ASCE Los Angeles Section

Colton, CA

The Colton Crossing Flyover involved the construction of an 8,150-foot flyover structure to take Union Pacific Railroad’s east/west tracks 35 feet above the north/south tracks of BNSF Railway. The project eliminated the at-grade rail-to-rail intersection bottleneck with an average of 125 trains crossing daily.

The project featured an innovative design, featuring an unprecedented amount of cellular concrete at an unparalleled height. Though never before used in this quantity or at this height, cellular concrete offered the exact properties needed to solve the challenge posed by the site constraints. Cellular concrete - a cement and water slurry infused with very small air bubbles- has a 70 percent lower density than earth backfill. The strong, yet lightweight nature of the cellular concrete eliminated the need for conventional retaining structures because of its self-supporting quality. Therefore, the design no longer required replacement of underlying soils to support a heavier structure and vastly improve seismic performance. This novel design also aided construction within the confined site by reducing the amount and size of equipment necessary.

The Colton Crossing Flyover improved the efficiency of freight movement for the more than $287 billion in goods that flow through California’s port s annually, making a critical impact on the Southern California and U.S. economies. Reducing train and vehicle delays improved the environment and community with better air quality and lower noise levels. The project also improved safety and contributed to the visual landscape of the site. See attached document for more details.

The design team negotiated a web of project complexities to deliver a successful project that satisfied the needs of more than 20 project stakeholder groups. In addition to the site challenges, the team collaborated with a massive public-private partnership to meet an aggressive project schedule deemed necessary to secure U.S. Department of Transportation’s (DOT) Transportation Investment Generating Economic Recovery (TIGER) Grant funding.

Working with more than 20 stakeholder groups to overcome the site constraint s and right-of-way challenges, designers delivered the first ever flyover structure to feature two tracks and a continuous maintenance. The project involved 11 outside public agencies, nine separate utilities and numerous departments within the two largest freight railroads in the U.S. and two passenger rail lines. Leadership and proactive communication played critical roles in functioning smoothly as a team and developing consensus on critical decisions. Because UPRR needed to maintain rail service, the flyover alignment could not be located on the existing tracks’ alignment, but had to be designed to connect to it without long service disruptions. A confined site footprint and right-of-way issues created challenges to tie in the new flyover both horizontally and vertically. The selected alignment did not permit space for sloped embankment s, so the flyover required retaining structures for the bridge approaches. A conventional retaining wall approach including soil replacement and shoring to overcome poor soil amounted to 40 percent of the original $202 million cost estimate for a traditional design solution.

The project received the San Bernardino and Riverside Counties Branch Outstanding Private Sector Project of the Year Award. The project has also been selected as one of five finalists for the ASCE’s Outstanding Civil Engineering Achievement Award (OCEA).

See attached document for more details and news articles.

The Colton Crossing Flyover is an “at grade” rail-to-rail intersection situated about 50 miles east of Los Angeles. With an average of 125 crossings daily, it is one of the busiest and most congested railroad crossings in the U.S. Engineering firm HDR designed an innovative approach to eliminating the chokepoint by constructing an 8,150-foot flyover structure to take the Union Pacific Railroad’s east-west tracks 35 feet above the north-south tracks of the BNSF Railway.

The Colton Crossing Flyover is an “at grade” rail-to-rail intersection situated about 50 miles east of Los Angeles. With an average of 125 crossings daily, it is one of the busiest and most congested railroad crossings in the U.S. Engineering firm HDR designed an innovative approach to eliminating the chokepoint by constructing an 8,150-foot flyover structure to take the Union Pacific Railroad’s east-west tracks 35 feet above the north-south tracks of the BNSF Railway.