Transportation :: Transit and Railroad
Tacoma Trestle: Reservation Junction Track and Signal Design
DEA is leading the design and public involvement for the replacement of the existing single-track, 1,625-foot-long trestle, just east of Freighthouse Square and the Tacoma Dome. The existing timber and steel trestle was built by the Milwaukee Road in the 1920s on a narrow, curving right-of-way, crossing three city streets. The replacement structure will increase the bridge width to a modern two-track structure, and will improve safety and maintenance. To meet Sound Transit’s aggressive schedule to open the bridge by 2017, the improvements must be within the existing right-of-way so that they avoid lengthy property purchases. Additionally, careful construction phasing will be critical to the project’s success for reducing or eliminating impacts to Sound Transit’s expanding Sounder Commuter Rail operations, the existing daily operations of Tacoma Rail freight trains, and operations within Sound Transit’s adjacent link light rail maintenance facility. Segmental construction is just one of many options being considered for reducing these impacts. The design will also account for the historic nature of the existing bridge, future Amtrak train operations, and expanded Sounder operations, and for the continued access under the bridge via city streets.
As part of this project, DEA delivered the design of a 600-foot-long station platform connected to the Tacoma Trestle Rail Bridge. Tasks included all stages of the design, from the preliminary to the IFC stage. The project included 400 feet of elevated platform and 200 feet of on grade platform, steel canopy, and steel stair structure. The platform is supported on steel pipe piles, CIP columns, and precast hollow core slab girders and is self-supported for the gravity forces, laterally supported by a combined structure with the main trestle bridge. The hollow core slab girders served as a conduit for the civil and electrical utilities. High level coordination between all disciplines was required.