Tunnelling works are now finished on an extension of the Muni Metro system through downtown San Francisco.
The San Francisco Municipal Transportation Agency (SFMTA) has announced that the tunnel portal entrance – the final component of the main tunnelling contract for the Central Subway Project – has been completed.
Around $1.6 billion is being spent on the Central Subway Project, which will extend the T Third Street line by 2.7 kilometres under Union Square and through to Chinatown by 2019.
Two 750-tonne tunnel boring machines (TBMs), Mom Chung and Big Alma, have constructed the 2.4-kilometre twin-bore tunnels.
The federal government is providing $942.2 million to fund the project’s construction. The remaining balance will be met by the state and local sources.
