Central Subway Reaches Substantial Completion

The Central Subway project achieved Substantial Completion on April 15, 2015, with completion of the Portal Structure under the Interstate 80 overpass at 4th and Harrison streets, according to the McMillen Jacobs Associates website.

The website reports:
The project owner is the San Francisco Municipal Transportation Agency (SFMTA). The Program Management/Construction Management contract is held by a joint venture of AECOM and EPC, with subconsultant McMillen Jacobs Associates providing design oversight and cost estimate review during final design, and construction management (CM) and inspection services. The designer was PB/Telamon. The $241 million construction contract was awarded to Barnard/Impregilo/Healy JV. Overall program cost for tunneling and construction of four stations, the systems, and the trackwork is $1.6 billion.

The excavation of the twin bore tunnels was completed on June 11, 2014, at the Old Pagoda Theater site. The underground alignment follows 4th and Stockton streets, through the convention center, downtown San Francisco, Chinatown, and ends in North Beach. Tunnel excavation was completed with little or no settlement observed—average settlement to the surrounding structures was limited to less than 0.5 inch. The contractor also successfully performed TBM excavation under two active Bay Area Rapid Transit (BART) tunnels, which serve over 500,000 commuters, and have only 12 ft of separation between them.

The Central Subway tunnels have a 17.8-ft inside diameter and are lined with an 11-in. thick reinforced precast concrete segmental lining. The segments include both steel fiber and steel bar reinforcing. The project was completed within budget and on schedule.