Cast-in-Place Parking Garages

Federal Way Transit Center

Location: Federal Way

Owner/developer: Sound Transit

OProject team: PCL Construction Services, general contractor; McClone Construction, concrete contractor; Hewitt Architects, architect; KPFF Consulting Engineers, structural engineer; Glacier Northwest, ready-mix supplier

More than 15,000 cubic yards of concrete was used to build the Federal Way Transit Center parking garage and bus platform. The five-level garage has 1,200 parking stalls.

In addition to the typical cast-in-place elements and post-tensioned beams and slabs, the project used several innovative applications, including a slab design that allowed the beams to be placed farther apart, which reduced the number of beams, girders and columns needed. Post-tensioned slabs are 7 inches thick.

Waterproof concrete was used on the top level, which eliminated the need for an expensive traffic-bearing waterproof membrane. More than 10,000 square feet of 10-inch-thick concrete slab was poured for the bus travel areas.

A detention vault made of concrete was located beneath the site’s access drive to handle storm drainage and water quality. The combined facility eliminated the need for two structures and took the place of a large, above-ground pond that was on the site.

Precast concrete panels were used to face a mechanically stabilized-earth wall to complement the rest of the garage.