The City of San Francisco has narrowed the potential options for connecting Caltrain and High Speed Rail to the Transbay Center and potentially across to the East Bay, redeveloping the 20-acre Caltrain Depot at 4th and King Streets, and tearing down the northern terminus of I-280 in San Francisco.

The surviving options include the possibility of re-routing Caltrain up Third Street north of 23rd, with a new underground station near Ceasar Chavez and another adjacent to the Giants’ Mission Rock project, a few blocks from the proposed Warriors’ Arena.

Prior to the Third Street twist, the City’s Planning Department was expected to deliver a meaningful list of alternatives for the San Francisco Railyard and I-280 redevelopment project by the middle of 2016, with a best-case scenario of implementation sometime after 2020 “as money and priorities allow.”

But with the second phase of Planning’s Railyard Alternatives and I-280 Boulevard (RAB) Study, which will explore the potential options and develop up to three refined plans for moving forward, now ready to roll and slated to take at least nine months and up to a year, the meaningful list of alternatives won’t be ready until mid-2017.

And assuming the alternatives are deemed feasible, follow-on phases will then include the selection of a Preferred Alternative (a 12-18 month project) and the securing of Environmental Clearances (for which another 18 months to 5 years have tentatively been budgeted).