemption 

work properly under every coordination plan?

 Is right-of-way transfer time consistent with defi ned preemption timing?

 When does the highway traffi c signal controller release the intersection back to normal 

operation?

 Is the highway traffi c signal controller programmed to cycle during preemption? If so, does it 

cycle properly?

 Does the rail preemption operation involve multiple locations? If so, does the preemption 

operation work according to defi ned plans?

 What is the electrical/mechanical condition of the interconnect circuit/contact in the railroad 

grade crossing equipment bungalow and/or highway junction box?

 Does the interconnect circuitry support required fail safe operation?

 Do installed standby or backup electrical power source systems operate as designed?

 Do installed special features (supervisory circuit, power failure monitoring circuit, etc.) function as 

designed?

 Do actual intersection characteristics (signal displays, stop line locations, pavement markings, 

signing, etc.) match the most current as-built plan? Are modifi cations or additional measures 

necessary? If so, document fi ndings.

 Highway agencies and railroads should jointly establish their own unique checklist based 

on particular needs. The checklist would likely be a subset of current FRA and future FHWA 

regulations. Several inspection checklists and forms are provided in Appendix F as practical 

examples for use in developing and adopting specifi c jurisdictional processes and procedures.

Updated or upgraded signal systems may have the capability to be monitored remotely, which 

does not require personnel to be on-site. However, it is recommended that inspecting and testing 

be conducted on-site to visually confi rm acceptable condition and verify proper functionality of all 

relative traffi c control devices including pavement markings, signing, etc. This will serve to ensure 

that no critical item is overlooked that may not be identifi ed through remote monitoring.

It is recommended that highway agency and railroad personnel download and review data stored 

within an event recording device (if installed). The proposed minimum required events/circuits to be 

monitored and recorded have been identifi ed in the “Technical Information”, as listed in Table 7.
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Table 7: Minimum Proposed Events/Circuits to be Monitored and Recorded

HIGHWAY RAILROAD

Preempt (Active/Inactive)

Vehicle/Pedestrian Signal

Right-of-Way Transfer Time

Track Clearance Green Interval

Flash Operation

Cabinet Electrical Service

Main Cabinet Door (Open/Closed)

Supervisory Circuit

Railroad Preempt Request

Approach Circuits

Railroad Crossing Relay

Entrance Gate Status

Exit Gate Status

Island Circuit Occupancy

Train Direction

Lock Out Protection

Power (On/Off)

Entrance Alarm (Open/Closed)

This data archive will help identify abnormalities in the operation of interconnected highway-rail 

grade crossing signal systems, particularly with railroad preemption sequencing. It also allows 

personnel to determine if either control cabinet/bungalow has been accessed, fl agging instances 

where changes to operations may have been made without being manually documented on work 

forms and thus requiring further investigation. The ability to download and review archived data 

eliminates the reliance on an isolated crossing event or simulated activation as the sole basis for 

determining whether or not all aspects of the system are working properly.

All inspection activities should be documented according to the inspection and testing form jointly 

adopted by the highway agency and railroad. Any fi ndings needing further investigation, repair, or 

modifi cations made during the inspection should be clearly noted and brought to the attention of 

appropriate highway agency and/or railroad personnel. The form(s) should be signed and dated by 

the personnel performing the inspection and testing activities and fi led. Consideration may be given 

to universally adopting the 49 CFR 234 mandate for recording and fi ling of inspection and test results.

4.3 Post–Inspection

It is important that any issues identifi ed during the annual joint inspection are addressed 

immediately. This requires coordination and cooperation between the highway agency and 

railroad. Highway agencies and railroads should establish agreements to facilitate partnerships 

and meet common goals and objectives. The agreements should clearly defi ne the immediate 

follow-up and continuous maintenance obligations of each agency. The responsibilities of each 

agency in terms of furnishing and funding specifi c elements at highway-rail grade crossings with 

interconnected signal systems should also be established. For example:
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 The railroad or its contractor will furnish and install a relay to provide simultaneous/advance 

preemption to the existing highway traffi c signal and/or proposed traffi c signal/advance fl asher.

 The railroad or its contractor will provide traffi c control in accordance with MUTCD guidelines.

 The highway agency or its contractor will furnish and install or replace appropriate pavement 

markings and signs in accordance with MUTCD guidelines.

 The highway agency agrees to trim and maintain trees and vegetation for adequate visibility of 

the crossing signals and advance warning signs.

Post-inspection activities may also include responding to issues at interconnected highway-rail 

grade crossing locations in between annual joint inspections. Issues relating to incorrect operation 

or system failure (highway, railroad, or both) may be identifi ed by motorists, pedestrians, highway 

agency personnel, railroad personnel, train conductors, emergency personnel, etc. They may also 

be identifi ed through alarms registered by an event recording device (if installed). Abnormalities 

in the events being recorded can be programmed to create an alarm, which is logged within 

the device. The device may also send a remote notifi cation of the alarm to either or both of the 

responsible agencies to alert them of a potential problem.

The highway agency and railroad should establish protocols to respond to potential issues with the 

operation of interconnected highway-rail grade crossing signal systems. This includes identifying a 

point of contact to receive comments and concerns, as well as a single point of authority to make 

decisions regarding necessary modifi cations to resolve problems with the grade crossing operation. 

Additional consideration may be given to personnel and protocol for remotely monitoring and 

addressing event recording device alarms.

Each agency may have or adopt independent inspection, testing, and maintenance activities to 

be conducted at intervals less than 12 months. For example, 49 CFR 234 specifi es components of 

the grade crossing warning system that are to be inspected, tested, and maintained on a monthly 

and quarterly (3 month) basis by FRA. Six-month preventive inspection and testing activities have 

been proposed for highway agencies. Interim independent activities and modifi cations should be 

documented and fi led to keep a record for subsequent joint inspections.

4.3.1 AGREEMENTS

Current practices establish agreements between highway agencies and railroads prior to the 

design and construction of improvement projects. These agreements are required to defi ne the 

responsibilities of both parties to include a detailed scope of work, a method for completing work, 

a reference to appropriate plans and specifi cations, and a maintenance strategy. For federal-aid 

projects, the agreements must also explicitly identify the crossing, describe the improvements being 

made, provide a cost estimate, and establish a proposed work schedule (as required by 23 CFR 

464.216 and 23 CFR 464.218).

One strategy is the use of a “master agreement”. This arrangement can be structured to specify 

the responsibilities of an individual project or for several projects. Depending on the desires of the 

participating highway agencies and railroads, the agreement can also cover the entire project or 

specifi c project tasks. In situations where only partial project responsibilities are defi ned, subsequent 

provisions can be enacted through a change order to the master agreement.

Cooperation and coordination between highway agencies and railroads is required for the joint 

inspection process to be successful. It is also important to ensure that identifi ed problems are 

addressed and resolved in a timely manner to support safe operation of highway-rail grade crossing 

locations. Several “best practices” identifi ed by highway agencies and railroads to promote effective 

partnerships include:
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• Establishing open lines of communication between the agencies;

• Identifying points of contact in each agency with the authority to make decisions;

• Developing agreements to address critical issues such as insurance, rights-of-entry, liability, 

easements, construction safety, and recurring maintenance;

• Training design, construction, and maintenance personnel; and,

• Providing standard process manuals for project development and maintenance.

Developing an agreement between highway agencies and railroads helps to facilitate partnerships 

and meet common objectives. Much like the agreements formed for construction projects, similar 

agreements can be written for conducting the joint inspection. The agreements should clearly state 

the responsibilities of each agency during the process, as well as defi ne the responsibilities of each 

agency immediately following the inspection and in between the next scheduled inspection.

Two sample agreements are attached in Appendix G. These agreements can be modifi ed by 

highway agencies and railroads for the joint inspection of highway-rail grade crossings. The fi rst is 

a railroad-highway master agreement addressing the installation, maintenance, and improvement 

of warning devices. The second is a diagnostic checklist that also specifi es the responsibilities of 

each agency in terms of furnishing and funding specifi c elements at a highway-rail grade crossing 

location.

4.4 Funding Sources

Federal, State, and local government agencies as well as the railroad industry administer funds 

for highway-rail grade crossing improvements. The major source of Federal funding is the Safe, 

Accountable, Flexible, Effi cient Transportation Equity Act: A Legacy for Users (SAFETEA-LU). Also 

known as Section 130 funds, these monies can be used for several types of highway-rail grade 

crossing safety improvement projects, including track circuit improvements and interconnection. 

State and local agency monies are typically used for maintenance of highway traffi c control devices, 

roadway approaches, and vegetation at the highway-rail grade crossing. Railroad monies are 

commonly used for improvements within the railroad right-of-way.

Current practice does not use these funding sources for the conduct of inspections at highwayrail grade crossing locations. The inspections are usually funded through the general operating 

budget of the State (district) or local highway agency offi ce, accounting for the time requirement to 

complete and document the inspection. Since the identifi ed funding sources allow for improvements 

and maintenance, highway agencies and railroads should seek to use these monies for intermediate 

activities as well as for the detailed annual joint inspection of highway-rail grade crossing locations. 

Installation of the event recording device(s) at the location should also be considered in funding 

allocations.
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REFERENCES

1. National Transportation Safety Board. “Collision of Northeast Illinois Regional Commuter 

Railroad Corporation (METRA) Train and Transportation Joint Agreement School District 

47/155 School Bus at Railroad/Highway Grade Crossing in Fox River Grove, Illinois, on October 

25, 1995”. PB96-916202 NTSB/HAR-96/02. Washington, D.C. http://www.ntsb.gov/doclib/

reports/1996/har9602.pdf

2. United States Department of Transportation, Federal Railroad Administration Safety Advisory 

2010-02. Federal Register. Volume 75, Number 190. Friday, October 1, 2010. http://www.fra.

dot.gov/downloads/safety/sa201002.pdf

3. United States Department of Transportation Federal Railroad Administration National HighwayRail Grade Crossing Inventory database. http://safetydata.fra.dot.gov/Offi ceofSafety/publicsite/

crossing/crossing.aspx

4. Traffi c Signal Installation and Maintenance Manual. Institute of Transportation Engineers. 1989.

5. Traffi c Signal Maintenance Manual, Institute of Transportation Engineers, 2010.

6. Code of Federal Regulations. Title 49 Part 234 Subpart D. http://ecfr.gpoaccess.gov/cgi/t/text/

text-idx?c=ecfr&sid=647ff67a5d9d8ca901d518b082942094&rgn=div6&view=text&node=49:4.1.1.1.

28.4&idno=4

7. Manual on Uniform Traffi c Control Devices. 2009 Edition. FHWA. http://mutcd.fhwa.dot.gov/

pdfs/2009/pdf_index.htm

8. 1570 IEEE Standard for the Interface Between the Rail Subsystem and the Highway Subsystem at 

a Highway Rail Intersection. IEEE. 18 October 2002.

9. AREMA Communications and Signals Manual. Revised 2008. http://www.arema.org/

publications/cs/index.aspx

10. Traffi c Engineering Handbook, 6th Edition, Institute of Transportation Engineers, 2009.

11. Traffi c Control Devices Handbook, 2001. Institute of Transportation Engineers.

12. Railroad-Highway Grade Crossing Handbook – Revised Second Edition August 2007. FHWA. 

http://safety.fhwa.dot.gov/xings/com_roaduser/07010/sec06.htm; http://safety.fhwa.dot.gov/

xings/com_roaduser/07010/sec07.htm
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OTHER RESOURCES

13. “Highway-Rail Crossing Program”. FRA. http://www.fra.dot.gov/rrs/pages/fp_86.shtml

14. “Technical Standards and Inspection, Testing and Maintenance Requirements”. Part D – 

Maintenance, Inspection, and Testing. Transport Canada. DRAFT October 24, 2002. http://

www.tc.gc.ca/media/documents/railsafety/StdErv12.pdfMn/DOT Traffi c Signal Timing and 

Coordination Manual. Guidelines for Inspection and Operation of Railroad Preemption 

at Signalized Intersections. May 2011. http://www.dot.state.mn.us/traffi ceng/publ/

signaloperations/2011_Timing%20&_Coordination_Manual2011.pdf

15. “Guideline For Inspecting and Testing Preemption of Interconnected Traffi c Control Signals and 

Railway Crossing Warning Systems.” TP 13755. Transport Canada. http://www.tc.gc.ca/media/

documents/railsafety/TP13755.pdf

16. “Mn/DOT Annual Traffi c Signal and Railroad Preemption Inspection Form”. Version 11/21/2007. 

http://www.dot.state.mn.us/traffi ceng/signals/signalworksheets/html

17. “North Carolina Department of Transportation Highway-Railroad Interconnection and 

Preemption Inspection Form”. July 2007. http://www.ncdot.org/doh/preconstruct/traffi c/itss/

docs/RRForm.pdf

18. “State of Nevada Department of Transportation Railroad Safety Diagnostic Review Form”. 

http://safety.fhwa.dot.gov/xings/com_roaduser/07010/appengform2.pdf

19. “Strategies for Improving the Project Agreement Process Between Highway Agencies and 

Railroads”. SHRP2 Report S2-R16-RR-1. Executive Summary and Appendix C. http://onlinepubs.

trb.org/onlinepubs/shrp2/SHRP2_S2-R16-RR-1.pdf

20. Preliminary Document – Texas Department of Transportation. http://safety.fhwa.dot.gov/xings/

com_roaduser/07010/appeng.htmIEEE 1570 User Guide for Advanced System Controllers 

ASC/3, Econolite Control Products, Inc. 4 December 2009.
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APPENDIX A: IGOR INFORMATIONAL BROCHURE
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APPENDIX B: HIGHWAY AGENCY AND RAILROAD QUESTIONNAIRES

Highway Agency Questionnaire

1. What is involved in the process for the initial inspection of newly installed locations that have 

interconnected at grade rail and highway traffi c signal control systems? Is there an approved 

checklist or required procedures that are required to be followed? If so, could you provide a 

sample of this checklist/test procedure? Is the rail carrier required to be present during initial 

testing and fi nal deployment?

2. Does your agency perform regularly scheduled preventative maintenance/testing of these 

rail / highway traffi c control preemption facilities? If so, what are the time intervals that the 

maintenance/testing are preformed? If testing is performed, is there a written test procedure 

that the test personnel reference/used to perform the tests? If there are written test procedures, 

were they jointly co-authored by the railroad or assembled with input from the railroad? Are the 

results of the testing work recorded and copies maintained for future use?

3. What, if any, special equipment is specifi ed or installed in such facilities that are used to assist 

the agency in a preventative maintenance program?

4. Are there any devices installed in these facilities that record events or system status elements 

which can be used to assist the agency in a preventative maintenance program? If yes, 

are these devices now required for all new installations? If yes, could you please provide the 

amount of use (number of grade crossings in the state versus the amount that have recording 

capability), the manufacturer and part numbers most commonly used recording devices?

5. At a regularly scheduled maintenance/testing, what agencies are required to be in 

attendance? Are these additional agencies required to observe the testing and sign the 

inspection/test reports (if any)?

6. Are your facilities remotely monitored? If yes, please describe method and operation of these 

remote monitoring facilities (example; operation control center, manned 24 hours per day)?

7. Can you provide a description or standard plans that your state uses for the interconnection 

between rail and highway traffi c signal control systems? (For example, two conductor, normally 

closed circuit activation)?

8. Do any of your facilities currently have (or in the future may have) standby battery back-up 

systems to support critical functions within the facilities? If yes, is both the railroad and highway 

traffi c signal control preemption circuitry supported by this electrical power back-up system?

9. In addition to a rail preemption circuit, is there any other information/data currently being 

exchanged between rail and highway traffi c signal control facilities at the fi eld level?

10. Does your agency have any future plans for modifying how rail and highway traffi c signal 

control facilities are interconnected?
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Railroad Questionnaire

Testing Procedure Questions

1. Can you please provide your grade crossing test procedures?

2. Can you describe your formal process for the initial inspection of newly upgraded or installed 

interconnected grade crossings that have railroad preemption systems? Is there an approved 

checklist or required procedures that are required to be followed? If so, could you provide a 

sample of this checklist/test procedure? Is the highway authority required to be present during 

initial testing and fi nal deployment?

3. Does the railroad’s written test procedure for grade crossings include a specifi c test procedure 

for those crossings with preemption? Does the test procedure vary by state?

4. Does the railroad perform regularly scheduled testing of traffi c preemption beyond what is 

required by 49 CFR 234.261? How often is the test performed?

5. Are there any states in which your railroad performs a joint inspection of the traffi c preemption 

with the highway authority? If so, at what intervals does this occur? Do both parties sign off on 

the inspection?

6. What percentage of your grade crossings is remotely monitored? If so, please describe the 

monitoring method.

Preemption Design Questions

1. Beyond AREMA standards, does your railroad have standard designs or practices for 

preemption circuits, including standard cable sizes? If so, can you provide samples?

2. Other than the preemption request circuit, is any information currently exchanged between 

the grade crossing controller and the traffi c signal controller?

Event Recorder Questions

1. How many grade crossings on your railroad are equipped with event recorders?

2. What models of event recorders are currently installed at your grade crossings, and how many 

of each model are in service? Are event recorders required for all upgraded or new grade 

crossing installations? Are these event recorders standalone devices or integrated into another 

device, such as a predictor or controller? Can you provide manufacturers and models of event 

recorders currently being installed at upgraded and new installations?

3. What specifi c alarms and inputs/outputs do you normally record at crossings? Do you record 

alarms and inputs/outputs relating to preemption? 

4. Are these recording devices used to assist in testing and monitoring of the grade crossing and 

preemption?

5. How long is event recorder information stored? Is it regularly transmitted to a control center or 

downloaded by fi eld personnel, or is it only utilized if an incident occurs? Is there a procedure 

that personnel follow in the handling of this data? If fi eld personnel download data, how often 

is this done? Is it part of the maintainer’s monthly/quarterly/yearly tests?
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Policy Questions

1. Do you have any concerns in the development of a joint preemption test with the highway 

authority?

2. What requirements would you like to see as part of a joint preemption test?

3. Would you consider a device that would perform a self-test of the preemption? If so, at what 

interval do you feel self-tests should occur?
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APPENDIX C: EXAMPLE BLOCK DIAGRAMS/WIRING DIAGRAMS

• AREMA C&S Manual: Recommended Vital Circuit Design Guidelines for Highway Traffi c Signal 

Interconnection

• Illinois Commerce Commission: Specifi cations and Design Criteria for Traffi c Signal Control 

Equipment at Locations Interconnected with Railroad Warning Devices, Chicago

• Minnesota DOT: Double Break Railroad Preempt Interconnect Circuit with Supervisor, Gate Down, 

and Supervisor Latch

• Minnesota DOT: Railroad Double Break Interconnect Circuit with Supervisor and Gate Down Logic
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APPENDIX E: RAILROAD 49 CFR TESTING AND INSPECTION REGULATION DETAILS

The following is a summary of the monthly, quarterly and annual requirements for inspection and 

testing at highway-rail grade crossings and the current standard inspection and testing practices 

from the railroad industry as a whole.

Warning System Operation

Monthly Tests

The 49 CFR regulations explain in detail the method by which the railroad carrier must warn the 

public of an oncoming train at an active at-grade crossing. Active crossings are crossings that 

have automatic fl ashing lights, bell and gates as well as any other active warning device which may 

support the Automatic Highway Warning System (AHWS).

Currently, every AHWS system in the country is tested monthly by the railroad carrier as defi ned by 

CFR Rule 234.257 – Warning System Operation:

a. Each highway-rail crossing warning system shall be tested to determine that it functions as 

intended when it is placed in service. Thereafter, it shall be tested at least once each month 

and whenever modifi ed or disarranged. 

b. Warning bells or other stationary audible warning devices shall be tested when installed to 

determine that they function as intended. Thereafter, they shall be tested at least once each 

month and whenever modifi ed or disarranged.

Railroad testing procedures generally direct inspecting personnel to ensure that warning system 

equipment is visible and audible to highway users approaching the crossing and that they operate 

together with the fl ashers.

Quarterly Tests

The 49 CFR also defi nes inspections at highway-rail grade crossings that must be completed at least 

once every 3 months or quarterly:

CFR Rule 234.269 - Cut-out circuits, railroads must test any cut-out circuits at least once every three 

months to determine that the circuit functions as intended. These are usually tests of specialty 

circuits used to bypass or override the operation of the automatic warning systems, or in some 

cases even preempt or activate the crossing warning system.

CFR Rule 234.271 requires the inspection of insulated rail joints, bond wires, and track connections, 

at least once every three months. These tests are used to assure that trains are being properly 

detected on each of the railroad approaches.

Annual Tests

In addition to the monthly and quarterly testing, a complete test of the grade crossing occurs once 

every year. The annual inspection is normally performed by different personnel from those that 

perform the monthly and quarterly tests. Several components of highway-rail grade crossing warning 

systems that are not required to be tested in the monthly or quarterly inspections must be inspected 

in the annual inspection. These tests include those for fl ashing light alignment and fl ash rate, lamp 

voltage, hold clear devices and timing relays.
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CFR Rule 234.265 requires that timing relays and timing devices are tested at least once every 

twelve months. Railroad testing procedures instruct inspection personnel to observe the time 

delay of starting circuits and cut-out circuits and check that they are between 90 and 110 percent 

of the predetermined time interval shown on the plans.

CFR Rule 234.263 - Relays, defi nes the required inspections and the inspection frequency for 

different types of relays associated with the grade crossing warning system. Railroad testing 

procedures generally instruct inspecting personnel to check relay operation for each track and 

in each direction and to ensure that the relays are de-energized after testing is complete. Some 

railroads provide specifi c instructions for inspection of each relay type and for testing with current 

and voltage.

Warning Time

CFR Rule 234.225 - Activation of warning system, states:

A highway-rail grade crossing warning system shall be maintained to activate in accordance with 

the design of the warning system, but in no event shall it provide less than 20 seconds warning 

time for the normal operation of through trains before the grade crossing is occupied by rail traffi c.

Once every 12 months, railroads are required to test the prescribed crossing warning time as stated 

in the CFR, Rule 234.259 - Warning time:

Each crossing warning system shall be tested for the prescribed warning time at least once every 

12 months and when the warning system is modifi ed because of a change in train speeds.

Railroads’ testing procedures generally describe the purpose of this as to ensure the grade crossing 

warning system activates as it is designed to, and in no event provides less than 20 seconds of 

warning time. 

Inspection personnel are instructed to observe the crossing warning time and verify that it is in 

accordance with the designed warning system as shown on the circuit drawings.

If the crossing is equipped with an electronic recording device that accurately records warning 

times, it may be used to perform the test. If no such device is installed, the warning time must be 

found by observing a train movement or calculating the warning time by measuring the approach 

track circuits and using the highest timetable speed.

If the warning time is found to be less than 20 seconds, inspecting personnel are directed to 

immediately take corrective action. Corrective action must also be taken if the warning time is 

consistently found to be less than the designed warning time.

Highway Traffi c Signal Preemption

The required inspection of highway traffi c preemption is defi ned in CFR Rule 234.261 - Highway traffi c 

signal pre-emption:

Highway traffi c signal pre-emption interconnections, for which a railroad has maintenance 

responsibility, shall be tested at least once each month.

The majority of railroad testing procedures identify the test frequency for highway traffi c signal 

preemption as when the traffi c preemption system is placed in service, is modifi ed or disarranged, 
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and at least once per month. Railroad test procedures also typically state that the railroad is 

only responsible for maintenance and testing up to the point of interconnection with the highway 

traffi c control system, and that the local authority is responsible for maintenance and testing of all 

remaining circuitry and traffi c signal control devices.

The test purpose generally described is to ensure that an approaching train activates the crossing 

warning devices and highway traffi c signals and that they are operating properly.

Railroads’ testing procedures generally instruct testing personnel to check contacts and devices 

interconnected with the highway traffi c signals and advanced warning signs to ensure they perform 

as intended.

Inspection personnel are also instructed to verify the proper operation of the interconnect circuit 

and to observe the traffi c preemption is operating as it is intended. Some railroads specify that this 

can be done by observing a train movement and verifying that the warning signs and traffi c signal 

preemption are activated. If observing a train movement is not possible, inspecting personnel 

must simulate a train movement by de-energizing the interconnection circuit thereby activating the 

preemption sequence. If the crossing is equipped with advanced preemption, some railroad testing 

procedures require inspection personnel to observe a train movement to verify proper operation.

Inspection personnel are instructed to note any repairs or adjustments made during the inspection. 

If the interconnection circuit is discovered to be not operational and/or any inconsistency is 

discovered, inspection personnel are instructed to notify the local roadway authority and report it 

to their supervisor. If the railroad equipment is found to be operating properly and the traffi c signal 

system does not respond, inspection personnel are instructed to notify the local roadway authority of 

the problem.

Some railroads state that it may be necessary to have a local highway authority representative 

present to assist with tests and perform maintenance and repairs if necessary. A few states have 

developed detailed joint inspection procedures for highway-rail grade crossings equipped with traffi c 

preemption.
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APPENDIX F: SAMPLE INSPECTION AND DIAGNOSTIC REVIEW FORMS

• Mn/DOT Annual Traffi c Signal and Railroad Preemption Inspection Form

• North Carolina Department of Transportation Highway - Railroad Interconnection and Preemption 

Inspection Form (Instructions)

• State of Nevada Department of Transportation Railroad Safety Diagnostic Review Form - Quiet 

Zones
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APPENDIX G: SAMPLE AGREEMENTS

• Railroad-Highway Master Agreement for Warning Devices

• TxDOT Diagnostic Checklist and Responsibilities
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For More Information:

Visit http://safety.fhwa.dot.gov

FHWA, Offi ce of Safety

Guan Xu

Guan.Xu@dot.gov

202-366-5892

FHWA-SA-12-020