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Sound Transit replaces wooden train bridge over former Tacoma tidelands

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$160 million project promises faster passenger rail service

For more than a century, the wooden single-track Tacoma Trestle has served as a bridge over former tidelands. In mid-February, service on the timber trestle – which has seen major repair, complete replacement and many renovations over the years – ends and a new era of higher-capacity rail transportation begins. After seven months of building a new steel bridge adjacent to the old trestle, Sound Transit is ready to move Sounder commuter rail service to the new tracks. The new 1,600-foot bridge between the Tacoma Dome Station and East M Street is part of a $160 million project to increase Sounder service and improve reliability for Amtrak passenger trains. 

To minimize disruption, most of the work to transfer service from the aging timber trestle to the new bridge will take place over Presidents’ Day weekend. Work will begin after the morning commute on Friday, Feb. 17, and end by the evening commute Wednesday, Feb. 22. The first stage of the crossover will involve sliding a steel girder into place and demolishing the corresponding section of the old trestle before restarting commuter rail service. 


Graphic of Tacoma Trestle cutover work

Bus shuttles for Sounder riders

During the switchover, Sound Transit will provide express bus shuttles for Sounder riders between Lakewood and Puyallup Stations. 

Old timbers hold a rich history of rail service

Built in 1909 by the Milwaukee Railroad on swampy, unstable and poorly compacted soil, the Tacoma Trestle once carved a straight path from East K Street to the railroad’s freighthouse on East 25th Street. Piles driven some 126 feet into the ground enabled the trestle to bear 300-ton locomotives. Over the years, weight and vibration from heavily loaded trains drove support piles even deeper into the dampness. Tracks sagged and the constant ground moisture hastened wood rot. The railroad had a choice: keep replacing timbers or start all over. In 1937, crews built a new wooden trestle that snaked around something that was once in its path, leading to the name the Tacoma S-Turn Trestle. With the advent of lighter trains, track settling eventually ceased, but wood rot remained a problem – as was the mysterious S-curve. Only one train could cross the trestle at a time, and then only at speeds of less than 10 mph.

In 2000 Sound Transit Sounder began commuter rail service between Tacoma and Seattle. To support rapidly expanding rail operations, the aging, earthquake-vulnerable trestle needed major structural upgrades or replacement. Thanks to voter approval of the Sound Transit 2 expansion plan in 2008, Sound Transit received funding to build a better bridge. A $10 million grant from the U.S. Department of Transportation enabled Sound Transit to accelerate the project schedule from 2023 to 2017. Additional support has come from Federal Transit Administration and Federal Railroad Administration grants. 

New bridge means faster, more reliable trips

When complete next September, the double-track bridge will eliminate bottlenecks; trains will be able to cross at speeds of up to 35 mph. The Tacoma Trestle Track and Signal Project includes demolition of the old trestle, construction of new tracks and a crossover track, sign upgrades, road improvements, utility relocation and erosion control. Sound Transit is also working with the Washington State Department of Transportation to extend the length of the station platform to accommodate longer Amtrak Coast Starlight trains that will begin using the track next September. The longer platform will enable Amtrak trains to stop at the station without blocking East C and East D streets.

Preserving trestle memories

While Tacoma’s S-Turn Trestle will soon be gone, Sound Transit is making sure its history is not forgotten. In addition to incorporating the Milwaukee Railroad logo into the design of the new bridge, Sound Transit is creating an interpretative exhibit highlighting the history and important characteristics of the trestle to be on permanent display in Freighthouse Square. Incorporating pictures, stories and original trestle hardware, the exhibit will serve as a reminder of how far rail service has traveled over the years.

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