Tetra Tech INCA provided final design services for LINK Light Rail Section S700: International District to Royal Brougham to the West Beacon Hill Tunnel. INCA was responsible for final structural design services for this light rail alignment, including aerial structures, transition structures, and embedded and direct fixation track slabs. This $55-million project was the first section of Sound Transit’s LINK light rail corridor to go to final design.

The structural effort included:

• Aerial structures and retaining walls including connections to the maintenance facility.
• Drilled shaft foundations in poor soil conditions with large seismic forces and a stringent two-level design criteria.
• Complex trackwork loads on the aerial structure (numerous turnouts and complex geometry).