The Pennsylvania Avenue Extension project will support future uninterrupted passenger rail service through San Francisco. The project will place current Caltrain and future California High-Speed Rail passenger rail lines underground, allowing transit, pedestrian, bicycle, and vehicle traffic to flow uninterrupted and improve safety for all road users.
The Transportation Authority is studying potential tunnel alignments that will have trains running underground along Seventh Street and Pennsylvania Avenue, in order to remove existing Caltrain rail crossings at Mission Bay Drive and 16th Street and eliminate the need for road users to wait while trains cross.
The Transportation Authority has completed the Pennsylvania Avenue Extension Project Initiation Report (PDF), which developed and evaluated a range of conceptual alignment alternatives. The alignment alternatives reflect different tunnel lengths, configurations and construction methods, with varying implications for existing and potential future station locations along the alignment.
The project was originally recommended by the San Francisco Planning Department’s Railyard Alignment and Benefits Study, which was completed in 2018. The project will be designed to connect to the Downtown Rail Extension, also known as The Portal, which will bring Caltrain and California High-Speed Rail from 4th and King streets to the Salesforce Transit Center.
The Transportation Authority is closely coordinating the Pennsylvania Avenue Extension work with related initiatives, including:
- The Portal led by the Transbay Joint Powers Authority
- The Southeast Rail Station Study completed by the SF Planning Department
- The Bayview Station Study led by the Transportation Authority
- Multi-agency planning and coordination for the 4th and King Railyards
Increase connectivity between Mission Bay, Potrero Hill, and Design District/SOMA neighborhoods
Improve safety of pedestrian, bicycle, and vehicle traffic on surface streets
Enable improved efficiency of Caltrain operations and service planning
Improve quality of life in surrounding neighborhoods by substantially reducing existing congestion and air quality and noise effects associated with existing Caltrain and future rail expansion
Timeline and Status
2020 – 2022: Project Initiation
Development of preliminary technical planning study and preparation of Project Initiation Report
In July 2022, the Transportation Authority Board approved the Pennsylvania Avenue Extension Project Initiation Report, which identified three broad alternatives, based on a preliminary evaluation of constructability, rail operations and interfaces, traffic impacts, utility conflicts, geotechnical and hydrological considerations, cost, schedule, risk, environmental considerations, and benefits.
2023 – 2024: Pre-Environmental Bridging Study
Pre-Environmental Bridging Study to prepare the project technically and organizationally for subsequent environmental review:
- Refinement and analysis of alternatives
- Public and stakeholder engagement
- Implementation approach
Presentation of project pre-environmental report and recommendations for next steps
Environmental review and preliminary design; final design; procurement and construction. The project timeline is subject to funding availability.
The Transportation Authority is leading the conceptual design study work for the Pennsylvania Avenue Extension in close coordination with:
- City and County of San Francisco, including SFMTA, SF Planning Department, SF Public Works, and SF Public Utilities Commission
- Caltrain/Peninsula Corridor Joint Powers Board
- California High-Speed Rail Authority
- Transbay Joint Power Authority
The Transportation Authority Board appropriated $2.5 million in Prop K funds for the Pre-Environmental Bridging Study phase.
Funding for construction will be identified in later phases of work.
Pennsylvania Avenue Extension Tunnel Alternatives Under Study
This alternative would provide a tunneled rail alignment (either single bore or twin bores) from the Downtown Rail Extension to a point immediately north of Cesar Chavez Street. This long alternative requires replacement of the existing 22nd Street Caltrain Station.
This alternative would provide a tunneled rail alignment (either single bore or twin bores) from the Downtown Rail Extension to a point immediately north of the existing 22nd Street Caltrain Station. This alignment would require some modifications to the 22nd Street Station, as well as a more complex interface with existing Caltrain tunnels.
This alternative would provide a “split-tunnel” configuration, with southbound and northbound tunnels separated, with the northbound tunnel within the existing Caltrain right-of-way, and an interface point north of the 22nd Street Station. This alternative would allow for preservation of the existing 22nd Street Caltrain Station, with minor modifications. However, this alternative would have a more significant impact on Caltrain operations during construction.
In 2022, the SF Planning Department completed the Southeast Rail Station Study. The study assessed alternative locations for a station in the Pennsylvania Avenue Extension study area (including the option of retaining the existing 22nd Street Station), as well as sites for a Caltrain Station in the Bayview. The SF Planning Commission endorsed the study and made recommendations for the Bayview and Potrero/Dogpatch/Mission Bay neighborhoods:
- Advance Bayview station study independent of the Pennsylvania Avenue Extension for restoration of Caltrain services
- Next phase of Pennsylvania Avenue Extension project development should address station-related considerations within the Pennsylvania Avenue Extension alignment
The Bayview Station Study will finalize the selection of a station location (Evans Avenue or Oakdale Avenue) along the existing Caltrain alignment in the Bayview. The Transportation Authority is currently leading the Bayview Station Study.
The Pennsylvania Avenue Extension Pre-Environmental Study will assess station-related considerations within the potential Pennsylvania Avenue Extension alignment, including with respect to the existing 22nd Street Station.
Reports and Documents
Executive Summary: Rail Alignment and Benefits Study, SF Planning, 2018 (PDF)