Anticipating further federal financial help, the $1.6-billion Central Subway project in San Francisco is moving ahead with construction of an underground Chinatown Municipal Railway Metro station and has gotten a commitment to fund preparation work on the twin-bore tunnels.

The Central Subway project will extend the T Third Muni Metro Line from the Fourth Street Caltrain Station to Chinatown. Four new stations will be built along the 1.7-mi route: an above-ground station at Fourth and Brannan streets, and three underground stations at Moscone Center, Union Square and Chinatown.

The San Francisco Metropolitan Transportation Agency, which is spear-heading the project, said that SF Mayor Ed Lee met with Transportation Secretary Ray LaHood during last week’s mayors conference in Washington, D.C., and confirmed receipt of a “letter of non-prejudice” from the Department of Transportation to go ahead with one of the largest phases of the project, in this case the tunnel under Stockton and Fourth streets.

Other funding is expected from the state and city as well as a full-funding grant request of nearly $1 billion from the Federal Transit Administration, which, if passed, will be doled out in increments. President Obama’s FY2013 budget also has $150 million committed to the project, but has yet to be approved.

The $234-million tunneling phase, which will be handled by the joint venture of Barnard Impregilo Healy, Bozeman, Mont., will begin with a $50-million launch box dug on Fourth Street to accommodate the placement of two tunnel boring machines. The project will follow a deep tunneling approach in which the vast majority of the route will be 40-ft to 120-ft deep.

Meanwhile, the underground Chinatown station’s location, at 933-949 Stockton Street (at Washington Street), will be wrapped in vinyl while demolition of the vacant building gets under way this year. The wrapping features renderings of the new station design provided by the Chinese Historical Society of America and artwork from the Chinatown YMCA.

A joint venture of Parsons Brinckerhoff, Michael Willis Architects and Kwan Henmi Architects served as designers of the Chinatown station.

Bids for the construction contract of the $213-million Chinatown station opened this week.

Other bid contracts coming up include the construction of the Union Square and Moscone stations (second quarter of this year) and track work, systems and the Fourth and Brannan station (third quarter of this year).

In addition, crews are continuing to relocate utility lines around Union Square to prepare the project alignment for the Union Square Station. Completion is expected by June.

Completion of the entire project is scheduled for 2019.