i 

FEDERAL EMERGENCY MANAGEAMENT AGENCY FEMA - 221 October 1991 

Collocation Impacts 

on the 

Vulnerability of Lifelines During 

Earthquakes with Applications 

to the 

Cajon Pass, California 

Study Overview 

Published in Support of the 

Decade for Natural Disaster Reduction 

Earthquake Hazard Reduction Series 59 

I. 

I 
COLLOCATION IMPACTS ON LIFELINE EARTHQUAKE VULNERABILITY


Figure 1: General Location of the Cajon Pass, California ...... 3


Figure 2: Identification of Lifeline Collocations at


Figure 3

Figure 4

Figure 5

Figure 6: Power Line, Natural Gas and Petroleum Products


Figure 7: Power Lines at a Ravine Edge at the San Andreas


Figure 8

Figure 9

AT THE CAJON PASS, CALIFORNIA


STUDY OVERVIEW


TABLE OF CONTENTS ­


ITEM PAGE


EXECUTIVE SUMMARY .................... 1.........
 1


ADDITIONAL CONCLUSIONS ......................... 2


STUDY RESULTS .................................. 5


The Screening Tool .. 5


Cajon Pass, California . . 6


Communication Lifelines . ...... 7


Electric Power Lifelines . . 10


Fuel Pipeline Lifelines ................... 13


Transportation Lifelines ................... 17


List of Figures


Cajon Pass ..........................................
 4


: Fiber Optic Conduits Hung Under a Water 

Distribution Pipe On a Bridge Over a Railroad ...... 8


: Fiber Optic Conduits on a Bridge On An Abandoned


Portion of Highway 66 . ................................ 9


: Details of Fiber Optic Conduit Supports on a Highway 

Culvert Wall .................. 9


Pipelines Over the San Andreas Fault ......... 11


Fault ............................................... 12


: Electric Power Towers in a Landslide Scar (Directly


Above a Fuel Pipeline and a Railroad) ............... 12


: Two Natural Gas Pipelines, One Exposed One Buried,


Next to Highway 138 ................................... 14


Figure 1O:A Railroad Bridge Estimated to -Collapse Onto 

Highway 138 ........................................... 18


Figure ll:Railroad and I-15 Bridges in Cajon Wash Subject


to Liquefaction Damage ........................... 19


i 
COLLOCATION IMPACTS ON LIFELINE EARTHQUAKE VULNERABILITY


AT THE CAJON PASS, CALIFORNIA


STUDY OVERVIEW


EXECUTIVE SUMMARY


Lifelines are those systems and facilities that deliver vital 

services and products to a community. These include transportation


facilities; electric power systems; fuel transmission pipelines and


facilities; communication facilities; and such health facilities as


drinking water and sewer systems. For a number of reasons,


lifelines frequently are collocated or routed in close proximity to 

each other. The current emphasis on the use of "utility corridors,"


has increased the likelihood of lifeline collocation.


Under at-risk conditions1 such as natural events like earthquakes


or large storms or man-made disasters like train derailments or


explosions, failures on one lifeline can increase the risks of


subsequent damage on a collocated or nearby second lifeline. A


1989 train derailment just south of the Cajon Pass! California,


damaged a collocated gasoline transmission pipeline. The


subsequent explosion and fire destroyed a number of homes and


resulted in several fatalities.


In response to these and similar accidents and disasters, the 

Federal Emergency Management Agency (FEMA) authorized this study of


lifeline systems at the Cajon Pass, California (see Figure 1 on


page 3), and how their collocation may influence each lifeline's


vulnerability to failure during an earthquake event. The study has


produced two important products:


1) the development of 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 critical locations and to provide an


estimate of the increased risk that results when collocated


facilities are subjected to an earthquake event; and


2) the analysis of the lifelines in Cajon Pass, California, to 

demonstrate how the screening tool can be used and to examine


specific conditions in the Pass.


Important conclusions developed during the study include:


o Lifeline collocation can produce both benefits and increased


risk of failure during earthquake events. For example, 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, the


failure of one intersecting lifeline generally increases the 

risk of failure of the lifelinefs) it crosses. 

o Topographic conditions understandably have led to the routing 

I 
of lifeline systems that repeatedly cross over each other.


Additionally, Federal and State policies and requirements as


well as economic considerations were a significant contributor


to the decisions to collocate widely different lifelines in


very close proximity to each other.


o lifeline siting practices have not fully considered 

the serious impacts that one lifeline may have on


another lifeline;


o special design or routing considerations generally


are not required where the lifelines cross known


active faults; and


o although it was found that each lifeline owner has


prepared some type of study as to how they would


respond to a earthquake event that damaged their


lifeline system, the resulting analyses varied


significantly in their scope and detail. As a


result, lifelines at the same location are designed


and operated to significantly different standards


and accepted risk levels.


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-inducted lifeline failures. It will be of


value to lifeline owners, designers and providers, operators,


users, and regulators. An improvements in earthquake analysis


of lifeline systems are developed, they can be easily


introduced into the screening tool method.


o At the Cajon Pass over 100 separate collocations involving 

over 250 potential lifeline interactions were evaluated. The


collocations evaluated are identified in Figure 2. In most


cases there was a dominant lifeline failure that led to the


principal impacts on the other collocated lifelines.


ADDITIONAL CONCLUSIONS 

The development of the analysis methodology as well as its test


application to the Cajon Pass has highlighted several additional


important conclusions.


o Earthquake shaking is the dominant factor that leads to


building damage. Ground movement is more important for


lifeline components, especially buried lifelines and electric


transmission towers. There is considerable less available


data base on earthquake-induced ground movement compared to


shaking intensity data. This suggests that future studies


need to emphasize obtaining ground movement information.


2

Figure 1: General Location of the Cajon Pass, California


TOI JCL 

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=X~i5<^1=--- c _ 1 W- t 

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o The analysis tool has been successfully applied to the Cajon


Pass. It has. identified 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.


Fuel pipeline failures have the greatest impact on other 

lifelines during the immediate recovery period.


Current siting practices for fiber optic cables and 

increased reliance on these lifelines indicate that more


severe telephone communication failures (than have been 

experienced in past earthquakes) can be anticipated in 

future earthquakes. 

Lifeline siting practices have not fully considered the 

impacts that a new lifeline will have on existing 

lifelines and visa versa. 

Transportation service restoration is highly dependent on 

sequential repair since the lifeline itself often 

provides the access to the next damage site. Parallel 

repair operations are more probable for the other


lifeline systems. When multiple lifelines are


collocated, repair times increase because of local


congestion and the concern that work on one lifeline 

component could lead to damage on another lifeline component. 

3 
---- 

------ 

-- -

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OD 

3 * .3" t 

Figure 2: Identification of Lifeline Collocations at Cajon Pass 

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STUDY RESULTS 

The Screening Tool


The screening tool is described in detail in the project report


"Collocation Impacts on Lifeline Earthquake Vulnerability With


Application to the Cajon Pass, California", August 1991. That


report represents the first published work on how to systematically


examine collocation impacts on lifeline vulnerability because of


earthquakes. The specific details of the method are focused on


earthquake response analysis, but the sequence of analysis steps


could equally be applied to other regional natural disasters such


as floods or hurricanes. In those applications, of course, new


details on the response of individual lifeline components and


systems to the forces generated during the disaster event would


have to be identified and used..


In the case of earthquakes, the screening tool builds upon earlier


FEMA studies that used collective expert opinion and actual lessons


learned from specific earthquakes to identify the earthquake


loadings on individual lifelines and each lifeline's subsequent


damage state, the probability that the damage state occurred, and


the time required to repair the lifeline back to its needed


operational performance level. The analysis method emphasizes the


need to conduct detailed site reconnaissance surveys to guide the


selection of the specific earthquake/lifeline data from the FEMA-


sponsored previous. studies and from other local sources.


The screening tool introduces the concept of a "zone of influence!


within which one lifeline failure could impact the performance of a


second lifeline, and the "most probable restoration time". The 

latter relates the probability of actual damage occurrence with the


sum of: the estimated time to obtain the equipment and material


needed to repair a lifeline failure, the estimated time for the


equipment and repair personnel to reach the damaged section of the


lifeline, and the estimated time to repair the damaged section once


the equipment and personnel have been assembled at the damage


location. Once the critical collocations have been identified by


the screening process, their total impact (which has been defined


as the most probable restoration time) can be used to characterize


the impact of lifeline collocation during the analyzed earthquake


event. However, in many cases it would also be appropriate for


subsequent, more detailed analyses of those collocation conditions


to be performed to reduce the level of uncertainty and to identify 

specific, appropriate mitigation approaches that could be applied


to each lifeline. This could involve conducting field examinations


such as developing soil borings, and conducting detailed stress and


equipment response analyses to further define the lifeline damage


state. 

The 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


5

- facilities. As improvements are made in the fundamental 

analysis methods for individual lifelines or earthquake


conditions, they can be readily 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 FEMA, 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.


Cajon Pass, California


The Cajon Pass is a natural opening between the San Bernardino and


the San Gabriel mountain ranges. As such, it has been used for


years as a major lifeline route between the Los Angeles coastal


plain and the high desert regions. Included in the Pass are


interstate and state highways, railways, and their bridges; natural


gas and-petroleum products pipeline systems; hydroelectric power


generation, substations, and high voltage electric power


transmission lines; and radio towers, fiber optic, and telephone


tower systems. There are also a number of smaller, local, water


and sewer systems, low pressure natural gas distribution pipelines,


low voltage electric power distribution systems, and local wood


pole-mounted telephone systems.


Figure 2 is a composite plot of all of the lifelines studied at the


Cajon Pass. It shows that the lifelines are concentrated in a band


that roughly follows the valley floor of the Pass. However, the


close and crossing routings of the lifelines was not imposed by the


topology of the Pass, as it varies from about 0.5 miles wide at its


narrowest at Blue Cut to over several miles wide at the southern


and northern ends of the Pass. The dark circles indicate the 101


collocation locations studied. The figure shows that although


there are collocation sites all along the lifeline routes, they are


mostly bunched into six or seven groupings. When the estimated


earthquake impacts of landslide, ground liquefaction, and fault


surface displacement were considered, it was-found that the most


significant lifeline damage was concentrated at about six


locations.,


From the study the following general results were identified.


6

Although there are many collocations for each lifeline, the


controlling or major impact locations varied from one to eight,


depending on the lifeline. In most cases, there was *adominant


lifeline failure that led to the principal impacts on the other


collocated lifelines. Thus, all the lifelines do not have to have


postulated damage before a collocation effect can lead to problems.


Conversely, communication lifeline failures have no immediate


effect on the other collocated lifelines, although the collocation


itself was judged to be the cause of the communication lifeline


failure (for example, a fiber optic cable hung from a bridge as is


done in Cajon Pass will fail from shaking intensities that are not


strong enough to significantly damage the bridge).


Finally, some collocation may be a benefit since it provides for


system redundancy within the lifeline system. However, collocating


pipelines in the same trench or power transmission lines from the


same towers does not add redundancy, it lowers the separate system


reliabilities to the lowest value of the two lifeline (e.g., the


weakest link sets the overall reliability of both systems). In


general, intersecting different lifeline systems increase the most


probable restoration time to return service on each individual


lifeline system.


The additional minimum delay, due to collocation, before temporary


service can be restored through the Cajon Pass was, determined and


is given below. The additional time is the increase in time due to


collocation impacts compared to the estimated time to restore


service if the lifeline were assumed to be isolated from any


collocation impacts.


Minimum Additional Delay Before


Lifeline Temporary Service is Restored, days


Fiber Optic Telephone Communication 61 

High Voltage Electric Power Transmission 19 

Natural Gas Bulk Transmission 25 

Petroleum Products Transmission 41 

Interstate Highway Traffic 35 

Railroad Service 17 

Communication Lifelines 

Within Cajon Pass there are several communication transmission


towers: including radio, microwave, and cellular telephone towers.


Since they are isolated from the other lifelines, they have no


collocation impacts on the other lifelines. Also, there are wood


poll-mounted and hard-wired telephone systems that essentially


serve local customers within the Pass. They were not analyzed as 

this study examined the lifelines that serve regional customers. 

From the southern section of the study area north to just below 

Cajon Junction the old Highway 66 (now a county road called the 

Cajon Blvd. extension) runs west and parallel to the new I-15


alignment. The eastern side of this divided road has been


7

abandoned, 

and the 

western side 

has been 

converted to 

a two lane 

county road. 

Four fiber 

optic

conduits 

(each with a 

capacity to 

hold two or 

three fiber 

optic cables) 

and two 

petroleum

products

pipe 1 ines 

have been 

routed in the 

median strip 

between the Figure 3 Fiber Optic Conduits Fung Under a jac_er road beds. Distribution Pipe on a Bridge Over a Railroad The fiber 

optic conduit 

installation was completed in 1989. In the study area, they were 

buried next to the two petroleum products pipelines for much of 

their route. The mechanical trenching equipment used during their 

installation damaged the pipelines at several location, requiring 

local pipeline repairs. 

At the bridge locations along the Cajon Blvd. extension, the fiber 

optic conduits are brought to the surface and hung from the 

bridges, using light anchoring systems. The practice of hanging

the fiber optic cables from bridges and other lifeline structures 

is common throughout the Cajon Pass area, they are on bridges over 

railroads (see Figures 3 and 4) and on the bridges over the 

California Aqueduct. They are routed at the foot of a crib wall 

used to retain the 1-15 road bed, after which they are brought to 

the surface and hung from the wall of a concrete culvert that 

passes under 1-15. Figure 5 shows the details of the typical light 

wall anchors and supports that are used. 

The communication lifelines (the fiber optic cable systems) had no 

impact on increasing the probable time to restore service for any 

of the other lifelines. The fact that all four cable conduits are 

routed together for much of their routes through the Cajon Pass 

increases the potential that these valuable lifelines will be lost 

during an earthquake event. The practice of hanging the conduits 

from bridges and other lifeline structures using very light anchor 

supports increases the risk of failure of these communication 

lifelines at earthquake shaking intensities which would not impact 

them if they had been buried or supported by more robust anchors. 

8 
Prior


earthquakes


have shown


that the most


vulnerable


telephone


lifeline


component is


the switching


equipment.


The current


industry


emphasis to


shift from


hard-wired to


fiber optics,


coupled with


the co-


routing of


the fiber


optic cables,


is expected


to increase


probability Abandoned Portion of Highway 66


of telephone


line failures during earthquakes. The co-routing removes system


redundancy since an event that would cause the failure of one cable


will probably fail all of the cables. The fact that the fiber
 nti ' ables

transmit more


calls per cable


than do hard-


wired systems


means that the


impact of a


lost cable will


be more


significant


than the


impacts


previously


experienced 

when a hard-


wired line has


been lost.


Finally, the


construction


practices do


not appear to


have considered


earthquake


impacts,


. UL LL a Highway Culvert Wall 

9

increasing the risk to the fiber optic systems. However, since


these are not problems associated with collocation, they do not


necessarily impact the results of the present study. The fact that


a fiber optic cable fails on a bridge due to shaking failure of its


anchor system is not a collocation impact if the bridge itself does


not contribute to the failure.


Of the 55 fiber optic collocation conditions analyzed, nine were


estimated to lead to increased probable times to restore the fiber


optic systems to their intended service level. Most of the


significant time impacts occurred because of ground movements


(liquefaction and fault surface displacement) causing significant


damage to a collocated fuel pipeline. The earth movement was


hypothesized to fail the fiber optic cables, independently of the


other collocation lifelines. Thus, the collocation impact was not


a change in damage state, but an increase in both the probability 

of damage and the delay required to mitigate the hazardous


environmental conditions so that workers could repair the fiber


optic cables without undue risk to themselves. A special case was


where the fiber optic cables were buried at the foot of a crib wall


used to support the I-15 highway. Although the liquefaction


condition was not severe enough to cause the failure of the


highway, because the fiber optic cables are routed at the toe of


the crib wall, any soil movement could damage them. Thus, the


damage at the road was slight, but the delays in being allowed to


retrench the cables was found to be significant.


As previously stated, the overall estimate of the impact of


collocation was defined as the most probable restoration time,


which was the time to restore service compared to the time to


restore service if no collocations impacts were considered. For


the fiber optic cables this calculated to be:


Increase in Probable Time Increase in Probable Time 

Lifeline to Restore Service, days to Restore Service. % 

Fiber optic Cables 61 86 

Electric Power Lifelines 

The electric power lifelines in the Cajon Pass include eight


separate high voltage transmission lines (two public sector- and


six private sector-owned lines), a major power substation (the Lugo


substation located in the north east corner of the study area), and


a hydroelectric power generation station. However, only the


transmission lines are directly involved in collocation situations.


The two public sector-owned 287.5 kV transmission lines (City of


Los Angeles owned) were constructed in 1936. Combined, they


transmit about 600 MW of power. They are the western most


transmission lines in the study area and are isolated from other


lifelines through much of their route. They are routed basically


from north to south, and they deliver power generated at Hoover Dam


to Los Angles. Six private sector-owned high voltage transmission


10

lines (Southern


California


Edison Company
 nwnadl a.re also 

routed through


the study area.


Three 500 kV


lines (which


transmit


approximately


1,700 MW)


travel


southwest and


then south from


the Lugo


substation to


Mira-Loma


substation


(which is


located outside


of the study


area). Two of


h 1; - IX's 

kJ. Products Pipelines Over the San Andreas Fault
 and 2) were


installed in


the early 1960s and upgraded to 500 kV in the early 1970s. The


third line was added in 1983, and just south of the Lugo substation


it is collocated on the same transmission tower system as is line


#2. These three power lines and the two public sector-owned lines


account for all of the significant electric power collocation


impacts.


However, there are three additional privately owned high voltage


power lines in the study area. Although these three lines have a


number of intersections or collocations with other lifelines, the


predicted earthquake intensities and lifeline damage are small


enough that they have a minor collocation impact compared to the


five transmission lines discussed above.


Failure of other lifelines generally will have a small impact on


the electric power transmission lines since they are carried on


towers well above the other lifelines. However, if fuel pipeline


lifelines leak, the power transmission lines can provide an


ignition source, and the resulting fire could result in significant


damage to both the power lines and the other lifelines located in


the flame path. The other earthquake condition of importance


occurs when there is ground movement due to landslide,


liquefaction, or fault displacement. This could cause the tower


foundations to fail, dropping the transmission lines to a height


where they could have a direct interaction with the other


lifelines. With this in mind, the following describes where there


might be such potential interactions.


Figure 6 shows the location where the two separate electric power


11

I I - I I 1; 11 transmission lines are in - I-- , 

Z51FY-71MOMI 

close proximity to both a I n 

natural gas and the


petroleum products pipelines I

I 

in the vicinity of the San


Andreas fault zone.


i Although the surface


features look pastoral, the
 I f

fact that the lifelines are I .. 

i 

in the zone of the fault
 I -1

trace increases both their


risk and the potential


magnitude of the damage that


could be induced. Figure 7


is a photograph in the


opposite direction to the


one shown in Figure 6. It


shows an electric power


transmission tower located


at the edge of a steep


embankment, suggesting that


a foundation failure may


also be a contributing


factor to causing the power


lines to drop to a height


where they could readily


interact with spilled fuel. at the San Andreas Fault


South of the San 

?*rA.. uLrLAL= X furl1

LuLALl. 4 7StfLjf..JLX= 

there are two 

additional areas 

where the electric 

transmission lines 

pass through a region 

susceptible to 

landslides and where 

there are nearby 

railroad and buried 

natural gas pipeline 

lifelines. Figure 8 

shows two 

transmission towers 

that were rebuilt 

when the prior ones 

were damaged by a 

local landslide. Not 

shown at the bottom 

of the figure are a 

buried natural gas 

pipeline and a 

railroad. 

r ±LuLrie ZeLtr.LLal. .LUWers Un a L U±u.LU1 

The electric power Scilr (Directly Above 

rx - zzz ^ oad)

a Fuel Pipeline & a 

12

transmission towers are quite resistant to shaking intensity.


Although actual earthquakes have demonstrated that line vibration


can cause separate circuits on the same pole or support tower to


gallop and electrically short by either touching each other or by


arcing between adjacent lines, this failure mode has not been


characterized in the available data bases. Thus, only tower


failure by ground motions was considered in the present analysis.


Liquefaction and landslide conditions were identified as causing a


light, moderate, and heavy damage state, depending on the local


conditions; whereas, the surface displacement at the fault rift


zone causes a catastrophic damage.


The collocation impacts at the landslide locations included


increasing the damage state when there was a fuel pipeline present


as well as increasing the time delay to initiate repairs due to the


general congestion and the need to allow for debris removal from


collocated railroad beds or environmental cleanup to remove the


hazard from spilled fuels.


The overall estimate of the impact of collocation on the electric


power lifelines was: 

Increase in Probable Time Increase in Probable Time 

Lifeline to Restore Service, days to Restore Service, % 

Los Angeles City Lines 49 28 

So. California Edison 19 10 

Line 1 (Lugo-Mira Loma) 

So. California Edison 28 13 

Lines 2&3 (Lugo-Mira Loma) 

Fuel Pipeline Lifelines 

Within Cajon Pass there are two fuel pipeline transmissions


systems: natural gas and petroleum products lifelines.


Natural Gas Pipelines


From the north part of the study area traveling south, there are


two 36-inch natural gas pipelines. Sections of the pipeline were 

installed in 1960, 1966 and 1976. They are operated at 845-936 

pounds per square inch gage (psig). They presently supply about


600 million cubic feet of natural gas per day to the Los Angeles


Basin, although their combined capacity is up to about 1 billion 

cubic feet per day.


One pipeline is routed south along Baldy Mesa Rd. (two petroleum


products pipelines and two fiber optic conduits are also routed


along this road), and the other is routed southwest and south from


the eastern boundary of the study area. The two pipelines join at


a valve station located between the railroads and Highway 138,


north and east of Cajon Junction. From there one pipeline is


13

---- -- - - --- --

routed south on the west side of I-15. 
The other is routed south


but on the east side of I-15. The eastern most pipeline is buried


throughout its route, the western most pipeline has 18 exposed


locations with open spans ranging from 10 to 138 feet.


Figure 9 shows a section (north of Cajon Junction and next to


Highway 138) where the two pipelines are routed parallel to each


other. A 1990 realignment of Highway 138 (to remove curves) placed


the exposed section of the one pipeline about 40 feet from the road


bed. The gas line markers shown in the figure identify the route


of the buried pipeline.


From that location, the western most pipeline heads south and


crosses I-15. It continues south passing across Lone Pine Canyon


just north of Blue Cut. The San Andreas earthquake fault zone is


in that canyon, and the two petroleum products pipelines also are


routed parallel and in the fault zone. Thus, when the natural gas


pipeline crosses the petroleum products pipelines, it too is in the


fault zone. In addition, two high voltage power lines cross within


a few hundred feet from the pipeline intersections (see the


discussion for Figures 6 and 7 for additional details about this


collocation condition).


South from the San Andreas fault-pipeline-power line intersections,


the natural gas pipeline follows the route of the railroad (it is


located next to and frequently crosses beneath the track bed). At


Blue Cut the railroad and natural gas pipeline are at the foot of a


landslide prone region, and directly above them on the mountain


(and also in the landslide zone) are high voltage electric power


*VrAncmi C nil 

lines. A


similar


situation


exists about


2.5 miles


further south.


From the valve 

station north 

and east of 

Cajon Junction, 

the other 

natural gas 

pipeline is 

routed east of 

I-15 until 

about a mile 

north of the I15/I-215 

intersection, 

where it 

crosses under 

I-15 and it 

eventually -a On - 1Bried. - - - F Next to Highway 138 

- ' - -- ­ , -, 

14 
joins with the other natural gas pipeline. The mountains are steep


along the eastern side of I-15, and there has been a prior case


where a rain-induced landslide damaged the natural gas pipeline. 

After crossing under I-15, and about a mile north of the T-15/I-215


junction, the eastern pipeline crosses under the two petroleum 

products pipelines (which along with the fiber optic cable conduits.


are located in the median strip of Old Cajon Canyon Rd.). This is


a region of high water table subject to possible liquefaction


during an earthquake event.


After the two natural gas pipelines join together they are routed


under I-15 to a valve station and then south out of the study area. 

At the valve station a third 16-inch distribution pipeline leaves 

the valve station to provide gas to cities of Devore and San


Bernardino.


The buried natural gas pipelines are relatively insensitive to


earthquake shaking. The present study did not estimate the natural 

period of the 18 exposed sections of the western most 36-inch


pipeline, but it is possible that they could be impacted by shaking 

intensity if their resonant frequency is close to the earthquake


vibration frequencies. The principal cause of damage for the


pipeline was earth movement due to landslide, liquefaction, and


fault displacement. Since the movements result in catastrophic


failure of the pipe, the collocation impact does not increase the


damage state but it increases the time delays for beginning


restoration work. The dry climate of the study area means that the


unpaved roads provide sufficient access to the damage sites,


freeing these lifelines from dependance on the transportation


lifeline availabilities. Of the 61 collocation locations examined,


eight contributed to the estimated increase in probable restoration


time. 

There were two key collocation impacts at locations were ground


movement occurred. One was the spilling of petroleum products at


liquefaction areas. This was assumed to cause a delay in being


allowed access to the damage site while the environmental hazard


was removed. At the landslide locations it was assumed that the


debris on the railroad bed above the pipeline had to be removed and


then the pipeline exposed and inspected for damage. This was


required to lower the risk to workers that the construction


activities could *damagethe pipe, causing leaks would be too great


a risk to allow them to work with a pressurized pipeline directly 

below them. Conversely, if a leak had occurred during the


landslides then the collocated high voltage power lines directly


above could cause an explosion and fire, increasing the potential


damage level. Either case would lead to a delay in the restoration 

of service. 

The triple collocation of high voltage power lines, petroleum


pipelines, and natural gas pipeline at the San Andreas fault rift


zone caused the largest single delay due to the resulting fire, the


need to remove spilled fuel that failed to burn, and the general


level of confusion and construction expected at that location.


15

Petroleum Products Pipelines


There are two petroleum products pipelines in the Cajon Pass. An


8-inch line was installed in 1960, a 14-inch was installed in 1969­


1970, and a portion of the 8-inch line was rerouted in 1980 to


place it next to the 14-inch line. The two lines operate at 1060­


1690 psig and transfer about 80,000 barrels per day of product.


They are the primary fuel source for several military air stations


and provide the bulk of the gasoline used in the Las Vegas area.


The locations where they are routed in close, parallel trenches


reduces their overall reliability as a failure to one pipeline is


expected to lead to the subsequent failure of the other. A train


derailment in 1989 in San Bernardino led to a rupture of the 14­


inch pipeline and to subsequent fires and fatalities (this event


was specifically identified in the congressional authorization for


the present study).


The 14-inch pipeline enters the study area from the south along a


railroad right-of-way. It periodically crosses back and forth


under the track bed. As previously indicated, just south of the I-


15/I-215 intersection it passes through a potentially liquefiable


area along with the railroads, a natural gas pipeline, and most of


the fiber optic conduits. North of that junction it is joined by


the 8-inch petroleum products pipeline and the fiber optic conduits


and they all are routed along and within the median zone of the


abandoned Highway 66. 
 About a mile north of the I-15/I-215


intersection, the two petroleum products pipelines enter a


potentially liquefiable area. There they are crossed at right


angles by a 36-inch natural gas pipeline.


At Blue Cut the two petroleum products pipelines separate from the


fiber optic conduits, cross the Cajon Creek, continue northwest,


and then turn and run parallel to and within the San Andreas


earthquake fault zone (this is Lone Pine Canyon). As previously


discussed, they cross a 36-inch natural gas pipeline and are near


to two high voltage electric power transmission lines collocated in


this region.


The petroleum products pipelines are similar to the natural gas


pipelines in their response to the earthquake loadings. Thus, they


are insensitive to the shaking intensities experienced at the Cajon


Pass, but are sensitive to ground movement. Since the movements


anticipated generally lead to catastrophic failures, the


collocation impact is similar to natural gas pipeline case: 
an


increase in the time delays to initiate restoration work. Of the


32 collocation locations analyzed, eight contributed to the


collocation impacts.


In general, the petroleum products pipelines contributed more to


the delays in initiating repair for the other collocation lifelines


than did the other lifelines' impact the petroleum products


pipelines. This is because the spill of the petroleum products was


one of the more significant impacts. Liquefaction was the primary


cause of the ground displacements that impacted these lifelines,


16

but the probable increase in restoration time only ranged from two


to nine days. However, the impact at the San Andreas fault was


probably underestimated by the screening tool. There the increase


in probable restoration time was estimated at 30 days, but the fact


that the pipelines parallels several miles of the fault indicates


that there should be multiple pipe failures. There is a strong


possibility that the regulatory authorities would not allow the


pipeline to be rebuilt along the fault trace, thus the earthquake


could lead to the requirement to negotiate new rights-of-ways,


further increasing the estimated probable restoration of service


delay (but the increase would not be attributable to'collocation).


The overall estimate of the impact of collocation on the fuel


pipeline lifelines was: 

Increase in Probable Time Increase in Probable Time 

Lifeline to Restore Service, days to Restore Service. % 

So. California Gas 57 64 

Western 36-inch line 

So. California Gas 25 83 

Eastern 36-inch line 

So. California 'Gas 8 80 

16-inch distribution line 

CALNEV Petroleum Products 41 '63 

8- & 14-inch lines 

Transportation Lifelines


Highways


The Cajon Pass contains Interstate Highway I-15 and part of the I­


215 connector to San Bernardino. This highway system was


originally completed in the late 1960s. It presently carries about


60,000 vehicles per day, on weekends this traffic includes about


28% large trucks. The other major paved highway is the State


Highway 138, and the intersection of I-15 and Highway 138 forms


Cajon Junction. In addition to these paved roads, there are


numerous unpaved roads used for fire equipment access, for


maintenance routes for the other lifelines, and for general off-


road recreation. The dry climate of the region means that most of


the unpaved roads are fully accessible throughout the year.


The highway bridges and road beds, in general, are not subjected to


damage from other nearby lifelines. The exception is when a


railroad bridge crosses over a highway. At such locations, the 

failure of the bridge has a direct impact on the highway. Figure 

10 shows one such bridge. Because of its skew and simple supports,


the bridge was estimated to collapse onto Highway 138, effectively


removing that segment of the road as a bypass or detour route for


17

traffic past 

I-15's 

damaged 

sections. 

It is noted 

that the 

bridge span 

that crosses 

Highway 138 

is the right 

span in the 

Figure. 

Very close 

to this 

bridge was a 

highway 

bridge over 

the 

railroad. 

Even thniih 

it had the 

same amount 

of skew with Figure 10 A Railroad Bridge Estimated to Collapse 

respect to 

the road 

alignment, 

Onto Highway 138 (Highway 138 is located 

under the right span) 

its 

continuous column design is more robust and it was not estimated to


collapse onto the railroad. None of the highway bridges were


predicted to completely collapse, although partial collapse is


possible. Fortunately, the "diamond" interchange design used in


the Pass provides a direct detour route (although one with reduced


capacity compared to the I-15 road beds) past any partially damaged
 bridge.


Railroads


Three railroads (the Southern Pacific, the Union Pacific, and the


Atcheson Topeka and Santa Fe (Santa Fe)) generally run north-south


through the Pass. Most of the bridges are over 50 years old, and


the railroads were unable to provide descriptive material on their


design or their foundation conditions. The track bed receive


regular maintenance, and some realignment has been done to


eliminate the need for tunnels. About 75 trains per day travel


through the Pass.


The Union Pacific and the Santa Fe actually share track over part


of the Pass (sharing track is one of the positive aspects of their


collocation, it provides a redundancy for each of the railroads),


using one track for south bound traffic for both lines and the


other track for north bound traffic.


Buried next to and along side much of the rail track in the


southern half of the study area are either a 36-inch natural gas


is 
__ 

pipeline or a 14-inch petroleum products pipeline (its principal


product is gasoline). At several locations the rail bed (along


with the buried pipeline) are located at the foot of potential


landslide regions, and on the hillside above the railroad and


within the landslide zone are high voltage electric power


transmission lines. In the northern part of the study area there


are a number of small railroad bridges, often with a fiber optic


conduit or a natural gas or petroleum products pipeline routed


under the rail bed next to the bridge.


The bridges (see Figure 11) over the Cajon Wash (in the southern


part of the study area) are in a localized region of high ground


water tables, thus the ground could be subjected to liquefaction


during an earthquake event. Also in this general area are buried


36-inch and a 16-inch natural gas pipelines, a 14-inch petroleum


products pipeline, and fiber optic cable conduits.


The application of the screening tool to the highways and railroads


identified that failures of collocated lifelines, other than


transportation lifeline components, do not increase the damage


level in nearby transportation lifelines. That is, the failure of


a fuel pipeline or an electric power transmission line is not


expected to increase the damage level sustained by the highways,


railroads, or their bridges. Fuel spills can, however, increase


the time delay before work on the transportation system can be


initiated. That is because there is a delay time required to clean


up the fuel so that repair workers on the transportation lifeline


are not put at risk due to the potential fire hazard from the


spilled fuel. Similarly, in cases where high voltage electric 

power

+tVrsMVi Qci? 1 

lines sag or 

otherwise 

become close 

to the 

transportatio 

n lifeline 

component, 

the power 

line must be 

de-energized 

or 

permanently 

restored hfor hvv-. 

large 

equipment 

needed for 

the 

transportatio 

n lifeline 

repair can be .. _A mi.,; c uZ=U. LJLJL.LX 

too can delay Figure 11 Railroad and I-15 Bridges in Cajon Wash Subiect to Liquefaction Damaqe -

19 
the start of repair work on the transportation lifelines.


The collocation of the transportation lifelines is both a benefit


and a problem. Nearby roads or railroads can provide the access or


detour route for the large equipment needed to repair a damaged


bridge or road or rail bed. This redundancy is a benefit.


However, the collapse of a bridge over a highway or railroad is a


case of one transportation lifeline component interrupting the


ability of the collocated transportation lifeline from functioning.


This, in fact, was the major cause for the increase in the


calculated time to restore the I-15 highway to its needed service


level.


In the case of the railroads, two locations were the major


contributors to the increase in the time to restore service. One


location was at Blue Cut where the railroad is collocated with a


buried natural gas pipeline (buried in the railroad right-of-way)


and two high voltage power transmission lines. The railroad and


pipeline are in the toe of a landslide zone and the power lines are


above and also in the slide zone. The major impact on the railroad


would occur if the pipeline had no noticeable ruptures. In that


case, the railroad repair would be delayed until the pipe could be


exposed and inspected to assure that it was not leaking gas.


Alternatively, the work on the railroad could continue and the gas


line should be shut down until the railroad work had been


completed. Then the gas line would be exposed, inspected, and


returned to service after it was confirmed that it was safe.


Just south of the intersection of I-15 and I-215 (see Figure 12),


the railroads are collocated with a natural gas pipeline, a


petroleum products pipeline, and fiber optic conduits. The area is


susceptible to liquefaction and the subsequent fuel pipeline


failures were estimated to add a thirty day delay while the hazards


from spilled fuel were mitigated (which was assumed to be necessary


before heavy equipment and work on the railroad bridges could


commence).


The overall estimate of the impact of collocation on the


transportation lifelines was:


Increase in Probable Time Increase in Probable Time 

Lifeline to Restore Service, days to Restore Service, % 

Highway I-15 35 22 

Southern Pacific 17 8 

Railroad 

Atcheson Topeka & 85 33 

Santa Fe Railroads 

20


*U.S. GOVERNMENT PRINTING OFFICE: 1998 -617-775/90560