July 29, 2020 

EMI Project No. 20-126 

HNTB Corporation 

200 E Sandpointe Avenue, Suite 200 

Santa Ana, CA 92707 

Attention: Mr. Yung-Nien Wang, PE 

Subject: Preliminary Geotechnical Report 

XpressWest Extension Project 

Rancho Cucamonga to Apple Valley, California 

Dear Mr. Wang: 

Attached is our Preliminary Geotechnical Report for the proposed XpressWest Extension Project. 

This report is prepared to support the preliminary 15% design phase of the project. 

The recommendations and conclusions provided in this report are based on available subsurface 

soil information. These conclusions and recommendations are considered preliminary and should 

be verified in the future by conducting additional site-specific geotechnical field investigations, 

laboratory testing, and engineering analyses. 

We appreciate the opportunity to provide geotechnical services for this project. If you have any 

questions, please do not hesitate to contact us. 

Sincerely, 

EARTH MECHANICS, INC. 

Alahesh A. Thurairajah, GE 3123

Senior Engineer

NO. GE 3123

EXP. 9-30-2021

Jody Castle, CEG 2592 

Senior Geologist 

Eric Brown, GE 2806

Principal Engineer 

Hubert Law, PE 2345 

Principal 12-31-2020 

17800 Newhope Street, Suite B, Fountain Valley, CA 92708 ⚫ Tel: (714) 751-3826 ⚫ Fax: (714) 751-3928 
i 

TABLE OF CONTENTS 

Section Page

1.0 PROJECT DESCRIPTION .............................................................................................. 1

2.0 SCOPE OF WORK............................................................................................................ 1

3.0 SITE GEOLOGY AND SUBSURFACE CONDITIONS............................................... 3

3.1 Regional Geology............................................................................................................. 3

3.1.1 Peninsular Ranges Geomorphic Province, Rancho Cucamonga Section, Sta.12929+00 to

Sta. 12100+00 .......................................................................................................................3

3.1.2 Transverse Ranges Geomorphic Province, Mountain and Cajon Pass Section, Sta. 

12100+00 to Sta. 11200+00 ..................................................................................................4

3.1.3 Mojave Desert Geomorphic Province, Apple Valley Section, Sta. 11200+00 to Sta. 

10037+00 ..............................................................................................................................5

4.0 PRELIMINARY SEISMIC INFORMATION AND RECOMMENDATIONS .......... 5

4.1 Faulting and Seismicity.................................................................................................... 5

4.2 Seismic Design............................................................................................................... 17

5.0 PRELIMINARY FOUNDATION RECOMMENDATIONS ...................................... 17

6.0 REFERENCES................................................................................................................. 20
ii 

TABLES 

Page

Table 1. Fault Data.......................................................................................................................... 6

Table 2. Project Seismic Design ................................................................................................... 17

FIGURES 

Page

Figure 1. Project Location............................................................................................................... 2

Figure 2. Peninsular Ranges Geomorphic Province Geologic Map ............................................... 8

Figure 3. Transverse Ranges Geomorphic Province Geologic Map, 1 of 3 ................................... 9

Figure 4. Transverse Ranges Geomorphic Province Geologic Map, 2 of 3 ................................. 10

Figure 5. Transverse Ranges Geomorphic Province Geologic Map, 3 of 3 ................................. 11

Figure 6. Mojave Desert Geomorphic Province Geologic Map ................................................... 12

Figure 7. Regional Fault Map ....................................................................................................... 13

Figure 8. Sierra Madre Fault Alquist Priolo Map ......................................................................... 14

Figure 9. San Jacinto Fault Alquist Priolo Map............................................................................ 15

Figure 10. San Andreas Fault Alquist Priolo Map........................................................................ 16

Figure 11. ARS Curves................................................................................................................. 19

APPENDIX 

Appendix A. As-Built LOTB Sheets 

Appendix B. Locations of Proposed Structures 
 

 

 

 

 

1 

1.0 PROJECT DESCRIPTION 

The XpressWest Extension is a Federally authorized high speed passenger railroad that proposes 

to connect Rancho Cucamonga and Apple Valley. The route will be a 50-mile track through the 

Cajon Pass into Rancho Cucamonga and an expansion of the planned XpressWest service from 

Apple Valley to Las Vegas. The proposed alignment will generally follow the existing Caltrans’ 

right of way through the Cajon Pass, along the Interstate 15 freeway and connect with the Rancho 

Cucamonga Metrolink station. The fully electric high-speed trains would make the trip along the 

I-15 corridor to Las Vegas at speeds in excess of 150 mph. 

The main proposed improvements of the project include construction of over 50 miles of single 

and double track that travels along the I-15 freeway and crosses existing bridges. The HSR track 

alignment will travel parallel to and within I-15 freeway corridor and adjacent to the bent supports 

of the existing bridges. Several existing structures will also be replaced as part of the overall 

project. The project location is presented in Figure 1. 

2.0 SCOPE OF WORK 

This Preliminary Geotechnical Report (PGR) has been prepared to provide preliminary 

geotechnical information for the XpressWest Extension alignment and to assist the structural 

designers in the preliminary phase of the XpressWest Extension project. The preliminary 

recommendations provided in this report are based on subsurface information contained on the asbuilt Log-of-Test-Borings (LOTB) sheets included in Appendix A. A site-specific geotechnical 

investigation will be performed for these bridges during the final design phase; therefore, the 

following preliminary recommendations require verification when additional site-specific 

information becomes available. 

The geotechnical scope of work included: (1) reviewing available geotechnical/geologic 

information including reports, published geologic maps, and seismic hazard reports, (2) reviewing 

as-built plans of nearby existing bridges, (3) reviewing preliminary structure exhibits prepared by 

the structural designers; and, (4) assessing the foundation types for the proposed bridge structures. 

The geotechnical and geologic references reviewed for this project are listed in the references 

section of this report. 
 

 

Earth Mechanics, Inc. 

Geotechnical and Earthquake Engineering 

XpressWest Extension 

Project No. 20-126 

Project Location 

Date: July 2020 Figure 1 
 

 

 

 

 

 

 

 

 

3 

3.0 SITE GEOLOGY AND SUBSURFACE CONDITIONS 

3.1 Regional Geology 

The XpressWest Extension track alignment extends across three distinct geomorphic provinces 

through highly varied, faulted, and complex geology. From the southern terminus in Rancho 

Cucamonga, the alignment begins in the northern portion of the Peninsular Ranges Province. Near 

the juncture of the Sierra Madre (Cucamonga segment) and San Jacinto (Lytle Creek segment) 

faults, the alignment crosses into the mountainous terrain of the Transverse Ranges Province, and 

traverses Cajon Canyon between the San Gabriel Mountains and San Bernardino Mountains. 

Within the Transverse Ranges, the alignment crosses the San Jacinto, San Andreas, and Cleghorn 

fault zones. Descending from Cajon Summit, the alignment then enters the Mojave Desert 

Province about 12 miles southwest of Victorville. The discussion of geologic conditions along 

alignment will be in three sections, subdivided generally by geomorphic province. Regional 

geologic maps are presented in Figures 2-6. 

3.1.1 Peninsular Ranges Geomorphic Province, Rancho Cucamonga Section, 

Sta.12929+00 to Sta. 12100+00 

From Rancho Cucamonga to Sierra Avenue, the alignment proceeds northwesterly across large 

alluvial fans emanating from the San Gabriel Mountains to the north. Topography is generally 

level, with a regional slope of about 2.5% down to the south. At the base of the mountains is the 

east-west trending Cucamonga segment of the Sierra Madre thrust fault. Headwaters of local 

creeks originate in the nearby San Gabriel Mountains and drainage is to the south. Most local 

creeks have been channelized for flood control and urban development. Creeks crossed by the 

alignment include the Day Canyon Channel and the East Etiwanda Creek. The Day Canyon 

Channel is located at Sta 12523+00 and, to the west of the I-15/I-210 interchange, near Sta. 

12364+00, the alignment crosses East Etiwanda Creek. A large flood control catch basin is located 

to the north of the alignment at the I-15/I-210 interchange for control of stormwater from winter 

rains. 

This portion of the alignment crosses Quaternary (less than 2.6 million years old) and Holocene 

(less than 11,000 years old) aged alluvial fan sediments consisting of unconsolidated to slightly 

consolidated, dense, sand and silty sand with granitic gravel, cobbles, and boulders. Overall, 

sediments generally become more coarse-grained with higher percentages of gravels, cobbles, and 

boulders to the northwest as the alignment comes closer to the base of the San Gabriel Mountains. 

Within the Peninsular Ranges geomorphic province, the alignment does not cross any faults. The 

alignment does come within 1000 feet of the Sierra Madre fault from approximately Sta. 12131+00 

to 12155+50 and at Sta.12102+00, the eastern terminus of the fault. The alignment is located south 

of the fault and oriented subparallel to the fault. 
 

 

 

 

 

 

 

 

4 

3.1.2 Transverse Ranges Geomorphic Province, Mountain and Cajon Pass Section, Sta. 

12100+00 to Sta. 11200+00 

The Transverse Ranges geomorphic province section is the most geologically complex portion of 

the proposed alignment. From Sierra Avenue to Oak Hill Road, the alignment passes through the 

mountainous Transverse Ranges geomorphic province, across the faulted boundary between the 

Pacific and North American tectonic plates, and over Cajon Pass before descending into the 

Mojave Desert. Elevations range between about 2000 feet at Lytle Creek to about 4200 feet at 

Cajon Pass. Within this section, the alignment crosses the San Bernardino segments of the San 

Jacinto and San Andreas fault zones. Together, the San Jacinto and San Andreas fault zones 

accommodate up to 80% of the slip rate between the North American and Pacific plates. 

Major drainages include the northwest trending Lytle and Cajon Creeks. The orientation of both 

creeks is controlled by the San Jacinto and San Andreas faults. Lytle Creek is crossed by the 

alignment approximately between Sta. 12073+00 to Sta.12053+00. Just south of the I-15/I-215 

interchange, Cajon Creek is crossed by the alignment approximately between Sta. 11915+00 to 

Sta. 11909+00. 

Due to extensive faulting, subsurface conditions are highly variable within this section and defy 

broad generalization. Geologic units include Quaternary alluvium, Cenozoic sandstone and 

conglomerates, Cenozoic and Cretaceous aged granitics, and Mesozoic aged metamorphic rocks. 

Bedrock may be locally shallow. 

The alignment crosses the San Jacinto, San Andreas, and Cleghorn faults within this section. The 

San Jacinto fault zone is a right-lateral Holocene-active fault with multiple strands and is zoned in 

accordance with the Alquist-Priolo Act. The fault is capable of producing a M7.7 earthquake. The 

width of the fault zone extends approximately 2.7 miles and includes the Lytle Creek, San Jacinto, 

and Glen Helen fault strands. The alignment crosses the fault at approximately Sta. 12109+80 

(Lytle Creek fault strand), Sta. 11992+50 (San Jacinto fault strand), and Sta. 11943+80 (Glen 

Helen fault strand). Bridges less than 1000 ft from fault crossings include Sierra Ave., Lytle Creek, 

Glen Helen Parkway, and Glen Helen Road. 

The San Andreas fault zone is a right-lateral Holocene-active fault and is zoned in accordance with 

the Alquist-Priolo Act. The fault is capable of producing a M7.9 earthquake. The alignment crosses 

a secondary strand of the fault (the Peters fault) at Kenwood Avenue at Sta. 11836+50 and the 

main fault at Oakie Flats at Sta. 11705+50. Bridges less than 1000 ft from fault crossings include 

Kenwood Avenue and Oakie Flats. Cleghorn Creek Bridge near Sta. 11652+00 is located within a 

mapped Alquist Priolo (AP) fault zone, but a previous Caltrans fault rupture evaluation found that 

the inferred fault strand is more than 15,000 years old and dismissed likelihood of surface rupture 

at the bridge. 

The Southern Cleghorn section of the Cleghorn fault is a left-lateral fault and is dated as late 

Quaternary (less than 130,000 years old) in age by the USGS, while the Caltrans fault database 

dates it as Holocene active. It is not an AP-zoned fault. While Meisling (1984), considered the 

Southern Cleghorn section to have features indicative of Holocene surface rupture, Bryant (1987) 

believed the Holocene-aged features to be due to landsliding, not tectonic forces. The fault is 

capable of producing a M6.7 earthquake. The fault crosses the alignment at an oblique angle near 
 

 

 

 

 

 

 

 

 

 

 

5 

Sta. 1158+00 and is less than 1000 ft from alignment from about Sta.11506+00 to 11585+00. 

Bridges less than 1000 ft from the fault crossing include Cleghorn Rd and Brush Creek. 

3.1.3 Mojave Desert Geomorphic Province, Apple Valley Section, Sta. 11200+00 to Sta. 

10037+00 

From Oak Hill Road to the XpressWest Extension terminus in Apple Valley, the alignment is 

within the Mojave Desert geomorphic province. The province is characterized by isolated 

mountain ranges, separated by expanses of desert plains, and broad playas. Most of the area is 

undeveloped, open desert terrain with extensive soil and rock exposures and sparse vegetation. 

Victorville is the only urban area in this section of the alignment. Elevations range from a high of 

about 4095 feet at Oak Hill Road to a low of about 2720 feet at the Mojave River. 

The alignment crosses the California Aqueduct, which conveys water from Northern and Central 

California to Southern California, near Sta. 10911+00. The major river drainage in this section is 

the Mojave River. The Mojave River originates in the eastern slopes of the San Bernardino 

Mountains and flows northeastward for approximately 100 miles, terminating at the dry Soda Lake 

near Baker, in eastern California. Except for during extreme floods, most of the river’s flow is 

underground with the surface channels remaining dry. The alignment crosses the river between 

about Sta. 10410+00 and Sta. 10404+00 

Most of the proposed alignment crosses alluviated areas underlain by Quaternary (less than 2.6 

million years old) sediments. The Quaternary deposits include unconsolidated Holocene (less than 

11,000 years old) sediments and generally more consolidated Pleistocene (11,000 to 2.6 million 

years old) alluvial fan and playa deposits. Shallow granitic bedrock, mostly quartz monzonite and 

granodiorite, may be present at Stoddard Wells Rd overcrossing and Bell Mountain Wash. 

4.0 PRELIMINARY SEISMIC INFORMATION AND RECOMMENDATIONS 

4.1 Faulting and Seismicity 

The project area is located in seismically active southern California and is subject to shaking from 

both local and distant earthquakes. The XpressWest Extension alignment spans across a region of 

complex active faulting. The project alignment is crossed by or comes within 1000 feet of four 

major faults: the Sierra Madre (Cucamonga section), the San Jacinto (San Bernardino Valley 

section which includes the Lytle Creek, San Jacinto, and Glen Helen fault strands), the San 

Andreas (San Bernardino section), and the Cleghorn (Southern Cleghorn section). In accordance 

with Caltrans Memo To Designers 20-10 (Caltrans, 2013), the track alignment does have structures 

which fall within an Alquist-Priolo Earthquakes Fault Zone or within 1,000 ft of an unzoned fault 

that is Holocene or younger in age; therefore, further fault studies will be necessary. 

Other major regional faults which do not cross the XpressWest Extension alignment include: the 

Red Hill-Etiwanda Ave, Fontana Seismic Trend, Waterman Canyon, Tunnel Ridge, Arraste 

Canyon Narrows, North Frontal Thrust, San Antonio, and Helendale-South Lockhart faults. 

Fault details are summarized in Table 1 and regional faults are shown in Figure 7 with details of 

Alquist-Priolo fault zones shown in Figures 8-10. 
 

 

6 

Table 1. Fault Data 

Fault Crosses Alignment, 

Approx. Sta. 

Nearest 

Structure(s) Dist., km Fault Type1 

Slip Rate, 

mm/yr 

Max Fault 

Surface 

Rupture 

Displacement

(ft) 

2

Avg Strike 

of Fault Dip 

Fault 

Length, 

km 

Fault 

Age3 Mag 

AP 

Fault 

Zone? 

Structure 

Outside AP 

Zone? 

Sierra Madre 

(Cucamonga 

Section) 

Does not cross Duncan Canyon 

Rd 0.5 R 1.0-5.0 - N78E 45 135 H 6.6 Yes Yes 

San Jacinto 

(San Bernardino 

Section) 

Crosses at: 

RL 16.1 23 N58W 65-90 244 H 7.7 Yes 

~Sta. 12091+50 Sierra Ave 0.2 No 

~Sta. 12109+80 Lytle Creek Br 0.3 Yes 

~Sta. 11992+50 Glen Helen Pkwy 0.3 Yes 

~Sta. 11943+80 Glen Helen Rd 0.2 Yes 

San Andreas 

(San Bernardino 

Mtns Section) 

Crosses at: 

RL 12.8 mm/yr 33 N79W V 1100 H 7.9 Yes No 

~Sta. 11836+50 Kenwood Ave 0, crosses 

structure 

~Sta. 11705+50 Oakie Flats 0, crosses 

structure 

~Sta. 11688+00 (Strand 

is >11k yr.) 

Cleghorn Creek 

Bridge 0.9 

Cleghorn 

(Cleghorn 

Southern 

Section) 

~Sta. 1158+00 

Cleghorn Rd 0.2 

LL 2.0-3.3 2.5 N82W 85 25 LQ/H 6.7 No Yes 

Brush Creek Br 0.2 

Helendale-South 

Lockhart 

834+50 (Crosses next 

segment of alignment.) Quarry Rd Br 7.4 RL 0.2-1.0 13 N39W North 35 H 7.4 Yes Yes 

Red Hill 

Etiwanda Ave Does not cross SR-210 2.8 LL N/A - N60E N50 15 H 6.2 Yes, NE portion Yes 

Fontana Seismic 

Trend Does not cross SR-210 5.1 LL N/A - N39E N80 9 H 6.5 No Yes 

Waterman 

Canyon Does not cross Cajon Wash/Cajon Blvd 4.1 R N/A - N95E N45 29 LQ 6.7 No N/A 
7

Fault Crosses Alignment, 

Approx. Sta. 

Nearest 

Structure(s) Dist., km Fault Type1 

Slip Rate, 

mm/yr 

Max Fault 

Surface 

Rupture 

Displacement2 

(ft) 

Avg Strike 

of Fault Dip 

Fault 

Length, 

km 

Fault 

Age3 Mag 

AP 

Fault 

Zone? 

Structure 

Outside AP 

Zone? 

Tunnel Ridge Does not cross Cajon 

Wash/Cajon Blvd 17.3 LL N/A - N45E V 18 LQ 6.4 No N/A 

North Frontal 

Thrust Does not cross La Mesa Nisqualli Rd 15 R 0.2-1.0 - N87W S30-35 67 H 7.2 Yes N/A 

Arraste Canyon 

Narrows Does not cross Bear Valley Rd 21.3 R N/A - N50E V 11 LQ 6.2 No N/A 

San Antonio Does not cross SR-138 16.5 RL N/A - N25E V 25 LQ 6.5 No N/A 

Notes: 

(1) RL=Right-lateral, LL=Left-lateral, R=Reverse 

(2) Based on relationship between surface fault displacement and moment magnitude for strike-slip faulting (Wells and Coppersmith, 1994) 

(3) H=Holocene, LQ=Late Quaternary 
Earth Mechanics, Inc. 

Geotechnical and Earthquake Engineering 

Duncan Canyon Road 

Map Source: Morton, D.M., and Miller, F.K., 2006, Geologic map of the San 

Bernardino and Santa Ana 30' x 60' quadrangles, California: U.S. Geological 

Survey, Open-File Report OF-2006-1217, scale 1:100,000. 

2 1 0 2 miles 

Qw Qw1 Qw2 Very young wash deposits 

Qf1 Very young alluvial fan 

deposits 

Qaf Artificial fill 

Qyf Qyf1 Qyf2 Qyf3 Qyf4 Qyf5 Young alluvial fan deposits 

Qya Young axial channel 

deposits 

Qls Landslide deposits 

Qdg Disturbed ground 

Tcd Conglomerate and 

sandstone 

Tgtp Granodiorite of Telegraph 

Peak 

Kmm Leucocratic muscovite 

monzogranite 

Pm Granulitic gneiss, mylonite, 

and cataclasite, retrograde 

Pgu Granulitic gneiss, mylonite, 

and cataclasite 

XpressWest Extension 

Project No. 20-126 Date: July 2020 

Peninsular Ranges Geomorphic 

Province Geologic Map 

Figure 2 
 

Project No. 

Lytle Creek Bridge 

Sierra Avenue 

Glen Helen 

Parkway 

Glen Helen 

Road 

Qw Qw1 Qw2 Very young wash deposits 

Qf Qf1 Very young alluvial fan deposits 

Qaf Artificial fill 

Qyf Qyf1 Qyf2 Qyf3 Qyf4 Qyf5 Young alluvial fan deposits 

Qya Young axial channel deposits 

Qls Landslide deposits 

Qdg Disturbed ground 

Tcd Conglomerate and sandstone 

Tgtp Granodiorite of Telegraph Peak 

Tdg Olivine diabase and gabbro 

Kmm Leucocratic muscovite monzogranite 

Kgc Mylonitized leucogranite 

Pm Granulitic gneiss, mylonite, and cataclasite, retrograde 

Pgu Granulitic gneiss, mylonite, and cataclasite 

Pzgs Metasedimentary schist and gneiss 

Map Source: 

Morton, D.M., and 

Miller, F.K., 2006, 

Geologic map of the 

San Bernardino and 

Santa Ana 30' x 60' 

quadrangles, 

California: U.S. 

Geological Survey, 

Open-File Report 

OF-2006-1217, 

scale 1:100,000. 

2 1 0 2 miles 

XpressWest Extension Transverse Ranges Geomorphic 

Geotechnical and Earthquake Engineering 

Earth Mechanics, Inc. Province Geologic Map, 1 of 3 

Project No. 20-126 Date: July 2020 Figure 3 
Earth Mechanics, Inc. 

Geotechnical and Earthquake Engineering 

Project No. 

Transverse Ranges Geomorphic 

Province Geologic Map, 2 of 3 

Date: July 2020 Figure 4 

Qw Qw1 Qw2 Very young wash deposits 

Qf Qf1 Very young alluvial fan deposits 

Qaf Artificial fill 

Qyf Qyf1 Qyf2 Qyf3 Qyf4 Qyf5 Young alluvial fan deposits 

Qya Young axial channel deposits 

Qyls Qols Qvols Landslide deposits 

QTfz Crushed rock in fault zones 

Tcv2 Tcv3 Tcv4 Tcv5 

Project No. 20-126 

Cajon Valley Formation 

2 1 0 2 miles

Kenwood Avenue 

Oakie Flats Road 

Tgtp Granodiorite of Telegraph Peak 

TKtp Pelona Schist and granodiorite of 

Telegraph Peak 

Kpa Pelona Schist, amphibolite grade 

unit— 

Kpg Pelona Schist, greenstone unit 

Kps Pelona Schist, muscovite schist 

unit 

Kcd Sedimentary rocks of 

MzPd Gneiss of Devil Canyon 

Mzsl Mixed granitic rocks of Silverwood 

Lake 

Map Source: Morton, D.M., and Miller, 

F.K., 2006, Geologic map of the San 

Bernardino and Santa Ana 30' x 60' 

quadrangles, California: U.S. Geological 

Survey, Open-File Report OF-2006-1217, 

scale 1:100,000. 

XpressWest Extension 
 

Earth Mechanics, Inc. 

Geotechnical and Earthquake Engineering 

Transverse Ranges Geomorphic 

Province Geologic Map, 3 of 3 

Project No. 20-126 Date: July 2020 Figure 5 

XpressWest Extension 

Map Source: Morton, D.M., and Miller, F.K., 2006, 

Geologic map of the San Bernardino and Santa Ana 

30' x 60' quadrangles, California: U.S. Geological 

Survey, Open-File Report OF-2006-1217, scale 

1:100,000. 

Qw Qw1 Qw2 Very young wash deposits 

Qyw Young wash deposits 

Qyf Qyf1 Qyf2 Qyf3 Qyf4 Qyf5 Young alluvial fan deposits 

Qyf Young alluvial fan deposits 

Qof Older alluvial fan deposits 

Qvof Very old alluvial fan deposits 

Qh Harold Formation 

Qsh Shoemaker gravel 

Tcr1 Tcr2 Tcr3 Tcr4 Tcr5 Crowder Formation 

Tcv2 Tcv3 Tcv4 Tcv5 Cajon Valley Formation 

2 1 0 2 miles

Cleghorn Canyon Road 

Kgdc Biotitie granodiorite, Cajon 

area 

Mzsl Mixed granitic rocks of 

Silverwood Lake 
 

Cleghorn Canyon Road 

Earth Mechanics, Inc. 

Geotechnical and Earthquake Engineering 

Mojave Desert Geomorphic 

Province Geologic Map 

Date: July 2020 Figure 6 

Qa Quaternary alluvium 

Qo Older alluvium 

Qw Quaternary wash deposits 

Project No. 20-126 

Kjqm Cretaceous or Jurassic quartz monzonite 

Mzv Mesozoic metavolcanics rocks 

ms Metasedimentary rocks 

Map Source: Bortugno, E.J., and Spittler, T.E., 1986, 

Geologic map of the San Bernardino quadrangle, 

California, 1:250,000: California Division of Mines 

and Geology, Regional Geologic Map 3A, scale 

1:250,000. 

2 4 miles 

1 

4 0 

XpressWest Extension 
 

 

5 

12 

3 

4 

6 1 

10 

2 11 

8 9 

7 

Fault 

No. Fault Name Max. Mag. 

1 Sierra Madre 6.6 

2 San Jacinto 7.0 

3 San Andreas 7.4 

4 Cleghorn 6.7 

5 Helendale-South

Lockhart 7.4 

6 Red Hill Etiwanda

Ave 6.2 

7 Fontana Seismic

Trend 6.5 

8 Waterman Canyon 6.7 

9 Tunnel Ridge 6.4 

10 North Frontal Thrust 7.2 

11 Arraste Canyon

Narrows 6.2 

12 San Antonio 6.5 

Earth Mechanics, Inc. XpressWest Extension 

Geotechnical and Earthquake Engineering 

Project No. 20-126 Date: July 2020 

Overview of Regional 

Quaternary Faults

Figure 7
 

 

Earth Mechanics, Inc. 

Geotechnical and Earthquake Engineering 

Project No. 20-126 

Sierra Madre Fault, 

Alquist-Priolo Map 

Date: July 2020 Figure 8 

Map Source: California Division of Mines and Geology, 1995, Special Studies Zones Map, Devore quadrangle, scale 1:24,000. 

https://gmw.conservation.ca.gov/SHP/EZRIM/Maps/DEVORE.PDF 

Duncan Canyon Road 

XpressWest Extension 
 

Sierra Avenue 

Lytle Creek Bridge 

Glen Helen Pkwy 

Glen Helen Road 

Map Source: California Division of Mines and Geology, 1995, Special Studies Zones Map, Devore quadrangle, scale 1:24,000. 

https://gmw.conservation.ca.gov/SHP/EZRIM/Maps/DEVORE.PDF 

XpressWest Extension San Jacinto Fault, Earth Mechanics, Inc. Alquist-Priolo Map 

Geotechnical and Earthquake Engineering 

Project No. 20-126 Date: July 2020 Figure 9 
 

 

Map Sources: California Division of Mines and Geology, 1995, Special Studies Zones Map, Devore quadrangle,

scale 1:24,000.

Kenwood Avenue 

Cleghorn Creek 

Oakie Flats 

 https://gmw.conservation.ca.gov/SHP/EZRIM/Maps/DEVORE.PDF 

California Division of Mines and Geology, 1974, Special Studies Zones Map, Cajon quadrangle, scale 1:24,000. 

https://gmw.conservation.ca.gov/SHP/EZRIM/Maps/CAJON.PDF 

XpressWest Extension San Andreas Fault, Earth Mechanics, Inc. Alquist-Priolo Map 

Geotechnical and Earthquake Engineering 

Project No. 20-126 Date: July 2020 Figure 10 
 

 

17 

4.2 Seismic Design 

The preliminary Acceleration Response Spectrum (ARS) curves were developed for three levels 

of Seismic Hazard Evaluation criteria as defined in Table 2. The ARS curves were developed 

using the USGS Unified Hazard Tool with the Dynamic: Conterminous U.S. 2014 (v4.2.0) 

edition. 

Table 2. Project Seismic Design 

Seismic Hazard Evaluation Level 

Return 

Period 

(years) 

Performance Level 

Lower Level Earthquake (LLE) 50 Rail Serviceability 

Functional Evaluation Earthquake 

(FEE) 225 Operational 

Safety Evaluation Earthquake 

(SEE) 975 Life Safety 

The preliminary ARS curves are presented in Figure 11 and were developed according to Caltrans 

ARS Online V3.0 (2019). The preliminary ARS curve, the design magnitude, and the preliminary 

PGA will be updated during the final design phase following the field investigation, based on a 

Vs30 measured with the P-S wave suspension logging or SPT correlations obtained from sitespecific soil borings. 

5.0 PRELIMINARY FOUNDATION RECOMMENDATIONS 

HNTB has currently proposed 52 structures for XpressWest Extension alignment. The proposed 

structures include: 

• 2 Trench (T): HSR will enter into trench when it goes under existing overcrossings.

• 12 Trench with Retaining Wall (T/RW): HSR accommodated by widening the I-15 with

Ground Anchor Wall in front of the existing bridge abutments.

• 3 Trench with Replacement Bridge (T/R): Replace the existing bridge to allow HSR under.

• 1 Siderunning Trench (T/SR): HSR goes under the existing railroad.

• 31 Underpass (UP): HSR goes over creek/river, local street, or railroad.

• 3 Viaduct (V): Viaduct lengths generally range between about 2900 and 9000 feet.

For the Underpass and Viaduct structures, based on the available subsurface information, the nearsurface site soils are not anticipated to have sufficient bearing resistance to support the proposed 

structure on spread footings and therefore deep foundations are recommended. The preliminary 
 

18 

recommendation is footing on piles for all abutments and bents. Of the deep foundation 

alternatives, site conditions may be conducive to driven or drilled piles. 

Pile driving conditions for each of these structures will be highly variable due to the different 

geologic conditions at each bridge site. Difficult pile driving conditions, including shallow 

bedrock, cementation, or the presence of significant oversized materials (thick gravel layers, 

cobbles, or boulders), may exist at some locations. 

Locations of proposed structures are shown in Appendix B. 
 

Earth Mechanics, Inc. 

Geotechnical and Earthquake Engineering 

Project No. 20-126 

ARS Curves 

Date: July 2020 

XpressWest Extension 

Figure 11
 

 

 

 

20 

6.0 REFERENCES 

American Association of State Highway and Transportation Officials (AASHTO), 2018, 

AASHTO LRFD Bridge Design Specification, 8th Edition, Washington, DC: AASHTO. 

Bortugno, E.J., and Spittler, T.E., 1986, Geologic map of the San Bernardino quadrangle, 

California, 1:250,000: California Division of Mines and Geology, Regional Geologic Map 

3A, scale 1:250,000. 

Burnett, J.L., and Hart, E.W., 1994, Holocene faulting on the Cucamonga, San Jacinto and related 

faults, San Bernardino County, California: California Division of Mines and Geology Fault 

Evaluation Report FER-240, 20 p., in Fault Evaluation Reports Prepared Under the 

Alquist-Priolo Earthquake Fault Zoning Act, Region 2 – Southern California: California 

Geological Survey CGS CD 2002-02 (2002). 

Bryant, W.A., compiler, 2017, Fault number 325, Arrastre Canyon Narrows fault, in Quaternary 

fault and fold database of the United States: U.S. Geological Survey website, 

https://earthquakes.usgs.gov/hazards/qfaults, accessed 06/24/2020 04:37 PM. 

Bryant, W.A., compiler, 2017, Fault number 327, Tunnel Ridge fault, in Quaternary fault and fold 

database of the United States: U.S. Geological Survey website, 

https://earthquakes.usgs.gov/hazards/qfaults, accessed 06/24/2020 03:49 PM. 

Bryant, W.A., compiler, 2017, Fault number 328, San Antonio fault, in Quaternary fault and fold 

database of the United States: U.S. Geological Survey website, 

https://earthquakes.usgs.gov/hazards/qfaults, accessed 06/24/2020 05:08 PM. 

Bryant, W.A., compiler, 2017, Fault number 332, Red Hill-Etiwanda Avenue fault, in Quaternary 

fault and fold database of the United States: U.S. Geological Survey website, 

https://earthquakes.usgs.gov/hazards/qfaults, accessed 06/24/2020 01:53 PM. 

Bryant, W.A., compiler, 2017, Fault number 334, Waterman Canyon fault zone, in Quaternary 

fault and fold database of the United States: U.S. Geological Survey website, 

https://earthquakes.usgs.gov/hazards/qfaults, accessed 06/23/2020 11:37 AM. 

Bryant, W.A., compiler, 2017, Fault number 515, unnamed fault near Fontana, in Quaternary fault 

and fold database of the United States: U.S. Geological Survey website, 

https://earthquakes.usgs.gov/hazards/qfaults, accessed 06/24/2020 02:54 PM. 

Bryant, W.A., compiler, 2003, Fault number 109a, North Frontal thrust system, Western section, 

in Quaternary fault and fold database of the United States: U.S. Geological Survey website, 

https://earthquakes.usgs.gov/hazards/qfaults, accessed 06/24/2020 04:14 PM. 

Bryant, W.A., compiler, 2003, Fault number 108a, Cleghorn fault zone, Southern Cleghorn 

section, in Quaternary fault and fold database of the United States: U.S. Geological Survey 

website, https://earthquakes.usgs.gov/hazards/qfaults, accessed 06/24/2020 12:19 PM. 
 

 

21 

Bryant, W.A., 1987, Cleghorn and related faults, San Bernardino County: California Division of 

Mines and Geology Fault Evaluation Report FER-187, microfiche copy in California 

Division of Mines and Geology Open-File Report 90-14, 9 p., scale 1:24,000. 

Bryant, W.A., 1986, Western North Frontal Fault Zone and related faults, San Bernardino County, 

California: California Division of Mines and Geology Fault Evaluation Report 186, in Fault 

Evaluation Reports Prepared Under the Alquist-Priolo Earthquake Fault Zoning Act, 

Region 2 – Southern California: California Geological Survey CGS CD 2002-02 (2002). 

Bryant, W.A., and Lundberg, M., compilers, 2002, Fault number 1i, San Andreas fault zone, San 

Bernardino Mountains section, in Quaternary fault and fold database of the United States: 

U.S. Geological Survey website, https://earthquakes.usgs.gov/hazards/qfaults, accessed 

06/23/2020 06:02 PM. 

California Department of Transportation (Caltrans), 2019a, ARS Online Web Tool V2.3.09, 

http://dap3.dot.ca.gov/ARS_Online/. 

____, 2019b, ARS Online Web Tool V3.0, http://dap3.dot.ca.gov/ARS_Online/. 

——, 2019c, California Amendments to AASHTO LRFD Bridge Design Specifications - Eighth 

Edition, January. 

——, 2019d, Caltrans Seismic Design Criteria, Version 2.0, April. 

____, 2018a, Corrosion Guidelines, Version 3.0: Division of Engineering Services, Materials 

Engineering and Testing Services, Corrosion Branch, March. 

____, 2018b, Foundation Reports for Bridges, August. 

____, 2018c, Standard Specifications. 

____, 2017, GeoDOG Digital Archive of Geotechnical Data, accessed July 13, 2020, 

https://geodog.dot.ca.gov/index.php . 

____, 2013a, Memo To Designers 20-10, January. 

____, 2013b, Memorandum “Seismic Design and Selection of Standard Retaining Walls”, June. 

____, 2012, Methodology for Developing Design Response Spectrum for Use in Seismic Design 

Recommendations, November. 

Crook, R., Jr., Allen, C.R., Kamb, B., Payne, C.M., and Proctor, R.J., 1987, Quaternary geology 

and seismic hazard of the Sierra Madre and associated faults, western San Gabriel 

Mountains, in Recent reverse faulting in the Transverse Ranges, California: U.S. 

Geological Survey Professional Paper 1339, p. 27–63, scale 1:24,000. 
 

 

 

 

 

 

 

 

 

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Dibblee, T.W., Jr., 1975, Late Quaternary uplift of the San Bernardino Mountains on the San 

Andreas fault in southern California: California Division of Mines and Geology Special 

Report 118, p. 127-135. 

Jennings, C.W., 1994, Fault activity map of California and adjacent areas, with locations of recent 

volcanic eruptions: California Division of Mines and Geology Geologic Data Map 6, 92 

p., 2 pls., scale 1:750,000. 

Meisling, K.E., 1984, Neotectonics of the North Frontal fault system of the San Bernardino 

Mountains, southern California, Cajon Pass to Lucerne Valley: Pasadena, California 

Institute of Technology, unpublished Ph.D. dissertation, 394 p., 2 pls., scale 1:24,000. 

Meisling, K.E., and Weldon, R.J., 1989, Late Cenozoic tectonics of the northwestern San 

Bernardino Mountains, southern California: Geological Society of America Bulletin, v. 

101, p. 106-128. 

Mezger, L.L., and Weldon, R.J., 1983, Tectonic implications of the Quaternary history of lower 

Lytle Creek, southeast San Gabriel Mountains: Geological Society of America Abstracts 

with Programs, v. 15, no. 5, p. 418. 

Miller, F.K., and Matti, J.C., 2001, Geologic map of the San Bernardino North 7.5'' quadrangle, 

San Bernardino County, California: U.S. Geological Survey Open-File 01-131, 1:24,000. 

Morton, D.M., and Miller, F.K., 2003, Preliminary geologic map of the San Bernardino 30’ x 60’ 

quadrangle, California: U.S. Geological Survey Open-File Report 03-293, scale 1:100,000. 

Morton, D.M., and Yerkes, R.F., eds., 1987, Recent reverse faulting in the Transverse Ranges, 

California: U.S. Geological Survey Professional Paper 1339. 

Sanders, C., and Magistrale, H., 1997, Segmentation of the northern San Jacinto fault zone, 

southern California: Journal of Geophysical Research, v. 102, no. B12, p. 27,453-27,467. 

Sharp, R.V., 1967, San Jacinto fault zone in the Peninsular Ranges of southern California: 

Geological Society of America Bulletin, v. 78, p. 705–730. 

Sieh, K.E., and Matti, J.C., 1992, San Andreas fault system between Palm Springs and Palmdale, 

Southern California, in Sieh, K.E., and Matti, J.C., ed., Earthquake geology, San Andreas 

fault system, Palm Springs to Palmdale: Association of Engineering Geologists, 35th 

annual meeting, Southern California section, Guidebook, v. 35, p. 1-12. 

Treiman, J.A., compiler, 2000, Fault number 105h, Sierra Madre fault zone, Cucamonga section, 

in Quaternary fault and fold database of the United States: U.S. Geological Survey website, 

https://earthquakes.usgs.gov/hazards/qfaults, accessed 06/23/2020 02:48 PM 

Treiman, J.A., and Lundberg, M., compilers, 1999, Fault number 125a, San Jacinto fault, San 

Bernardino Valley section, in Quaternary fault and fold database of the United States: U.S. 

Geological Survey website, https://earthquakes.usgs.gov/hazards/qfaults, accessed 

06/23/2020 05:32 PM. 
 

23 

Wallace, R.E., 1990, General features, in Wallace, R.E., ed., The San Andreas fault system: U.S. 

Geological Survey Professional Paper 1515, p. 3-12. 

Weldon, R.J., II, and Sieh, K.E., 1985, Holocene rate of slip and tentative recurrence interval for 

large earthquakes on the San Andreas fault, Cajon Pass, southern California: Geological 

Society of America Bulletin, v. 96, no. 6, p. 793-812. 

Wells. D.L., and Coppersmith. K.J., 1994, “New empirical relationships among magnitude, rupture 

length, rupture width, and surface displacements”, Bulletin of the Seismological Society of 

America, v. 84. p. 974-1002.