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
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.
Table 14
LIFELINE ZONES OF PHYSICAL INFLUENCE
Liquid Fuel Pipeline 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.
Natural Gas Pipeline 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.
Fiber Optic Cables Zero feet (e.g., no physical impact 
on other lifelines).
Roadways 40 feet from the road edge; a 
possible ignition source for fuel
lifelines.
Railroads 40 feet from the track edge; a 
possible ignition source for fuel
lifelines.
Overhead Electrical A radius equal to the height of the 
Transmission Towers & tower for physical contact; 
Power Lines a possible source of ignition for
fuel lifelines.
Bridges For an area centered on the bridge, 
twice the length of the bridge and 40
feet-on either side of the bridge.
Dams., Reservoirs & The drainage path and inundation 
Canals, areas for the spilled water.
Water & Sewer Lines 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.
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
conditions, are P1 and P2, they represent an upper bound on the
For example, if probability that a collocation damage would occur. 
the probability that lifeline 1 would fail is PI, and it is, known
with a100% probability,
that if lifeline I fails it will cause, 
damage to lifeline 2, then the probability that lifeline 2 receives
(e.g., P1 x 100%). Similarly, the
collocation damage is also P1 
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
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, Inventory 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", 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.
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

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. "CALTRANS 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 study) 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
Figure 5, MAP OF THE GENERAL LOCATION.OF THE CAJON PASS STUDY AREA 
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
Figure 6, A COMPOSITE OF THE LIFELINE ROUTES AT CAJON PASS SCALE 
Larger Scale Figure
Located at 
EXPLANATION 
End of Document 
FLUME-PENSTOCK 50 
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.
Figure 7, IDENTIFICATION OF LIFELINE COLLOCATION AT CAJON PASS
SCALE
0 1 2 MIZS 
2 K2I WMKDITFUS j LargerScale Figure 
Located at 
EXPLANATION
End of Document 
1-15-INTERSTATE. 
2 PAVED HIGHWAY 
RAII.ROAD 
0 -P POWER UINS 
PETROLEUM PRODUCT PIPEUINES
I -NATURAL 
GAS PIPEUNES 
FIBER OPTIC CABLE 
If -v 
FLUME- 52
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
6K. That comparison showed
with those of previous researchers 5,
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
7)and the
regions. The historical landslides were identified 6.
method of Legg (see Section 4.2, Table 7) was applied. A computer-
based 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 I-
15/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
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
INTERSECTION 
NO. 
1 
2 
3 
4 
5 
71 
10 
23 
11 
12
10X 
13 
14 
16 
17 
is 
19 
24 
25 
26 
2 7 
28 
29 
Table 15 
MATRIX OF LIFELINE COLLOCATIONS AND INTERACTIONS 
HIGH-RAIL-POWER FIBER NATURAL PETRO 
WAYS ROADS LINES OPTIC GAS LINES 
A B C D E A B C A B C D E F A B C D A B C A B 
X x x 
X X 
X X X 
X X X 
X X XX X 
X X XX
X X X 
X
x X 
X 

X 
X X 
x 
X X X X X X X 
X X 
X X X 
X 
x xX 
=X-X l X = XX 
X X 
= : x I XXXXx 
X X XX XXX 
X X X X 
I XI X X X 
Table 15 (Continued) 
MATRIX OF LIFELINE COLLOCATIONS AND INTERACTIONS 
FIBER NATURAL PETRO
INTER-HIGH-RAIL-POWER 
OPTIC GAS LINES
SECTION WAYS ROADS LINES 
A B
NO. A B CD E A B C A B C D E F A B C D A B C 
30 X X
31 X X 
32 
xx xx x
33 X X 
34 X ,X 
35 
x x H 
XX*36 XX XX x 
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 
X45 X X 
46 X 
XXXX X
47 
I X X
48 X X X X
49i 
X X X .s5 
51 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 
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 xXX 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 
E l2 x x x xx 
84 .x x x x 
86 X XXX 
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 
8X X X XX 
89 HX XX X XX 
90 X X X 
NOT USEDX 
93 H 
NOT USED = X XXX 
96 
9397 _X 
X 
HX I 
XX 
X X XX 
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
The assumed
probabilities that the damage occurred of 40%. 
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
landslides (with a probability of occurrence of 45%) 
and 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.
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 1986, 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). Furthermore the 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
II COMMUNICATIONLIFELINEROUTS.
Figure 9 COMMUNICATION LIFELINE ROUTES 
SCALE 
Larger Scale Figure
Located at 
EXPLANATION 
End of Document 
Figure 10 Fiber Optic Conduits On A Bridge On The 
Abandoned Portion of Cajon Blvd. Extension 
Figure 11 Details of the Fiber Optic Conduits of Figure 10
Figure 12 Fiber Optic Conduits On A Concrete Culvert 
That Passes Under 1-15 
Figure 13 Wall Support Details For The Fiber Optic 
Conduits Of Figure 12 
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 
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 I-
15/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
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 
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 motion-
induced 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
Figure 16, Electric POWER LIFELINE ROUTES 
SCALE Larger Scale Figure
Located at
End of Document 
EXPLANATION 
 (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 Figure 17 A Landslide Scar With Power Towers In The 
data base and Slide Area 
thus was not 
considered in 
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). 
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 Figure 18 Power Lines, Natural Gas & Petroleum
landslide Products Pipelines Intersection Over the San Andreas 
failure. 
This general Fault Rift Zone 
location (in 
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. It was constructed in 1936 to transmit power 
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 
study. At a section between
Highway 138 and the Lone
Pine Canyon, the lines
experienced slow foundation
movement or shifting at a '7 k 
region were a local bowl or I I' 
depression exists. The V; , 
cause was determined to be a
high water table fed by
surface waters collected in
I s 
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 Figure 19 Power Tower At A Ravine Edge
that earthquake-induced
fires could have on this In The San Andreas Fault Rift Zone
lifeline system.
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
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-of-
way 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
Line 3 was added in
upgraded to 500 kV service in the early 1970s. 
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
and other equipment
because of the need to work with large cranes 
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
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 36inch 
natural gas pipeline that is itself next to and in the right-
of-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 southeast-
direction. 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
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: 
Increase in Probable Increase in Probable 
Time to Restore Time to Restore 
Lifeline Service. days Service. % 
Los Angeles Dept. 
of Water & Power 
49 28 
Southern California 19 10 
Edison Co. Line #1 
Southern California 28 13 
Edison Co. Line #2&3 
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 
Figure 20, FUEL PIPELINE LIFELINE ROUTES 
SCALE 
LargerScale 
figure
EXPLANATION Located at 
End of Document
1-15 INTIESAh 
a PAID SUBWAY 
-…-0-
0 -PZTUOLIM PRODUCT 76 
-0-NATURAL
DU PhP 
0 0 0ALM 
1 4 -F i 1 i ran f = a 
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
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 ?igure23 Natural Gas Pipeline 
refined products, the Crossing Under Railroad Beds 
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 
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
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
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.
Figure 24, TRANSPORTATION LIFELINE ROUTES 
SCALE 
4 Larger Scale Figure 
Located at
EXPLANATION 
End of Document 
2 ramrod 
The purpose 
of these as 
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
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 
the lifeline I
section being Figure 26 I-15 Bridge Over Cajon Wash
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 
If California 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 subjected Figure 27 Highway 138 Bridge Over 1-15 
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 Figure 30 Santa Fe Railroad Rubble Masonry Pier Bridge 
needed for 
the 1-15 repairs. 
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 I 
Pacific 
railroad 
bridge at the 
Figure 31 Union Pacific Railroad Bridge With Power 
Lines Overhead 
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
The smaller
percent
in increase 
time to l 
restore l 
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
for the
others.
Figure 33 I-15 & Access Road Bridges Over the Southern
Pacific Railroad
90


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?
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.

Appendix A Modified Mercalli Intensity (MMI) Index Scale 93 Modified Mercalli (MM) Intensity Scale I. Not felt-or, except rarely under especially favorable Circumstance e. Under certain conditions, at and outside the boundary of the area In which a great shock is felt: sometimes birds, animals, reported uneasy, disturbed; sometimes dizziness or nausea experienced; sometimes trees1 structures, liquids, bodies of water, may sway--doors mayo swing, very slowly.
II. Felt indoor by few, especially on upper floors, or by sensitive or nervous persons.
Also, s in grade I, but often more noticeably: sometimes hanging objects may swing,' especially been delicately suspended; sometimes trees, structures, liquids, 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 passing 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.
Felt indoors by many, outdoors by few.
Awakened few, especially light sleepers.
Frightened no one, unless apprehensive from previous experience.
Vibration like that due to passing of heavy, or heavily loaded trucks.
Sensation like heavy body striking building, or falling of heavy objects inside.
Rattling of dishes) windows, doors; glassware and crockery clink and clash.
Creaking of walls frame, especially in the upper range of this grade.
Hanging objects swung, in numerous instances.
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 Generally.
Overturned vases, small or unstable objects, in many Instances, with occasional fall.
Hanging objects, doors, swing generally or considerably.
Knocked pictures against walls, 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 extent Spilled liquids in small amount a from well-filled open containers.
Trees, bushes, shaken slightly.
"Adapted from Sieberg'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, some alarm, many ran outdoors.
Awakened &l.
Persona made to move unsteadily.
Trees, bushes, shaken slightly to moderately.
Liquid set In strong motion.
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, glassware, In considerable quantity, also some windows.
Fail of knick-knacks, books, pictures.
Overturned furniture in many instances.
Moved furnishings of moderately heavy kind.
. Frightened all-general alarm, all ran outdoors.
Some, or many, found it difficult to stand.
Noticed by persons driving motor cars.
Trees and bushes shaken moderately to strongly.
Waves on ponds, lakes, and running water.
Water turbid from mud stirred up.
In caving to some extent of sand or gravel stream banks.
Rang large church bells, 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.
Fright general-alarm approaches panic.
Disturbed persons driving motor ears.
Trees shaken strongly-branches, 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 houses 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.
Cracked ground conspicuously.
Damage considerable in Masonry) structures built specially to withstand earthquakes: threw out of plumb some wood-frame houses built especially to withstand earthquakes; peat in substantial masonry) 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; fissures up to a yard in width ran parallel to canal and stream banks.
Landslides considerable from river banks 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, lakes rivers, etc.
Damage serious to dams, dikes, embankment Damage severe to well-built wooden strictures and bridges, some destroyed.
Developed dangerous cracks in excellent brick wails.
Destroyed most masonry 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 surfaces.
XI. Disturbances In ground many and widespread, varying with ground material Broad fissures, earth slumps, 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 long distances.
Few, if any masonry), 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 great and varied, numerous shearing cracks.
Landslides, falls of rock of significant character, slumping of river banks, etc., numerous and extensive.
Wrenched loose, tore off, large rock masses.
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 rivers, etc.
Waves seen on ground surfaces (actually seen, probably, in some cases).
Distorted lines of sight and level.
Threw objects upward Into the air.
1. Not felt except by a very few under especially favorable circumstances.
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 recognize it 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 dishes, 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 few instances of fallen plaster or damaged chimneys. Damage slight.
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; some chimneys broken. Noticed by persons driving motor cars.
VIII. Damage slight in specially 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 strictures 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. Earth 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.
INTERSTATE PAVED HIGHWAY COLLOCATION LOCATION RAILROAD POWER LINES PETROLEUM PRODUCT PIPELINES NATURAL GAS PIPELINES FIBER OPTIC CABLE FLUME-PENSTOCK 117 31 30 25 117 22 FIGURE 9, COMMUNICATION LIFELINE ROUTES SCALE MILES 0 12 KILOMETERS EXPLANATION INTERSTATE PAVED Highway FIGURE 16, ELECTRIC POWER LIFELINE ROUTES SCALE I 2 MILES EXPLANATION 15 Interstate 12 PAVED HIGHWAY POWER LINES BURIED AQUEDUCT 117 317 117 31 117 22 FIGURE 20, FUEL PIPELINE LIFELINE ROUTES SCALE 0 I 2 MILES 0 1 2 KLOMETMES EXPLANATION 1-15 INTERSTATE 2 PAVED EIGHWAY PETROLEUM PRODUCT PIPEANES NATURAL GAS PIPEIUNES 0 VALVES 117 31 117 31 30 117 22 FIGURE 24. TRANSPORTATION LIFELINE ROUTES SCALE EXPLANATION 1-15 INTERSTATE 2 PAVED HIGHWAY RAILROAD