Mount Vernon Viaduct

Traylor, as sponsoring partner of the Traylor-Granite Joint Venture and in partnership with COWI, is leading the Mount Vernon Viaduct Design-Build Project for the San Bernardino County Transportation Authority. The original 1,016-foot-long Mount Vernon Avenue Viaduct, built in 1934, spans the Burlington Northern Santa Fe Railroad (BNSF) Railway Intermodal Yard in San Bernardino, CA. This critical structure connects pedestrians, cyclists, and vehicles to economic centers and transit facilities.

The project involves demolishing the aging viaduct, preparing the site for construction without disrupting the 20 active rail tracks below, and constructing a modern replacement structure that is twice as wide (80 feet). Key features of the new viaduct include drilled shaft foundations, T-Wall approach walls, and a cast-in-place deck. It will also provide wider travel lanes, sidewalks, and bike lanes, enhancing safety and accessibility for the community. In March 2021, demolition of bridge spans over BNSF’s mainline tracks began during a carefully planned four-hour nighttime closure to minimize disruptions to rail operations.

As of May 2024, the project has made significant progress. The team successfully completed the double-T girder placement on the Third Street Bridge, advanced work on the north and south approach walls, and began casting bent caps for the main bridge using a form cycling system to accelerate construction. All precast concrete components are complete, and in September 2024, the team installed 61 girders over the BNSF Railway yard, including 182-foot-long girders—the longest precast pretensioned girders ever placed in California. The Mount Vernon Viaduct project remains on track for completion in the second half of 2025.