Sound Transit Central Link
light rail C755 project

Location: Tukwila

Owner/developer: Sound Transit

Project team: PCL Construction Services, general contractor; Tuk Construction Services, concrete contractor; Hatch Mott MacDonald Group, architect; International Bridge Technology, structural engineer; Stoneway Concrete, ready-mix supplier

Sound Transit’s C755 project was the fourth major contract of the 15-mile Link light-rail system connecting Sea-Tac Airport with downtown Seattle. The 5.5-mile project included precast segmental concrete spans, cast-in-place piers and nearly one mile of slab-on-grade work cut into the slopes of the valley.

The focal point of the project is the flagship passenger station on 154th Street. The cast-in-place structure is supported by 12 72-inch-diameter piers rising an average of 60 feet into the air. The piers are founded on 14-by-14-foot spread foundations and connect to six straddle bents and three mid-level mezzanine girders that support the mezzanine platform.

The straddle bents tie the precast segmental superstructure to the cast-in-place structure. They are 57 to 117 feet long and have multi-directional post-tensioning systems for the guideway and girders themselves. This integration required high levels of coordination and the use of 3-D drawings to avoid field conflicts between the systems and numerous embeds. The line is scheduled to open in 2009.