SFMTA plans new 1.3 million square foot transit facility at Potrero Trolley Coach Division

The City of San Francisco held a significant meeting on July 4, 2025, to discuss the proposed redevelopment of the SFMTA Potrero Trolley Coach Division maintenance and operations facility located at 2500 Mariposa Street. The existing facility, which includes a two-story building constructed in 1915, is recognized as a historical resource under the California Register of Smart Resources. The proposed project aims to demolish this facility and replace it with a new, expansive 1,300,000 square foot transit facility.

The new structure is designed to include a modernized transit facility standing 75 feet tall, accommodating 720,000 square feet of space for 213 buses, 97 non-revenue vehicles, and 18 bus maintenance bays, along with battery electric infrastructure. Additionally, the project plans to incorporate up to 75 housing units and 33,000 square feet of commercial space.

The draft Environmental Impact Report (EIR) highlighted significant and unavoidable impacts resulting from the demolition of the historic building and potential air quality issues due to toxic air contaminants. Although the EIR proposed four mitigation measures to address the historical resource impact—such as documenting the existing building and developing an interpretive display—the impacts were deemed significant and unavoidable.

To address air quality concerns, mitigation measures including an off-road construction equipment emissions minimization plan and an emergency diesel generator health risk reduction plan were suggested. However, these measures also did not reduce the air quality impacts to a less than significant level.

The draft EIR explored various alternatives to the proposed project, including a full preservation alternative that would retain the entire office wing without vertical additions, thereby reducing the historical resource impact to less than significant. This alternative would also lower air quality impacts to a less than significant level. A partial preservation alternative was also discussed, which would retain the office wing but allow for some new construction above it, resulting in a significant and unavoidable historical resource impact.

Another alternative, the transit facility plus commercial only option, would maintain the same transit and commercial capacity as the proposed project but exclude residential units. This alternative would similarly face significant unavoidable impacts on the historic resource due to demolition.

The meeting concluded with a clear emphasis on the need for careful consideration of the historical significance of the site and the environmental impacts associated with the proposed redevelopment. Further discussions and evaluations of the alternatives will be necessary as the project moves forward.