City of San Francisco questions alignment of “Downtown Extension” to Transbay Terminal

At last week’s Transbay Joint Powers Authority Board meeting, Board Member Gabe Metcalf, the representative of San Francisco Mayor Lee on the Board, and the executive director of transportation policy think tank SPUR, questioned the tight “s-curve” alignment that is currently planned for the Downtown Extension (TDX) to Transbay Terminal, which will bring Caltrain and High Speed Rail trains into the heart of downtown San Francisco.

In his comments, Director Metcalf stated, that “the various partners that will be necessary to connect Caltrain to the Transbay Terminal do not agree with the alignment. The San Francisco mayors office does not agree with this alignment, I don’t believe that the San Francisco County Transit Authority does. Getting agreement with these parties in addition to High Speed Rail and Caltrain is the task before us.”

The Downtown Extension to Transbay Terminal is not yet funded; the megaproject is projected to cost $2.5 billion; the City of San Francisco and the San Francisco County Transit Authority are key partners in funding the project and pursuing further federal funding, and these partners have concerns.

The alignment, which was environmentally cleared in 2004, is technically challenging because of a tight “s-curve” to navigate the crowded underground landscape in Downtown San Francisco, and to support the existing Caltrain station at 4th and King. The tight curves will require trains to travel very slowly, reducing travel time and throughput into the station.

At last week’s meeting, the TBJPA board considered and approved a $1.3 million, 2-year contract to update the 2004 Environmental Impact Report for the Downtown Extension, to take into account changes based on new information about High Speed Rail.

The changes will improve the “Extremely tight curves” issue described by Clem Tillier in his classic 2009 blog post on design issues with the Transbay terminal and DTX. The changes cover the environmental impacts of widening the turn radius of the “throat” and adding longer platforms for longer High Speed Rail trains.

However, some critics have been arguing that these moderate changes don’t go far enough. In this presentation to the San Francisco County Transportation Authority, Roland Lebrun suggests that deep tunneling technology, which has become more sophisticated and lower in cost since the plans were approved a decade ago, could save money and reduce the severe impacts of “cut and cover” construction.

Another issue and opportunity alluded to by Director Metcalf and Director Jane Kim (supervisor for District which includes Mission Bay and SOMA, was San Francisco’s interest in developing the land currently used for rail storage at 4th and King. The railyards, which were built when the area was industrial, now occupy prime downtown San Francisco real estate. If the location of the station were moved, perhaps the “s-curve” could be flattened and land currently used for railcar storage could be used for more valuable office and residential use.

Executive Director Maria Ayerdi-Kaplan argued strongly against expanding the scope of the immediate environmental project to look at these larger issues. The changes to throat design, platform length, and ventilation were required by the Federal Railroad Administration as a condition of accepting a $400 million grant to move forward with the project. Without making these moderate changes now, the Transbay project would need to return the money.

However, Directors Metcalf and Kim both encouraged nearterm discussion – at the December or January board meeting – to air these alignment issues. San Francisco wants these issues addressed before working to raise the funds needed to complete DTX.

While the team working on Transbay/DTX project are understandably extremely leery of changes that would affect the ongoing project, the result of the alignment decisions will shape downtown San Francisco for the next 50 to 100 years.

For advocates who have been asking these questions, this is an important opportunity to review this major project and assess if the current design is truly the most effective option, or if there are better options to be had. Supporters of the Downtown Extension should watch these discussions closely.