San Francisco Municipal Transportation Agency (SFMTA), which oversees all surface transportation in the city, including the Municipal Railway (Muni), announced the initial notice to proceed (NTP) authorization for the Central Subway's largest construction contract, $233.5 million, will be issued this week.

The SFMTA will move forward with the first of three NTP authorizations for the tunneling contract, awarded in June. This NTP allows the contractor to proceed with ordering the two tunnel boring machines (TBM) needed to construct the twin bore tunnels for the underground portion of the Central Subway Project.

The contract has three distinct NTP authorizations: NTP 1 ($35M) authorizes procurement of the TBMs; NTP 2 ($36M) authorizes construction of the tunnel launch box and contractor's work area; and NTP 3 ($163M) authorizes commencement of tunneling, which includes construction of approximately 8,240-foot-long precast concrete segmental lined twin-bored guideway tunnels, construction of five emergency cross passages between bored tunnels and construction of station end walls.

A construction approach called "deep tunneling" will be used to construct the Central Subway. Deep tunneling allows most of the work to be done below ground, reducing disruption on the surface by using the TBMs, a technology that has been used extensively throughout the world. Deep tunneling has great potential for controlling project costs by minimizing surface construction staging, reducing utility relocations and shortening construction time.

The only visible tunneling activity will occur at the portal construction location (4th Street between Bryant and Harrison streets) and at the excavation site (Columbus Avenue at Union Street).

The second utility relocation contract began this spring and is underway on Stockton Street to prepare for construction of the Union Square/Market Street Station.

Central Subway business outreach, conducted at more than 60 events and in collaboration with nearly 50 partners, has resulted in more than $115 million in contract awards combined for local, disadvantaged or small business enterprises (SBE) to date. In fact, six of the 11 prime contractors working on the Central Subway Project are certified as SBE, DBE or LBE.

Thus far, the project will bring in nearly $90 million to local businesses and create thousands of job opportunities.