gas or electricity to replace or supplement the existing diesel-powered fleet, increasing the costs. In 1995, estimates for the new terminal were projected to cost from to . Notes In December 1995, the Market and Beale site was dropped for consideration as City of San Francisco planners were considering that location for a bus station. Since the Transbay Terminal itself was scheduled for demolition and redevelopment, the site of the Transbay Terminal was endorsed by PCJPB as the future downtown terminal. Transbay Transit Center development While a draft environmental impact report was prepared in 1997 for the downtown extension by the Peninsula Corridor Joint Powers Board, the report was never certified and was abandoned in an incomplete state. Subsequently, the voters of San Francisco reaffirmed the project in the November 1999 election by approving Proposition H, which mandated the extension of Caltrain to a newly rebuilt Transbay transit facility and the electrification of Caltrain. At the time, the downtown extension was estimated to cost $600 million. In 2000, the City and County of San Francisco and the Peninsula Corridor Joint Powers Authority begin the environmental review process for the revived project. The Transbay Joint Powers Authority (TJPA) is established in 2001 in order to manage the project and oversee its design and implementation. The environmental review process concludes in 2004 with the publication of the final environmental impact report (FEIR), which is certified by the TJPA. The TJPA's plan for the downtown extension splits the project into two phases. The phased plan was approved in 2006 with the adoption of the First Addendum to the 2004 FEIR. The first phase consists of the construction of the Transbay Transit Center, which contains a train box on its underground levels to accommodate Caltrain and high-speed rail. The second phase consists of the actual downtown extension, with an alignment that will carry trains from an underground station near 4th and King Station to Second Street via Townsend Street, and then from Second Street into the train box in the Transbay Transit Center. The first phase broke ground in 2010 and opened to the public on August 11, 2018. The Railyard Alternatives and I-280 Boulevard Feasibility Study In 2013, Mayor Ed Lee pushed for a revised downtown extension plan that could substantially differ from the alignment approved in the 2004 EIR. The suggested revisions included moving the alignment to the Mission Bay neighborhood in