FEDERAL EMERGENCY MANAGEMENT AGENCY

Collocation Impacts on the

Vulnerability of Lifelines During

Earthquakes with Applictions to

the Cajon Pass, California

Issued in Furtherance of the Decade

for Natural Disaster Reduction

Earthquake Hazard Reduction Series 61

FEMA 2261 February 1992
Collocation Impacts on the

Vulnerability of Lifelines During

Earthquakes with Applications to the

Cajon Pass, California

Submitted to the Federal Emergency Management Agency

Washington, D.C.

Submitted by:

INTECH Inc.

11316 Rouen Dr.

Potomac, MD 20854-3126

Co-Principal Investigators:

Dr. Phillip A. Lowe, INTEC, Inc.

Dr. Charles F. Scheffey, INTEC, Inc.

Mr. Po Lam, Earth Mechanics, Inc.
COLLOCATION IMPACTS ON THE VULNERABILITY OF LIFELINES DURING

EARTHQUAKES WITH APPLICATION TO THE CAJON PASS, CALIFORNIA

TABLE OF CONTENTS

Volume 1

ITEM PAGE

Table of Contents ..................... t .i

List of Figure............................................ ii

List of Tables........................................ v

1.0 CONCLUSIONS ................................... 1

2.0 INTRODUCTION ..................... . . 4

2.1 Background .. . ...... 4

2.2 Study Approach . . .................... . . 5

2.3 Chapter 2.0 Bibliography ................................ 6

3.0 SUMMARY .................................. . 6

4.0 ANALYSIS METHOD ...................................... 8

4.1 Data Acquisition . . . ............. 11

Lifeline and Geologic Information ... . . 11

Ground Shaking Intensity . . ............................... 13

Selection of the Earthquake Event ...................... 16

4.2 Calculation of Lifeline vulnerability .................. 16

Damage Assessment ................................... . 16

Shaking Damage .. . ..... 18

Fault Displacement. . . 23

Soil Movement . . ........................................ 24

Landslide .... 24

Liquefaction or Lateral Spread . . . .30

Highway and Railway Bridges . . ... 31

Times, to Restore the Lifeline to its Needed Service 37

Repair Time .............. 37

Access Time .... 38

Equipment and Material Time ........................... 39

4.3 Collocation Analysis .................................... 39

Impacts on Damage State....... .... 42

Impacts on Probability of Damage .... 42

Impacts on Time to Restore Lifeline Service . .43

4.4 Interpretation of the Results. .......................... 44

4.5 -Chapter 4.0 Bibliography ............................... 45

5.0 APPLICATION OF THE METHOD TO CAJON PASS ........ 47

5.1 Data Acquisition .... 47

5.2 Lifeline Collocation Vulnerability Analysis Results 55

Communication Lifelines .... 61

Electric Power Lifelines . . ............................ 6.8

Fuel Pipeline Lifelines ............................... 75

Transportation Lifelines .... 81

5.3 Chapter 5.0 Bibliography. . . 91

6.0 FUTURE STUDY NEEDS .... 91

Appendix A Modified Mercalli Intensity (MMI) Index Scale

i
LIST OF FIGURES

FIGURE PAGE

1 Flow Chart of the Analysis Method ....................

2 The "Attenuation Parameter k" for Use in Calculating

Earthquake Shaking Intensity .........................

3 Map of the U.S. Seismic Hazard Regions ................

4 Liquefaction Induced Damage ...........................

9

15

22

32

5 Map Showing the General Location of the Cajon

Pass Study Area ....................................... 48

6 A Composite of the Lifeline Routes at Cajon Pass ...... 50

7 Identification of Collocations At Cajon Pass ... ....... 52

8 Lifeline Routes With Shaking Intensity and

Potential Landslide and Liquefaction Areas ... ......... 54

9 Communication Lifeline Routes .......................... 62

10 Fiber Optic Conduits On A Bridge On The Abandoned

Portion of Cajon Blvd. Extension ...................... 63

11 Details of the Fiber Optic Conduits of Figure 10 ...... 63

12 Fiber Optic Conduits On A Concrete Culvert

That Passes Under I-15 ................................ 64

13 Wall Support Details for the Fiber Optic Conduits

Shown in Figure 12 .................................... 64

14 Surface Water Conditions Near The Toe of The I-15S

Retaining Crib Wall ................................... 65

15 Fiber Optic Conduits Under a Heavy Water Pipe, Both

on a Highway Bridge ................................... 65

16 Electric Power Lifeline Routes ........................ 69

17 A Landslide Scar With Power Towers in the Slide Area .. 70

18 Power Lines, Natural Gas and Petroleum Products Pipelines

Intersecting Over the San Andreas Fault Rift Zone ..... 71

ii

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure
Figure 19 Power Tower at a Ravine Edge in the San Andreas Fault

Rift Zone .............. 72

Figure 20 Fuel Pipeline Lifeline Routes ...................... 76

Figure 21 Typical Long Open Span on the 36-Inch Natural

Gas Pipeline ...................................... 75

Figure 22 Two Natural Gas Pipelines Located Next to Highway 138 . 77

Figure 23 Natural Gas Pipeline Crossing Under Railroad Beds . 78

Figure 24 Transportation Lifeline Routes .......................... 83

Figure 25 I-15 Bridge Over Railroads in Cajon Wash .............. 84

Figure 26 I-15 Bridge Over Cajon Wash .................... ........ 84

Figure 27 Highway 138 Bridge Over I-15 .......................... 85

Figure 28 Railroad Bridges in Cajon Wash (I-15 Bridge in

Background) ................................... 886.... 

Figure 29 Railroad Bridge Over Highway 138 (Collapse Expected) .. 86

Figure 30 Santa Fe Railroad Bubble Masonry Pier Bridge .8........ 87

Figure 31 Union Pacific Railroad Bridge With Power Lines

Overhead.....................................8....... 7

Figure 32 Typical I-15 Box Bridge Over the Railroads .90

Figure 33 I-15 and Access Road Bridges Over the Southern

Pacific Railroad .............. ...... 9090........

iii
LIST OF TABLES

TABLE PAGE

Table 1. CAJON PASS IMPACTS OF LIFELINE PROXIMITY: EXPERT

TECHNICAL ADVISORY GROUP .............................. 6

Table 2. ATC-13 DEFINITION OF LIFELINE DAMAGE STATE ... ......... 17

Table 3 SHAKING DAMAGE PROBABILITY MATRICES,

ATC-13 Tables 7.10 .................................... 19

Table 4 MMI ADJUSTMENTS FOR SHAKING DAMAGE EVALUATIONS TO ACCOUNT

FOR LOCAL CONDITIONS .................................. 23

Table 5 LIFELINE DAMAGE STATE FOR FAULT SURFACE DISPLACEMENTS,

ATC-13 Table 8.9 ...................................... 24

Table 6 SOIL PARAMETERS FOR CALCULATING LANDSLIDE POTENTIAL ... 26

Table 7 LANDSLIDE SLOPE FAILURE PROBABILITY MATRICES,

ATC-13 Table 8.7 ...................................... 27

Table 8 CONVERSION OF LANDSLIDE SLOPE FAILURE STATE TO DAMAGE

STATE, ATC-13 Table 8.8 ................................ 29

Table 9 RELATIONSHIP BETWEEN LIQUEFACTION SEVERITY INDEX (LSI)

AND DAMAGE STATE ...................................... 30

Table 10 PROBABILITY OF LIQUEFACTION GROUND FAILURE, PERCENT ... 31

Table 11 RELATIONSHIP OF BRIDGE VULNERABILITY INDEX TO

BRIDGE DAMAGE STATE ................................... 33

Table 12 BRIDGE VULNERABILITY INDEX FOR EARTHQUAKE SHAKING

DAMAGE ................................................ 35

Table 13 ESTIMATED LIFELINE REPAIR TIMES TO 100% OPERATING

CAPACITY, ATC-13 Table 9.11 ........................... 38

Table 14 LIFELINE ZONES OF PHYSICAL INFLUENCE .................. 41

Table 15 MATRIX OF LIFELINE COLLOCATION AND INTERACTIONS ....... 56

iv
COLLOCATION IMPACTS ON THE VULNERABILITY OF LIFELINES DURING

EARTHQUAKES WITH APPLICATION TO THE CAJON PASS, CALIFORNIA

1.0 CONCLUSIONS

The purpose of this study was to:

develop a management screening tool that can be used by

lifeline owners, designers and providers, operators, users,

and regulators to sort through numerous collocation conditions

to identify the critical locations and to provide an estimate

of the increased risk that results when such collocated

facilities are subjected to an earthquake event; and to

analyze the Cajon Pass, California, situation to demonstrate

how the screening tool can be used and to examine specific

conditions at the Pass.

The resulting screening tool is an important development for

several reasons:

1) it is the first documented method for examining multiple

collocation conditions and it is applicable to all lifeline

facilities. As improvements are made in the fundamental

analysis methods for individual lifelines or earthquake

conditions, they readily can be introduced into the screening

tool to improve its predictive ability;

2) its use can identify the most critical collocation

conditions at a specific study area, thereby allowing limited

resources to be focused on the most important conditions for

improving the overall ability of the lifelines to survive an

earthquake event;

3) its use can identify technical areas of uncertainty and/or

poor siting practices. This can identify the need for and

lead to further research and studies to reduce the identified

technical uncertainty or it can identify ways to mitigate

siting practices that are more vulnerable to inducing

collocation failure conditions; and

4) by being documented and made widely available by the

Federal Emergency Management Agency, it is anticipated that it

will stimulate the earthquake and lifeline communities to

developed improvements in the analysis method or even to

develop new, improved screening methods.

The development of the analysis methodology as well as, its test

application to the Cajon Pass has highlighted several important

conclusions.

I
o Lifeline collocation can produce both benefits and increased

risk of failure during earthquake events. A benefit of

closely located transportation lifelines is that the second

lifeline can provide the detour or access route to the damaged

sections of the first lifeline. However, intersecting

lifelines generally result in the failure of one lifeline

increasing the risk of failure of the lifeline(s) it crosses.

o It is understandable that topographic conditions have led to

the routing of lifeline systems in corridors. However,

manmade considerations that force the lifeline owners to use

the same rights-of-way for widely different lifelines (for

example, locating petroleum fuel pipeline and communication

conduits next to each other, routing natural gas pipelines

back and forth under a railroad bed, and having a mix of

lifelines cross the earthquake fault zone at the same

location) greatly increase the risk of failure for the

individual lifelines and the complications that will be

encountered during site restoration after an earthquake.

o As compared to buildings, ground movement is more important

that ground shaking for lifeline components, especially buried

lifelines and electrical transmission towers. This means that

much of the technical data base on earthquake shaking

intensity is not critical for lifeline analysis, whereas

important ground movement data and analyses are not as well

developed as the shaking intensity data. This suggests that

future studies need to emphasize obtaining ground movement

information.

o A very useful screening tool has been developed during this

study. The tool can be used to identify the critical lifeline

collocation locations and the conditions that make them

critical. It can identify areas of technical uncertainty and

poor siting practices, and its use can identify important

research and development activities that can lead to lowered

risk of collocation-induced lifeline failures. It will be of

value to lifeline owners, designers and providers, operators,

users, and regulators.

o The analysis tool has been successfully applied to the Cajon

Pass, California. It has identified that for this semi-desert

region that:

The Cajon Junction, Lone Pine Canyon (which contains the

San Andreas fault zone), Blue Cut, and the area just

south of the interchange between I-15 and I-215 are the

critical locations in terms of collocation impacts at the

Cajon Pass.

Fuel pipeline failures have the greatest impact on the

other lifelines during the immediate recovery period

2
after an earthquake.

Current siting practices for fiber optic cables indicates

that more severe telephone communication failures than

have been experienced in past earthquakes can be

anticipated in future earthquakes when fiber optic

systems have become more dominant in providing the basic

telephone service.

Lifeline siting practices have not fully considered the

impacts that a new lifeline will have on existing

lifelines and, conversely, the impacts that the existing

lifelines will have on the new lifeline.

Transportation lifeline restoration of service is highly

dependent on sequentially repairing the lifeline damage

as the lifeline itself is needed to provide access to the

next damage location. Parallel repair operations are

more probable for the other lifeline systems.

Communication, electric power, and fuel pipeline

lifelines can generally be analyzed as a set of discrete

collocation points. The restoration of service at any

one point is not a strong function of the restoration

work that is needed at other collocation points. Thus,

if there is a restoration problem that will take a long

time compared to the other locations, it becomes the

"critical path" that sets the time period for the

restoration of the entire lifeline system.

When multiple lifelines of the same class are collocated

(such as installing all fiber optic cables or all fuel

pipelines in the same or parallel trenches) or when

multiple different lifelines intersect at a common point,

the reliability of each individual lifeline decreases to

the value of the "weakest link" of the combined lifeline

systems. In addition, repair times increase because of

local congestion and the concern that work on one

lifeline component could lead to damage of the other

different lifeline components.

o There is a need for further collocation lifeline studies: to

apply the newly developed screening tool to other locations to

assure that the methods can be transferred to other U.S.

locations and to analyze different lifelines, geographic, and

earthquake conditions; and to develop data and approaches that

can be used to further improve the predictive capabilities of

the screening tool.

3
2.0 INTRODUCTION

2.1 Background

Lifelines (e.g., systems and facilities that deliver energy and fuel and systems and facilities that provide key services such as water and sewage, transportation, and communications are defined as lifelines) are presently being sited in "utility or transportation corridors" to reduce their right-of-way environmental, aesthetic, and cost impacts on the communities that rely upon them. The individual lifelines are usually designed, constructed, and modified throughout their service life. This results in different standards and siting criteria being applied to segments of the same lifeline, and also to different standards or siting criteria being applied to the separate lifelines systems within a single corridor. Presently, the siting review usually does not consider the impact of proximity or collocation of the lifelines on their individual risk or vulnerability to natural or manmade hazards or disasters. This is either because the other lifelines have not yet been installed or because such a consideration has not been identified

as being an important factor for such an evaluation.

There have been cases when some lifeline collocations have increased the levels of damage experienced during an accident or an earthquake. For example, water line ruptures during earthquakes have led to washouts which have caused foundation damage to nearby facilities. In southern California a railroad accident (transportation lifeline) led to the subsequent failure of a collocated fuel pipeline, and the resulting fire caused considerable property damage and loss of life. Loss of electric

power has restricted, and sometimes failed, the ability to provide water and sewer services or emergency fire fighting capabilities.

In response to these types of situations, the Federal Emergency Management Agency (FEMA) is examining the use of such corridors, and FEMA initiated this study to examine the impact of siting multiple lifeline systems in confined and at-risk areas.

The overall FEMA project goals are to develop managerial tools that can be used to increase the understanding of the lifeline systems' vulnerabilities and to help identify potential mitigation approaches that could be used to reduce those vulnerabilities. Another program goal is to identify methods to enhance the transfer of the resulting information to lifeline system providers, designers, builders, managers, operators, users, and regulators.

This report is the second of a series of three reports. The first report(' presented an inventory of the major lifeline systems located at Cajon Pass, California, and it summarized the earthquake and geologic analysis tools available to identify and define the

* The numbers in superscript are references found at the end of each chapter. 4
level of seismic risk to those lifelines. This report presents the

analytic methods developed to define the collocation impacts and

the resulting analyses of the seismic and geologic environmental

loads on the collocated lifelines in the Cajon Pass. The assumed

earthquake event is similar to the 8.3 magnitude, San Andreas

fault, Ft. Tejon earthquake of 1857. In this, report a new analysis

method is developed and applied to identify the increase in the

vulnerability of the individual lifeline systems due to their

proximity to other lifelines in the Cajon Pass. A third reports

presents an executive summary of the study. The Cajon Pass

Lifeline Inventory report and this present report taken together

provide a specific example of how the new analysis method can be

applied to a real lifeline corridor situation.

2.2 Study Approach

The approach used to develop the information for this report was as

follows. The Cajon Lifeline Inventory report('), additional

information provided during direct meetings with the lifeline

owners, site reconnaissance surveys to validate the information and

to examine specific site conditions of interest to the study, and

existing literature that describes lessons learned from actual

earthquake events were compiled and thoroughly studied. The

principal investigators then hypothesized an analysis method that

could be applied to the Cajon Pass lifelines to estimate the

impacts of proximity on their earthquake-induced performance and

repairs.

This analysis method emphasizes building upon existing data bases

and analytic methods. In applications, it is recommended that the

analyses, studies, and information available from the lifeline

owners be used whenever possible. In the event that sufficient

data on the lifeline response to earthquakes and the expected time

to restore the lifeline back to its, required service level are not

available from the lifeline owners, the analytic methods, with some

important modifications, of "Earthquake Damage Evaluation Data for

Californial, ATC-13(3 ), are recommended as an appropriate alternative

analysis method. In this project the "most probable restoration

time" was defined as the analysis parameter that best could be used

to define the impact of lifeline proximity on the individual

lifeline's earthquake vulnerability.

The resulting method was then applied to the Cajon Pass lifelines.

The U.S. Geologic Survey's digitized topographic map of the Cajcn

Pass and the contiguous quadrangles were utilized. The commercial,

computer aided, design program AutoCAD was used as it is readily

available to the public, thus the methodology is not limited to

being dependent upon a specialized or proprietary computer program.

With this tool, overlays of the lifeline routes with seismic and

geologic information presented in the inventory reportcl' were used

to identify the conditions and locations where the individual

lifelines were most vulnerable to the hypothesized earthquake. The

5
analysis methods described in Section 4.0 of this report were then

applied to the lifelines and the results are presented in Section

5.0. Section 6.0 identifies future studies that could be

undertaken to further qualify the analysis methods and to improve

the details of the specific analysis activities. Section 3.0

provides a summary of the study.

As part of the study validation process, the draft results of the

study were submitted to the project advisors, see Table 1, for

their independent professional evaluation and to the lifeline

owners and regulators who provided information for the preparation

of the report or the Cajon Pass Inventory report. FEMA also sent

draft report copies to a select list of independent reviewers.

Each comment received was addressed, and this final report then was

prepared and submitted to FEMA.

Table 1

CAJON PASS IMPACTS OF LIFELINE PROXIMITY:

EXPERT TECHNICAL ADVISORY GROUP

William S. Bivins T.D. O'Rourke

James H. Gates Dennis K. Ostrom

Le Val Lund Kenneth F. Sullivan

John D. (Jack) McNorgan

2.3 Chapter 2.0 Bibliography

1. P. Lowe, C. Scheffey, and P. Lam, "Inventory of Lifelines in

the Cajon Pass, California", ITI FEMA CP 120190, August 1991.

2. P. Lowe, C. Scheffey, and P. Lam, "Collocation Impacts on

Lifeline Earthquake Vulnerability at the Cajon Pass, -

California, Executive Summary", ITI FEMA CP 050191-ES, August

1991.

3. C. Rojahn and R. Sharpe, "Earthquake Damage Evaluation Data

for California", ATC-13, 1985.

3.0 SUMMARY

This report presents a systematic approach to calculate the impacts

due to the collocation or close proximity of one lifeline to

another during earthquake conditions. Specifically, the

collocation vulnerability impact is defined as the increase in the

most probable time to restore the lifeline to its intended level of

service. The analysis methods proposed are intended to be used in

screening analyses that determine which lifelines or lifeline

segments are most impacted by the collocation or close proximity of

other lifelines. Once the critical locations or conditions are

known, it may be equally important to reanalyze them using more

detailed analyses to further define the collocation impacts.

6
The methods proposed are to use the best available information to

determine the lifeline damage state, the probability that the

damage state or greater will occur, and the time to restore the

lifeline to its intended service. Normally, such information is

obtained from the lifeline owner/operator. However, a alternative

method is proposed when such information is not available from that

source.

The alternative method is based on building upon existing

earthquake damage information and analysis methods which have been

'compiled by the Applied Technology Council (ATC). In that manner,

the analysis results can be compared with earlier or future studies

that use the data base without the need to compare or justify the

data base. However, important improvements to the existing ATC

data base also are presented.

Collocation impacts, can be described in one of two broad terms: 1)

the resource impacts (i.e., the increase in personnel, equipment,

and material resources) that are required to return the total

lifeline system to its needed operating capacity. This is

performed in the present method by summing the impacts at each

component along the entire lifeline route. 2) the resource impacts

at a specific location where multiple lifeline components are

located. In both cases, the present method uses the most probable

time to restore the lifeline component or system to its needed

operating capacity as the appropriate measure of the resource

impacts.

The analysis method has been applied to the lifeline systems in the

Cajon Pass, California, as a test case. It is clear that the

communication, electric power, and fuel transmissions lifeline

systems that have the potential for collocation impacts are, in

general, not very sensitive to earthquake ground shaking for

shaking intensities represented by Modified Mercalli Intensity

indices of VIII or less (these are the values found at Cajon Pass

for the assumed earthquake event). They are, however, very

sensitive to ground movement expressed as fault displacement,

landslides, or lateral spreads. Bridges are sensitive to both

ground shaking and ground conditions (displacement, landslide,

lateral spread, and local liquefactions at their foundation

locations).

It is understandable that topographic conditions have led to the

routing of lifeline systems into corridors. However, manmade

considerations that force the lifeline owners to use the exact same

rights-of-way for widely different needs (for example, locating

petroleum fuel pipeline and communication conduits next to each

other, routing natural gas pipelines back and forth under a

railroad bed, and having a mix of lifelines cross the earthquake

fault zone at the same location) greatly increases the individual

lifeline risks and the complications that will be encountered

during site restoration after an earthquake.

7
The Cajon Pass example has identified that the communication,

electric power transmission, and fuel pipeline lifelines generally

can be analyzed as a set of discrete collocation points. The

restoration of service at any one point is not a strong function of

the restoration work that is needed at other collocation points.

Thus, if there is a restoration problem that will take a long time

compared to the other locations, it becomes the "critical path"

that sets the time period for the restoration of the entire

lifeline system. Transportation lifeline collocation points,

however, are sensitive to the damage that has occurred along the

route of the transportation system. That is, often it is necessary

for the heavy equipment and material needed to have access to the

damage location by traveling along the highway or railroad itself.

Thus, before access to a particular bridge can be made, it may be

necessary to first repair all the damage sites on the route prior

to that location.

4.0 ANALYSIS METHOD

In performing an analysis of the impacts of collocation or close

proximity on lifeline systems and components for earthquake or

other at-risk conditions, it is important that the most accurate

data and analyses be used to characterize the response of the

individual lifelines to the loads applied. Whatever method is

applied must be applicable to all the components within the

lifeline system, because the evaluation of the collocation impacts

requires comparing the calculated time to restore the lifeline to

its intended service for both the collocation and an assumed noncollocation condition. The general methods for performing such an

analysis are shown in the flow chart of Figure 1. If ownersupplied or site specific analysis methods are not available for

use in the detailed calculations, the following material (Sections

4.1, 4.2, 4.3, and 4.4) can be used as the alternative analysis

method. This is discussed more fully in the following material.

Figure 1 shows a four step approach that can be used to analyze any

lifeline under at-risk conditions (e.g., an natural or manmade

disaster condition). However, the present study only develops the

detailed information needed to analyze earthquake conditions. The

steps are:

1) Data Acquisition;

2) Calculation of Lifeline Vulnerability;

3) Collocation Analysis; and

4) Interpretation of the Collocation Impacts.

Briefly, these activities include:

Data Acquisition

This task is to assemble all of the information that defines the

lifelines and their routes as well as the geologic and seismic

8
Figure 1, FLOW CHART OF THE ANALYSIS METHOD

FLOW CHART OF ACTIVITIES FOR

CALCULATING COLOCATION-INDUCED LIFELINE

VULNERABILITIES DURING EARTHQUAKES

RESULT

Most probable Incremental

change in restoration time

9

STEP 1

DATA ACQUISITION

a Lifelines and routes

* Geologic and seismic conditions

* Colocation points

a Lifeline analysis segments

STEP 2

CALCULATION OF LIFELINE VULNERABILITIES

Assuming no colocation

& Damage state

4 Probability of damage

a Restoration time

STEP 3

COLOCATION ANALYSIS

* Lifeline zones of Influence

* Damage scenario

a Recalculate new

o Damage state

o Probability of damage

o Restoration time

Il F

STEP 4

iMPACT OF COLOCATION

- Incremental Change In restoration time

I Colocation damage probability
conditions that will place loads on the lifelines. Some analysis

and organization of the resulting information is included in this

step to facilitate the application of the analysis method to the

specific conditions of interest. Such analyses include identifying

the collocation sites as well as dividing the lifelines into

consistent sections for subsequent analysis.

Calculation of Lifeline Vulnerability

The geologic conditions identified during the data acquisition are

used as input to a seismic analysis. Such data include the

topology of the area being studied, a description of the sediment

and rock structures, locations of water, and identification of

surface ground slopes. Seismic conditions include identifying the

location and type of the anticipated earthquake. These are used to

estimate the earthquake shaking intensities (it is recommended that

Modified Mercalli Intensity (MMI) indices be used to characterize

the shaking intensity) and earthquake-induced landslides and soil

liquefaction locations.

During this analysis step, the earthquake intensities and ground

movements are use to determine the vulnerability of each lifeline

at each collocation site as if it were the only lifeline at that

site (e.g., as if there were no collocation there). Based on the

design and placement of the lifeline component or segment and the

seismic loads placed on it, the resulting damage state, probability

that the damage state will occur, and the time required to restore

the lifeline to its intended service can be calculated. The

restoration time is the sum of the time to repair the lifeline

assuming all the equipment, material, and repair personnel are

available at the damage location, plus the access time required to

transport them to the damage location, plus the time required to

have them available to transport to the site.

If owner-supplied damage information is not available, it is

recommended that the analysis methods, as modified in this report,

of "Earthquake Damage Evaluation Data for California", ATC-13,

1985, (prepared by the Applied Technology Council of Redwood City,

California) be used. When a study is to be performed for locations

outside of California, professional judgement must be applied to

determine how to adjust, if at all, the data base of ATC-13. The

methods of "Seismic Vulnerability of Lifelines in the Conterminous

United State, ATC-25, (presently in print at the Applied Technology

Council, and identified as reference 20 in this report section) can

be considered for use. However, it is noted that the consistency

and validity of the ATC-25 approach has not been examined during

the present study, and thus the methods of that study can not be

recommended by the Principal Investigators of the present study.

It is identified here for information only.

10
Collocation Analysis

This analysis step builds upon the results obtained from the

previous two analysis steps. Based on the actual anticipated

damage states for each lifeline at the collocation site as

determined in the previous analysis steps a collocation interaction

scenario is postulated. The scenario can change either the damage

state, the probability that the damage will occur, the restoration

time (typically only the access time would be changed and the

repair time then would be a new calculation), or any combination of

those items. After the individual items are specified, the

remaining items (i.e., the non specified damage state, probability,

or repair time) are determined using the calculation method applied

in the previous analysis step.

Interpretation of the Collocation Impact

This analysis step uses the calculated information of the two

previous steps to characterize the impact of lifeline collocation.

The most realistic measure of the impact is the "most probable

incremental change in the restoration of service time"'. This is

defined as the product of the probability of collocation damage

occurring times the incremental increase in restoration of service

time (the incremental change in the time to restore service is the

restoration time for collocation minus the restoration time with no

collocation considered).

Additional details on the recommended analysis, approach are

provided in Sections 4.1, 4.2, 4.3, and 4.4 below.

4.1 Data Acquisition

Lifeline and Geologic Information

Data acquisition is the first step of any lifeline vulnerability

analysis. Information is needed to define the lifelines and their

routes as well as to define the geologic and seismic conditions

that apply to the lifelines of interest.

Information on the lifelines can be obtained from a number of

sources. It is recommended that a site reconnaissance visit be

conducted first to help the researchers understand the physical

conditions and to preliminarily define the lifelines of interest.

In addition, maps from the U.S. Geologic Survey (such as

topographic maps, published at the quadrangle scale of 1:24,000),

state departments of natural resources or mines and geology, the

U.S. Forest Service, and highway maps are excellent sources of

data. They often indicate lifeline components and routes as well

as identify geographic features. The U.S. and state geologic

surveys (or departments of mines and geologies etc.) will also

have maps and studies that characterize the earthquake faults,

ground units (e.g., the types of sediments and rock formations in

11
the areas of interest), landslide locations, water table data,

etc.. State offices of emergency response (such as offices of

emergency preparedness or seismic safety offices), fire marshal

offices, state public utility commissions, water boards and

commissions, and the general professional literature on earthquakes

are other important sources of information on lifelines and the

potential geologic/seismic conditions of interest.

The single most important source for lifeline information is the

owner/operators. They will each have detailed route maps and

details on their design, construction, and installation. However,

as built drawings and construction information are frequently

different than the "design" information. Thus, it is important to

discuss the information received with the suppliers, and to

validate the understanding received with data from other sources

and site reconnaissance visits.

Once the applicable lifeline data has been assembled, the lifeline

collocation or close proximity locations in the study region should

be identified and given a reference number. Also, each lifeline

should be divided into convenient segments that are reasonably

uniform in their characteristics. These activities are done to aid

in the subsequent analysis steps. The application of the analysis

algorithms (to be described below) can be separately applied to

each lifeline collocation location, using the list of collocation

location points as a check that all the needed locations were

considered, and using the lifeline segments to identify the

physical conditions at the collocation point being analyzed.

The lifeline segments or divisions selected for analysis should be

reasonably "uniform" in that the lifeline components should be

similar within the segment, the shaking intensity (as measured by

the Modified Mercalli Intensity (MMI)) index should be similar, the

ground conditions should be similar (that is, areas of ground

movement should be analyzed separately from areas of stable

ground), and access for repair crews, equipment, and material to

the lifeline proximity points along the segment should be

reasonably the same. With this approach, lifelines, such as buried

pipelines or electrical transmission lines, can be divided into

long segments. Their division is primarily set by the ground

conditions and the MMI values. Other lifeline systems that have

frequent component changes in them, such as transportation systems

that include bridges separated by roadbeds, need to be separated by

component and access route, and sometimes the roadbed must be

further divided to account for ground condition or MMI changes.

Whenever possible, standard measures of earthquake events should be

used to characterize the seismic conditions in the study area. In

this way the results of the study more readily can be compared with

other published data, which allows the conclusions to be validated

by such other available information. Thus, earthquake magnitude or

the earthquake "size" can be represented by the Richter scale.

12
Ground Shaking Intensity

Several methods to characterize the intensity of the shaking of an

earthquake were considered. Items considered included the

magnitude and extent of the shaking. Although ground acceleration,

velocity, and displacement are more appropriate for evaluating

specific lifeline designs, the use of intensity scales are more

dominant in the literature. Rossi-Forell (RF) and Modified

Mercalli Intensity (MMI) scales are commonly used as a measure of

intensity. MMI is recommended for use since it is more widely used

in the earthquake literature, although it is a subjective scale

that is dependent on individual interpretation of its meaning.

Appendix A presents the detailed definitions of MMI..

The MMI scale includes 12 categories of ground motion intensity

from level I (not felt) to level XII (total damage). The use of

Roman numerals was done to discourage analysts from trying to

consider half scale values. This further implies that the MMI is a

broad measure of the shaking intensity. The individual MMI scales

are almost exclusively characterized in terms of building damage,

so their usefulness for modern lifeline structures and components

is somewhat restricted. ATC-l3 (2, provides a detailed estimate of

lifeline damage probability as a function of the MMI scale. As an

example of potential interpretation problems, the MMI scale IX

identifies that "runderground pipes are sometimes broken" while ATC13 for MMI = IX estimates in California that pipe breaks will occur

with a total probability of 91.3%. This illustrates the subjective

nature of the MMI scale. Nevertheless, it is commonly used to

characterize earthquake intensity, *and for consistency it

recommended as the proper characterization parameter for examining

the collocation impacts on lifeline vulnerability to earthquakes.

Although there are two computer models,(3,4 ,5) that calculate

earthquake intensit and that are applicable to the conterminous

U.S., the Evernden ) model is recommended because it has been

verified by comparison with historical earthquakes, it incorporates

the local sediment conditions and such sediment conditions are

generally available in the national U.S. Geological Survey geologic

data base and in the data bases of the various state offices of

mines and geology or natural resources, it is easy to use, it is

readily available to researchers, lifeline owners, and to others

who may need to apply the methods of this study to other regions in

the U.S., and it facilitates comparisons of this research with that

of others 7) who have used the Evernden Model. The Advisors to this

Project were concerned that the Evernden model may not be as

accurate near the earthquake fault location (it appears to

underestimate the EMI values there) as it is in predicting the far

field effects. Discussions with the staff of the California

Division of Mines and Geology confirmed that they had similar

concerns. The recommended solution is to increase the calculated

MMI value by one scale level at locations near the earthquake fault

zone. For most lifeline components this is expected to have a

13
small impact, because the fault displacement effects there are

expected to overshadow the shaking effects represented by the

increased MMI value.

The Evernden model has been coded in a computer program, QUAK2NW3.

Appropriate input data files are available with the model, and they

were verified for use in the present study. They include:

(1) a fault data file that identifies the location of the

geologic fault by a series of uniform point sources.

They can be spaced as closely as desirable.

(2) a ground condition file that identifies the soil

conditions (soil and ground geologic units or

descriptions). The spacing of these ground units

provides the calculation grid for the program. Evernden

typically organizes the ground condition into 0.5 minute

latitude by 0.5 minute longitude grids, and they were

used for the present study.

(3) a pseudodepth term "C" which is chosen to give the proper

near-field die-off of the shaking intensities. Evernden

has previously analyzed earthquakes along the San Andreas

fault, and his value of C (10 kilometers) was used in

this study. Values for other faults can be selected with

consultation with Dr. Evernden or by professional

judgement.

(4) an attenuation parameter "k" which controls the rate of

die-off of peak acceleration as a function of distance

from the fault being analyzed. Evernden has identified a

value for coastal California, eastern California and the

Mountain States, the Gulf and Atlantic Coastal plains,

and the rest of the eastern U.S., and these values are

shown in Figure 2. The coastal California value was used

in this study, k = 1.75.

With the above input, QUAK2NW3 computes the acceleration associated

with the energy release along each position of the fault.

Earthquake intensities are calculated in terms of the Rossi Forell

scale, and then the MMI value is computed from a correlation that

Evernden developed for that purpose. The intensity is first

computed for a reference ground unit condition (e.g., saturated

alluvium), and then the intensity value at each grid point is

adjusted for the actual ground condition specified in the ground

condition file. The output of QUAK2NW3 can be used as input into a

digital plotting program, so that the regions of uniform MMI index

can be automatically plotted over the routes of each lifeline

system studied. In the present study the commercially available

program "AutoCAD" was used, although other similar programs would

be just as appropriate. An important criteria for the selection of

the plotting program is that it should be able to read the

14
Figure 2, THE "ATTENUATION PARAMETER k" FOR USE

EARTHQUAKE SHAKING INTENSITY

IN CALCULATING

APPROXIMATE PATTERN OF ATTENUATION CHARACTERISTICS (k-VALUE DISTRIBUTION)

THROUGHOUT THE CONTERMINOUS UNITED STATES

15
ditigitized files of the U.S. Geological Survey topographic maps.

Those maps include the routes of many of the lifelines and the

geographic elevation contours. Later when ground slopes are needed

to calculate landslide and liquefaction potential, the computer

program can be used to automatically perform the calculations.

Thus, a single program can conveniently incorporate and graphically

present all the key data: lifeline location, fault traces, MMI

values, and ground slopes.

Selection of the Earthquake Event

The next step is to identify the earthquake event for the analysis.

Based on the faults in or near the study region, the QUAK2NW3

program can be used to perform a sensitivity evaluation to identify

the appropriate earthquake event. All that is required is to input

various earthquake events (length and location of the fault

movement, the ground conditions, the depth of the earthquake, and

the attenuation parameter). The results of several analyses can

then be compared to identify the most realistic event for the

analysis. Key additional data that should be considered is the

prediction of the magnitude and the probability that an earthquake

will occur near or in the study region. Such predictions are

available from Federal and state seismologic offices.

4.2 Calculation of Lifeline VulnerabilityAgain, it is recommended that the lifeline owners/operators be

consulted to determine if they already have detailed calculations

on their lifeline's vulnerability to earthquake events. If so,

that approach may be the most detailed available. As an

alternative, the following sections identify how the ATC-13

information, with important modifications, should specifically be

used if such owner/operator information is not available.

Damage Assessment

To determine the potential damage state that occurs, the impacts of

shaking, fault displacement, and soil movement due to either

landslide or liquefaction conditions have to be considered. The

total damage state is the sum of these individual components;

however, if one of these components dominates the others it can be

used without adding the other damage states (this is often the

actual situation). However, when that is done a similar approach

must be used for both the analysis performed while assuming no

collocation impacts and for the analysis performed while assuming

collocation impacts. Also, adding the separate damage states may

over estimate the total damage state. Knowledge of the physical

situation and professional judgement must be applied to determine

the realistic total damage state.

There are seven categories of damage state defined in ATC-13. They

are shown in Table 2.

16
Table 2

ATC-13 DEFINITION OF LIFELINE DAMAGE STATE

Lifeline For Non Pipeline For Pipeline

Damage State Lifelines Lifelines

No. Description % Damage Breaks/kilometer % Damage

1 - None 0 0 0

2 - Slight 0.5 0.25 0.6

3 - Light 5 0.75 2

4 - Moderate 20 5.5 14

5 - Heavy 45 15 3.8

6 - Major 80 30 75

7 - Destroyed 100 40 100

In the present method, the important parameter is the

identification of the Damage State Number, a number from 1 to 7.

Thus, percent damage or breaks per kilometer are not the needed

variable. The experts that developed ATC-13 used the following

definitions for damage state: percent damage meant the estimate of

the dollar value of the earthquake damage divided by the dollar

cost to replace the entire lifeline. However, for pipelines they

were asked to think in terms of breaks in a pipeline per kilometer

of pipeline length. Within a kilometer segment, 15 breaks may

actually cost the same as 40, since the expected procedure would be

to simply replace the entire kilometer length rather than to make

such a large number of individual repairs and still be concerned

that an additional partial break was undiscovered and thus remained

unrepaired. Similarly, an electrical transmission tower with 45%

physical damage would probably be replaced entirely, as it would

not be worth the risk to the owner to make such extensive repairs

when a new tower may be less expensive to install and certainly

would be more reliable in the future. Thus, when the ATC-13

definition is applied to a large number of similar lifeline

components, then, on the average, the damage state may properly

predict the condition of the sum of the individual repair costs

divided by the total replacement costs for all the components.

However, in the present analysis method, the ATC-13 data will be

applied to individual lifeline components. It is acceptable to use

the data in this. manner as it provides an expert knowledge base for

estimating the damage state, and the final result of interest in

the present analysis method is not the damage state but a time to

restore lifeline service. Its use for single lifeline components

would be less accurate if the desired result were the percent

damage to be used to calculate a cost of repair (that is, ATC-13 is

more accurate for costs averaged over a large number of cases than

it would be for a single case). The proposed analysis method

could, however, be improved if -a new expert opinion study of the

damage state and probability for that damage state for single

lifeline components were to become available.

The following material indicates how the data of ATC-13 are

17
proposed for use in evaluating the collocation impacts of lifelines

during earthquake events.

Shaking Damage

The shaking impact of the earthquake event can be estimated by

using Table 7.10 (pages 198-217) of ATC-13. For convenience, the

more frequently needed tables for lifeline analysis are reproduced

in this report as Table 3.

These tables present the collective judgement of the probability

that a class of lifeline components will incur a given damage state

level, as a function of the Modified Mercalli Intensity (MMI)

index. They were developed by using a modified Delphi method that

employed a large number of experts who provided their opinion as to

what was the probability that a damage level would be experienced

for a given imposed value of shaking intensity, MMI.

The trend in the probability data would normally be expected to

show that, as the MMI increases, more of the lifeline components

would be expected to experience higher damage states. Thus, for

increasing values of MMI, the shape of the probability curve should

be expected to have its peak value move towards higher damage

states and the magnitude of the peak value decrease as the width of

the probability curve increases. However, at MMI = XII the

probability curve should again focus over the narrow band of damage

states 6 and 7. The information for bridges, highways, and buried

pipelines and conduits follow this pattern. It is less evident for

electrical transmission towers and railroads. The methodology for

calculating shaking damage collocation impacts, because it is based

on the ATC-13 data, will be less accurate for electrical

transmission towers and railroads, compared to buried pipeline and

conduits, highways, and bridges. Still, the Principal

Investigators and Advisors for this project judged that the data

was adequate for the analysis purposes proposed in this report.

In Table 3 the lifeline items are: Facility Class 24-multiple

single span bridges; Facility Class 25-continuous/monolithic

bridges; Facility Class 31-underground pipelines; Facility Class

47-railroads; Facility Class 48-highways; Facility Class 55-

electrical towers less than 100 feet high; and Facility Class 56-

electrical towers more than 100 feet high.

In this report the ATC-13 shaking damage data is used in the

following manner. For the lifeline component or segment being

considered, the appropriate table is entered using the MMI value at

the collocation'being analyzed. The table is entered to identify

the greatest probability value in the column under the MMI listing.

In the sample below enter the table (on page 21) for MMI = VIII.

Reading to the left of that maximum probability, the most probable

damage state is then read from the left most column.

18
Table 3

SHAKING DAMAGE PROBABILITY MATRICES, ATC-13 Tables 7.10

Damage Probability Matrices Based on Expert Opinion for

Earthquake Engineering Facility Classes

Damage

State

Modified Mereaili Intensity

Multiple Single Span Bridges

vYI VIi I III [S II XIII

1 3.0 iii fit Itt iii nj it

2 57.0 12.3 in i} in IF tiF

3 i1i 85.7 70., fi t ri ii iti

4 - fi i 29.1 71.1 iffi iM

5 it Mi i 28.9 82.4 *ti t ii

6 iiit t1i i-n 1H.9 100.0 int

7 i i ii off ii t 100.0

Continuous/Monolithic Bridges

v] V II VIII II I II III

1 93.6 8. 1 0.9 i ii itn ii

2 6.4 77.8 17.6 itt it ii tt

3 it 14.1 78.6 56.5 it i ifn

4 tit tt 2.9 43.5 1.9 1.2 0.7

5 i.E.! ii iii it 98.2 36.8 5.7

6 fiti i tit fit in 61.9 39.1

7 ti iii iti tit tin 0.1 54.5

lUnderground Pipelines and Conduits

VI VII VIII II I II XII

1 100.0 9.a, 20.9 8.7 tlIt ti it:

2 it 0. 2 54.1 34.2 1.3 tit tlit

3 itn a:: 17.2 36.1 7.9 os5 i1t

4 it: t11 7.8 21.9 ;89.5 64.5 4.5

5 tit tit t1t 2t1 1.1 29.6 56.4

6 Itt tit t1t it: 0.2 3.3 37.9

7 ilI sit iI in Iti 0.1 1.2

***Very small probability

19
Table 3 (Continued)

SHAKING DAMAGE PROBABILITY MATRICES, ATC-13 Tables 7.10

Modified Mercalli Intensity

Railr

VI ViI Vill

9.8

55.4

34.9

oft,

it#

0.1

12.3

87.0

0.6

off

off

it

-oads -

II I I1 III

M

0.3

73.9

25.8

off

"I

',0

35.5

64.1

0.4

off

MI

fit

10.2

80.8

9.0

Hit

I..

III

tI

0.4

25.5

67.9

6.2

tt

VI Yll

Highways

Vill ll

3.3

6.7

ftt

It

HIII

18.9

61.5

19.7

tt

ft

III

2.9

27.0

68.8

1.4

itt

off

III

Electrical Towers

VI VIl Vlll

94.1

5.9

fit

tt

M

Ht

itt

6.9

78.8

14.3

Itt

ott

.i.f

1.0

51.0

48.0

itI

tt

HtI

MI

Electrical Towers

VI VII Vll

93.6

6.4

off

off

fit

it

itI

7.3

72.1

20.6

ttt

off

tII

itt

1.8

50.9

47.3

off

Hf

iII

Mt

1.0

-13.8

75.4

9.8

Ht

Less

II

#iI

2.9

96.3

0.8

If

*I

#it

it

1.3

59.0

39.1

0.6

H

lt

Than 100 Feet High

I

63.7

36.3

MI

fiI

MI

More Than 100

1X I

III

7.5

92.2

0.3

III

It*

it

oft

0.3

72.5

27.2

iIIfit

ft

II Ill

itI

10.6

82.7

6.7

itI

Feet

11

Ftt

16.6

79.4

4.0

H

it§

***Very small probability

Damage

State

1

2

3

4

5

6

7

94.1

5.9

III

H,

ttt

HI 

Ht

1

2

3

4

5

6

7

I II XII

ilI

0.1

20.5

65.2

14.2

ft

itI

4.6

50.2

43.4

1.8

off

1

2

3

4

5

6

7

1

2

3

4

5

6

7

III

0.5

39.0

59.2

1.3

High

Ill

III

0.8

38.2

5B.8

2.2

i.

20
Sample ATC-13 Shaking Damage Matrix

Damage State Modified Mercalli Intensity Index

VI VII VIII IX X XI XII

1 100 99.8 20.9 8.7 - - -

2 - .2 54.1 34.7 1.3 - -

3 - - 17.2 36.1 7.9 .5 -

4 - - 7.8 21.9 89.5 66.5 4.5

5 - - - - 1.1 29.6 56.4

6 - - - - .2 3.3 37.9

7 - - - - - .1 1.2

For a EMI = VIII, the largest probability is 54.1 (identified in

bold); therefore the assumed damage state is damage state 2 (also

in bold). The probability that the damage state or greater will

occur is the sum of its probability and all the probabilities for

larger damage at the MMI value of interest: (54.1 + 17.2 + 7.8) =

79.1%, or 79% for use in the subsequent analyses.

The data represented in Table 3 was developed based on assuming the

facility construction methods were in California. Since California

has incorporated seismic design criteria in some of their codes and

standards, it raises a question as to how the data should be

applied to other U.S. regions. The most direct approach would be

to consider the design and construction practices at the study area

in question, and to adjust the damage state predicted by Table 3 to

account for differences with respect to California.

Rojahn 2 0

3 has developed a different approach. He suggests that the

EMI value can be adjusted to account for the different design and

construction practices. Increasing the MMI value would imply that

the local practices are less conservative for earthquake

considerations than those used in California. Decreasing the XMI

value would imply the opposite. Figure 3 shows the U.S. divided

into seismic hazard regions. The Rojahn adjustments for are

presented in Table 4. He has used Figure 3 to divide the U.S. into

five broad regions: California region 7; Other U.S. areas, of region

7; California regions 3 to 6; Puget Sound region 5; and all other

U.S. regions.

Table 4 is provided for information purposes. Data for additional

lifeline components are provided in reference 20. Rojahn did not

justify the selection of the Table 4 values or explain why

adjustments are needed for California (recall that ATC-13 was based

on assuming that it applied to California). One of the important

recommended follow-on studies to the present work is to apply the

present screening tool to another U.S. location. One purpose of

such a study would be to examine the validity of the adjustments to

MMI recommended by Rojahn.

21
Figure 3, MAP OF U.S. SEISMIC HAZARD REGIONS

NEHRP Seismic Map Areas OTC, 1978; BSSC, 1988).

Seismic Risk

Regions

76 

1 6

g S

4

3

2

U1

22
Table 4

EMI ADJUSTMENT FOR SHAKING DAMAGE EVALUATION

TO ACCOUNT FOR LOCAL CONDITIONS

(the region numbers correspond to the numbers of Figure 3)

Region

California, #7

Other area, #7

California, #3-6

Puget Sound, #5

Other U.S. regions

Multiple Span Continuous Rail beds &

Bridges Bridges Hichways

0 0 0

I

1

0

3

1

1

1

2 or 3

0

0

0

0

Region and Number

California, #7

Other area, #7

California, #3-6

Puget Sound, #5

Other U.S. regions

Railroad

Bridges

-1

0

-1

0

1

Water Trunk Water Pipe

Lines Distribution

O 1

0 1

0 1

0 1

1 2

Region and Number

California, #7

Other area, #7

California, #3-6

Puget Sound, #5

Other U.S. regions

Region and Number

California, #7

Other area, #7

California, #3-6

Puget Sound, #5

Other U.S. regions

Electrical Electrical

Towers Over Towers Less than

100 ft. high 100 ft. high

0 '

o 0

o 0

Of 0

'0 1

Natural Gas Natural Gas Oil

Transmission Distribution Pipelines

-1 '0 -1

-l

-l

-1

0

0

1

1

-1

-1

-1

-1

Fault Displacement

In ATC-13, the maximum fault surface displacement, D, in meters is

calculated from the equation:

Log D = -4.865 + 0.1719 x M; where M is the earthquake

magnitude

ATC-13 identifies that the fault average displacement is typically

77% of the maximum, and that 30% of the maximum displacement on the

main fault is characteristic of the displacement on subsidiary

faults.

The damage states for the estimated displacement are obtained from

23
ATC-13 Table 8.9 and are presented in Table 5.

Table 5

LIFELINE DAMAGE STATE FOR FAULT SURFACE DISPLACEMENTS,

ATC-13 Table 8.9

Facility Type Damage State (% damage is given in the parentheses)

and Location For Various Values of Displacement in meters

Displacement = 0.2 m 0.6 m 1 m 3.5 m 10 m

Subsurface Structure

In Fault Zone 5(50) 6(80) 7(100) 7(100) 7(100)

In Drag Zone 4(20) 5(40) 5(60) 6(80) 7(100)

Surface Structures

In Fault Zone 3(10) 4(30) 6(70) 7(100) 7(100)

In Drag Zone 0(0) 0(°) 3(2) 3(10) 4(20)

The "Fault Zone" is defined as being within 100 meters of the fault

trace, the "Drag Zone" is defined as being within 100 to 200 meters

of the fault trace. If lifeline components are judged to have

failed because of fault displacement, then the collocation impact

would be only an increase in the time to restore the lifeline to

its needed level of operation (e.g., damage greater than

catastrophic is not meaningful). Such time increases would be

attributed to the construction activity and the need to assure that

construction on one lifeline does not lead to damage on

reconstructed other lifelines.

Soil Movement

Many texts separately define the impacts due to landslides and

lateral spread (or liquefaction). However, they may be thought of

as being part of a continuum of soil movement with the slope of the

topography being a parameter that identifies whether the movement

should be calculated as a landslide or a lateral spread (or

liquefaction). That is the approach proposed in the present

analysis method.

Landslide (landslides occur on slopes greater

than 50)

It is proposed that the historical landslides in the study area be

identified and considered as potential landslide req ions when the

collocation evaluation is made. Keefer and Wilsonsi0) and Sadler

and Morton" 1 ') have identified that landslides are associated with

many historical earthquakes and that shaking is one of the main

triggering agents for landslides. Actual site reconnaissance

visits are recommended as a means to verify the location of

historical landslides for any area being studied. In the present

study, a comparison of the known slides with the geologic unit map

identified that many of the landslides were associated with areas

24
where Pelona Schist is the bedrock unit. Other researchers are

advised to examine the geologic sediments and rocks in the areas

where they intend to evaluate collocation and to be sensitive to

the location of Pelona Schist.

It is proposed that the method of Legg et. al. CY2 ) be used to

identify additional areas where landslides may occur. It is based

on the sliding block model proposed by Newmark 1 3 ); Wilson &

Keeferc'4) have proposed a similar model.. However, the Wilson and

Reefer model requires using recorded accelerograms or predictions

of ground acceleration while the Legg method is related to using

MMI. The Legg model is the method used in ATC-13 to define the

damage state and probability of damage for landslides. Also, it

will be easier to apply the Legg model to other regions in the

U.S.. Because of these items, the Legg method was adopted for

predicting additional landslide areas.

The Legg method consists of the following basic steps:

Step I Solve for the "critical acceleration" of the slope

for a given combination of slope angle and soil

properties. A formula derived from the stability

solution of an infinite slope was used by Legg and

also by Wilson and Reefer, and it is provided below.

Step 2 Use the critical acceleration to enter a table of

"slope failure state"' versus DMI value. The table

values identify the potential for the slope to move

as a landslide. The tables are provided as Table

8.7 of ATC-13 and are reproduced below as Table 7.

Step 3 The slope state is related to damage state in Table

8.8 of ATC-13, which is presented below as Table 8.

However, the ATC-13 Table 8.8 has been extended to

more accurately account for buried lifelines, based

upon expert opinion obtained during the present

study.

The formula for the critical acceleration is given by:

ar/g = c/(yh) + cos e tan ¢ - sin 0 ; where

a= the critical acceleration, ft/sec2

g = the gravitational constant, 32.2 ft/sec2

c = the effective soil cohesion factor, lb/ft2

= the soil density, typically 100 lb/ft3

h = the thickness of the soil block, typically 10 ft

l = the slope angle, degrees

= the angle of friction of the slope material,

degrees

Note, this equation applies to dry slopes.

25
The soil parameters recommended for use are given in Table 6.

Table 6

SOIL PARAMETERS FOR CALCULATING LANDSLIDE POTENTIAL

Shear Strength Parameters

Geologic Unit Cohesion. c (Vfs) Friction Angle, (degree)

Paleozoic Rocks 300 35

Older Cenozoic Rocks 0 35

Older Alluvium 0 30

Young Alluvium at Shallow

Ground Water & Pelona Schist 0 20

Wilson and Keefer (14 have also developed an analysis for saturated

and dry slopes. They use a 35 degree friction angle for sands,

sandstones, and crystalline rocks, and 20 degrees for clayey soils

and shales. They present a graph of the critical acceleration as:

0.5 - -_ _ _ _ _ _ _ _

Z Plots of critical acceleration (Ad) versus slope steepness 0

for three sets of lithologies: group A, strongly cemented rocks G% \ \ \ \(crystalline rock and well-cemented sandstone); group B, weakly uj 0.3 ) v \ \ rocks X \ cscemented (sandy soil and poorly cemented sandstone); group U \ \ O~y&> 9 96\ C, argillaceous rocks (clayey soil and shale). The cohesion factor, < 0 S C- 0 c'I'yh, for group A assumes values of c'-=300 psf. -y = 100 pcf. and X God O'er \S\ h -10ft. The angle of internal friction (e ) (peak strength, undrained U \ '0< ,\ \ O \ 0 conditions) is 35° for sands, sandstone, and crystalline rocks and

I \\ \ 200 for clayey soils and shales. The solid lines depict dry slope

| _0_1 materials, and the dashed lines depict saturation from the slide

plane to the surface.

10¢ 20' 300 i 400 500

5% 15% 30% 50% 70% 100%

SLOPE

Either the Legg formula or the Wilson graph is acceptable for

determining the critical acceleration, it's numeric value will be

used in the Legg tables discussed below.

The appropriate soil parameters from Table 6 or other references

should be identified. The formula or graph is then used to

determine the value of the critical acceleration, which in turn

determines the slope stability (unstable, low, moderate, high,

stable, very stable) so that the ATC-13 Table 8.7 (Table 7 given

below) can be used to define the state of slope failure (Table 7

uses the Legg definitions for terms of slope failure state and

slope stability scale, and those definitions also are provided with

the table).

26
Table 7

LANDSLIDE SLOPE FAILURE PROBABILITY MATRICES, ATC-13 Table 8.7

Sope Fitflue Probabfity ¶abieft

(Summer Conditico)

SLOPE SrABIErrY: UNSTABLE, .4 c .01 r

SLOPE YMI

FAILURE

STATE VI VD vm TX x Xl Xly

LUG&T 0 0 0 a 0 0 0

MODERATE a 0 a a a 0 0

HEAVY f00 50 40 30 20 5 a

SEVERI S0 40 45 50 55 60 S5

CATASTROPHIC l 1a i5 20 i5 15 50

1⁄2 10I% 100% 100% 30% 100% 100% 2100%

LOnPE SriBLMrs LOW, .01 a , c 0 

SLOPE MMI

YADLUR!

STATE VI Vy Y3 ix X XI XE

LIGHT 40 25 15 10 5 0 0

iODERAIE 50 30 35 l0 20 10 0 O

HEAVY 25 35 40 40 35 35 30

SEVERC 5 10 10 15 20 35 40

CATASTROPHIC 0 0 a 5 10 20 30

1⁄2 1 100% t00 300% I00% 100% 100% 100%

SLOPE STABSLTYi XODIXATE, 0.1 a, -3 E

SLOPE MMI

FhALURE

STATE VI VI VM TX x xi 

LIGHT 100 100 15 1 55 20 0

MODERATE O a 10 20 25 Jo 10

HEAVY 0 0 5 la 15 25 40

SEVERE 0 0 0 0 5 i5 20

CATASTROPHIC a a 0 0 0 10 10

Zp 100% l10 100% 100% 100% 300% l0

SLOPE STABEJrYza MIR, 0.3 p < a, c 0.5 r

SLOPE

FAILUR E

STATE Vi VE vm rX X xi xEl

LIGHT 100 100 100 95 &5 !0 s0

MODERATE 0 0D 0 5 II 15 20

HEAVY 0 0 0 0 5 5 15

SEVERE C, o 0 0 

CATASTROPH 0 o0 a 0 0 0 0

Zp 100% 300%. 10a 100% 100% 1005S 10%

SLOPE SABUI STAEL., 0.5 c %( 0.7 

SLOZ MM RFAGER FAILURE

STATE VI vu vY 1x x X1 XII

LIGHT 10O 100 100 100 00 Is 75

MODERATE 0 0 0 0 10 l0 15

HEAVY 0 0 0 0 C 5 la0

SEVERE 0 0 0 0 0 0 C

CATASTROPHIC C 0 0 0 0 0 0

: D100%. 10096 I00 I00% 100% 100% 10C%

SIAPE sTABIlfrft Y=V 1TA l 0.1 E < 4e

SLOPE MMI

STATE V yn a TX X n XE

LIGHT 100 100 100 100 100 t SO

iAODERATE 0 0 0 0 0 1 15

HEAVY I 0 0 0 0 0 5

SEVERE 0 0 0 0 0 0 1

CATASTROPHIC 0 0 0 0 0 a 0

, 100 100 10100 %00% 100% 100% 100%

27
Table 7 (Continued)

Definitions

SLOPE FAILURE STATE SCALE

LIGHT- Insignificant ground

movement, no apparent

potential for

landslide failure,

ground shaking effect

only. Predicted

displacement less

than 0.5 cm.

MODERATE- Moderate ground

failure, small cracks

likely to form,

cracks similar to

having a lurch

phenomena. Predicted

displacement 0.5 to

5.0 cm.

HEAVY- Major ground failure,

moderate cracks and

landslide

displacements with

effects similar to

liquefaction or

lateral spread.

Predicted

displacement 5.0 to

50 cm.

SEVERE- Extreme ground

failure, large cracks

and landslide

displacements with

effects similar to

large-scale fault

displacement.

Predicted

displacement 50 to

500 cm.

RELATIVE SEISMIC SLOPE

STABILITY SCALE

V - Very stable, not likely to

move under severe shaking,

ac 2 0.7g.

S - Stable, may undergo slight

movement under severe

shaking, 0.5g < a < 0.7g.

H - High, may undergo moderate

movement under severe

shaking, some landslides

related to steep slopes,

saturated conditions, and

adverse dips, 0.3g < ac <

0.5g.

M - Moderate, may undergo

major movement under

severe shaking or moderate

movement under moderate

shaking, numerous

landslides, rock falls

abundant, unconsolidated

material deforms and

fails, 0.lg < ac < 0.3g.

L - Low, may undergo major

movement under moderate

shaking, abundant

landslides of all types,

0.0lg 5 ac < 0.1g.

U - Unstable, may undergo

major movement under

slight shaking, most of

the area and/or material

falls, ac < 0.01g.

cm = centimeter

CATASTROPHIC- Total ground g = gravitational constant

failure, with

predicted

displacement greater : than 500 cm.

28
To use Table 7, it is necessary to enter it with the critical

acceleration, ac, and the MMI value. The critical acceleration

value determines which sub-table is used. Within that sub-table,

in the MMI column, identify the location with the peak probability.

The slope failure state is read from the left-most column at the

row that contains the peak probability value. The probability that

the condition or worse will exist is the sum of the individual

probabilities for that slope state and all worse slope state

conditions. This is similar to how the shaking damage state and

its probability were calculated.

Next, the slope failure status (light, moderate, heavy, severe,

catastrophic) is converted to a damage state (and also a percent

damage) by using ATC-13 Table 8.8 (Table 8 below). ATC-13 provides

a single conversion value for all lifelines.. This has been

expanded in Table 8 to account for key buried lifelines. The new

values were based on expert opinion obtained during the present

study.

Table 8

CONVERSION OF LANDSLIDE SLOPE FAILURE STATE TO DAMAGE STATE

Damage State and (% Damage)

ATC-13 Values New Values Determine During This Study

Slope Failure for all High Strength Low Strength

State Lifelines Lifelines Lifelines

Light 0-3 (0%) 0-2 (0%) 0-3 (0%)

Moderate 4 (15%) 3 (0%) 4 (30%)

Heavy 5 (50%) 4 (15%) 5 (60%)

Severe 6 (80%) 5 (50%) 6 (90S%)

Catastrophic 7 (100%) 7 (100%) 7 (100%)

The definition of high strength buried lifelines used to determine

the damage state is: continuous steel pipelines constructed

according to modern quality control standards with full penetration

girth welds; welds and inspection performed according to API 1104

or equivalent.

The definition of the buried lifelines which should be represented

by the original ATC-13 definitions is: pipelines and conduits

constructed according to modern standards with average to good

workmanship, other than the high strength lifelines defined above.

Lifelines in this category are expected to include electric cables,

steel pipelines with welded slip joints, ductile iron pipelines,

telecommunication conduits, reinforced concrete pipe including

concrete steel cylinder pipe, and plastic pipelines and conduits.

Also, if the high strength lifelines are oriented so that the

landslide motion is expected to place them into compression, they

should be analyzed in this category. Other lifelines not included

in the High Strength or Low Strength definitions should be

29
evaluated using the ATC-13 column.

The definition of low strength buried lifelines is: pipelines and

conduits sensitive to ground deformation because of age, brittle

materials, corrosion, and potentially weak and defective welds.

Lifelines in this category include cast iron, rivetted steel,

asbestos cement, and unreinforced concrete pipelines; pipelines

with oxyacetylene welds; and pipelines and conduits with corrosion

problems. If other non high strength buried lifelines are oriented

so that they are perpendicular to the expected landslide motion

(e.g., their orientation is such that they will be put into

compression by the landslide), then they should be analyzed as a

low strength lifeline rather than with the ATC-13 column.

Liquefaction or Lateral Spread (lateral spread

occurs on slopes of 1-5°)

It is proposed that the Liquefaction Severity Index (LSI) be used

to correlate the liquefaction or lateral spread damage and the

probability of damage. The LSI is defined in the work of Youd and

Perkins'15). The following material was developed from expert

consultive support provided during this study by Dr. T.D. O'Rourke

of Cornell Universityt 6 '

8 '9 '1 6 '.

In a manner similar to the critical acceleration defined for

landslides, a critical LSI is defined in Table 9 below. The basis

for its use and the LSI damage probabilities of Table 10 is the

work of Harding 6) which has shown that substantial lateral

spreading can be triggered at a critical acceleration, ac, of 0.05

to 0.15 g.

Table 9

RELATIONSHIP BETWEEN LIQUEFACTION SEVERITY INDEX (LSI)

AND DAMAGE STATE

Physical Lateral Equivalent

Ground Movement LSI Damaqe State DamaQe Condition

< 0.5 inch <1 3 light

0.5 to 5.0 inches 1-5 4 moderate

5 to 30 inches 5-30 5 heavy

30 to 90 inches 30-90 6 severe

> 90 inches > 90 7 catastrophic

O'Rourke has prepared a regression analysis of the observed

relationship between the MMI index and the LSI index for four

earthquakes; the 1906 San Francisco, the 1964 Alaska, the 1971 San

Fernando, and the 1979 Imperial Valley earthquakes. The

observations identified LSI values of 5 to 100 for MMI values of V

to X. The resulting regression curve (with an r2 = 0.68) is:

LSI=O . 226x1 0 0 255 x'MM

30
The equation can be used to calculate the LSI number, and then

Table 9 can be used to define the damage state. Graphically, the

relationship between MMI and damage state is presented in Figure 4

below.

The probability that the liquefaction damage state will occur is

given in Table 10. Table 10 (which replaces ATC-13 Table 8.4)

applies to soil environments in which liquefaction is likely to

occur under strong earthquake shaking. These environments include:

active flood plains, deltas, other areas of gently sloping late

Holocene fluvial deposits, and loose sandy fill below the water

table (which are generally placed by end dumping or hydraulic fill

methods). The table does not apply to late Pleistocene Alluvium,

for which the probabilities of liquefaction are negligible for

intensities equal to or less than MMI of X. Thus, the combination

of the LSI equation and Table 9 (or the use of Figure 4) with Table

10 is analogous to landslide calculations for low stability

material.

Table 10

PROBABILITY OF LIQUEFACTION GROUND FAILURE, PERCENT

Liquefaction Damage MMI Value

State VI VII VIII IX X XI XII

3 - Light 75 50 20 10 0 0 0

4 - Moderate 20 30 40 25 15 10 0

5 - Heavy 5 20 30 40, 25 25 20

6 - Severe 0 0 10 20 35 40 30

7 - Catastrophic 0 0 0 5 15 25 50

The new method developed during this study adds details to the

level of analysis available from ATC-13. It identifies a range of

damage from light to catastrophic (compared to the assumed

catastrophic levels of ATC-13) and a full range of probabilities

that the damage state will occur. Since it is based on observed

liquefaction damage from California earthquakes, additional

evaluation of the recommended approach at other U.S. locations is

warranted.

Highway and Railroad Bridges

The ATC-13 shaking intensity matrices (Table 3) identify three

broad classes for bridges: multiple simple span bridges, continuous

and multiple span bridges, -and long span or major bridges. It is

difficult to fit every railroad and highway bridge into one of

these broad classifications. One example of how owner-supplied

information can be used to improve upon the direct use of the ATC13 guidance is found in the methods of the California Department of

Transportation( 71 ,18 ,19 )' (CALTRANS). CALTRANS has a method to identify

the priority for performing retrofits, to their bridges to reduce

their vulnerability to earthquakes. This improved data was

31
LIQUEFACTION INDUCED DAMAGE

7-

6

S~~

4--

/ ,~~~~-0* Range Of Field Observation Data _

3- '-11

I ii III IV V VI VIl Vil IX: X Xi XIl

Modifed merCami index
integrated with the ATC-13 data to provide more discrimination

capabilities for evaluating railroad and highway bridges. The

resulting procedures (described below) are fully applicable to

locations outside of California if the needed data on the

individual bridges are known. The CALTRANS method includes

factors, such as traffic loading and detour routes1 that are

important for making decisions about whether to spend money to

retrofit a bridge, but they are not important for determining the

damage state of the bridge. However, other factors, such as the

bridge sub and superstructure, the design codes used, and the

bridge geometry can be related directly to the ability of the

bridge to resist earthquake damage.

The method being proposed in this report calculates a parameter

that can be used to adjust the damage state value for shaking as

determined by the ATC-13 matrices (Table 3 of this report). The

evaluation is based on starting with the ATC-13 shaking probability

matrix for Continuous and Multiple Span Bridges. The procedures

discussed above on how to use Table 3 to define the damage state

and the probability that the damage state or greater will occur are

used to calculate a tentative damage state. A bridge vulnerability

index then is calculated and used to determine if the tentative

damage state should be changed (the probability is not changed).

The decision to adjust the Table 3 tentative damage state value is

based on the numeric values identified below in Table 11 (high

values of the Bridge Vulnerability Index mean that the damage will

be more severe than that predicted by Table 3).

Table 11

RELATIONSHIP OF BRIDGE VULNERABILITY INDEX TO

BRIDGE DAMAGE STATE

Change to Table 3 Continuous

Bridge Vulnerability & Multiple Span Bridge

Index Value Damaae State Value

0.0 - 0.2 Lower the Damage State by

two increments

0.2 - 0.4 Lower the Damage State by

one increment

0.4 - 0.6 No Change

0.6 - 0.8 Increase the Damage State by

one increment

0.8 - 1.0 Increase the Damage State by

two increments

33
The numeric value of the Bridge Vulnerability Index is calculated

by multiplying a Raw Score by a Multiplying Factor (in the

CALTRANS' method, the terms were weighting factor and pre-weighting

factor, respectfully). The Raw Score is assigned by the importance

of the bridge factor being evaluated, the Multiplying Factor is a

weighting scale that determines how earthquake resistant the Raw

Score items is. Table 12 presents the numeric values of the Raw

Score and the Multiplying Factors.

There are seven categories that are analyzed: 1) abutments; 2)

piers; 3) soil type; 4) superstructure type; 5) design code or

specification used; 6) bridge height; and 7) bridge skew and

curvature. A separate number (the raw score times the multiplying

factor) is calculated for each of the seven categories and then the

individual numbers are summed. The sum is divided by 100 to give

the total Bridge Vulnerability Index value.

In applying the incremental change to a tentative damage state from

Table 3, if this results in a damage state less than 1 or greater

than 7 use those limit values. Damage states for long span (length

greater than 400 feet) and major bridges may be estimated using

this procedure, but it is recommended that such structures be

subjected to special studies whenever possible. It is emphasized

that the above Bridge Vulnerability Index is for shaking damage.

Special conditions, such as liquefaction, require additional

analysis.

The analysis factors required to enter Table 12 can be obtained

from the general design drawings of the bridge or by field

reconnaissance. Some assumptions may have to be made with respect

to foundation design in the latter case.

Railway bridges have proved to be somewhat more resistant to ground

shaking than highway bridges, in spite of the fact that the

American Railway Engineering Association (AREA) specifications make

no specific recommendations with regard to earthquake forces. This

is probably due to the fact that railroad brides have an allowance

for lateral loads (originally, the allowance was to account for the

loads produced by steam locomotives). Prior to 1935, this

allowance was 5% of the live load (typically based on a Cooper E60

engine, or about 852,000 lbs. on a 109 ft. span), but not more than

400 lbs. per foot of track. In 1935, this was changed to provide

for a lateral load of 20,000 lbs. applied at the top of the rail at

any point in the span. In 1950, AREA provided for higher allowable

stresses, so that the allowance became somewhat less conservative.

The multiplying factors of Table 12 for railroad bridges reflects

these facts.

34
Table 12

BRIDGE VULNERABILITY INDEX FOR EARTHQUAKE SHAKING DAMAGE

Multiplying Factor Criteria

Multiplying

Factor Value

SUBSTRUCTURE

Abutments

Piers

10 Integral with pile foundation

Integral with spread footing

Hinge seat with restraints

Hinge seat, all other types

15 wall

multiple column bent

single column bent

0.0

0.5

0.6

1. 0

0.2

0.5

Note, if a spread footing foundation is used, add 0.2 to the

pier multiplying factor, if the columns have been reinforced

to recent seismic codes, subtract 0.3 from the pier

multiplying factor.

Soil Type

SUPERSTRUCTURE

Type

15 Rock or soil with bearing of

more than 4 tons/ft2 0.0

Soil with bearing of 2 - 4 tons/f t 0.1

Soil with bearing of less than 2 tons/ft2 0.5

20 Highway Bridges

Simple span, box or slab

Single span, arches, reinforced concrete

*or well constructed masonry

Simple span, steel or concrete beams

Simple span, steel truss

Multiple spans, continuous with no hinges

Multiple spans, continuous with 1 hinge

Multiple spans, simple beams

Multiple spans, continuous with 2 or

or more hinges

ro . o

O0 . 1

0.5

0.5

0. 0

0.5

1. 0

1 . 0

Railroad Bridges

Simple spans, steel with full truss

Simple spans, deck or half truss

Simple spans, steel or concrete ballasted

Simple spans, steel or concrete beams

Multiple spans, fully continuous

Multiple spans, simple beams.

Multiple spans, continuous with hinges

0.3

0.4

0..5

1..0

0.0

1.0

1.0

Note, for both highway and railroad bridges with hinges,

subtract 0.4 from the multiplying factor if restrainers have

been added. Subtract an additional 0.3 if the columns have

been reinforced to resist earthquake forces.

35

Bridge

Element

Raw

Score
Table 12 (Continued)

BRIDGE VULNERABILITY INDEX FOR EARTHQUAKE SHAKING DAMAGE

Bridge Raw Multiplying

Element Score Multiplying Factor Criteria Factor Value

DESIGN CODE OR SPECIFICATION

Code used 20 Highways

CALTRANS* after 1978 or AASHTO* after 1987 0.0

CALTRANS between 1972 and 1978 0.2

CALTRANS prior to 1972 and

AASHTO prior to 1950 0.5

AASHTO from 1950 to 1987 1.0

Note, AASHTO, from 1950 to 1987, leaves the earthquake

considerations to the States. If it is known that the State has

no such consideration, use 2.0 as the Multiplying Factor value.

Railroads

AREA* from 1935 to 1950 0.5

AREA from 1950 to present 0.7

AREA prior to 1935 0.8

Note, for the condition of bridge, modify the design code or

specification Multiplying Factor by adding the following to the

factor:

Good or fair condition 0.0

Poor condition 0.2

GEOMETRY

Height 10 Less than 5 feet 0.2

5 to 15 feet 0.7

15 to 25 feet 0.9

25 feet and greater 1.0

Skew* and 10 Skew less than 200 and

curvature radius greater than 1000 ft. 0.0

Skew 200-400 and/or

radius greater than 500 ft. 0.1

Skew greater than 400 and/or

radius less than 500 feet 0.4

Key *

AASHTO, American Association of State Highway & Transportation

Officials

AREA, American Railroad Engineering Association

CALTRANS, California Department of Transportation

Skew is defined as the angle that abutments and piers make with

respect to the normal to the highway (or railway) alignment.

That is, when the plane of the abutment or pier is aligned

parallel to the normal to the road (or rail bed) alignment, the

skew is 0°.

36
Times to Restore the Lifeline to its Needed Service

Once the lifeline components of interest have been identified and

the damage state and probability that the damage condition or worse

will occur have been calculated from the above tables and formulas,

the time to restore the lifeline component or segment from the

total calculated damage state to the operating level needed has to

be determined.

The restoration time is a combination of the time to repair the

lifeline segment or component assuming all the equipment, material,

and personnel are available at the damage site, plus the access

time to get the equipment and material to the damage site, plus the

delay time needed to obtain the equipment and material required for

making the repair. The way to calculate these items is given next.

Repair Time to restore the damaged lifeline to service

With the damage state known, the time to rep-air the lifeline

component or segment (assuming the equipment and material are at

the damage location) can be calculated from Table 9.11 of ATC-13.

The key information of Table 9.11 is provided below as Table 13.

If intermediate operating conditions (e.g., repair to less than

100% capacity) are acceptable, the intermediate repair times of the

ATC-13 tables can be used or the plots of those tables provided by

Rojahn(20) can be used to estimate such intermediate condition

repair times. The newer curves by Rojahn are curve fits of the

data of ATC-13l23, thus they are not exact replications of the data.

But they may be more convenient to use since they relate the repair

time to MMI instead of to the damage state as is done in ATC-13.

Also, if there is concern about the magnitude of the repair time

estimated, Table I.1 of Appendix I of ATC-13 can be used to

determine the range of repair times identified by the experts that

prepared Table 9.11. It is important to recognize that the actual

repair time is not used directly to estimate the impact of

collocation on the vulnerability of lifelines to earthquakes (as

will be shown below).

Eleven of the more important repair tables are presented in Table

13 (some of the tables were adjusted from the ATC-13 values to

account for expert opinion obtained during the present study). To

make a specific estimate of lifeline repair time, enter the proper

lifeline table at the row that identifies the damage state and move

to the right until the correct lifeline column is encountered.

Then read the time, in days, required to restore the lifeline to

full capacity from that damage state. The ATC-13 lifelines of

interest are: lac-petroleum transmission pipelines, 25a-highway

major bridges, 25c-highway conventional bridges, 25d-freeways and

highways, 26a-railroad bridges, 26c-railroad roadbeds, 29belectrical transmission towers, 30f-water trunk lines, 31a-sewer

lines, 32a-natural gas transmission lines, and 32d-natural gas

distribution lines. It should be recalled, however, that better

37
estimates of repair time are probably available from the individual

lifeline owners, as they may have site specific conditions included

in their estimates.

.Table 13

ESTIMATED LIFELINE REPAIR TIMES TO 100% OPERATING CAPACITY

ATC-13 Table 9.11

(Times in Days)

Railroad

Bed**

1

1

2

11

41

82

120

Highway**

Conventional

Bridge

1

1

8

84

303

686

752

Highway

Major

Bridge

1

2

7

141

392

845

947

Railroad

Bridge

1

1

8

58

213

468

606

Natural Gas** Natural Gas

Distribution & Transmission

Petroleum Lines Pipelines

1 1

1

3

6

19

44

55

1

3

11

25

44

75

Fiber

Optic**

Conduits

1

1

1

3

10

24

30

Electrical

Transmission Sewer

Towers Lines

1 1

1 3

2 5

17 18

49 63

82 102

127 141

* Damage State 1 has a 1 day allowance to allow for

inspection to determine the actual damage state that

exists at the lifeline

** These values were determined by expert opinion during

this study

Access Time to get the equipment and material to the

damage site

Next it is necessary to estimate the time to get the equipment and

repair material to the site. This time is the time to get

construction equipment and material to the damage site, and it

should not be confused with the time it would take to get general

population traffic to the site or with the time it would take for

repair crews to get to the damage site. In many situations, and

especially for lifelines such as pipelines, fiber optics, and

electrical transmission towers, most of the necessary equipment and

material can be driven to the damage location either along the

highways, unpaved access roads, or cross country if the land is dry

38

Damage

State

1*

2

3

4

5

6

7

Highway

Bed

1

1

7

41

147

292

437

Water

Trunk

Line

1

2

3

10

25

74

156

Damage

State

1*

2

3

4

5

6

7
and accessible. In some of the more rugged regions they can be

helicoptered to the site. An exception would be if wet ground or

large water bodies must be negotiated. Thus, in general, for those

lifelines the access time is one or two days, depending upon the

location of the segment or component of the lifeline system being

examined. If access along the highway is required it should be

calculated as described below for the railroads and the highways.

For many of the railroad or highway components and segments, the

access will have to be along the railroad or highway itself because

of the size and weight of the material and equipment that is

required. In such cases, it will be necessary to estimate the

repair times for damage along the route prior to the location being

studied. The individual repair times must then be added for each

disruption that occurs before the location being studied to obtain

a total estimated access time. Alternatively, detours can be used

to calculate a "by pass" time estimate.

Equipment and Material Time to have those items available

For many of the lifelines, the owners have their own operating

equipment and have prepositioned repair material along their

lifeline routes. When they don't have suitable repair equipment in

their operating stock, they may have existing agreements with other

firms, to provide such equipment during emergencies. Frequently,

utility lifeline owners have reciprocal agreements with other

utilities to provide personnel and equipment during emergency

periods. This preplanning can decrease the time it takes to have

equipment and repair material available to transport to the damage

location.

The problem of material availability can be pronounced for railway

and highway bridge repairs. In those cases, the time required to

fabricate off site the needed components must be accounted for in

the estimation of the delays in having equipment and material

available.

In almost all cases, it can be assumed that the equipment will not

be available during the emergency phase of the earthquake, since it

will be diverted to life-saving duty at that time. However, prior

earthquake response experience indicates that most equipment and

needed material will be made available within one or two days.

4.3 Collocation Analysis

Section 4.2 presented a number of analysis methods that can be used

to determine the damage state, the probability that the damage

state or worse will occur, and the estimated restoration time to

return each lifeline component or segment to its needed service

level.

In the collocation analysis activities, a collocation damage

39
scenario is developed and the unknown conditions (either damage

state, probability of damage, restoration time, or any combination

of those items) are recalculated for the assumed collocation damage

scenario using the methods of Section 4.2. The collocation damage

scenario should be based on the knowledge of how the individual

lifelines would have responded if they had be the only lifeline at

the collocation point, the estimate of the types of impacts that

one lifeline failure could impose on another nearby lifeline, and

the zone of influence that one lifeline has.

This process requires that technical judgements be applied, based

on knowing the expected damage states of the collocated lifelines,

the seismic and geologic conditions, information about the

lifelines themselves (such information as the design conditions,

construction history, repair and maintenance history, and other

pertinent facts), and other lessons learned from prior earthquakes.

It will be important to obtain as much information from the

lifeline owners as possible to help guide the collocation damage

scenario analyses.

It is also important to recognize that there is a zone of

influence, beyond which the impact of one lifeline on another would

be negligible. During this study, expert opinion was used to

estimate the appropriate radii of influence zones for the lifelines

found in the Cajon Pass. The results are given in Table 14.

Care must be taken to differentiate between the zone of influence

and the actual influence or damage caused. For example, the zone

of influence of a failed dam is based on the path of the water that

spills past the dam. It includes the actual pathway and the area

that the water would inundate. The actual impact of the failed dam

could be erosion of foundations of other lifelines (thereby causing

them to collapse) or the flooding of them (perhaps restricting

their ability to function). There may be no influence on one

lifeline, while the impact on another could be pronounced. Some of

the impacts may be subtle. For example, a failed communication

lifeline may have no immediate impact on the physical state or

condition of other nearby lifelines. Its impact, however, could be

tied to increasing the restoration time of nearby lifelines due to

the difficulty of maintaining communications with the repair

personnel. In the present context of lifeline vulnerability, the

impact of one lifeline on a collocated or nearby lifeline can be

the damage state, the probability of damage, or the restoration of

service time. Other impacts, although real, have no way to be

accounted for in the analysis method.

Although the values in Table 14 are considered appropriate for the

semi-desert region of the Cajon Pass, California, for which they

were prepared, it will be important to validate these values when

the lifeline zones of influence are evaluated for other at-risk or

collocation conditions.

40
Table 14

LIFELINE ZONES OF PHYSICAL INFLUENCE

Liquid Fuel Pipeline -

Natural Gas Pipeline -

Fiber Optic Cables -

Roadways -

Railroads -

Overhead Electrical -

Transmission Towers &

Power Lines

Bridges -

Dams., Reservoirs & -

Canals,

Water & Sewer Lines -

The drainage path and catchment area

for any liquids spilled; two times

the pipe burial depth for any soil

cratering impacts due to pipeline

ruptures; 100 feet if explosion

impacts are estimated; ground erosion

paths for liquids spilled; and the

burn path if fires are estimated.

Two times the burial depth for any

soil cratering impacts due to

pipeline ruptures.; 100 feet if

explosion impacts are estimated; and

the burn path if fires are estimated.

Zero feet (e.g., no physical impact

on other lifelines).

40 feet from the road edge; a

possible ignition source for fuel

lifelines.

40 feet from the track edge; a

possible ignition source for fuel

lifelines.

A radius equal to the height of the

tower for physical contact;

a possible source of ignition for

fuel lifelines.

For an area centered on the bridge,

twice the length of the bridge and 40

feet-on either side of the bridge.

The drainage path and inundation

areas for the spilled water.

The erosion area downstream of the

break (sewers only if they are

pressurized); the catchment area for

the spilled fluids.

It is anticipated/ but not required, that collocation impact

scenarios will follow the following general guidance.

41
Impacts on Damage State

One of the easier direct impacts to hypothesize will be that the

collocation conditions will lead to an increase in the damage state

of one or both of the collocated lifelines (if there are more than

two collocated lifelines this applies to all of them). It is easy

to understand the damage state, as it relates to a physical

condition. Because the individual lifeline damage states assuming

no collocation are known, those values can be used to help

understand how the lifeline could impact another nearby lifeline.

If, for example, light damage of a pipeline had been calculated, it

would be expected to cause no direct change in the damage state of

a nearby bridge. However, if the bridge had been estimated to

collapse, it would be reasonable to estimate that within the

bridge's zone of influence it would lead to failure of the pipeline

(this example also illustrates that the impacts are not necessarily

reciprocal).

As another example of how collocation impacts on damage state can

be estimated, consider the condition of a pipeline and a fiber

optic conduit hung from a bridge. The earthquake vibration may not

be enough to cause serious damage to the bridge or to the pipeline

or conduit if they were not collocated with each other. However,

the vibrations may cause the anchors holding the heavy pipeline to

the bridge to fail. As the pipeline sags (but does not fail) it

could fall onto the lower conduit, causing it to fail. The

collocation damage state hypothesis would then be: no impact on the

bridge; a small increase in damage state of the pipeline to account

for the work required to rehang the pipeline; and catastrophic

failure of the fiber optic conduit.

Special attention should be given to the collocation of fuel

carrying lifelines with other lifelines that have the ability to

provide an ignition source. The resulting fire and/or explosion

could lead to significant collocation damage. Similarly, broken

pipelines which eject fluids could lead to foundation erosion

problems that would result in increased damage to nearby lifelines.

Impacts on Probability of Damage

The probability of damage does not directly enter into the

calculation of the damage state level or the time to repair the

damage. It is, as will be discussed below, a very important item

for determining the key result of the collocation analysis, the

probable incremental change in restoration of service time.

There are several ways to estimate the change in the probability

that damage will occur, none are exact and there are no statistics

available from the literature on earthquakes. However, there are

some insights available to guide the analysts.

If the probabilities for two lifelines, assuming no collocation

42
conditions, are P1 and P2, they represent an upper bound on the

probability that a collocation damage would occur. For example, if

the probability that lifeline 1 would fail is PI, and it is, known

that if lifeline I fails it will cause, with -a 100% probability,

damage to lifeline 2, then the probability that lifeline 2 receives

collocation damage is also P1 (e.g., P1 x 100%). Similarly, the

upper bound on the probability that lifeline 2 has damaged lifeline

1 is P2.

As a practical matter, the collocation damage likely will be less,

since there is seldom a 100% chance that the collocation damage

scenario will occur. A useful measure of the probability that the

collocation event has occurred is the product of the two

probabilities that the single independent events that were used to

develop the collocation scenario have occurred (the independent

events are the estimate of the damage state of each lifeline

assuming there was no collocation). In the present case, that is

found by multiplying PI x P2. The product can be interpreted as

follows. It represents the increase in probability that the two

independent lifeline damages will occur during the same initiating

event. If both events must occur before the collocation damage

scenario can take place, then it is a measure of the probability of

the collocation damage scenario.

The actual probability that the collocation event will occur should

be a number between the numerical limits of P1 and (PI x P2) for

having lifeline 1 cause additional damage to lifeline 2, and P2 and

(P2 x Pi) for having lifeline 2 cause additional damage to lifeline

1. It is recommended that for calculational purposes, the product

Pi x P2 be used to characterize the hypothesized collocation damage

scenario.

Impacts on Time to Restore Lifeline Service

As discussed above, the time to restore lifeline service is

composed of the sum of the time to repair the lifeline damage, the

time to access the damage site with equipment and material, and the

time to obtain the equipment and material.

The hypothesized collocation damage scenario does not have to

assume a repair time. Once the collocation damage state is known,

the repair time can be obtained from Table 13.

However, it is reasonable to include in the collocation damage

scenario impacts on accessibility to the damage site, which has the

impact of increasing the overall restoration of service time

estimate. In fact, this is probably one of the more significant

aspects of the collocation damage scenario, e.g., the estimation of

the additional direct delays that will be incurred because of the

collocation of the lifelines. The greater the level of damage

estimated for each of the separate lifelines, assuming that there

is no collocation, the greater the anticipated delays that will

43
result from their actually being collocated.

The following are offered as possible examples of how collocation could create access delays that would increase the time to restore the lifeline to service. General congestion at the collocation location because there are multiple lifelines could delay the start of repair work on a lifeline. Concern over the possibility of leaking fuel may cause all work to be delayed until it can be confirmed that it is safe to have workers in the area. Spilled liquid fuels may have to be treated and/or removed before construction vehicles and welding (which could provide an ignition source for fuel vapors) would be allowed.

Work on a pipeline buried next to a railroad may be delayed while debris about and on the railroad is removed by heavy equipment. Then, because of the weight of the debris and/or the heavy equipment, the entire pipeline may have to be exposed and inspected before it is allowed to return to service. Often, power transmission towers are replaced with temporary towers while repair work on the damaged tower is performed. However, the use of a temporary tower may limit the access of pipeline and transportation lifeline repair crews because of the increased potential for electrocution if heavy equipment is operated near the temporary tower. Fires at collocation locations can increase the time required to inspect the nearby lifelines to determine the extent, if any, of damage caused by the fire. Water inundation can cause delays until the water is drained and the surrounding ground dries to a condition that allows the repair equipment and material to be delivered to the damage site. Major damage to a lifeline may result in a regulatory review about the suitability of rebuilding (or repairing) the lifeline. While the regulatory review is underway the repair on the lifeline may be delayed.

In summary, a collocation damage scenario must be developed, based on the knowledge of the lifelines and their anticipated damage state if they had been isolated or non-collocated. This will result in the estimation of a new damage state, new access times, or combinations of those items. With the damage state known, a new repair time is calculated, and the repair time and access time are used to determine the new time to restore service.

4.4 Interpretation of the Results

This is the activity that brings together all of the previous analyses.

The most appropriate measure of the impact of lifeline collocation because of an earthquake was judged to be the most probable incremental increase in the time to restore the lifeline to its needed service level. The restoration of service time is a broad measure of the impact of lifeline damage on personnel, equipment, and material resources, it does not measure the impact that the

44
loss of the lifeline has on the community that was relying upon it.

The difference between the restoration of service time assuming

collocation impacts and the shorter restoration time found by

assuming no collocation impacts gives the incremental impact that

collocation has caused to service restoration. The incremental

time impact is a better measure of collocation impacts as compared

to the estimated total time to restore service, because any biases

in the estimation procedures tend to be canceled by the subtraction

process.

It is important to multiply the incremental change in restoration

time by the probability that the collocation damage has occurred.

This recognizes, the uncertainties in the data base and analysis

methods provided in Section 4.2, and it also recognizes that in

actual earthquakes there is a real probability that a given level

of damage will occur, or conversely, will not occur. The product,

incremental change in restoration time multiplied by probability,

identifies the most probable incremental change in restoration

time.

There are two ways to use the final measure:

1) the most probable incremental change in restoration time

can be considered at a specific collocation site to evaluate

the impacts at that site. This will provide an insight on the

vulnerabilities that occur when specific types of lifelines

are collocated at at-risk locations. That is, this type of

information will help identify which lifeline types or which

lifeline design or construction practices, when collocated

with other lifelines, lead to the greatest increases to the

other lifelines' level of vulnerability.

2) the most probable incremental change in restoration time

can be summed along the route of a given lifeline to provide

an insight on the impacts that the specific lifeline route has

had on the vulnerability of the lifeline.. This type of

information can be used to help identify undesirable routing

decisions.

4.5 Chapter 4.0 Bibliography

1. P. Lowe, C. Scheffey, and P. Lam, uInventory of Lifelines in

the Cajon Pass, California", ITI FEMA CP 120190, August 1991.

2. C. Rojahn and R. Sharpe, "Earthquake Damage Evaluation Data

for California"l, ATC-13, 1985.

3. J. Evernden, et. al., "Interpretation of Seismic Intensity

Data"t, Bulletin of the Seismological Society of America, V 63,

1973.

45
4. J. Evernden, et. al., "Seismic Intensities of Earthquakes of

Conterminous United States - Their Predictions and

Interpretations", U. S. Geological Survey Professional Paper

1223, 1981.

5. S. Algermissen et. al., "Development of a Technique for the

Rapid Estimation of Earthquake Losses", U.S. Geological Survey

Open File Report 78-441, 1978.

6. Harding Lawson Associates, et. al., "Marina District &

Sullivan Marsh Area Liquefaction Study, San Francisco,

California", Draft report prepared for the City & County of

San Francisco, June 1991.

7. J. Davis, et. al., "Earthquake Planning Scenario for a

Magnitude 8.3 Earthquake on the San Andreas Fault in Southern

California", California Division of Mines and Geology, Special

Publication 60, 1982.

8. S. Barlett and T. Youd, "Case Histories of Lateral Spreads

Caused by the 1964 Alaska Earthquake", US/Japan Case Histories

of Liquefaction. Large Ground Deformation and Effects on

Lifeline Facilities, NCEER, in press.

9. T.D O'Rourke, et. al., "Large Ground Deformation and Their

Effects on Lifeline Facilities: 1906 San Francisco

Earthquake", US/Japan Case Histories of Liquefaction, Large

Ground Deformation and Effects on Lifeline Facilities, NCEER,

in press.

10. D. Keefer and R. Wilson, "Predicting Earthquake-Induced

Landslides, with Emphasis on Arid and Semi-Arid Environments",

Landslides in a Semi-Arid Environment with Emphasis on the

Inland Valleys of Southern California, Edited by P. Sadler and

D. Morton, 1989.

11. P. Sadler and D. Morton, Editors, "Landslides in a Semi-Arid

Environment with Emphasis on the Inland Valleys of Southern

California", Publications of the Inland Geological Society,

Volume 2, 1989.

12. M. Legg, M., J. Slosson, and R. Eguchi, "Seismic Hazard for

Lifeline Vulnerability Analyses", Proceedings of the Third

International Conference on Microzonation, Seattle,

Washington, 1982.

13. N. Newmark, "Effects of Earthquakes on Dams and Embankments",

Geotechnique, v.15, No. 2, p. 139-160, 1965.

14. R. Wilson and D. Keefer, "Predicting Aerial Limits of

Earthquake Induced Landsliding", Evaluating Earthquake Hazards

in the Los Angeles Region, U.S. Geological Survey Professional

46
Paper 1360, 1985.

15. L. Youd and R. Perkins, "Mapping of Liquefaction Severity

Index", Journal of Geotechnical Engineering, Vol. 113, No. 11,

pp 1374-1392, 1987, and "Mapping Liquefaction Induced Ground

Failure Potential", Journal of the Geotechnical Engineering

Division, ASCE, 104, GT4, pp 433-446, 1978.

16. T.D O'Rourke, et. al., "Large Ground Deformation and Their

Effects on Lifeline Facilities: 1971 San Fernando Earthquake",

US/Japan Case Histories of Liguefaction, Larae Ground

Deformation and Effects on Lifeline Facilities, NCEER, in

press.

17. "Seismic Design Procedures and Specifications 1940 to 1968",

CALTRANS Division of Structures, material provided for the

Cajon Pass Lifeline Study, September 1990.

18. B. Maroney and J. Gates, "Seismic Risk Identification &

Prioritization in the CALTRANS Seismic Retrofit Program",

material provided for the Cajon Pass Lifeline Study, September

1990.

19. "1CALTRANS Seismic Risk Algorithm For Bridge Structures", SASA

Division of Structures, June 30, 1990, material provided for

the Cajon Pass Lifeline Study, September 1990.

20. C. Rojahn, C. Scawthorn, and M. Khater, "Seismic Vulnerability

of Lifelines in the Conterminous United State", ATC-25, in

press.

21. T. Airman, et. al., "Pilot Study on Seismic Vulnerability of

Crude Oil Transmission Systems", NCEER-90-0008, May 1990.

5.0 APPLICATION THE METHOD TO CAJON PASS

5.1 Data Acquisition

The following material demonstrates the application of the analysis

method described in Section 4.0. The first step of the process is,

to assemble the data base that describes the lifelines and their

routes in the study area as well as the geologic and seismic

situation. The earlier Cajon Pass studytl) provides most of the

needed information. It should be consulted for specifics about

each lifeline and when it was installed.

Figure 5 shows the Cajon Pass study area and its relationship to

other cities in California. It is used with the permission of the

Automobile Club of Southern California (it is copied from the San

Bernardino County and Las Vegas Area map). It shows that the Cajon

Pass canyon (which is about 10 miles northeast of San Bernardino)

is a natural access route between the San Gabriel Mountains to the

47
Figure 5, MAP OF THE GENERAL LOCATION.OF THE CAJON PASS STUDY AREA

___ L E 1Y9 ' 

* I l, 

inI

~ t* 0 ,..Study Area

WI ,^;* -n a. * = °h°

pit. ,ftw.- 

- 3LN Mtdsi. AM lul*_ l L

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48

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^ -

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west and the San Bernardino Mountains to the east. The Pass

connects the Los Angles Basin in the south to the high desert

regions to the north. The City of San Bernardino is about 10 miles

southeast of the mouth of the Pass.

U.S. Geological Survey quadrangle maps (7.5 minute series

topographic maps published in 1988) were used to obtain more detail

and to develop a plan for a site survey. The site survey was then

conducted. It identified additional lifelines that were not

identified on the 7.5 minute quadrangle maps, which emphasizes the

heed to conduct actual site surveys to validate the published

information on lifeline systems. With the map and site visit

information as a background, the individual lifeline owners were

contacted and meetings were held with their staff to obtain more

details on the location, capacity, design basis, operating and

maintenance history, and emergency response systems in place for

each lifeline. The Cajon Pass site was revisited to validate our

understanding of the actual siting conditions, and in some cases

this led to additional visits and discussions with the lifeline

owners to resolve questions. This emphasis on the lifeline data

acquisition and validation is very important, as there are over 100

discrete locations (which include over 250 separate combinations of

collocated lifeline components) in the Cajon Pass study area where

different lifeline components are in close enough proximity that it

was necessary to evaluate their potential for collocation impacts.

Figure 6 is a plot of the communication, electrical power

transmission, natural gas pipelines, petroleum products pipelines,

railroad, and highway lifelines overlaid upon the U.S. Geological

Survey's quadrangle map of the study area. Figure 6 shows several

important items. First, the Pass is crowded with the lifelines

traveling in a general north-south orientation through the middle

of the study area. Second, the lifelines are clearly routed in a

utility corridor. Since the bed of the Pass varies, from about 0.5

miles near Blue Cut (which is located in about the center of the

figure) to over several miles wide at most other regions, topology

requirements alone would not require the observed congestion. The

conclusion reached was that routing criteria such as aesthetic,

cost, land use, and environmental considerations have had the

controlling impact on the lifeline routing decisions.

There are especially congested areas near the intersection of

Highways I-15 and I-215 in the southeast corner of the study area,

near Blue Cut in the center portion of the study areas, and south

and separately north of the intersection of Highway I-15 and State

Highway 138. In addition, there are crowded areas for several of

the lifeline systems, for example, near the railroad summit of

Cajon Pass, where natural gas pipelines, fiber optic lines, and the

railroads are closely located. Also in the northern portion of the

study area it is crowded where the two petroleum product pipelines

and two fiber optic conduits parallel one set of high voltage power

lines and also along Baldy Mesa Road where the two petroleum

49
'I

20

a

S.

*_ ` Wo') 1A ( '. I .- I 'f?

a . - .. I 

Fig u 306

Figure 6, A COMPOSITE

Is R ITH IN S A

OF THE LIFELINE ROUTES AT CAJON PASS

SCALE

allog

coW"= vAIMoIN3 F1 M

CFmouR DITVAL lMe o

EXPLANATION

Larger Scale Figure

Located at

End of Document

-~ 2a -

-: -

- - - -

- --- v- --...-- p - -

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-Ans

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50

v0
product pipelines, the fiber optic conduits, and a natural gas

pipeline all are routed alongside of the road bed. The two

petroleum product pipelines, a natural gas pipeline, and two high

voltage power lines cross the San Andreas fault in Lone Pine Canyon

at approximately the same region. The unfortunate routing for

several miles of the petroleum products pipelines along the San

Andreas fault's rift zone does not enter into the current study

since there are no collocated lifelines of interest along that

route. Finally, there are collocated railroad lines, power lines,

a natural gas pipeline, the petroleum products pipelines, and the

fiber optic conduits parallel to I-15 between the I-15/I-215

interchange and Blue Cut.

Figure 7 is another composite map of Cajon Pass. Each of the 101

collocations that were analyzed during this study are shown on this

figure. Within those 101 locations, over 250 individual

collocations occurred. This emphasizes how siting decisions have

resulted in crowded collocation conditions, even though there is

sufficient space to avoid most of them. Although there are several

broad grouping of lifeline intersections, it is clear that they

occur throughout the entire length of the study area.

The seismic and geologic information was also obtained during the

data acquisition phase of the study. A sensitivity evaluation of

six postulated earthquake events was performed to guide the

selection of the event for use in the study. Other 2 ,3) studies were

consulted to help select the earthquake events. The six events

were:

1) The 1857 Ft. Tejon earthquake on the San Andreas fault.

This was 300 km long fault with a magnitude 8.3 earthquake,

and with the southern edge of the surface displacement located

just north and west of Blue Cut.

2) An earthquake on the southern segment of the San Andreas

fault. This was a 200 km long fault of 7.8 magnitude. The

northern edge of the surface displacement was placed just

north and west of Blue Cut.

3) An earthquake similar to event 1, except that the southern

extreme of the surface displacement was moved about five mile

further east into the study region.

4) An earthquake similar to event 1, except that the length of

the fault was reduced to 105 km. This resulted in a 7.7

magnitude earthquake.

5) An earthquake similar to event 1, except that it was

-centered about the Cajon Pass. This resulted in a 8.3

magnitude earthquake.

6) A earthquake of 94 km length, but placed on the San Jacinto

fault. This resulted in a 7.5 magnitude earthquake.

51
.3

7, IDENTIFICATION

SCALE 0 1 2 MIZS

2 K2 I WMKDITFUS

EXPLANATION

1- 15-

- 2

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- -- -- - I - ... --_ -_

- -- - - - -If - - ---v 

OF LIFELINE COLLOCATION AT CAJON PASS

j Larger Scale Figure

Located at

End of Document INTERSTATE.

PAVED HIGHWAY *rMt.KAIT AuaIT,.

RAII.ROAD

POWER UINS

PETROLEUM PRODUCT PIPEUINES

NATURAL GAS PIPEUNES

FIBER OPTIC CABLE

FLUME-PENSrOCX 52

Figure
The sensitivity study was performed with the QUAK2NW3 computer

code 4,5) developed by the U.S. Geological Survey. Based on the

study, the ground shaking intensities were relatively insensitive

to the changes in fault rupture length The conclusions reached was

that the 1857 Ft. Tejon earthquake was a reasonable choice for the

study. It did not produce the most intense shaking, nor was it the

least intensive. However, by using it for the present study, it

will be possible to compare our solutions for earthquake intensity

with those of previous researchers 5 ,

6 K. That comparison showed

general agreement except at the fault rift zone. There the

QUAK2NW3 program predicted lower shaking intensities. than those

reported by DlavisL6). After discussions with Davis, it was decided

to increase the predicted MMI shaking intensity along the San

Andreas fault zone by one level from VIII to IX. This accounts for

the greater impacts that are expected to be associated with the

fault displacement and is consistent with the work of Davis.

The areas of potential liquefaction were determined by examining

the water well data for the Cajon Pass, and supplementing it with

other regions high water table as determined by the site

reconnaissance visits. Regions of high water table were correlated

to alluvial deposits to identify the liquefaction susceptible

regions. The historical landslides were identified 6 .

7 "') and the

method of Legg (see Section 4.2, Table 7) was applied. A computerbased check of the soil conditions at the Cajon Pass was used to

assure that the Legg method was applied at each slope of interest.

The landslide predictions based on the Legg model agreed quite well

with the record of historical landslides (that is, the Legg model

prediction included the historical landslides, but it also

identified many more potential areas of landslide).

Figure 8 presents the summary of the calculated seismic and

geologic conditions overlaid upon the lifeline routes. Although

the figure is complex and filled with data, it does highlight some

important information. In the figure the shaking intensities are

shown with various levels of shading. The highest intensities, MSI

= IX, are along the San Andreas fault rift zone. On the map they

are shown as solid lines where the fault is well located, dashed

where its location is estimated, and circled when it is hidden by

younger rocks. The potential landslides are predominantly south of

the San Andreas fault and lie in a southeast trend. There are four

important regions of potential liquefaction: just south of Cajon

Junction, at Blue Cut where they coincide with potential landslide

regions, southeast of Blue Cut about two miles northeast of the I15/I-215 intersection, and just south of the 1-15/I-215

intersection.

Figure 8 shows that many of the conditions of high M4I value,

landslide, and liquefaction overlap. This is important to note

because the lifeline components in the study area >(with the

exception of some bridges) are not very sensitive to shaking

damage. MMI values of VIII generally would only cause damage state

53
.I

a

2

Figure 8, LIFELINE ROUTES WITH EARTHQUAKE SHAKING INTENSITY,

AND POTENTIAL LANDSLIDE AND LIQUEFACTION AREAS

SCALE

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EXPLANATION

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Located at

End of Document

54

PU-L Us
2 or 3 to occur (less than 5% damage expected). At those

conditions, collocation induced additional damage would be slight

or none at all. However, the facilities are very sensitive to

ground movement and there are a number of potential landslide or

lateral spread (or liquefaction) locations along the lifeline

routes that coincide with MMI = VIII. North of the San Andreas

fault the earthquake risk comes predominantly from shaking, but

most of the peak shaking intensities are VII with a few isolated

locations of VIII.

Another important activity of the data acquisition phase of the

study is to divide each lifeline into segments for subsequent

analysis. Figures 6 and 7 were used to guide the segmentation

process. The communication lifelines were divided into 12 to 14

segments, depending on the route of the individual fiber optic

conduits; the electrical power transmission lifelines were divided

into four segments (the Arrowhead Calelectric-Shannin line at the

southeast corner of the study area was analyzed as a single

segment); the natural gas pipeline lifelines were divided into five

or eight segments; the petroleum products pipeline lifelines were

divided into 10 segments; the railroad lifelines required 30

segments; and the interstate highway required 36 segments. The

subsequent vulnerability calculations for the communication,

electrical, and fuel pipeline lifelines were performed by hand;

those for the transportation lifelines were performed with a

standard computer spreadsheet. These approaches recognized the

number of calculations that would be required.

5.2 Lifeline Collocation Vulnerability Analysis Results

Figure 7 identifies the locations of the 101 collocations that were

subsequently analyzed in this study. These collocations involved

over 250 separate potential lifeline interactions. Table 15 was

prepared to identify the collocation and the lifelines that were

involved at that location. As the collocation evaluation was

prepared, the results were tabulated against the index, thus

assuring that all potential interactions were located and

evaluated.

Table 15 and Figure 7 identify several critical clusters of

interactions. With this in mind, a collocation damage scenario was

developed for each critical cluster of interaction. Using a

standard collocation damage scenario at the critical clusters

helped assure the overall consistency of the interaction analyses4

The clusters where the standard collocation damage scenario was

used were:

1. The liquefaction zone south of the interchange of I-15 and

I-215. There were 10 separate potential interactions

involving I-15, railroad bridges, several fiber optic lines,

the 16-inch natural gas pipeline, and the 8-inch and 14-inch

55
Table 15

MATRIX OF LIFELINE COLLOCATIONS AND INTERACTIONS

INTER- HIGH- RAIL- POWER FIBER NATURAL PETRO

SECTION WAYS ROADS LINES OPTIC GAS LINES

NO. A B C D E A B C A B C D E F A B C D A B C A B

1 X x x

2 X _ _ _ _ _ _ _ X _ _ _ _

3 _ _ _ _ _ _ _ _ _ X X X _ _ _

4 X X X

5 X X XX X

10 X X X

71 . _ _ __X_ X X_ _ _ X_ _

23 X_ _ X _ _ X X

10X X X_ __ _ __ __ _ X _

11 x X __ _ __ _ _ X x

12 X X _ _ _ _ _ _ _ _ _ _ X X

13 X _ _ _ _ _ _ _ _ __ _ _ _ __X

14 X X X _ _ _ _ _ _ _ _ _

16 X

17 x x X

is =X- l =

19 X X XX

24 X X

25 = : x I XXX Xx

26 X X _ _ XX____XXX

2 7 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ I

28 X _ _ _ _ _ _ _ _ _ X X X _ _ _ _

29 I XI X X X

56
Table 15 (Continued)

XATRIX OF LIFELINE COLLOCATIONS AND INTERACTIONS

INTER- HIGH- RAIL- POWER FIBER NATURAL PETRO

SECTION WAYS ROADS LINES OPTIC GAS LINES

NO. A B CD E A B C A B C D E F A B C D A B C A B

30 X X .

31 X _X

32 . xx xx x

33 X X

34 X ,X _

35 _ _ _ _ x x H _ _ _

*36 XX XX x XX

37 X X XX

38 . XX ____ xx

3S~~~~~~~~~~~ XXXX XX

40 X XX X XXXX

. 41 X xX XX X X X __X

42 XX x

43 X XX

44 X X XX i XX XXXX

45 X X x X

46 X XXXX X

47 I X X

48 X X X X

49i X X X . -

s5 X

51 xx xx

52 . X X XX

53 X XX

54 X X X

55 X X ______ XXXX

56 x xxxx xx

57 X X X

58 X X ____________ XXXX ________ XX

57
Table 15 (Continued)

MATRIX OF LIFELINE COLLOCATIONS AND INTERACTIONS

INTER- HIGH- RAIL-. POWER FIBER NATURAL PETRO

SECTION WAYS ROADS LINES OPTIC GAS LINES

NO. A B C D E A B C A B C D E F A B C D A B C A 3

59 X X X X X

601 X X xX X X X

62 x x x xxx X

63 __ _ _ _ X_ _ _ _ _ _

64 X X

65 X X

66 X ._. XX

67 XXX XX

68 X X _ _ _ _ _ _ _ 

69 X X

70 x x

71 = X '_== -

72s x x

73 xxx x x

74 x x x xx xx

75 1 I _ _ _ _ _

76 x x x x

77 81_X' X X X

7 8 I _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

el2 x x x xx 

84 .x x x x

86 X XX X

87 X X X X

58
Table 15 (Continued)

MATRIX OF LIFELINE COLLOCATIONS AND INTERACTIONS

INTER- HIGH- RAIL- POWER FIBER NATURAL PETRO

SECTICON WAYS ROADS LINES OPTIC GAS LINES

NO. A S C D E A B C A 8 C D E F A 3 C D A BC A B

8_ X X X XX

.89 ______ HX XX X XX

90 X X X

NOT USEDX

93 H _ _ _ _ _ _ _ _ _ _ _ _

NOT USED = X XXX

96 X XX

93_ _ _ _ _ _ _ _ _ _ _ _ _ _ HX X X X 97 ~X I X __ _ __ _

* 98 _ _ _ _ _ _ _ _ _ _ X _ _ _ _ _ _ 

99 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ X _ _ _ _ _

100 X X

101 XX 

X - X

103 _ _ ,__ ,~~~~~~X X:

petroleum products pipelines. All of the buried lifelines

were found to have incurred damage state 7 (catastrophic) with

probabilities that the damage occurred of 40%. The assumed

collocation interaction was that the petroleum pipelines could

drain 1-2 miles of pipe but that no secondary fires or

explosions would occur. This contributed to an additional 30

day delay to the site before repair could commence, due to the

requirements to assure that fire conditions and environmental

concerns could be alleviated before work could start on the

individual lifelines. An additional 10 days of delay were

hypothesized due to the need to coordinate the work on so many

individual lifelines.

2. A second cluster exists along the Cajon Blvd. extension

into the Cajon Pass from north of the I-151I-215 interchange

to Blue Cut. There are two separate locations where

59
landslides (with a probability of occurrence of 45%) anu two

liquefaction areas (probability of occurrence of 20% and 40%)

are possible, including eight separate collocation impact

areas where there are collocated power lines, railroads, and a

natural gas pipeline. At the two landslide areas along the

Cajon Blvd. extension (which was the prior highway 66 before

I-15 was built), a natural gas pipeline and the railroads are

located at the toe of the slide area, and landslide debris is

expected there. Debris removal for clearing the railroad

would be required before work on the pipeline (which is

located in the railroad right-of-way and sometimes under the

rail bed) could begin. The debris removal was assumed to

cause a 30 day delay before work on repair of the pipeline could occur.

3. At Blue Cut itself there is another landslide and

liquefaction zone. Due to its proximity to the San Andreas

fault rift zone, a 70% probability of occurrence was

estimated. At that location, a power line, a natural gas pipeline, and a railroad are in the flow area of the slide, which could cause the pipeline to surface and rupture as well

as to be covered with debris. The collocation damage scenario

assumed that an explosion and fire could result, increasing the damage to the power line and its repair time by an

additional 20 days, compared to the delays described for the

other slide area, to repair the more extensive damage the fire

caused. The potential for landslides blocking the Cajon Creek

with a slide dam, and the subsequent impact on downstream

lifelines if the dam should catastrophically fail were

considered to be outside the scope of this study. At Blue Cut

itself, the liquefaction zone has a 50% probability of

occurrence.

4. In the San Andreas fault rift zone there are six

collocation points that involve the power lines, the

railroads, the fiber optics, a natural gas pipeline, the two

petroleum products pipelines, and the Cajon Blvd. extension.

Fuel spills are assumed to require a 30 day delay for

alleviating environmental and fire concerns. An additional 60

day delay was assumed for the petroleum products pipelines

because the estimated extensive damage to their right-of-way

along the fault trace will require regulatory review and

acceptance before the pipeline can be worked on. An

additional 30 day delay for the other lifelines was assumed

because of the general congestion in the area. Since the

fault displacement causes catastrophic failure of the

lifelines, the collocation damage scenario does not assume any further damage.

With these scenarios in mind, the collocation vulnerability

analysis was performed for each separate lifeline system.

60
Communication Lifelines

Figure 9 shows the communication lifeline routes in the study area.

The location of the photographs presented in this. section of the

report are also shown on the figure. The microwave, radio, and

cellular phone communication towers are sited such that they are

not collocated with other lifelines. Thus, they do not enter into

the analysis of the impact of collocation. The impact of degraded

communications (if these towers should fail) on the ability to

restore the other lifeline systems to acceptable delivery

conditions is beyond the scope of the present study..

There are five fiber optic systems located in the study area. They

include American Telephone and Telegraph (AT&T), Continental

Telephone (Contel), MCI Communications (MCI), WTG West (WTG,

formerly WilTel), and US Sprint.

The individual fiber optic cables are multi-layered with an inner

structure that allows the cable to be pulled and maintained in a

state of tension without placing tension on the individual glass

fibers. This assembly is then wrapped with various insulating

materials, including a metal sheath. In the fall of 19.86, the U.S.

Forest Service provided MCI and WTG right-of-ways on the basis that

they would each provide two conduits and that each conduit would be

four inches in diameter so that cables from two different systems

could be placed in each individual conduit (thus, provisions were

made to lay eight cable systems along the two routes through the

Forest Service land). Furthermorethe Forest Service required that

the routes be combined as quickly as, practical. Thus, the MCI and

Contel systems enter the study area from the north along Baldy Mesa

Road, while the AT&T, WTG, and US Sprint systems enter from the

north along the access road to I-15. The routes join together just

south of the separation of I-15N and 1-15S (about 1.8 miles north

of the Cajon Junction of I-15 and Highway 138). From there they

travel together as a bundle of four conduits. Much of their route

is along the Cajon Blvd. extension where they are laid in the

median strip. Also routed along much of the median strip are the

two petroleum products pipelines (the Cajon Blvd. extension was the

former divided highway 66, but only the western two lanes are still

maintained for traffic). For the purposes of this study, the fiber

optic cables are analyzed as buried conduits. Because of their

collocation, if one conduit fails, all fail.

When the conduits, (which are normally buried) are routed to a

bridge location, they are generally brought to the surface and hung

with light anchors from the bridge. Figure 10 shows them on a

typical bridge crossing on the abandoned portion of Highway 66;

Figure 11 shows some of the details of the bridge hangers and the

conditions of the conduits; Figure 12 shows them hung from a

highway culvert wall just south of Cajon Junction; Figure 13 shows

some of the details of the wall anchors, near the culvert location

of Figure 12. Just south of the culvert shown in Figure 12 the

61
. II

,3h U30.

Figure 9

SCALE o 1 Z m S2 

~m _

COMMUNICATIONLIFELINEROUTS. 35 ~II =4. a

COMMUNICATION LIFELINE ROUTES

44

EXPLANATION

-D I-s -_

~~ a

... ... . .. ... ... . . .. .... ,.. .......

INMWIATE

PAVED MONV1AY

FM= 0MOtC CM&3

62

Is

.'

a

Larger Scale Figure

Located at

End of Document
-- - -. ~~ 

Figure 10 Fiber Optic Conduits On A Bridge On The 

Abandoned Portion of Cajon Blvd. Extension 
I 

I 

Figure 12 Fiber Optic Conduits On A Concrete Culvert 

That Passes Under 1-15 

I 

Figure 13 Wall Support Details For The Fiber Optic 

Conduits Of Figure 12 

64 
Figure 14 Surface Water Conditions Near The Toe Of The 

1-15s Retaining Crib Wall 

Figure 15 Fiber Optic Conduits Under a Heavy Water 

Pipe, Both On A Highway Bridge 

65 
fiber optic cables are buried at the toe of a crib wall used to

support the southbound alignment of 1-15. Figure 14 shows the

surface water in this region, which was identified as a potential

liquefaction region. Figure 15 shows the conduits hung under a

water distribution system pipe, both of which are supported from a

road bridge over a railroad. Other important collocations include

where the conduits are buried near buried fuel pipelines, a number

of which are in liquefaction or landslide prone regions.

In all of these cases, the fiber optic cables are at potential risk

because the light anchors used could be expected to fail due to

shaking. The heavy water pipe just above the fiber optic cable

conduit can be expected to fall on and fail those cables.

The analysis of the fiber optic cable systems indicates that they

are not at significant risk until the MMI values equal VIII or

more. In the Cajon Pass that occurs at liquefaction areas or at

the San Andreas fault where surface displacements of up to 12

meters are anticipated. Thus, shaking damage is not expected to be

significant compared to displacement-related damage. However, the

screening method data base does not directly account for the light

anchors and the conditions of the conduits as shown in the figures.

It is possible that they are more sensitive to shaking damage than

the screening method predicts.

At the San Andreas fault location (just north of and close to Blue

Cut) the fiber optic conduits are not collocated with other

lifelines within the zone of influence of the lifeline. Thus, for

purposes of this study there is no collocation impact there.

However, the large number of near by lifelines does suggest that

general construction congestion could delay the permanent repair of

the communication lifelines in this region. Also, it probably

would be possible to temporarily lay the fiber conduits on the

ground surface, restoring service on a temporary basis. These

types of changes to the assumed restoration of service time are

noted, but they were not used in the present study to estimate the

service restoration time.

Four liquefaction regions have the potential to impact the fiber

optic systems. At the liquefaction region just southeast of the I15/I-215 interchange, the fiber optic cables are in separate and

dispersed conduits. However, two cable conduits cross this zone

near the railroad beds. One cable conduit crosses the 16-inch

natural gas pipeline and the 8-inch petroleum products pipeline,

and then it runs parallel to the 8-inch line. Another cable conduit

crosses the liquefaction zone and is perpendicular to the 16-inch

natural gas pipeline, which is also in the liquefaction zone. The

liquefaction impact is calculated as a damage state 7

(catastrophic) but it only has a 40% probability of occurring. The

conduit repair time in this region is hypothesized to triple, based

on the delays required to repair the natural gas and the petroleum

products pipelines and the delays associated with the repair of the

66
nearby damaged I-15 and railroad bridges. This causes the fiber

optic conduits' most probable repair time to increase by about ten

days.

In the second liquefaction region the four cable conduits are

collocated and they are parallel and next to the 8-inch and 14-inch

petroleum products pipelines. In this region they cross over the

36-inch natural gas pipeline. The liquefaction impact is a damage

state 7 with a 20% probability of occurrence. The collocation

damage scenario assumed that the petroleum product pipelines would

have to be repaired before the fiber optic cables could be replaced

within their conduits along their old route, causing a 55 day delay

in being able to access the five fiber optic cables. Another 10

days delay for equipment availability is expected. However, the

low probability of liquefaction resulted in the most probable

restoration time increasing by only about four days.

The third liquefaction zone is just south of Blue Cut. The

collocated lifelines include the fiber optic conduits, fuel

pipelines and a high voltage power line also crosses over the

region. The liquefaction probability at this locations is

estimated at 50%. Most of the repair activities for the power line

will not impact the fiber optic cable conduit repair. The only

impact could come when the power lines directly over the conduits

are being worked on. The most probable restoration time increased

by only about 12 days.

The fourth liquefaction zone is where the fiber optic conduits

cross the toe of an I-15 retaining wall crib and then are connected

along the concrete culvert under I-15 (see Figures 13 and 14). The

concrete culvert is a massive structure, and its damage is expected

to be small. Analysis of the crib wall found that its movement

would not substantially impact the highway, however, just partial

movement of the crib wall could severely damage the fiber optic

cables. In such a case they could not be replaced permanently

until the wall had been stabilized. Fortunately, the probability

of liquefaction is.only 40% in this region, resulting in the 140

day crib wall-induced delay becoming a 22 day most probable

restoration time increase for the fiber optic conduits.

Where the AT&T and WTG cables are hung from the bridge over the

Southern Pacific railroad is the final collocation damage location

where the collocation impacts were found to be serious (see Figure

15). There, because the shaking intensity is only MMI=VII, not

much damage would normally be expected to the cable conduit itself.

However, the wall brace and anchor supports for the water pipe and

the fiber optic conduit are small and have not been sized for

earthquake conditions. Thus, it was assumed that they fail

allowing the fiber optic conduit to sag. The heavier water pipe

was assumed to fall on top of the fiber optic conduit which is

located directly under it, causing the fiber optic conduit to

rupture and fail. The probability of this, failure scenario is

67
estimated to be 80%, causing the most probable restoration time to

increase by about 4 days.

Thus, of the 55 collocations analyzed for the fiber optic systems,

nine were estimated to lead to increased probable times to restore

service. Most of these conditions resulted from ground motioninduced failures, and the impact on the fiber optic systems was

that the failures of the other collocated lifelines lead to

increases in the delay time before the fiber optic systems could be

repaired. The practice of collocating all of the fiber optic

conduits together, along with the practice of hanging them from

bridges and culverts with very light anchor bolts, suggests that in

future earthquake situations the loss of telephone communications

will be more severe than have been experienced in the past. That

is because the loss of a few hard-wired telephone lines in past

earthquakes has not been significant in terms of the ability of the

systems to handle call traffic. Fiber optic cables, however,

handle many more calls per line than does a hard-wired system, and

if one cable is lost then probably all of the collocated cables

will be lost in the same event.

The overall estimate of the impact of collocation on the

communication lifelines was:

Increase in Probable Increase in Probable

Time to Restore Time to Restore

Lifeline Service, days Service, %

Fiber Optic 61 86

Cables

Electric Power Lifelines

Figure 16 shows the electric power transmission lifeline routes in

the study area. The location of the photographs presented in this

section of the report are also shown on the figure. Experience has

shown that power transmission towers are quite resistant to

earthquake shaking, principally because of the conservative wind

loading criteria used in their design. Thus, only fault

displacement, landslide, or liquefaction are expected to caused

significant levels of damage to the towers.

The electric power lifeline systems include a major transmission

system substation at Lugo in the northeast corner of the study

area, a hydroelectric generation station in Lytle Creek Canyon, and

four major high voltage transmission systems. The hydroelectric

station is not collocated with any of the lifeline components of

interest to this study. Although the substation is collocated with

two of the high voltage transmission systems, component failures in

the substation are not expected to lead to transmission line

failures, and visa versa. The transmission lines are not expected

to have any failures at the shaking intensity expected at Lugo

68
e I

II7 S1

Figure 16, EL

SCALE

a I Z mum

e... ,-~ AWLn= z 

fib

U?'

iECTRIC POWER LIFELINE ROUTES

4'

EXPLANATION

Larger Scale Figure

Located at

End of Document

-~ n-Is -~ INtK~Mh

- z . KVrD ActzrAX

--- --oM AS=

------- V-------- - A -w anUCrm

69

.1 
(where MMI = VII). Thus, although the substation is a potential 

weak link in the overall electric power transmission system, the 

lack of collocation impacts means it was not be examined further in 

the present study. 

In general, power transmission lines are not impacted directly by 

the other lifelines, as they are either above or otherwise outside 

of the zone of influence of the other lifelines. However, they 

can be impacted by construction delays or fires induced by the 

failure of other lifelines. The general tower design and footings 

used are quite rugged and earthquake resistant (resistant to 

shaking damage). There have been some cases when shaking has 

caused the 

lines 

themselves to 

gallop or 

vibrate, 

resulting in 

their coming 

close or even 

touching 

other lines 

routed on the 

same tower. 

The resulting 

arc and 

electrical 

short can 

cause fires 

and/or drop 

both lines 

from service. 

However, this 

failure mode 

is not 

addressed in 

the available 

data base and 

thus was not 

considered in 

~~ 

'igure 17 A Landslide Scar With Power Towers In The 

Slide Area 

the present study. 

Transmission lines often traverse more rugged areas, and as such 

they are susceptible to landslide damage. Figure 17 shows two 

transmission towers located in an old landslide scar (the original 

towers were damaged in the landslide). This location is an 

important collocation site, as a buried natural gas transmission 

pipeline and the railroad tracts are located just below the slide 

area. Figure 18 shows the location of two high voltage power 

transmission tower systems, a buried natural gas transmission 

pipeline (shown by a surface marker), and the 8- and 14-inch buried 

petroleum products pipelines (also shown by a surface marker). 

70 
This location 

is in the 

fault rift 

zone of the 

San Andreas 

fault ( in 

Lone Pine 

Canyon). 

Figure 19 is 

a photograph 

from the same 

location 

looking in 

the opposite 

direction. 

It shows a 

transmission 

tower located 

at the edge 

of a steep 

ravine where 

it is subject 

to possible 

landslide 

failure . This general 

location (in 

I 

'igure 18 Power Lines, Natural Gas & Petroleum 

Products Pipelines Intersection Over the San Andreas 

Fault Rift Zone 

the San Andreas fault and rift zone) is the most significant 

collocation condition for the electric and the fuel lifelines. 

The Southern California Edison (SCE) 115 kV Arrowhead:Calelectric 

Shannin transmission line (located in the southeast corner of the 

study area) is routed through some local landslide and liquefaction 

zones, however, it is not collocated at those regions. Its other 

collocation impacts were negligible. In the northern section of 

the study area the SCE Lugo-Vincent two-line, 500 kV transmission 

lines traverse from Lug0 station west and then northwest. Because 

of the low shaking intensity (low for power lines), they only 

experience damage state 1 or 2. Thus, these two SCE transmission 

systems are not of interest for collocation impacts in the present 

study. There are, however, a Los Angeles Department of Water and 

Power (LADWP) two-line transmission system and a three-line SCE 

transmission line system that resulted in collocation impacts. 

The LADWP Victorvil1e:Century 287.5 kV transmission line system (it 

has two full circuits) extends from the north (located at about the 

center of the northern boundary of the study area) to the south of 

the study region. 

from the Hoover Dam in Nevada to the Los Angles Basin. It has been 

upgraded in 1970, 1974 and 1980 to allow switching between the 

287.5 and other 500 kV lines as well as to add new controls. Parts 

of the line have previously experience problems of interest to this 

It was constructed in 1936 to transmit power 

71 
study. At a section between

Highway 138 and the Lone

Pine Canyon, the lines

experienced slow foundation

movement or shifting at a

region were a local bowl or

depression exists. The

cause was determined to be a

high water table fed by

surface waters collected in

the bowl that allowed the

tower foundations to slowly

respond to the tension

imposed by the lines

themselves. The solution

was found to be to cover the

ground with a concrete

mixture so that surface

waters would could not seep

into the water table at that

location. The towers now

appear to be stable. On

several other occasions,

local brush/forest fires

have heated the copper

conductors to the extent

that they partially annealed

and sagged. This problem

was resolved by retensioning

the line in those regions.

It is of importance because

it indicates the problems

that earthquake-induced

fires could have on this

lifeline system.

Figure 19 Power Tower At A Ravine Edge

In The San Andreas Fault Rift Zone

The LADWP power lines cross the San Andreas fault zone in Lone Pine

Canyon very close to where the petroleum products and a 36-inch

natural gas transmission line cross the fault trace (see Figures 18

and 19). The expected 12 meter fault displacement causes a damage

state 7 to all the lifeline components in this region, with a

probability of 100%. The collocation scenario assumes that the

resulting petroleum products spill (several miles of those

pipelines could drain from the rupture, depending on how many other

ruptures are assumed since the petroleum products pipelines run

parallel to the fault trace for several miles) causes a 30-day delay in the repair activities while the resulting environmental

and fire hazards are evaluated and mitigated. The general congestion in the area and the need to coordinate the use of heavy equipment so that its use will not adversely impact the other

lifelines is assumed to add another seven days to the power line

repair times. Because of the high probability of damage at this

72

, V; ,

I s 

I

'7 k

I I' 4 
location, the probable restoration time increases by 37 days. This

accounts for about 75% of the collocation-induced delays in the

restoration of service to the LADWP power lines.

The other significant collocation region for the LADWP power lines

is also at Blue Cut. The power lines cross the eastern edge of a

landslide zone, and at the toe of the zone at a lower elevation a

36-inch natural gas pipeline is sited next to and in the right-ofway of a rail line. The probability of a slide in this region is

70%, it produces a power line damage state of 5 (heavy damage).

The collocation scenario includes a seven day period while the gas

line is prepared and tested for leaks, and a increase in damage

state to level 6 because of potential natural gas pipeline failure

impacts. That scenario increased the repair time from 49 to 66

days and the net impact on the change in restoration time was about

12 days.

There are three 500 kV circuits on SCE's Lugo - Mira Loma system.

They were installed in the early 1960s for about 300 kV service and

upgraded to 500 kV service in the early 1970s. Line 3 was added in

1983.

Line 1 is to the west, line 2 is in the center, and line 3 is the

eastern line. Line 1 is routed south by southwest from the Lugo

substation. Lines 2 & 3 leave Lugo station on a single tower

system for about 1.5 miles, then they divide into two separate

tower systems. The power lines cross the railroad lines a short

distance before they cross Highway 138. From there they head

generally south until they cross I-15. In this high desert region

the only earthquake load comes from shaking characterized by MMI =

VII. At that intensity there is no appreciable damage to the

towers or the lines, and no collocation impacts were hypothesized.

At the I-15 crossing, lines 1 & 2 cross at the northern boundary of

a local liquefaction zone. Because their power towers are located

on local hill tops in this region, it is assumed that there are no

impacts due to the liquefaction or due to collocation. However,

they cross near a concrete culvert that crosses under the highway.

At the culvert (see Figure 12) location there is also a metal crib

wall (see Figure 13) that provides support to the road bed, the

fiber optic cables cross at the same location, there are two

railroad bridges in the downstream path from the run off that

passes through the culvert, and there is a 36-inch natural gas line

which crosses I-15 in the same area. In addition, the crossing is

in an area of high water table and of surface water, indicating a

potential liquefaction zone. Although the power towers and lines

are not expected to experience damage at this location, they will

cause some delays in responding to damage on the other lifelines

because of the need to work with large cranes and other equipment

that could get close enough to the power lines to cause the need

for caution to avoid potentials for electrocutions, etc... Line 3

crosses I-15 further south and is not impacted by the crowded

73
conditions described above.

After crossing I-15, lines 1 & 2 are routed as parallel lines.

Where they cross the San Andreas fault they will experience damage

state 7 due to the 12 meter displacement expected at the fault

trace. The two lines pose a collocation potential that is assumed

to increase their repair time by 15 days. This increases their

probable restoration time by 15 days because of the high

probability that the large fault displacement will occur. After

this, the lines again separate, with line 1 heading south, and line

2 heading southeast until it joins with line 3 at Blue Cut.

As line 1 heads south it enters a liquefaction zone that is north

and abuts against a landslide zone. Within the liquefaction zone

it crosses over the two petroleum product pipelines, the fiber

optic conduits, and Cajon Blvd. extension. Near the boundary

between the liquefaction and landslide zones it crosses over a 36-

inch natural gas pipeline that is itself next to and in the rightof-way of a railroad line. The liquefaction zone results in a 50%

probability of damage state 7 occurring to the power towers. The

collocation scenario is a 20 day delay due to the general

congestion in the region, which results in a probable delay in

restoration of 4 days. There are no other significant collocation

regions for line 1 further south along its route.

After they join together, lines 2 & 3 head in a south by southeastdirection. They cross the Cajon Blvd. extension at the northern

boundary of a local liquefaction zone and head up the steep slopes

to the higher elevations of the San Gabriel Mountains. Just above

the Cajon Pass floor as they rise into the mountains they enter a

landslide zone. Figure 17 shows that in the past they have

experienced slides that have required extensive repair. At the toe

of the slide a 36-inch natural gas pipeline is located next to and

in the right-of-way of a railroad bed. The landslide causes a

damage state 5 (with a probability of 45%). It is assumed that the

congestion and the need to shut down the power line when the gas pipeline is to be tested for leaks will add 40 days to the repair of the power towers. This makes their probable restoration time

increase by nine days at this location.

The typical collocation damage scenario is that other lifelines

have a minor physical impact on power lines because the power lines

are above or removed from the zone of influence of the other

lifelines. However, when fuel-based lifelines are involved, they

can cause important delays in the power line restoration. This is

to assure that the power lines do not become a source of ignition

for the fuel. Also, when the other lifelines are directly under

the power lines, the expected use of temporary support towers may

not be acceptable because of the increased risk of electrocution

when other large repair equipment is operated near a temporary

tower. As was the case for the communication lifelines, ground

movement was the principal cause of electrical transmission

74
lifeline damage. 

One hundred and four collocations involving the electric power 

lifelines were analyzed. The overall estimate of the impact of 

collocation on the electric power lifelines in the Cajon Pass was: 

Lifeline 

Increase in Probable Increase in Probable 

Time to Restore Time to Restore 

Service. days Service. % 

Los Angeles Dept. 49 

of Water & Power 

Southern California 19 

Edison Co. Line #1 

Southern California 28 

Edison Co. Line #2&3 

28 

10 

13 

Fuel Pipeline Lifelines 

Figure 20 shows the fuel pipeline lifeline routes in the study 

area. The location of the photographs presented in this section of 

the report are also shown on the figure. The lifelines include one 

8- and one 16-inch petroleum products pipelines, three 36- and one 

16-inch natural gas pipelines, and the associated valves for each 

line. Modern 

buried 

pipelines of 

the type 

installed at 

Cajon Pass 

are very 

resistant to 

shaking 

damage. 

Thus, the 

earthquake 

conditions of 

most interest 

for the 

pipelines are 

the 

conditions 

where ground 

movement is 

expected. 

However, when 

they are 

buried next 

to or under Figure 21 Typical Long Open Span On The 36-Inch 

another Natural Gas Pipeline 

75 
7l a a s 1 17§i 17 PI It Ff I J .

Figure 20, FUEL PIPELINE LIFELINE ROUTES

SCALE

0 I l o rk 2 

EXPLANATION

- ~ 1-15 INTIESAh

a PAID SUBWAY

- ...---0------ 0 - PZTUOLIM PRODUCT mPWUNE

----------------- 0-- NATURAL DU PhP

0 0 0ALM

Larger Scale r igure

Located at

End of Document

76

*a

.I

a

aC.

Ž .1-

611

if - V-- - -
they are with

the

railroads),

there is an

additional

concern that

heavy

equipment

used to

remove debris

or otherwise

restore the

railroad

lifeline

could lead to

pipe wall

damage of the

nearby buried

fuel

pipeline.

Because they Figure 22 Two Natural Gas Pipelines Near Highway 138,

are buried, One Buried, One Exposed

there are no

convenient

features that can be shown with photographs. However, there are 18

locations along the route of the western most 36-inch natural gas

pipeline that are exposed spans which range from 10 to 138 feet in

length. Figure 21 shows one of the longer spans across a dry creek

bed north of Highway 138 and east of I-15. Figure 22 shows a

location about 40 feet from the recently realigned Highway 138. At

that location two 36-inch natural gas pipelines are routed parallel

to each other. The line on the left is exposed, the one on the

right is buried and marked with the surface sign. In general, open

spans are estimated to increase the potential shaking damage state

by up to 1 level, compared to a buried pipeline damage state

condition.

When the pipelines cross under railroads, roadbeds, and sometimes

power line rights-of-way, many of the right-of-way owners required

the pipeline to be cased inside a larger pipe in the belief that

this adds safety and/or it reduces the lifeline interactions if

damage on one lifeline should occur (there is a current technical

question whether the casing increases or reduces the overall safety

of the crossing). Figure 23 shows a location where a 36-inch

natural gas transmission line crosses under two different rail

beds. One railroad requires the use of the extra casing, the other

does not. If the use of a casing increases the safety of the

crossing, the close proximity of the railroads means that the extra

benefit is lost. If the use of a casing decreases the safety of

the crossing, then the railroad expecting extra safety has not

77

1 4 -F  1 i ran f = a
achieved it because of the close proximity in this situation. 

Two of the most critical collocations involving fuel pipelines were 

shown in Figures 17 and 18. In Figure 17 the pipeline and the 

railroads are located directly below a landslide prone area that 

includes electrical transmission towers. Figure 18 shows that both 

types of fuel pipelines and high voltage electrical transmission 

systems all cross the San Andreas fault rift zone at approximately 

the same location. The results of these conditions are discussed 

below. 

The western most 36-inch natural gas pipeline from valve station 14 

(near the Cajon railroad summit east of the I-lS/Highway 138 

interchange) south to the end of the study area was installed in 

1960. The eastern most 36-inch natural gas pipeline was installed 

in 1966. They operate at a mean operating pressure of 845 psig. 

The 16-inch distribution supply line branches off of those lines at 

Valve 15 (south and west of 

the 1-15/1-215 interchange) 

and provides service to San 

Bernardino. It operates at 

a mean operating pressure of 

350 psig. The line from the 

north of the study area 

(along Baldy Mesa Road) to 

valve station 14 was 

installed in 1976. It 

operates at a mean operating 

pressure of 936 psig. All 

of the lines were arc welded 

and constructed from high 

grade steel pipe. They 

deliver 0.6-1.0 billion 

cubic feet of natural gas 

per day. 

The 8-inch petroleum 

products pipeline was 

installed in 1960 and the 

14-inch line was installed 

in 1969. In 1980, several 

miles of the 8-inch line 

were abandoned and a new 

line was routed from the 

west side of Cajon Creek to 

join the 14-inch line on the 

east side. On the east side 

of Cajon Creek they are 

routed along the Cajon Blvd. 

extension. The lines 

transport a number of 

refined products, the 

?igure 23 Natural Gas Pipeline 

Crossing Under Railroad Beds 

78 
transport a number of refined products, the principal ones being

gasoline and jet fuel. They are made of high grade carbon steel.

They operate at 1060-1690 psig. The lines pump about 30,000

barrels of fuel per day.

Most of the pipeline highway or railroad bed crossings are cased

crossings. However, none of the Southern Pacific crossings are

cased, and a few of the I-15 and Highway 138 crossings are uncased.

That occurred because the Southern Pacific did not require casing

when they authorized the right-of-way crossing, and when I-15

replaced Highway 66 and when Highway 138 was recently realigned (in

1990-1991) they did not follow all of the old routes. At new

crossings the pipeline was already installed, and new casings were

not required to be retrofit.

In the regions of MMI = VII or less, the shaking damage state for a

buried gas or petroleum products transmission line is 1, and no

collocation damage is estimated except for unusual conditions to be

described below.

Following the pipelines from the center of the northern part of the

study area and heading south, the first location for significant

damage occurs at the crossing of the San Andreas fault. Here the

12 meter fault displacement is assumed to rupture the lines. The

location includes the 36-inch natural gas pipeline and the two

petroleum products pipelines (all of which rupture) and the

Victorville-Century 287.5 kV lines 1 and 2. The damage scenario

includes assuming that an explosion/fire occurs in addition to the

discharge of petroleum products. The need to mitigate the impact

of the fire and adverse environmental conditions and the delays

caused by the general congestion in the area results in an assumed

37 day delay before restoration work can begin. Because of the

high probability (100%) of the damage state, the incremental

increase in the lifeline restoration time is also 37 days.

At Blue Cut the natural gas pipeline is next to the railroad bed

and at the toe of a landslide area. High voltage power lines are

located above the gas line in the slide area. A damage state 4 is

predicted for the pipeline. The heavy equipment used to clear the

railroad bed is assumed to increase the damage state to level 5.

This increases the pipeline repair time by 18 days, and the debris

clean up adds another 20 day delay. The general congestion adds a

7 day delay. This results in a change in the most probable

restoration time of 12 days. Further south the pipeline follows

the railroad bed along the west edge of Cajon Creek. About 4 miles

further south, the pipeline and railroad are again at the toe of a

landslide region. In this case only the 18 day increase in repair

time and the 20 day debris removal delay are assumed. This results

in an 8 day increase in the probable restoration time for that

pipeline, for a total increase in time of 20 days.

Moving from the north to the south, the eastern most natural gas

79
pipeline first experiences a potential collocation damage condition

where it crosses I-15 in the region where the fiber optic conduits

cross under I-15 in a concrete culvert and the electric power lines

cross over the highway. This is a region of potential

liquefaction. The damage state is 7 but the probability of damage

is only 20% for the pipeline (but 40% for the lifelines that are

right in the local creek bed). The pipeline is somewhat removed

from the other lifelines, but there are railroad bridges also in

the general area. It is assumed that the other lifeline repairs

will be based on the requirement that long lengths of the natural

gas pipeline will need to be exposed and examined to assure that a

leak/explosion potential does not exist while they work on the

other lifelines. This leads to a 20 day delay in starting the

pipeline repair, resulting in a probable restoration delay of 8

days. About 3.2 miles further south the pipeline passes through

another landslide zone near where it crosses I-15, leading to a

probable increase in the restoration time of 16 days.

Across Cajon Creek from where the western pipeline was exposed to a

potential landslide, the eastern natural gas pipeline crosses

perpendicular to the two petroleum product pipelines and the fiber

optic cables. This is a potential liquefaction zone that results

in a pipeline damage state of 7 with a probability of 20%. There

is a 30 day delay while the petroleum product spill is cleaned up

and another 7 day delay for general congestion resolution

questions. This results in an incremental change in the probable

restoration time of 2 day.

Just south of the I-15/I-215 interchange the 16-inch natural gas

pipeline crosses a local liquefaction zone. It is collocated with

the two petroleum products pipelines, the railroads, and two of the

fiber optic cables. The liquefaction results in a damage state 7

with a probability of 40%. The collocation damage scenario assumes

a 30 day delay to clean up the petroleum product spills, and

another 20 days to account for the congestion and delays

experienced because of the repair to the nearby bridges. The net

increase in restoration time is 8 days.

The two petroleum products pipelines enter the study area from the

south in the Cajon Creek Wash. The 14-inch lines is collocated

along the railroad right-of-way, the 8-inch is on the western side

of the wash. Just south of the I-15/I-215 interchange, the 14-inch

pipeline enters a local liquefaction zone, along with the 16-inch

natural gas pipeline, the railroads, and two fiber optic cables.

Damage state 7 (40% probability) occurs in this region. There is a

20 day delay due to the general level of congestion, and because

the 14-inch pipeline is collocated with the railroad, there will be

a requirement to expose and inspect the pipeline before it can be

put back into service. This will add another 40 days of delay.

This results in a 10 day increase in the probable time to restore

service. About 6 miles further north, both pipelines enter another

liquefaction region, along with a 36-inch natural gas pipeline and

80
the collocated four fiber optic conduits. The low probability of

liquefaction (20%) and the delay due to congestion (7 days) results

in a 1 day increase in the probable restoration time. The

pipelines enter a third liquefaction zone near Blue Cut. There the

petroleum products pipelines cause delays in the repair of the

fiber optic cables. The fiber optic cables do not impact the

pipelines, and there is no collocation impact on the pipelines.

At the San Andreas Fault the pipelines are collocated with high

voltage power lines and a 36-inch natural gas pipeline. Because

the petroleum pipelines are located for several miles along the

fault rift zone, there will be a lengthy delay of several months

while the suitability of allowing them to relay the pipeline along

that route is resolved with the regulatory authorities. However,

that is not a collocation issue unless the pipelines are to be

rerouted near the existing natural gas pipeline. However the

damage scenario includes an explosion/fire, which will increase the

amount of pipeline that must be exposed and inspected. In

addition, the general congestion and environmental mitigation

activities will cause a 30 day delay, for a probable increase in

the pipeline restoration time due to collocation of 30 days. Thus,

the total increase in the probable time to restore service for

these pipelines is about 41 days, most of that impact is due to

conditions at the fault rift zone.

Ninety-three collocations involving fuel pipelines were analyzed

during this study. A summary of the collocation impacts is:

Increase in Probable Increase in Probable

Time to Restore Time to Restore

Lifeline Service, days Service. ,

Western Natural Gas 57 86

36-inch Pipeline

Eastern Natural Gas 25 83

36-inch Pipeline

Natural Gas 8 80

16-inch Pipeline

Petroleum Products 41 63

Pipelines

Transportation Lifelines

The Cajon Pass has been used for critical transportation routes

since early times. At present it is used by the Southern Pacific,

Santa Fe, and Union Pacific railroads, and Interstate Highway I-15.

In addition, there are connecting highways, including the I-215

spur into San Bernardino, State Route 138 coming from the west into

the Pass from Palmdale and continuing to the lake district in the

81
east, and a partially abandoned section of old Federal highway U.S.

66, now called the Cajon Blvd. extension. The routes of these

lifelines in Cajon Pass is shown in Figure 24. The location of the

photographs presented in this section of the report are also shown

on the figure.

Because these routes are discontinuous in the sense that each

bridge, each change in MMI intensity, and each local liquefaction

or landslide area must be separately checked. The railroads had to

be segmented into 30 separate analysis sections and the I-15

highway into 36 separate analysis sections. During the

vulnerability analysis of these facilities, it was necessary to

consider some extension outside the study area in order to provide

realistic estimates of time to restore service. In the case of the

Southern Pacific Railroad, for example, the route considered was

extended to the Highland Boulevard over-crossing in San Bernardino.

The assumptions with regard to equipment available to make repairs

differs from that used for the pipeline and communication lifelines

in that it is assumed that the railroads and highways both have

local active maintenance yards with their own heavy equipment for

construction activities. While some of this may be pressed into

service for life saving activities in the early emergency phase, it

is not likely that this will prevent immediate inspection and

reconnaissance. Therefore, no delay time waiting for equipment

availability was assumed.

Moving this equipment to the most critical sites along the

transportation lifeline, on the other hand, may present a

significant problem of access because the equipment must move along

the lifeline facility itself. In each analysis, it is first

assumed that the equipment must work from one end or the other of

the Cajon Pass, repairing each section as it goes before it can

reach the next section. The probable access time to a given

section is the sum of the products of times to repair all sections

up to that point multiplied by their respective probability of

damage. For the conditions existing in the Cajon Pass, this leads

to very long access times for those sections remote from the Pass

entrances. A second analysis was therefore made in which the

possibility of construction of temporary by-passes around damaged

sections to permit the access of construction equipment to more

critical sites was considered (this, of course, only applies to the

highway portions of the transportation lifelines). The access time

to a given site in that situation became the sum of the products of

the by-pass times and the probability that each of them is required

because of the damage-in the section being analyzed. Some of the

highway bridges on I-15 have built in by-pass capability, since

they are part of "diamond" interchanges in which the ramps may

serve this purpose. In the generally dry conditions of Cajon Pass,

it is possible in many cases to simply drive across country in

tracked vehicles and lightly loaded four wheel drive trucks. Some

road bed material would need to be placed to support heavy highway

construction equipment.

82
.- I

; 1. . I

Figure 24,

SCALE G 1 2 MU=

i * -mrs

EXPLANATION

, . 117 =

TRANSPORTATION LIFELINE ROUTES

'4 Larger Scale Figure

Located at

End ofDocument -~ I-Is 

-2 ramrod PATtI GIWAY 83

* r
The purpose

of these

as ,4 nA o I-.

access time

analyses was

to find the

critical

total time

for the

lifeline

section being

evaluated,

that is, the

time to gain

access to the

site with

repair

equipment

plus the time

to carry out

the needed

repairs. As

in the case Figure 25 I-15 Bridge Over The Railroads In Cajon Wash

and power

lines, each

lifeline was first divided into sections, such that the conditions

within each

section were

ra-m = r% n ;] l v I l. 

homogeneous.

Because of

the presence

of many

bridges on

the highways

and

railroads,

this leads to

more sections

for the

roughly 25

miles of

length of

each separate

transportation

system.

Prior to the

detailed

analysis of - I- - tne lifeline I

section being Figure 26 I-15 Bridge Over Cajon Wash

84
considered, the Bridge Vulnerability Index of each of these 

structures had to be determined, and the probable extent and type 

of damage to each postulated. 

The highway bridges along Interstate 1-15 were, for the most part, 

built in the late 1960fs, except for the section over Lytle Creek 

Wash. Although they are in an area generally considered to be 

IfCalifornia region 7", the status of retrofit is somewhat 

irregular. In this analysis, they are considered to be "California 

region 3-6" until proved to qualify for the higher degree of 

safety. Nevertheless, none of these bridges are expected to 

completely collapse, although partial collapse of several is 

possible. The 1-15 bridge over the railway lines (Figure 25) and 

the high level 1-15 bridge over Cajon Wash (Figure 26) are 

vulnerable, and there is some possibility of the partial collapse 

of the steel girders over 1-15 at its junction with highway 138 

(Figure 27). 

Many of the railroad bridges in the Cajon Pass are over 50 years 

old, but most are in relatively good condition. As noted in the 

discussion of the development of the Bridge Vulnerability Index, 

many of these bridges have inherent resistance to lateral loads. 

There are, however, several multiple simple span bridges over poor 

soil conditions (including possible liquefaction), such as both the 

Southern Pacific and Santa Fe bridges over the lower end of Cajon 

Wash (Figure 28). There are several more such crossings over the 

Cajon Creek and its branches. There is also a large two span, 

through 

plate, girder 

bridge on the 

Southern 

Pacific 

railroad over 

Highway 138 

which is 

sharply 

skewed, and 

which has 

bearings 

which are 

vulnerable to 

loss (Figure 

29). It is 

expected that 

the multiple 

span 

structures 

will have one 

or more spans 

dislodged 

where they 

are sub] ected Figure 27 Highway 138 Bridge Over 1-15 

85 
Figure 28 Railroad Bridges In Cajon Wash (-15 Bridge

In The Background)

Figure 29 Railroad Bridge Over Highway 138

(Collapse Expected)

86
to MMI= VIII 

shaking 

intensity 

zones or are 

on 

potentially 

liquefiable 

soils. The 

failure of 

the Bridge 

shown in 

Figure 29 was 

responsible 

for much of 

the access 

time estimate 

for repair of 

1-15, since 

it blocked 

Highway 138 

from being an 

immediate 

detour route 

for equipment 

needed for 

r 

the 1-15 repairs. 

Figure 30 Santa Fe Railroad Rubble Masonry Pier Bridge 

There is one 

bridge on the 

Santa Fe 

railroad just 

south of the 

1-15 truck 

weighing 

station which 

is founded on 

rubble 

masonry piers 

on sandy soil 

with a high 

water table 

(Figure 30). 

Loss of one 

or more spans 

is 

anticipated. 

That is 

contrasted to 

the Union 

Pacific 

railroad 

bridge at the 

r: 

I 

"igure 31 Union Pacific Railroad Bridge With Power 

Lines Overhead 

87 
same location (Figure 31) which has steel column, pile piers.

Figure 14 shows surface conditions near these two bridges.

The calculations for the vulnerability analysis and time to restore

service involve only simple arithmetic, but they are quite time

consuming if carried out manually. For this report, the analyses

were done on a computer spreadsheet, which greatly aided an orderly

and efficient approach.

The primary objective of the study was to determine how the times

to restore full service would be affected by the collocation of

several types of lifelines in the same congested corridor. The

interaction scenarios have been discussed in this report in earlier

sections. There are, however additional problems because of the

highway-railroad interactions. For the Cajon Pass application,

these interactions occur at the same general areas as the

previously identified critical clusters:

(1) The area near the liquefiable zone just south of the

highway I-15 crossing over the railroads and the Cajon Wash,

near the junction with I-215. This includes intersection

points 8, 9, 10, 11, 13, 14, 15, 16, 18, and 19. A partial

collapse of highway bridge No. 54-0818 over the three rail

lines adds to the problems at this location. A delay time of

30 days due to this bridge problem (Figure 25) was added to

the previously noted 30 day delay due to pipeline damage and

hazards.

(2) The section of the steep slide prone slopes along the west

side of Cajon Canyon (see Figure 17) and the liquefiable zone

on the east side about one mile north of the junction of I-15

an I-215. This includes intersections 22, 25, 26, 27, 28, 29, 30 on the east side and 31, 32, 33, 34, and 35 on the west

side of the canyon. The 30 day delay previously established

appears adequate.

(3) The conditions in Blue Cut are so congested, combined with

the expected explosion and/or fire, that an increase in the

expected damage states for the railroads by one level is

justified. Intersections 38, 39, 93, and 99 are involved. A

60 day delay in access is also assumed.

(4) At the San Andreas fault zone, intersections 37, 40, 41,

and 91 are involved. Problems with fuel pipelines and power

lines have already been noted. The 30 day delay in initiating

repairs to other lifelines was applied to the railroads.

(5) The area just north of the section of Highway 138 and west

of Highway I-15. Problems with pipelines and power lines have

already been noted at intersection points 47, 48, 49, 51, 52,

and 53. There is also a possibility of partial collapse of

the Southern Pacific railroad bridge over Highway 138 (Figure

88
29). An additional delay time of 30 days was added for access

involving this bridge, over and above the 30 days to clear

fire hazards related to pipeline damage.

(6) There are several other minor critical areas:

(a) The area just west and south of the I-15 truck

weighing station. The crib retaining wall could slump

(see Figure 14). The principle effect is on Southern

Pacific railroad sections 15 (westbound) and 24

(eastbound). A 30 day delay was assumed.

(b) Highway Structures 0796, 0797 and 0827 which carry

1-15 over the rail lines at Alray and Gish at

intersections 55 and 57 (Figure 32). These structures

may only be lightly damaged, but a 10 day delay in

railroad access is assumed to permit time for inspection

and temporary shoring if required.

(c) The I-15 bridge 0664 (Figure 33) over the Southern

Pacific tracks north of the pass at intersection 83 is

expected to be lightly damaged, but 10 days delay is

allowed for inspection (also see Figure 15 which shows

details of this bridge).

The effect of these collocation delays on the restoration of the

transportation lifelines was evaluated by making a analysis with

collocation assumed. This is a "second pass" analysis with the

spreadsheet. A special problem developed in reassessment of the

alternate route by way of highway 138, in that access to the

connection point on the Santa Fe was blocked by the expected

partial bridge collapse on the Southern Pacific. For this reason

the delay time associated with this problem was added to the

previous estimated time to reach the connection point, that is 10

days plus 60 days delay time. This gives 70 days. The cumulative

access times for this route were then computed as before, working

both ways from this point.

A summary of the results of the study are presented below.

Increase in Probable Increase in Probable

Time to Restore Time to Restore

Lifeline Service, days Service, %

Highway I-15 35 22

Southern Pacific 17 8

Railroad

Atcheson Topeka & 85 33

Santa Fe Railroad

89
The smaller

percent

increase inI

time to l

restore l

c~ n^f or ; rnF :>ej v. VWU LvL

the Southern

Pacific

railroad

compared to

the other

transportation

lifelines.

is due in

part to its

more

favorable

location with

respect to

other

lifelines;

but it should

also be noted Figure 32 Typical I-15 Box Bridge Over the Railroads

probable

partial collapse of one the bridges on this line contributes to

large access

4 4 ma --- , ; o L L But: L t: L^ :

for the

others.

90

Figure 33 I-15 & Access Road Bridges Over the Southern

Pacific Railroad
5.3 Chapter 5.0 Bibliography

1. P. Lowe, C. Scheffey, and P. Lam, "Inventory of Lifelines in

the Cajon Pass, California", ITI FEMA CP 120190, August 1991.

2. R. Greensfelder, "Maximum Credible Rock Acceleration From

Earthquakes in California", California Division of Mines and

Geology Map Sheet 23, 1974.

3. T. Hanks, "

t The National Earthquake Hazards Reduction Program -

Scientific Status", U.S. Geological Survey Bulletin 1652,

1985.

4. J. Evernden, et. al., "Interpretation of Seismic Intensity

Data", Bulletin of the Seismological Society of America, V.

63, 1973.

5. J. Evernden, et. al.., "Seismic Intensities of Earthquakes of

Conterminous United States - Their Predications and

Interpretations", U.S. Geological Survey Professional Paper

1223, 1981.

6. J. Davis, et. al., "Earthquake Planning Scenario for a

Magnitude 8.3 Earthquake on the San Andreas Fault in Southern

California", California Division of Mines and Geology, Special

Publication 60, 1982.

7. S. Algermissen, et. al., "Development of a Technique for the

Rapid Estimation of Earthquake Loses", U.S. Geological Survey

Open File Report 78-441, 1978.

8. E. Bertugno and T. Spittler, "Geologic Map of the San

Bernardino Quadrangle", California Division of Mines and

Geology Geologic Map Series, Map No. 3A (Geology), 1986.

6.0 FUTURE STUDY NEEDS

Recognizing that this is the first comprehensive analysis of the

impact of lifeline collocation on the individual lifeline's

vulnerability, it is recommended that the follow-on studies, be

performed.

1. The collocation analysis should be repeated at another

location outside of California. It will provide information

on the following items:

Is there enough data available to conduct the analysis,

or was the data base available in California unique?

Can the methods suggested by Rojahn to adjust the

California data to other regions be applied to develop

reasonable results?

91
The site can include water and sewer systems or

reservoirs to assure that the collocation analysis method

can properly treat the impacts of these lifelines, which

were not available at the Cajon Pass.

The study can check the suitability of the LSI-MMI

relationship developed for analyzing liquefaction-induced

damage, the Bridge Vulnerability Index method, and the

lifeline zones of influence, all of which were developed

with the Cajon Pass situation in mind.

If possible, the study site should include lifeline

passage over a large water body, or at least over wet

ground. This will help clarify the impacts of equipment

and material access time compared to lifeline repair

time, as the dry ground of the Cajon Pass did not impose

very restrictive "detour" conditions.

2. In parallel with the above study to further refine the

collocation analysis method, a second study is warranted. It

should focus on presenting the material to a broad audience.

Special emphasis should be given to contacting lifeline owners

and operators to discuss the study and the results obtained.

Their perspective and response should provide valuable

information on where improvements in the analysis method would

clarify important issues that relate to the siting of

lifelines in "lifeline corridors". It should also help identify mitigation approaches that reflect the operational

and economic needs of the lifeline providers.

3. A longer term study is needed to provide more detailed data

and expert opinion for lifelines. Most of the current data

emphasizes earthquake impacts on buildings and secondly on

bridges. Most of the present data (including most of the

lifeline data) in the data bases were obtained from the

building and bridge technical sectors. An new study to

examine the present data base presented in ATC-13, but with

full emphasis on lifelines, should be undertaken to allow the

lifeline portions of earthquake analysis to have the same

level of technical input that buildings and structures

presently have.

92
Appendix A

Modified Mercalli Intensity (MMI) Index Scale

93
Modified MercaWli (MM) Intensity Scale *

I. Not felt-or, except rarely under especially favorable Circumsean e.. UJnder

certain conditions, at and outside the boundary of the ares In which

a great shock is felt:

sometimes birds, animals, reported uneasy o, disturbed;

sometimes dizzines or nausea experienced;

sometimes trees1 structures, liquids, bodies of water, may sway--doors

mayo swing, very slowly.

II. Felt indoon by few, especially on upper foors, or by sensitive or nervous

persons.

Also, *s in grade I, but often more noticeably:

sometimes hanging objects may swing,' especially -ben delkcately

suspended;

sometimes trees, structures, lquids, bodies of water, may sway, 'doors

may swing, very slowly;

sometimes birds, animals, reported uneasy or disturbed;

sometimes dizziness or nausea experienced.

III. Felt indoors by several, motion usually rapid vibration.

Sometimes not recognized to be in earthquake at first.

Duration estimated in some cases.

Vibration like that due to pasing of light, or lightly loaded trucks, or

heavy trucks some distance away.

Hanging objects may swing slightly.

Movements may be appreciable on upper levels of tall structures.

Rocked standing motor car slightly.

rV. Felt indoors by many, outdoors by few.

Awakened few, expecillly light sleepers.

Frightened no one, unless apprehensive from previous experience.

Vibration like that due to passing of heavy, or teavily loaded trucks.

Sensation like heavy body striking building, or falling of heavy objects

inside.

Rattling of dishes) windowg, doors; glassware and crockery clink and

clash.

Creaking of walsa frame, especially in the upper range of this grade.

Hanging objects swung, in numerous inttances.

Disturbed liquids in open vessels slightly.

Rocked standing motor cars noticeably.

V. Felt indoors by practically al, outdoors by many or most: outdoors

direction estimated.

Awakened many, or most.

Frightened few-slight excitement, a few ran outdoors.

Buildings trembled throughout.

Broke dishes, glassware, o some extent.

Cracked windows-in some cases, but not Kenerally.

Overturned vases, small or unstable objects, in many Instances, wiLt

ocecaional fall.

Hanging objects, doors, swing generally or considerably.

Knocked pictures against wlls, or swung them out of place.

Opened, or closed, doors, shutters, abruptly.

Pendulum clocks stopped,. started, or ran fast, or slow.

Moved small objects, furnishings, the latter to slight extenLt

Spilled liquids in small amounta from well-filled open containers.

Trees, bushes, shaken slightly.

"Adapted from Sieber3g's (1923) Mercalli-Cancani scale, modified and condensed. Quoted

from Wood and Neumann (1931).
Vl. Felt by all, indoors and outdoors.'

Frightened many, excitement general, orne alarm, many ran outdoors.

Awakened &l.

Persona made to move unsteadily.

Trees, bushes, shaken slightly to moderately.

Liquid set In strong motloo.

Small bells rang-church, chapel, school, etc.

Damage slight in poorly built buildings.

Fall of planter in small amount.

Cracked plaster somewhat, especially fine cracks chimneys In some

instances.

Broke dishes, glasaware, In considerable quantity, also some windows.

Fail of knick-knacks, books, pictures.

Overturned furniture in many instances.

Moved furnishings of moderately beavy kind.

Vll. Frightened all-general alarm, all ran outdoors.

Some, or many, found it difficult to stand.

Noticed by persons driving motor cars.

Trees aod bushes shaken moderaLely to strongly.

Waves on ponds, lakes, and running water.

Water turbid from mud stirred up.

Incaving to some extent of sand or gravel stream banks.

Rang large church bellt, etc.

Suspended objects made to quiver.

Damage negligible in buildings of good design and construction, slight

to moderate in well-built ordinary buildings, considerable in poorly

built or badly designed buildings, adobe houses, old walls (especially

where laid up without mortar), spires, etc.

Cracked chimneys to considerable extent, walls to some extent.

Fall of plaster in considerable to large amount, also some stucco.

Broke numerous 'windows, furniture to some extent.

Shook down loosened brickwork and tiles.

Broke weak chimneys at the roofline (sometimes damaging roofs).

Fall of cornices from tower and high buildings.

Dislodged bricks and atones.

Overturned heavy furniture, with damage from breaking.

Damage considerable to concrete irrigation ditches.

Vill. Fright general-alrm approaches panic.

Disturbed persons driving motor ears.

Trees shaken strongly-brancbes, trunks, broken off, especially palm

trees.

Ejected sand and mud In small amounts.

Changes: temporary, permanent; in flow of springs and wells; dry wells

renewed flow; in temperature of spring and well waters.

Damage alight in structures (brick) built especially to withstand

earthquakes.

Considerable In ordinary substantial buildings, partial collapse: racked,

tumbled down, wooden bouses in some cases; threw out panel walls in

frame structures, broke off decayed piling.

Fall of walls.

Cracked, broke, solid stone walls seriously.

Wet ground to some extent, also ground on steep slopes.

Twisting, fall, of chimneys, columns, monuments, also factory stacks,

towers.

Moved conspicuously, overturned, very heavy furniture.
IX. Panic general.

Craciked ground conspicuously.

Damage considerable in Cmasonry) structures built specially to withstand earthquakes:

threw out of plumb some wood-frame houses built especially to withstand earthquakes;

peat in substantial rmaaonry) buildings, some collapse in large part;

or wholly shifted frame buildings off foundations, racked frames;

serious to reservoirs; underground pipes sometimes broken.

X. Cracked ground, especially when loose and wet, up to widths of several

inches; fisures up to a yard in width ran parallel to canal and stream

banks.

LaLndslides considerable from river banGi and steep coasts.

Shifted sand and mud horizontally on beaches and flat land.

Changed level of water in wells.

Threw water on banks of canals, lakes1 rivers, etc.

Damage serious to dams, dikes, embankmenta

Damage severe to well-built wooden strictures and bridges, some destroyed.

Developed dangerous cracks in excellent brick wails.

Destroyed most maonry and frame structures, also their foundations.

Bent railroad rails slightly.

Tore apart, or crushed endwise, pipe lines buried in earth.

Open cracks and broad wavy folds in cement pavements and asphalt

road surfsoes.

XI. Disturbances In pround many and widespread, varying with ground

material

BEtoad fissures, earth alumpa,, and land slips in soft, wet ground.

Ejected water in large amount charged with sand and mud.

Caused sea-waves (tidal waves) of significant magnitude.

Damage severe to wood-frame structures, especially near shock centers.

Great to dams, dikes, embankments, often for ;ung distances.

Few, if any fmasonry),. structures remained standing.

Destroyed large well-built bridges by the wrecking or supporting piers,

or pillars.

Affected yielding wooden bridges less..

Bent railroad rails greatly, and thrust them endwise.

Put pipe lines burled in earth completely out of service.

XII. Damage total-practically all works of construction damaged greatly or

destroyed.

Disturbances in ground preat and varied, numerous shearing cracks.

Landslides, fai of rock of significant character, slumping of river banks,

etc., numerous and extensive.

Wrenched loose, tore off, large rock mases.

Fault slips in firm rock, with notable horizontal and vertical offset

displacements.

Water channels, surface and underground, disturbed and modified

greatly.

Dammed lakes, produced waterfalls, deflected riven, etc.

Waves seen on pround surfaces (actually seen, probably, in some cases).

Distorted Ulnes of sight and level.

Threw objects upward Into the air.
MODIFIZO MIRCALLI INTIN81TY SCALZ OF IS)

(Abrdgsd)

1. Not felt except by a very few under especially favorable oircumstances.

I. Felt only by a few persons at rest, especially on upper floors of buildings.

Delicately suspended objects may swing.

II. Felt quite noticeably indoors, especially on upper Boors of buildings, but

many people do not recognise it sa an earthquake. Standing motor can

may rock slightly. Vibration like passing of truck. Duration estimated.

TV. During the day felt Indoors by many, outdoors by few. At night some

awakened. Dishes, windows, doors disturbed; walls made cracking

sound. Sensation like heavy truck striking building. Standing motor

cars rocked noticeably.

V. Felt by nearly everyone; many awakened. Some disbes, windows, etc.,

broken; a few instances of cracked plaster; unstable objects overturned.

Disturbance of trees, poles and other tall objects sometimes noticed.

Pendulum clocks may stop.

VI. Felt by all; many frightened and run outdoors 8ome heavy furniture

moved; a fev instances of fallen plaster or damaged chimneys. Damage

oight.

VII. Everybody runs outdoors. Damage negligible in buildings of good design

and construction; slight to moderate In well-built ordinary structures;

considerable In poorly built or badly designed structures; oome chimneys

broken. Noticed by persons driving motor cas.

VIII. Damage slight in sp>eaally designed structures; considerable in ordinary

substantial buildings with partial collapse; great In poorly built structures. Panel walls thrown out of frame structures. Fall of chimneys,

factory stacks, columns, monuments, walls. Heavy furniture overturned.

Sand and mud elected in small amounts. Changes In well water. Disturbed persons driving motor cars.

IX. Damage considerable in specially designed structures; well designed frame

structures thrown out of plumb; great In substantial buildings, with

partial collapse. Buildings shifted off foundations. Ground cracked

conspicuously. Underground pipes broken.

X. Some well-built wooden structures destroyed; most masonry and frame

stnictures destroyed with foundations; ground badly cracked. Rails bent.

Landslides considerable from river banks and steep slopes. Shifted sand

and mud. Water splashed (slopped) over banks.

XI. Few, if any (masonry), structures remain standing. Bridges destroyed.

Broad fissures in ground. Underground pipe lines completely out of

service. Eartb slumps and land slips in soft ground. Rails bent greatly.

XII. Damage total. Waves seen on ground surfaces. Lines of sight and level

distorted. Objects thrown upward into the air.

*U.S. GOVESMEMI PRINfIl OFFICE: 2000-522-302/95081
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