Seismic Design of the Seattle Multi-Modal Ferry Terminal at Colman Dock

The Seattle Multi-Modal Ferry Terminal at Colman Dock serves 9 million passengers a year, is being replaced to improve seismic reliability, accessibility, and remove 7,400 tons (6,710,000 kilograms) of creosote-treated piles. The project consists of replacing 150,000 square feet (139,000 square meters) of timber trestle with a steel pile-supported concrete trestle, five buildings, and one pedestrian loading structure. The trestle will be the building foundations and vehicle bridge between Alaskan Way and the ferries. This paper addresses several seismic challenges. Because the buildings are founded on the trestle, the structure must efficiently meet the seismic requirements of the Seattle Building Code and the Washington State Department of Transportation Ferries Division Terminal Design Manual. Combining the buildings and trestle, uniquely impacts the seismic response by lengthening the building periods. Structure detailing was developed to accommodate drift requirements of the buildings, plumb pile trestle, battered pile trestle, and sea wall.