San Diego State University Station and Tunnel
Location
San Diego, California
Owner
Metropolitan Transit Development Board
Contract Price
$82,700,000
Completion
2003
Description
1,085 ft. underground tunnel via the New Austrian Tunnel Method (NATM) at San Diego State University. Includes cast in place cut & cover tunnel (2,915 ft.), underground station, installation of mechanical, electrical, communications, and utilities.
The 37 ft. wide x 29 ft. high single-tube double track NATM design was excavated by sequential mining methods and supported by shotcrete, lattice girders and welded wire fabric. Excavation is by mechanical excavator through a conglomerate geology comprised of hard round cobbles and occasional boulders held in a sandy clay matrix.