Sound Transit South 200th Link Extension – Seattle, Washington

The South 200th Link Extension project expands the existing light rail system from Sea-Tac Airport to South 200th Street and 28th Avenue South.

The structural design involves the construction of 1.6 miles (2.6 km) of double-track light rail transit on an elevated guideway. The guideway is a precast segmental structure including twin track, and single-track box girders. Typical spans are simply supported with a maximum length of 130 ft 6 in (39.8 m). Continuous structures are used for longer spans up to 156 ft (47.5 m).

The project includes two long span bridges with main spans of 333 ft (101.5 m) and 363 ft (110.6 m) in the area surrounding the Sea-Tac Airport. Typical spans are erected span-by-span with an overhead truss, long spans are erected in balanced cantilever with cranes on the ground or on deck.