SAN FRANCISCO (Map, News) - Muni officials say they are on schedule to open a new underground subway system running from the downtown Caltrain station to Chinatown by 2016 — a project which could also lay the groundwork for a future extension to Fisherman’s Wharf.

As planned, the Central Subway project is a 1.7-mile extension connected to the 5.1 mile Third Street Light Rail that includes a new stop at Fourth and Brannan streets, head underground at Bryant Street and conclude in Chinatown.

Estimated to cost $1.4 billion, the Central Subway would cross beneath Market Street, as well as the BART and Muni tunnels, and end at Stockton and Jackson streets. While the original plan included four new underground stations — located at Moscone Center, Market Street, Union Square and Clay Street — the new updated plan combines the Market Street and Union Square stations.

The extended station will have two entrances: a northern entrance along the Geary side of Union Square and a southern entrance that connects to the Powell Street BART and Muni station. An underground concourse would take passengers from the Central Subway platform to the Powell station, a four to five minute walk, according to John Funghi, a senior project manager with the Municipal Transportation Agency.

“One of the things we’re looking at is ways to make that walk pleasant and enjoyable,” Funghi said Wednesday at a forum hosted by the San Francisco Planning and Urban Research Association. “We have the ability to have retail and incorporate art to make that an enjoyable, beautiful walk.”

According to a Muni timeline, a final design for the Central Subway project is slated for completion by 2010, with construction taking five years and the new route being ready to run in 2016. Construction impact would be minimal, said Funghi, since most of the work would be done underground, with tunnel boring machines.

While the Central Subway — considered the second phase of the newly opened Third Street Light Rail project — will end at Stockton and Jackson streets, Muni is considering a plan to continue boring its tunnel up through the North Beach area, which “would lay the groundwork for a future phase three of this project,” Funghi said.

In 2002, Muni estimated a North Beach extension of the Central Subway would cost approximately $554 million, according to a report the transportation agency published in a SPUR newsletter. Current cost estimates are not available, Muni officials said. According to Funghi, just to bore a tunnel under North Beach would cost $70 million.

Central Subway

The proposed extension would connect to the Third Street Light Rail and include a stop at Fourth and Brannan streets. The line will run underground at Bryant Street, cross beneath Market Street and end in Chinatown, at Stockton and Jackson streets.

beslinger@examiner.com