FLOODPLAINS TECHNICAL REPORT 

Brightline West Cajon Pass High-Speed Rail Project 

October 2022 

Prepared for 

Federal Railroad Administration 

Prepared by 

HNTB 
 

 

 

 

BRIGHTLINE WEST CAJON PASS HIGH-SPEED RAIL 

Contents 

Abbreviations and Acronyms..........................................................................................................iii 

1. Introduction .............................................................................................................................. 1 

2. Project Description ................................................................................................................... 2 

2.1. Background...................................................................................................................... 2 

2.2. Project Area..................................................................................................................... 2 

2.3. Purpose of and Need for the Project .............................................................................. 4 

2.3.1. Purpose ................................................................................................................... 4 

2.3.2. Need........................................................................................................................ 4 

2.4. Project Elements ............................................................................................................. 7 

2.4.1. Build Alternative ..................................................................................................... 7 

2.5. Construction .................................................................................................................. 11 

3. Methodology........................................................................................................................... 13 

3.1. Relevant Regulations, Plans, and Policies ..................................................................... 13 

3.2. Study Area ..................................................................................................................... 13 

3.3. Methods Used ............................................................................................................... 13 

4. Existing Conditions.................................................................................................................. 14 

5. Environmental Effects and Mitigation .................................................................................... 16 

5.1. Construction Effects ...................................................................................................... 16 

5.1.1. Railway .................................................................................................................. 16 

5.1.2. Hesperia Station.................................................................................................... 16 

5.1.3. Rancho Cucamonga Station .................................................................................. 17 

5.2. Operation Effects........................................................................................................... 17 

5.2.1. Railway .................................................................................................................. 17 

5.2.2. Hesperia Station.................................................................................................... 19 

5.2.3. Rancho Cucamonga Station .................................................................................. 19 

5.3. Cumulative Effects......................................................................................................... 19 

5.4. Avoidance, Minimization, and/or Mitigation Measures ............................................... 20 

6. References .............................................................................................................................. 21 

Figures 

Figure 1. Project Area and Vicinity................................................................................................................ 3 

Figure 2. Project Area and Floodplain Map ................................................................................................15 

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Tables 

Table 1. HEC-RAS Model Results for Lytle Creek ........................................................................................18 

Table 2. HEC-RAS Model Results for Mojave River .....................................................................................18 

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Abbreviations and Acronyms 

BFE Base Flood Elevation 

BMP best management practice 

Caltrans California Department of Transportation 

cfs cubic feet per second 

CGP Construction General Permit 

FEMA Federal Emergency Management Agency 

FIRM Flood Insurance Rate Map 

FRA Federal Railroad Administration 

GHG greenhouse gas 

HEC-RAS Hydraulic Engineering Centers-River Analysis System 

I-15 Interstate 15 

Project Brightline West Cajon Pass High-Speed Rail Project 

SBCTA San Bernardino County Transportation Authority 

SWMP Stormwater Management Plan 

SWPPP Stormwater Pollution Prevention Plan 

VHT vehicle hours traveled 

VMT vehicle miles traveled 

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BRIGHTLINE WEST CAJON PASS HIGH-SPEED RAIL 

1. Introduction 

DesertXpress Enterprises, LLC (dba “Brightline West”) proposes to construct and operate the 

Cajon Pass High-Speed Rail Project (Project), a 49 mile train system reaching a top speed of 

approximately 140 miles per hour (mph) between the Victor Valley and Rancho Cucamonga, 

California (Project). The Project includes two new railway stations—one in Hesperia, and one in 

Rancho Cucamonga. The connecting station in Victor Valley would be constructed as part of a 

separate project that was evaluated in the DesertXpress Final Environmental Impact Statement 

(Final EIS; FRA 2011). 

The Project would be constructed within the Interstate 15 (I-15) right-of-way (ROW) for 48 

miles and on existing transportation corridors for the last mile into the proposed Rancho 

Cucamonga station. The Project would be powered by overhead electric catenary and require 

construction of one new traction power substation (TPSS) in the Hesperia area. The 

maintenance facility that was evaluated with the Brightline West Victor Valley High-Speed Rail 

(HSR) Passenger Project would provide the primary maintenance functions, although layover 

tracks are anticipated at the Rancho Cucamonga station, which could include light maintenance 

capability, such as interior cleaning and daily inspection. 

Trains are expected to operate daily on 45-minute headways between Victor Valley and Rancho 

Cucamonga. The trip between Victor Valley and Rancho Cucamonga would be approximately 35 

minutes. Service would be coordinated with existing and planned Metrolink service at the 

Rancho Cucamonga station to provide a convenient connection between the high-speed rail 

(HSR) and commuter rail systems. 

The Project would be constructed and operated under a lease agreement with the California 

Department of Transportation (Caltrans) for the use of the I-15 right-of-way and the station at 

Hesperia. Brightline West would secure additional agreements with Caltrans for Right-of-Way 

Use; Design & Construction Oversight and Reimbursement; and Operations & Maintenance, as 

necessary. For the last mile of the project from I-15 to the Rancho Cucamonga Station, there 

will be Agreements with the City of Rancho Cucamonga and the San Bernardino County 

Transportation Authority (SBCTA) for land rights, construction, operations and maintenance. 

This report provides an overview of the floodplain effects associated with the construction and 

operation of the proposed Brightline West Cajon Pass High-Speed Rail Project (Project). The 

information provided in this report is preliminary and is intended to support the National 

Environmental Policy Act process for the Federal Railroad Administration (FRA). This 

information will form the basis of further analysis and field work, as needed. Forthcoming 

information related to construction methods, project design, and agency coordination will 

support confirmation of the potential for project effects and identification of measures that 

could be incorporated into the project design to minimize and/or avoid adverse effects. 

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2. Project Description 

2.1. Background 

Early project coordination for HSR service from Victor Valley to Rancho Cucamonga began in 

2020, with Brightline West meeting with SBCTA to examine a connection between Victor Valley 

and Rancho Cucamonga. This meeting resulted in a memorandum of understanding (MOU) that 

was fully executed in July 2020 between Brightline West and SBCTA to study the potential of 

building HSR within the I-15 right-of-way between Victor Valley and Rancho Cucamonga. A 

separate MOU was executed in September 2020 between Brightline West and the Southern 

California Regional Rail Authority, which operates Metrolink, for connection to the existing 

Metrolink station in Rancho Cucamonga. Additionally, the California State Transportation 

Agency (CalSTA), Caltrans, the California High-Speed Rail Authority, and Brightline West have 

executed an MOU regarding the Project. The MOU reflects both the regional and statewide 

interest and value in the Project, including interconnectivity opportunities, and outlines how 

the parties will work together to advance their shared interest in the success of the Project. 

2.2. Project Area 

The Project would construct and operate a 48-mile train system capable of speeds up to 

approximately 140 mph between Victor Valley, California and Rancho Cucamonga, California 

(Project). The Project includes two new railway stations: one in Hesperia, and one in Rancho 

Cucamonga, and will connect to another Brightline West station in Victor Valley. The proposed 

rail alignment would be located within the median of the I-15 freeway between Victor Valley 

and Rancho Cucamonga except for the last mile approaching the proposed Rancho Cucamonga 

station. The Project area is depicted in Figure 1. The Project passes through the cities of 

Victorville, Hesperia, Rialto, and Fontana, and through unincorporated areas. 

The project area is the same as the project footprint, and nearly all of it is within the I-15 rightof-way. It incorporates the limits of disturbance for construction of the proposed rail line and 

associated development, including power stations, bridge structures, and two rail stations. The 

Project area is approximately 49 miles long and ranges in width from approximately 22 feet to 

71 feet. 

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Figure 1. Project Area and Vicinity 

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2.3. Purpose of and Need for the Project 

2.3.1. Purpose 

The purpose of the Project is to provide reliable and safe passenger rail transportation between 

the Los Angeles metropolitan region and the High Desert of San Bernardino County. The Project 

would provide a convenient, efficient, and environmentally sustainable alternative to 

automobile travel on the highly congested I-15 freeway. The Project would add capacity to the 

overall transportation system by introducing a new HSR service from Victor Valley to Rancho 

Cucamonga. The Project would reduce travel time, improve reliability, and increase the mobility 

options for travel between metropolitan regions. Travel time from Victor Valley to Rancho 

Cucamonga for Project users would be approximately 30 percent faster during normal 

conditions and at least twice as fast during congestion peak periods. The Project would reduce 

automobile vehicle miles traveled (VMT), resulting in a corresponding reduction in greenhouse 

gas (GHG) and air quality emissions. 

2.3.1.1. Multi-Modal Use of the I-15 Corridor 

Operation of the Project would significantly increase the capacity of I-15 as a multi-modal 

corridor in Southern California. This increase in capacity would benefit freeway operations by 

providing an alternative to automobile travel that would reduce travel time. This shift of people 

from automobile to train travel along the I-15 corridor would reduce the need for programmed 

and/or planned freeway improvement and widening projects. 

2.3.2. Need 

The Project is needed to address transportation capacity deficiencies, major points of 

congestion, limited travel mode choices, safety deficiencies, and reduce GHG emissions. 

Travel demand analysis completed on behalf of the project forecasts 49.1 million one-way trips 

between Southern California and Las Vegas in 2025, with approximately 85 percent of travelers 

making the trip by automobile. Most of these trips use the Cajon Pass segment of the I-15, 

which is capacity-constrained. Further, the freeway system leading into the I-15 from points 

west, east, and south, including I 10, State Route 210 (SR-210), I 215 and SR-60 have similar 

delays and capacity constraints. The Project would address this demand by providing a 

transportation alternative to vehicle travel, and it would allow access to the Brightline West 

service from the Greater Los Angeles and the Riverside-San Bernardino-Ontario Metropolitan 

areas, as well as points beyond, with a connection to the Metrolink system in Rancho 

Cucamonga. 

The Project would also support federal and state policies focused on climate change and the 

need to reduce VMT and associated GHG emissions. 

2.3.2.1. Capacity Constraints 

I-15 through the Cajon Pass is one of the most congested segments of I-15, with no alternative 

routes that provide comparable direct road travel capability because of the mountainous 

topography. Through the Cajon Pass, I-15 supports daily workforce commuters, recreational 

travel, and regional and interstate freight and goods movement. According to the traffic study 

prepared for the I-15 Corridor Project Initial Study/Environmental Assessment (Caltrans and 

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SBCTA 2018), unreliability in travel time along segments of I-15 and surrounding roadways is 

caused by roadway capacity constraints, frequent accidents, and various factors that cause 

unanticipated congestion. Travelers using the Project would no longer need to drive through 

the most congested parts of the corridor in the Cajon Pass for interstate or commuter trips, 

thereby avoiding driving next to many large freight trucks, idling, and inefficient stop-and-go 

traffic conditions. 

By 2045, travel speeds are expected to decrease on all but one segment of I-15 between the 

San Bernardino Valley and Apple Valley in the AM peak period, and travel speeds on most 

segments would also decrease—some by more than 10 mph—in the PM peak period (SCAG 

2020). Based on the Project Report for the I-15 Corridor Study (addition of express lanes), traffic 

volumes on I-15 between I-10 and SR-210 are expected to increase in the range of 31 to 38 

percent from 2014 to 2045. The Project Report states the existing level of service (LOS) is 

acceptable in most locations but that there are bottlenecks in each direction of travel that 

degrade traffic operation, especially between Baseline Road and SR-210. Because the express 

lane project is increasing capacity by adding express lanes, the traffic volumes are projected to 

increase by an additional 27 percent. The Project Report further mentions that, although the 

express lane project would improve conditions in the general-purpose lanes in many segments, 

it would cause the segment between the I-10 and Fourth Street to worsen in the PM peak hour 

(both directions). In the AM peak hour, the segment between Arrow Route and Fourth Street 

would worsen in the southbound direction. The segment between Baseline Road and SR-210 

would continue to operate at over capacity conditions in all scenarios. 

SCAG’s Connect SoCal Goods Movement Technical Report identifies I-15 as part of the U.S. 

Department of Transportation’s (USDOT) Primary Highway Freight Network and among the 

network segments that carry the highest volumes of truck traffic in the region. It also identifies 

the entirety of the Cajon Pass as a truck bottleneck, with over 15,000 annual vehicle hours of 

delay. 

As documented above, given the attractiveness of the origins and destinations, the 

transportation capacity constraints on I-15 as described in current and predicted average daily 

traffic (ADT) and LOS limit reasonable highway access between Rancho Cucamonga, Hesperia, 

and Victor Valley. 

2.3.2.2. Travel Demand 

The anticipated substantial increases in population, housing, and employment in San 

Bernardino County will result in greater demand for transportation facilities and services, 

including increased travel demand that will result in congestion on roadways if capacity does 

not keep up with the demand. The proposed Hesperia Station would provide convenient 

connections between High Desert communities and the more urbanized San Bernardino Valley 

and Metropolitan Los Angeles. The High Desert provides lower cost housing options for 

Southern California residents, while the Rancho Cucamonga/Ontario area around Ontario 

International Airport has become a significant employment center. 

SCAG forecasts, in its 2020-2045 Regional Transportation Plan/Sustainable Communities 

Strategy (RTP/SCS), that the population of San Bernardino County will grow to 2,815,000 by 

2045, a 29 percent increase from the U.S. Census Bureau’s 2018 population estimate of

2,180,085, and that the number of households will grow to 875,000, a 39 percent increase over 

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the 2018 household estimate of 630,633 (U.S. Census Bureau 2020). Additionally, the 2020-

2045 RTP/SCS forecasts employment in San Bernardino County will increase to 1,064,000 by 

2045, a 72 percent increase from the U.S. Census Bureau’s estimate of 617,828 in 2018.

While the proposed Victor Valley station site would be located at the convergence of all the 

highways en route to Las Vegas for Southern California travelers, the Rancho Cucamonga 

station would be closer to major population centers in Southern California. Compared to the 

Victor Valley station, the proposed HSR station in Rancho Cucamonga, located about 45 miles 

east of Downtown Los Angeles, would provide more direct access to the densely populated 

centers in Southern California for both drivers and Metrolink riders; 87 percent of the potential 

market for trips between Las Vegas and Southern California (equivalent to 42.7 million of the 

one-way, in-scope trips in 2025) live within 75 miles of the location of the proposed Rancho 

Cucamonga station. 

The proposed station in Rancho Cucamonga, with a Metrolink connection to Los Angeles, would 

further meet the forecasted demand of the 49.1 million one-way trips between Las Vegas and 

Southern California estimated in 2025. Similarly, the proposed Hesperia station would be at the 

convergence of US Highway 395 (US 395) and I-15, so it would serve commuters to Greater Los 

Angeles from the major corridors in the Victor Valley. 

The Project would also support SCAG’s Connect SoCal Passenger Rail Technical Report, which

identifies closing connectivity gaps as a major strategy to increase mobility and improve 

sustainability. The Project would facilitate transit connections and would allow residents of the 

Greater Los Angeles and the Riverside-San Bernardino-Ontario Metropolitan areas to travel 

exclusively by mass transit and passenger rail to and from the High Desert of San Bernardino 

and connect to the BLW station at Victor Valley for a connection to Las Vegas. Southern 

California residents could take the Los Angeles Metro rail, regional bus systems, Amtrak, or 

Metrolink to Los Angeles Union Station to connect via the Metrolink San Bernardino Line to the 

Rancho Cucamonga station. Residents could also take the planned West Valley Connector Bus 

Rapid Transit service that will operate between the Pomona station on the Metrolink Riverside 

Line in eastern Los Angeles County and the Rancho Cucamonga station. While still in early 

planning and design stages, the planned Tunnel to Ontario International Airport (ONT) project 

may provide an additional connection from the Rancho Cucamonga station to the Ontario 

International Airport. 

Additionally, SBCTA and SCAG’s 2015 Advanced Regional Rail Integrated Vision – East (ARRIVE 

Corridor) plan proposes strategies for transitioning the Metrolink San Bernardino Line, which 

would serve the Rancho Cucamonga station, from a traditional commuter rail line to one that 

promotes transit-oriented development. Improvements to Metrolink, its transit connections, 

and additional development of the station areas with transit-supportive uses at greater 

densities and intensities will encourage the formation of areas that are walkable and that 

provide mobility options in the region. The Project would further the goals of the ARRIVE 

Corridor plan by increasing the activity centers that can be accessed by Southern California’s 

rail network. Additionally, the Southern California Optimized Rail Expansion (SCORE) program is 

intended to increase speeds, reliability, and capacity on Metrolink lines including on the San 

Gabriel Subdivision which serves the Rancho Cucamonga station. 

In 2010, the San Bernardino Associated Governments (the predecessor agency to SBCTA) 

completed the Victor Valley Long Distance Commuter Needs Assessment, which identified a 

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BRIGHTLINE WEST CAJON PASS HIGH-SPEED RAIL 

phased set of commuter improvement projects. Those projects ranged from expanded park and 

ride facilities to an express bus service linking the Victor Valley area of the High Desert to the 

Rancho Cucamonga Metrolink station. The Joshua Street Park & Ride is near the Project’s 

proposed station in Hesperia. Such commuter-focused planned improvements highlight the 

need for travel options that reduce the number of single occupancy automobiles on I-15 in San 

Bernardino County, particularly through the Cajon Pass. 

FHWA’s Southern California Regional Freight Study (USDOT 2020) identifies I-15 as a major 

interstate highway corridor that provides access to the interior of the United States for goods 

arriving at the ports of the Los Angeles region and ranks it among the highest truck volume 

corridors in the western United States. Caltrans’ 2015 Interregional Transportation Strategic 

Plan identifies I-15 as a high priority corridor, among six nationally identified “Corridors of the 

Future,” and a “vital link between Mexico, Southern California, and locations to the north and 

east of the region.” I-15 also connects Southern California and the southwestern United States 

to the San Joaquin Valley’s agricultural goods via SR-58. By providing passenger rail capacity in 

the corridor, the Project would help maintain freeway capacity for truck freight use by 

removing passenger vehicles from the roadway network. 

2.3.2.3. Safety 

Alternatives to automobile travel would provide improved safety conditions on the I-15 corridor 

with diversion of vehicle trips to HSR. On a national level, comparing miles traveled via 

commercial aircraft, train, and automobiles on highways, auto travel on highways has by far the 

highest rate of passenger fatalities per mile traveled. In 2019, the average rate of passenger 

fatalities from highway travel was more than 75 times the comparable rate for travel by air and 

34 times the comparable rate by rail. For 2016, the Bureau of Transportation Statistics’ National 

Transportation Statistics (USDOT 2018) reported a rate of passenger fatalities per 100 million 

passenger miles traveled by highway nearly 10 times greater than the rates for travel by air or 

rail. HSR is one of the safest forms of travel. 

The California Office of Traffic Safety ranks San Bernardino County 16th-worst out of 58 

counties for total fatal and injury crashes in 2018 (the most recent year of data available). 

According to the University of California, Berkeley, and SafeTREC’s Transportation Injury 

Mapping System, there were 819 collisions with one or more deaths or injuries along I-15 in San 

Bernardino County in 2019. Of these, nearly one quarter (199) occurred in the 12 miles of the 

Cajon Pass, although the Cajon Pass accounts for only 6.5 percent of the length of I-15 in the 

county. 

A study by the I-15 Mobility Alliance found that the segment of I-15 from I-215 in San 

Bernardino to I-40 in Barstow had a fatality rate 0.009 per million VMT, well above the 

alliance’s performance goal of 0.003 fatalities per million. By connecting the Victor Valley to 

Rancho Cucamonga, the Project would allow more travelers to stay off segments of I-15. 

2.4. Project Elements 

2.4.1. Build Alternative 

The Build Alternative (i.e., the Project) consists of a proposed HSR passenger railway with 

associated infrastructure, including two proposed passenger stations. Nearly all of the Project 

would be built within the I-15 right-of-way. Near the proposed southern terminus station in 

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Rancho Cucamonga, approximately 1 mile of the rail alignment would be in city street, railroad, 

or utility rights-of-way. 

The proposed rail alignment would be located within the median of the I-15 freeway between 

Victor Valley and Rancho Cucamonga except at the approach to the proposed Rancho 

Cucamonga station. The rail alignment would be predominantly at grade (the same elevation as 

the existing freeway), with select segments of the alignment on aerial structures or in a trench 

to allow for grade separations (including 4 BNSF and 3 UP railroad crossings) and to provide a 

safe incline for train operation. The rail alignment would be predominantly single-track, with 

limited double-track segments in Victor Valley (2.6 miles, including 0.9 miles constructed as part 

of the DesertXpress High-Speed Passenger Train Project), Hesperia (5.5 miles), and Rancho 

Cucamonga (2 miles). This would allow for 45-minute headways in the opening year between 

Victor Valley and Rancho Cucamonga and with additional infrastructure, 22.5-minute headways 

after year 11. These headways, along with the ability to couple trains (double passenger 

capacity), would address projected ridership needs for the foreseeable future. 

Temporary construction areas, or TCAs, are properties that would be temporarily utilized for 

construction staging and storage. The Project would require TCAs along the alignment between 

Victor Valley and Rancho Cucamonga. 

For analytical purposes, the Build Alternative is described in three sections. Sections were 

developed to reflect similarly developed areas with similar environmental sensitivity. The 

sections include: 

• Section 1: High Desert – from the Victor Valley station, continuing south along I-15, to 

the I-15/Oak Hill Road interchange in Hesperia 

• Section 2: Cajon Pass – from the I-15/Oak Hill Road interchange, continuing south along 

I-15, through the Cajon Pass, to the I-15/Kenwood Avenue interchange 

• Section 3: Greater Los Angeles – from the I-15/Kenwood Avenue interchange in San 

Bernardino, continuing south along I-15, through the existing Metrolink station in 

Rancho Cucamonga to Haven Avenue 

2.4.1.1. Section 1 – High Desert 

The proposed rail alignment would connect to the DesertXpress High Speed Train alignment 

approximately one mile south of the Victor Valley station in Apple Valley. The Victor Valley 

station was proposed by the DesertXpress High Speed Train Project (DesertXpress Project) and 

approved in 2011 and modified by the re-evaluation in 2020. From this point, the alignment 

would continue south within the I-15 median. The rail alignment throughout Section 1 would be 

predominantly single track; however, the rail alignment would be double-track north of 

Stoddard Wells Road to the northern terminus of the alignment as it approaches the train 

platforms of the Victor Valley station. The Project would include a new structure over the 

existing CEMEX railroad bridge. Based on future discussion with CEMEX, the existing railroad 

bridge may be reconstructed as part of the DesertXpress project, in which case the alignment 

would run at-grade in the median under the railroad bridge. 

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BRIGHTLINE WEST CAJON PASS HIGH-SPEED RAIL 

Brightline West will build a new Southbound on ramp and bridge at South Stoddard Wells Rd. to 

replace similar existing facilities further south. This in-turn requires modifications of I-15 up to 

and including the Mojave River crossing. 

1 

At the Mojave River, a new rail bridge will be constructed within the median of I-15. The 

existing I-15 bridge would be widened to accommodate the rail line. The alignment would then 

continue at grade in the I-15 median with minor roadway widenings for the remainder of 

Segment 1. This portion of the alignment would interface with the following interchanges: 

Stoddard Wells Road North, Stoddard Wells Road South, D Street/E Street, Mojave Drive, Roy 

Rogers Drive/Hook Road, Palmdale Road, La Mesa Road/Nisqualli Road, Bear Valley Road, Main 

Street/Phelan Road, Joshua Street, US 395, Ranchero Road, and Oak Hill Road. 

A new substation would be constructed to support the Project along I-15, between Mesa Street 

and Mojave Street. The area is currently largely undeveloped, other than existing overhead 

power lines and utility access. 

Hesperia Station 

Section 1 includes a new passenger station in Hesperia, at the I-15/Joshua Street interchange. 

This station would serve daily travelers between the High Desert of San Bernardino County and 

the Los Angeles Basin. This would be a limited service for select southbound AM and 

northbound PM weekday on selected Brightline train coaches. The northbound on-ramp to 

Joshua Street would be realigned closer to the freeway, and station parking would be on the 

north side of Joshua Street. Parking would be accessed at the location of the existing 

northbound ramp intersection. To accommodate the rail alignment, the existing US-395 

northbound connector and the existing Joshua Street bridge would be replaced. The Joshua 

Street bridge would be reconstructed at a higher elevation, requiring raising of the I-15 ramps 

and Mariposa Road. The passenger platform would be located within the I-15 median, with 

direct access from the reconstructed Joshua Street bridge at the southern end of the doubletrack segment in Hesperia. The Project design includes adequate parking areas to 

accommodate parking demand. 

Design Elements 

Segment 1 of the Project includes the following design elements. 

• Reconstructions/Interchange Modifications: Widening portions of the I-15 freeway and 

modifications to interchanges at Stoddard Wells Road southbound on- and off-ramp, D 

Street/E Street, Mojave Drive, Roy Rogers Drive/Hook Road, Palmdale Road, La Mesa 

Road/Nisqualli Road, Bear Valley Road, Main Street/Phelan Road, US-395, Ranchero 

Road, Oak Hill Road, and Joshua Street 

• ·New Substation: Construction of a new substation along I-15 between Mesa Street and 

Mojave Street 

• Station Area: Hesperia station platform, station access/infrastructure, surface parking 

lot accommodating approximately 360 vehicles, bus pick up/drop off areas, Kiss and 

Ride 

1 These improvements would be consistent with Caltrans’ planned Interstate 15 Interchange Reconstruction (D Street, E Street, Stoddard Wells 

Road, and Mojave River Bridge)project, which was originally analyzed under an Initial Study / Environmental Assessment in 2008. 

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BRIGHTLINE WEST CAJON PASS HIGH-SPEED RAIL 

2.4.1.2. Section 2 – Cajon Pass 

Beginning at the I-15/Oak Hill Road interchange and traveling south, the alignment would run 

on the west side of the I-15 northbound lanes at grade and within the existing I-15 right-of-way. 

In this area, the I-15 runs through the San Bernardino National Forest for approximately 12 

miles. The rail alignment throughout Section 2 would be entirely single-track. The Project would 

require replacement of California Highway Patrol (CHP) emergency crossovers where the new 

guideway would block existing crossovers. Four new crossovers would be placed to take 

advantage of existing CHP access between the separated I-15 alignments in the following 

locations: 

• West of Forestry Road crossing the northbound lanes. 

• Approximately 1.25 miles in the southbound direction along I-15 from the crossover 

near Forestry Road, across the northbound lanes. 

• West of the Baldy Mesa (Trestles) OHV Staging Area, across the northbound lanes. 

• West of Perdew Canyon and approximately 1.25 miles north of Mathews Ranch Road, 

across both the north and southbound lanes. 

The alignment would remain at grade throughout Segment 2. 

Where I-15 northbound and southbound lanes reconnect at the foot of the Cajon Pass, the rail 

alignment would be within the I-15 median. This would require widening portions of the I-15 

freeway and minor realignment of ramps at the I-15/SR-138 interchange. 

Design Elements 

Segment 2 of the Project includes the following design elements. 

• Bridges/Viaducts: None 

• Reconstructions/Interchange Modifications: Widening portions of the I-15 freeway 

including several miles of retained fill, and realignment of ramps at the I-15/SR-138 

interchange 

• Other Facilities: CHP emergency crossovers 

2.4.1.3. Section 3 – Greater Los Angeles 

Beginning at the Kenwood Avenue interchange, the proposed rail alignment would continue at 

grade in the I-15 median. At the I-15/I-215 interchange, the alignment would continue between 

the divided I-15 freeway at the same elevation as the freeway including the Devore interchange 

viaduct, curving to the southwest parallel to freeway. The rail alignment would require I-15 

freeway and interchange ramp modifications at Baseline Avenue, SR-210, Beech Avenue, 

Duncan Canyon Road, Sierra Avenue, and Glen Helen Parkway. 

The rail alignment would transition to an aerial alignment and elevate over the I-15 southbound 

lanes south of Church Street and cross at Foothill Boulevard. It would continue along the west 

side of the I-15 freeway on an elevated alignment to enter the San Gabriel Subdivision and 

Eighth Street corridor. The alignment would transition onto an aerial structure and would turn 

west, running parallel to and partially within the existing rail corridor and partially within the 

Eighth Street right-of-way before entering the existing Rancho Cucamonga Metrolink station 

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area on an elevated structure. The rail alignment would maintain a single-track configuration 

prior to exiting the freeway median south of Church Street, where it would transition to a 

double-track configuration for the remaining distance to the Rancho Cucamonga station. At the 

Rancho Cucamonga station, an elevated station with a center platform and tracks on either side 

would be constructed parallel to and above the existing eastbound Metrolink platform, 

extending over Milliken Avenue. A new parking structure is proposed at Rancho Cucamonga 

Station, and would replace existing surface parking to accommodate increased parking 

demand. The Project design includes adequate parking areas to accommodate parking demand 

in the opening year. 

Design Elements 

Segment 3 of the Project includes the following design elements. 

• Bridges/Viaducts: Viaduct of approximately 3.5 miles to cross I-15 southbound lanes and 

along existing rail corridor near Rancho Cucamonga station 

• Reconstructions/Interchange Modifications: I-15 freeway and interchange ramp 

modifications at SR-210, Beech Avenue, Duncan Canyon Road, and Glen Helen Parkway 

• Station: Dedicated Brightline station adjacent to the existing Rancho Cucamonga 

Metrolink station, with vertical circulation down to the platform, shared access with 

existing Metrolink station, a share parking structure for vehicles, and a bus plaza 

2.5. Construction 

In general, construction activities would consist of clearing, grading, excavation, placing fill, 

stockpiling materials, installing sub-ballast and subgrade, placing and anchoring railroad ties, 

placing ballast material, and tamping ballast, mobilization and demobilization. Construction 

equipment would likely include dump trucks, excavators, loaders, cranes, water trucks, 

backhoes, scrapers, rollers, ballast tampers, concrete trucks, and drill rigs. 

For new and reconstructed overpasses and bridges, construction activities would include 

clearing, grubbing, demolition of existing structures, excavation and drilling for foundations, 

concrete pouring, formwork and rebar placement for foundations, falsework installation, 

construction of bridge decking, placement of ballast and ties, mobilization and demobilization. 

Most construction activities would occur on Caltrans right-of-way. Some, for the rail stations 

and power stations, would occur on public property owned by the City of Rancho Cucamonga, 

SBCTA, or State of California. Temporary construction areas, or TCAs, are properties that would 

be temporarily utilized for construction staging and storage. The Project would require TCAs 

along the alignment between Victor Valley and Rancho Cucamonga. 

Construction activities on Caltrans right-of-way would comply with the State Construction 

General Permit (CGP). The CGP and the Caltrans Storm Water Management Plan (SWMP) both 

require best management practices (BMPs) to be incorporated during all phases of construction 

to prevent contaminated stormwater runoff, a major contributor to water quality degradation. 

A Storm Water Pollution Prevention Plan (SWPPP), which will include placement of temporary 

water pollution control BMPs throughout the project site, will be required prior to 

commencement of construction. 

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Construction of at least two bridges, over the Mojave River and Lytle Creek, would involve work 

within the streambed. Placement of columns needed for those bridge spans may involve 

phased construction with best management practices (BMPs), such as flow diversion around 

work areas, to protect the stream during construction. Staging, equipment storage, and 

stockpiling would occur outside the floodplain. The final construction plans would include the 

BMPs for grading, erosion control, and flow diversion that are necessary to reduce erosion and 

sedimentation. Such BMPs would be selected to control erosion and sediment removal and 

would represent the best available technology that is economically achievable. Standard 

erosion control measures, such as management, structural, and vegetative controls, would be 

implemented for all construction activities that expose soil. BMPs to be implemented may 

include, but would not be limited to, the following: 

• Temporary erosion control measure BMPs that would apply to construction of the 

stations and the rail (such as silt fences, staked straw bales/wattles, silt/sediment basins 

and traps, check dams, geofabric, mulch or duff, and sandbag berms) for erosion control 

from disturbed areas 

• Grading to eliminate any direct conveyance routes such as rills or gullies that may allow 

runoff to flow directly to streams, rivers, floodplains and washes 

• Incorporation of BMPs in Temporary Water Pollution Control (TWPC) Plans that will be 

included in the Storm Water Pollution Prevention Plan (SWPPP) 

• Regular inspection and maintenance of BMPs shown in the TWPCs 

Construction BMPs specifically for rail installation would also include: 

• Erosion control material consisting of silt fences along the outside limits of construction 

on both sides of the disturbance corridor for track construction 

• Clearing the construction area of brush and vegetation 

• Stripping any topsoil and transporting it to stockpile (outside the limits of any 

floodplain) where it will be covered with a protective layer impervious to water for 

protection from rainfall 

• Excavation and fill for culvert extensions using good quality material for fill and 

transporting poor quality material to stockpile 

• Using stabilized construction entrances and exits along the project site (outside the limit 

of floodplains) to minimize deposition of tire dust and associated contaminants off of 

the track site 

• Placement of diversion BMPs around the area where construction activities are 

occurring in a floodplain, such as at proposed bridge columns and abutments 

• Storing construction equipment or materials outside the limits of influence of the 100-

year floodplain so as to avoid redirecting 100-year flood flows that could cause 

structural damage or pose a safety risk to workers. 

In addition to the BMPs listed above, the Project would restore disturbed areas after 

construction. 

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3. Methodology 

3.1. Relevant Regulations, Plans, and Policies 

Executive Order 11988 (Floodplain Management) addresses floodplain issues related to public 

safety, conservation, and economics and requires that federal agency construction, permitting, 

and funding of a project: 

• Identify risks of the action 

• Avoid incompatible floodplain development 

• Be consistent with the standards and criteria of the National Flood Insurance Program 

• Restore and preserve natural and beneficial floodplain values 

• Address measures to minimize any net rise in floodplain level 

The base floodplain is defined as “the area subject to flooding by the flood or tide having a one

percent chance of being exceeded in any given year.” An encroachment is defined as “an action 

within the limits of the base floodplain.”

3.2. Study Area 

The study area for floodplains is defined as the area within the Project footprint, which 

comprises the temporary and permanent Project footprint, except for the area at Lytle Creek 

and Mojave River where the study area extends further than the project footprint in order to 

study the Project’s effect on these two floodplains. At these two locations, the study area is 

extended both 500-ft upstream and downstream of the project limits for evaluation of 

hydraulics in the floodplain. Note that some areas adjoining the project limits include 

floodplains that are not in the project limits. However, these floodplains are in such close 

proximity to the project, they are also discussed in this report. 

As shown in Figure 2, the Project would cross or be next to five high-risk flood zones identified 

by the Federal Emergency Management Agency (FEMA). They consist of the Mojave River, 

Cajon Wash, Lytle Creek/Wash, Hawker-Crawford Channel, and Etiwanda Creek/Channel. 

3.3. Methods Used 

FEMA Flood Insurance Rate Maps (FIRMs) were reviewed to identify the location of high-risk 

flood zones within the study area. Existing design information was then reviewed to determine 

if the Project would affect identified flood zones by placing fill, including structures, within the 

floodplain. 

Based on the initial design, the Project would place bridge columns within the FEMA high-risk 

flood zones of the Mojave River and Lytle Creek. Preliminary, one-dimensional, hydraulic 

models were developed, using the Hydraulic Engineering Centers-River Analysis System (HECRAS) computer program, to analyze the potential effects of the Project on the upstream water 

surface during the 100-year storm event at the Project crossings of the Mojave River and Lytle 

Creek. Pre-project and post-project scenarios were developed for each of the two sites. 

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4. Existing Conditions 

The geography of the study area mainly consists of: 

• San Bernardino Valley (located south of Lytle Creek where runoff flows southwesterly 

toward Etiwanda Creek and ultimately to the Middle Santa Ana River) 

• Cajon Pass (located from Lytle Creek to the mountain peak located north of the Cajon 

Wash where runoff flows southerly to Lytle Creek and the Cajon Wash and ultimately to 

the Middle Santa Ana River) 

• High Desert (located north of the Cajon Pass where runoff generally flows northeasterly 

toward the Mojave River) 

FEMA subdivides floodplains into flood zones to capture the frequency of flood events in areas 

susceptible to flooding. Based on a review of the FEMA FIRMS that cover the study area, the 

project alignment would cross though two high-risk flood hazard zones: A and AE. FEMA defines 

these flood zones as follows: 

• Zone A: Areas subject to inundation by the 1-percent-annual-chance (100-year) flood 

event. Because detailed hydraulic analyses have not been performed, no Base Flood 

Elevations (BFEs) or flood depths are shown. 

• Zone AE: Areas subject to inundation by the 100-year flood event determined by 

detailed methods. BFEs are shown within these zones for floodways. 

Flood zones A and AE are in the cities of Victorville, Fontana, Rialto, and Rancho Cucamonga 

and in parts of unincorporated San Bernardino County. The locations of the high-risk flood 

zones are illustrated on Figure 2. The Project would cross the following high-risk flood zones: 

• Mojave River (Victorville) – Zone AE 

• Lytle Creek and Lytle Creek Wash (San Bernardino County/Rialto) – Zone A 

• Etiwanda Channel/Creek (Fontana/Rancho Cucamonga) – Zone AE (floodway is 

contained in the channel [FEMA 2020]) 

The Project is next to the following high-risk flood zones: 

• Cajon Wash (downstream of the Project, in unincorporated San Bernardino County) –

Zone A 

• Hawker-Crawford Channel (in Rancho Cucamonga) – Zone A 

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Figure 2. Project Area and Floodplain Map 

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5. Environmental Effects and Mitigation 

5.1. Construction Effects 

5.1.1. Railway 

During railway construction, site grading for rail, roadway, and structures would expose areas 

of bare soil to erosive forces (i.e., rainfall, runoff, and wind). In addition, Project construction 

could involve the use of heavy, earth-moving equipment in the floodplains of the Mojave River 

and Lytle Creek, and near the floodplains of Etiwanda Channel, and Hawker-Crawford Channel. 

Use of such equipment could expose disturbed and loosened soils to erosion. Most natural 

erosion occurs at slow rates; however, the rate increases when the land is cleared or altered 

and left disturbed. Activities involving soil disturbance, excavation, cutting/filling, and 

stockpiling could result in increased erosion and sedimentation to surface waters if precautions 

are not taken to control pollution in the runoff. 

Most of the Railway construction activities would occur on Caltrans right-of-way and would 

comply with the State CGP. The CGP and the Caltrans SWMP both require BMPs to be 

incorporated during all phases of construction. By implementing measures in the SWMP and 

SWPPP, the Project would reduce the potential for construction impacts on floodplains; 

however, some potential for erosion and spills, and for sediment or spilled material to reach 

floodplains would remain. 

As noted in Section 2.5, placement of bridge columns in the streambeds of the Mojave River 

and Lytle Creek may involve phased construction with flow diversion BMPs such as gravel bag 

berms placed around the construction areas during construction in the streambed. This would 

allow water to flow around the construction area and reduce potential for construction 

material to reach the waterway during a storm event. It would also keep the construction area 

dry. 

Project construction activities within floodplains would likely result in temporary effects on 

floodplains. These activities could include vegetation clearing, soil disturbance, and 

construction of bridge piers and abutments. However, disturbed areas would be restored after 

construction and bridge elements would be constructed in phases with flow diversion BMPs 

protecting the construction site, and no long-term effects are anticipated. This will be 

confirmed after more details of project design are available. For further information on 

restoration of disturbed wetland areas, refer to the Wetlands and Streams Technical Report 

Section 5.4. Avoidance, Minimization, and/or Mitigation Measures. 

5.1.2. Hesperia Station 

Site grading for structures would expose areas of bare soil to erosive forces. Activities involving 

soil disturbance, excavation, cutting/filling, and stockpiling could result in increased erosion and 

sedimentation to surface waters if precautions are not taken to control pollution in the runoff. 

However, the Project incorporates BMPs that would minimize the potential for construction 

impacts. 

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No FEMA-mapped floodplains are in or near the construction footprint of the proposed 

Hesperia Station. Therefore, the Project would not affect floodplains or water surface 

elevations in the proposed station area. 

5.1.3. Rancho Cucamonga Station 

No FEMA-mapped floodplains are in or near the construction footprint of the proposed Rancho 

Cucamonga Station. Therefore, the Project would not affect floodplains or water surface 

elevations in the proposed station area. 

5.2. Operation Effects 

5.2.1. Railway 

The high-risk flood zones of the Cajon Wash and the Hawker-Crawford Channel are next to, but 

not in, the footprint of the Project as shown in Figure 2 of this report. The FEMA mapped 

floodplain of the Cajon Wash is immediately downstream of the project site. The HawkerCrawford Channel floodplain adjoins the southbound I-15 embankment for approximately 

3,200 feet, from the Beech Avenue to Cherry Avenue crossings. 

At Cajon Wash, project improvements would be located upstream of the mapped floodplain 

and, therefore, would not affect downstream water surface elevations. For this crossing, the 

Project would place bridge columns in the streambed in a manner that would minimize impacts 

on the upstream water surface elevation, even though it is not in a floodplain. The proposed 

bridge columns would be in line with the existing northbound and southbound I-15 bridge 

columns located downstream and upstream, respectively). 

FEMA mapping shows the Hawker-Crawford Channel to overtop during the 100-year storm 

event, though the floodplain remains in low-lying area that is below the grade of the proposed 

Project. The Project would be located outside the floodplain, and proposed Project 

improvements would have no effect on it. 

When project features are located within a FEMA 100-year floodplain, the base elevation of the 

railway would be elevated above the 100-year floodplain or features would be located to avoid 

impacts. The Project would cross the FEMA high-risk flood zones of the Etiwanda 

Creek/Channel, Mojave River, and Lytle Creek. For the Etiwanda Creek/Channel crossing, the 

Project would fully span the floodplain and would not result in effects because the Etiwanda 

floodway is contained within the channel, which is owned and maintained by the San 

Bernardino County Flood Control District. Based on the initial project design, bridge columns 

would be placed within the floodplains of the Mojave River and Lytle Creek. The bridge columns 

would be placed next to existing I-15 bridge columns to minimize potential impacts and would 

result in minimal to no new redirection of flood flows or net rise. As demonstrated by 

preliminary hydraulic analyses, the Project is not anticipated to result in effects that would 

impede or redirect flows, as described below. 

Preliminary modeling was conducted for the pre-and post-project condition for Lytle Creek and 

the Mojave River. Results of the HEC-RAS models are provided in Tables 1 and 2. Flow rates 

were taken from the FEMA FIRMs. 

The proposed Lytle Creek Bridge is 1,982 feet long and has 112-foot bridge spans with columns 

placed between the existing northbound and southbound I-15 bridges. The I-15 bridges have 

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equivalent spans and columns placed in line with the flow at the same location along the creek 

cross-section. 

The proposed Mojave River Bridge is located in the median of I-15. It would include bridge piers 

at the same spacing of the existing I-15 bridge that currently crosses the Mojave River channel 

bottom. The I-15 bridge would also be widened on the upstream and downstream sides of the 

existing bridge, with proposed piers aligned with existing piers. 

As shown in Tables 1 and 2, the model results show no increase in water surface elevation for 

Lytle Creek and a small increase of 0.16 foot (1.9 inches) in the Mojave River Channel for a 

distance of approximately 1,600 feet upstream of the bridges, which is well within the 

minimum freeboard required of the 100-year channel under bridges as per the Caltrans 

Highway Design Manual. 

Table 1. HEC-RAS Model Results for Lytle Creek 

Lytle Creek Station 

Flow Rate 

(cfs)1 

Pre-Project Model 

Water Surface 

(feet) 

Post-Project Model 

Water Surface 

(feet) 

Change in 

Water Surface 

(feet) 

10075 29,800 1,975.5 1,975.5 0.0 

10748 (right-of-way) 29,800 1,993.6 1,993.6 0.0 

11215 (downstream of bridges) 29,800 2,007.8 2,007.8 0.0 

11476 (upstream of bridges) 29,800 2,016.3 2,016.3 0.0 

11813 (right-of-way) 29,800 2,025.2 2,025.2 0.0 

12422 29,800 2,036.9 2,036.9 0.0 

Notes: 1. Flow rate is for the 100-year storm event. 

Table 2. HEC-RAS Model Results for Mojave River 

Mojave River Station 

Flow Rate 

(cfs)1 

Pre-Project Model 

Water Surface 

(feet) 

Post-Project Model 

Water Surface 

(feet) 

Change in 

Water Surface 

(feet) 

1401 26,500 2,700.5 2,700.5 0.0 

1908 (downstream of bridges) 26,500 2,702.8 2,702.8 0.0 

2225 (upstream of bridges) 26,500 2,706.0 2,706.1 0.1 

2917 (700 feet upstream) 26,500 2,707.4 2,707.6 0.2 

4708 26,500 2,711.4 2,711.4 0.0 

Notes: 1. Flow rate is for the 100-year storm event. 

During final design, hydrology and hydraulics analyses for the Project would be completed to 

confirm whether final column placement in the Mojave River and Lytle Creek floodplains would 

result in a net rise in water surface elevation and/or impede or redirect flows at these two 

locations. 

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Preliminary modeling using the conceptual design for the Lytle Creek and Mojave River Bridge 

has been conducted as part of this analysis. A final HEC-RAS analysis will be conducted as part 

of the Design-Build process. Portions of the rail alignment that use track support columns 

located in the 100-year floodplain would be evaluated for upstream flooding impacts using the 

HEC-RAS model or similar. Modeling would be completed and evaluated by a registered 

professional during the design-build process. The design plans would incorporate all feasible 

recommendations of the final HEC-RAS analysis such as placement of columns in line with 

existing columns already in the floodplain and in the direction of flow. 

The Project would increase the amount of impervious surfaces, and, thus, the amount of 

stormwater runoff, in some areas, such as along I-15 where the pavement would be widened to 

place the track in the median. However, no effects are anticipated on floodplains from 

increased flows because the Project would follow applicable agency requirements for flow 

control. In addition to the planned hydrology and hydraulics analyses for the Project, further 

refinement of the project design and coordination with agencies, including the San Bernardino 

Flood Control District, will occur. 

To determine the appropriate size of drainage facilities during final design for the Project, the 

total increase in impervious surface will be included in the hydraulic calculations to determine 

the increase in peak storm discharges resulting from the Project. The 100-year, 24-hour storm 

event will be used in the calculations. Drainage facilities will be designed to retain flows so as 

not to contribute to additional flows in the Mojave River, Lytle Creek, or other streams or 

washes. The Project design would incorporate hydromodification facilities such as detention 

basins, infiltration basins, infiltration trenches, design pollution prevention infiltration areas, 

and other permanent BMPs included in the Caltrans SWMP. Also, drainage facilities for the 

proposed railway, as well as for station facilities and I-15 roadway, will be sized to 

accommodate the design flow. New culverts will be sized to accommodate the 100-year, 

24-hour storm flow so on-site flooding would not occur during such events. 

5.2.2. Hesperia Station 

The Hesperia Station would not affect floodplains because there are no floodplains in the 

proposed station area. 

Adding the station would add impervious surfaces and increase stormwater runoff. However, 

no effects are anticipated on floodplains because the Project would follow City of Hesperia MS4 

permit requirements for controlling peak storm water flow rates entering their systems. 

5.2.3. Rancho Cucamonga Station 

The Rancho Cucamonga Station would not affect floodplains because there are no floodplains 

in the proposed station area. 

Adding the station would add impervious surfaces and increase stormwater runoff. However, 

no effects are anticipated on floodplains because the Project would City of Rancho Cucamonga 

MS4 permit requirements for controlling peak storm water flow rates entering their systems. 

5.3. Cumulative Effects 

The Project would not contribute to cumulative effects because there would be minimal net 

rise in surface water elevations and no flood flow impediments or redirections are anticipated. 

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This will be verified through hydrology and hydraulic analyses that will be performed for the 

Project. 

5.4. Avoidance, Minimization, and/or Mitigation Measures 

Construction BMPs will be implemented prior to construction by the contractors to minimize 

the temporary effects on floodplains, and construction equipment and materials will not be 

stored within the floodplain. Any temporary effects on floodplains would be returned to 

preconstruction conditions. No additional mitigation measures are necessary. 

During operation, no mitigation would be required because virtually no effects on floodplains 

are anticipated. This would be confirmed at the final design stage when location hydraulics 

studies are completed for all bridges. 

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6. References 

Caltrans. 2019. Highway Design Manual. 

Executive Order No. 11988, 3 CFR 117 (1977). 

FEMA (Federal Emergency Management Agency). 2020. National Flood Hazard Layer Viewer. 

http://www.fema.gov/national-flood-insurance-program-flood-hazard-mapping/national-floodhazard-layer-nfhl. Accessed July 20, 2020. 

FRA (Federal Railroad Administration). 2011. DesertXpress High-Speed Passenger Train Final 

Environmental Impact Statement and Final Section 4(f) Evaluation. 

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