The first major subway project completed in San Francisco since the 1970s, the $241-million tunnels provide two miles of rapid transit from the southeast corner of the city to Chinatown, one of the country’s most densely populated neighborhoods and a thriving commercial district and tourist attraction. Completed in April, on time and on budget, the project required managing 450-ft radius curves, meeting stringent alignment tolerances and crossing 12 ft below active Bay Area Rapid Transit tunnels without service disruption. Five cross passages were built, along with a launch box under Fourth Street, a retrieval shaft and station headwalls. The toolbox of construction methods included tunnel boring machines with mono-block cutters, jet and compensation grouting, secant and tangent pile installation, slurry walls, cutter soil mixing and sequential excavation.
CENTRAL SUBWAY TUNNEL PROJECT
OWNER San Francisco Municipal Transportation Agency (SFMTA)
LEAD DESIGN FIRM Parson Brinckerhoff Telamon JV
CONTRACTOR Barnard Impregillo Healy JV
PROGRAM MANAGEMENT/CONSTRUCTION MANAGEMENT AECOM/EPC JV
CONSTRUCTION MANAGER, TUNNELS McMillen Jacobs Associates