The City and County of San Francisco, the Alameda – Contra Costa Transit District (AC Transit), and the Peninsula Corridor Joint Powers Board (Caltrain) proposed to replace the underused original Transbay Terminal with an entirely new and more functional building at roughly the same location. The final Environmental Impact Report (EIR) was published in 2004, and construction began in August 2010 on Phase 1, the new Transbay Transit Center (TTC) building. A new outdoor temporary terminal was opened nearby to serve commuters during construction of the new transit center.