SEATTLE MULTIMODAL TERMINAL AT COLMAN DOCK
Seattle
BEST PROJECT, AIRPORT/TRANSIT
Sent by: Hoffman Construction
OWNER: Washington State Ferries, WSDOT
LEADING DESIGN COMPANY: WSP USA
GENERAL CONTRACTOR: Hoffman-Pacific LLC, a joint venture
First built in 1882, Colman Dock has weathered multiple adversities during its long history, from the Great Seattle Fire of 1889 to a collision with the steel-hulled Alameda in 1912. Today , Colman Dock is Washington’s busiest ferry terminal. , with more than 10 million passengers annually. Completed on time and on budget in September 2023 after eight years of construction, this $367 million project upgraded the regional multimodal transportation hub, replacing aging and seismically vulnerable wood piles and trestle foundations with steel for its resistance and longevity.
Under the scope of the project, the existing ferry terminal and passenger facilities were demolished and rebuilt, and 7,400 tons of creosote-treated wood piles were removed from Elliott Bay, opening up an area of shoreline and nearshore habitat. The project team added a loading area and gangway, an 8,500-square-foot passenger-only ferry building, and a 23,000-square-foot LEED Silver terminal building.
Photo courtesy of Hoffman Construction
To keep construction moving at a steady pace, the project team resequenced the work, allowing for smoother transitions between phases. For example, strategically postponing the construction of the terminal building resulted in an opportunity to eliminate conflicts between demolition and rebuilding trestles.
Maintaining uninterrupted ferry operations was vital to the success of the project. As construction progressed at various points on the trestle, crews diverted traffic to facilitate both the construction work and the continuous flow of traffic. This coordinated approach allowed for the seamless progression of construction activities without affecting the ferry’s vital operations.
Photo courtesy of Hoffman Construction
To complete the utility installations beneath Colman Dock’s precast concrete trestles, the project team pioneered the use of pontoon vessels with drilled lift pods, providing a stable and adjustable platform that responded to the changing tides. This solution improved safety and accuracy, allowing crews to work continuously with tidal swings up to 14 feet wide. Meanwhile, the full laser scanning under the terminal completed during pre-construction also facilitated work on the water, ensuring the precise alignment of the newly installed girders amid the existing pile caps.
A modular steel bridge provided a pedestrian detour as construction progressed, allowing safe passage through an active job site and multiple lanes of traffic. To build the 270-foot-long two-span bridge on the pier, there could be no heavy point loads. Temporary shoring supported the structure during installation in 2019 and remained in use until November 2023. This highway-rated structure was also designed for future use.
Photo courtesy of Hoffman Construction
After local strikes affected concrete supplies at the job site in early 2022, the contractor quickly pivoted, refocusing attention on critical roadway elements that did not rely on concrete. This mitigated schedule and cost impacts while allowing crews to maintain momentum until the strikes concluded, at which point the team resequenced work to address strike-related delays.
