Mount Vernon Viaduct


San Bernardino, CA


San Bernardino County Transportation Authority


$109 million

As sponsoring partner of the Traylor-Granite Joint Venture and in partnership with COWI, Traylor is executing the Mount Vernon Viaduct Design-Build Project for the San Bernardino County Transportation Authority. The original Mount Vernon Avenue Viaduct is a 1,016-foot bridge built in 1934 that spans over the Burlington Northern Santa Fe Railroad (BNSF) Railway Intermodal Yard in the City of San Bernardino. The bridge provides access to rail and mass transit facilities at the San Bernardino Santa Fe Depot and is a connecting link for pedestrians and cyclists to economic centers within the city. The bridge had severely deteriorated to the point that some of the spans had to be supported with temporary shoring. It’s considered an obsolete and deficient structure by Caltrans and has been closed several times due to structural cracking.

The scope of work includes demolishing the Mount Vernon Avenue Viaduct; preparing the site for BNSF Railway and other construction prior to shoofly completion, without impacting the railroads; and constructing a replacement structure. The new structure will be twice as wide (80-feet) and utilize drilled shaft foundations, T-Wall approach walls, cast-in-place substructure, Caltrans precast girders, partial depth precast deck panels, and a cast-in-place deck.

After receiving the first of many notices to proceed, the team began the challenging task of planning the demolition of the existing structure over 20 railroad tracks including five passenger rail tracks servicing the San Bernardino Station (three Metrolink train lines, plus Amtrak), three transcontinental freight tracks out of the LA/Long Beach Port complex, six storage tracks and six intermodal yard tracks without disrupting daily operations.

As work began, there was no tolerance for slurry water or concrete debris on the main line tracks. The team took every precaution to ensure construction would not impact BNSF or Metrolink operations.

In March 2021, a four-hour railroad closure went into effect, allowing the team to demolish the bridge spans located over the BNSF mainline tracks. The full closure occurred in the middle of the night to avoid disrupting operations.

The next phase of construction is expected to begin in July 2022 and involves building the replacement bridge with wider travel lanes, sidewalks, and bike lanes, making it a safer structure for the community.