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Link21 Program Development

Planning for the Future of Train Service

For decades, rail agencies have envisioned new ways to improve Northern California’s existing train network and serve our communities. Link21 is building on a number of public mandates to bring this vision to reality.

The Link21 Team is steadily developing the Program and moving it forward. Recognized as an “anchor” program in MTC’s Plan Bay Area 2050, Link21 will help unite and support communities throughout the Megaregion.

The Link21 vision involves building a new train crossing of the Bay that will connect more communities throughout the Megaregion. A new train crossing between Oakland and San Francisco was included in two major regional funding measures: BART Measure RR (70.5% approval in 2016) and Regional Measure 3 (55% approval in 2018). Both measures presented voters with information on the new crossing and helped fund Link21. A new crossing is also included in the 2018 State Rail Plan.

We will evaluate how a second train crossing of the Bay and other improvements to the train network within Link21 can benefit the Northern California Megaregion. Improvements to the transbay corridor — and other rail improvement projects around the Megaregion — will provide cascading benefits by improving service throughout the rail network, even in locations that are far from those projects.

Building Blocks for Better Travel

The Link21 Program sponsors and partners want to deliver the greatest value for taxpayers’ investments. Here are the four foundational building blocks that are helping to shape the Link21 Program.

  • Markets: people and their travel patterns. The Link21 Team is identifying the most-promising travel markets around the Megaregion to target for train service improvements, resulting in a more optimal train network for all.
  • Service: your experience as a train rider in Northern California. Link21’s overarching goal is to transform the passenger experience. We can do that by improving train service and making our network more connected, convenient, and accessible.
  • Train Technology: the types of trains we're going to run. In the next 15 years, trains in California will be converting to zero-emission vehicles. Operators throughout California will be running modern, fast, and environmentally-friendly trains.
  • Infrastructure: the physical improvements needed for the expansion of service and markets.

Understanding travel patterns, establishing service improvements, and deciding on optimal train technology and infrastructure will guide future planning efforts. The Link21 Team has begun defining these four building blocks, but formal decisions to shape the Program still lie ahead. Link21 will continue analyzing and adding detail to these topics in the coming years. We encourage the public to provide feedback on the Program so far. 

Program Timeline

Link21 is committed to hearing people’s lived experiences and understanding their community’s needs. Engagement, outreach, and equity is being integrated throughout all phases of program planning.

Phase 0

Program Definition

2019-2022 (Complete)

Phase 1

Concept Identification

2022-2024 (We are here)

  • Preliminary Business Case
  • Identify Concept (with options)

Phase 2

Project Selection


  • Intermediate Business Case
  • Project Alternative(s)
  • Environmental Review
  • Final Business Case & Implementation Strategy

Phase 3

Project Delivery


  • Funding Strategy
  • Design
  • Construction
  • Testing & Commissioning
  • Ready for Service

Phase 0 began in 2019 and wrapped up in early 2022. Phase 0 set the foundation for Link21. Through analysis and early stakeholder and public engagement, BART and Capitol Corridor established the vision, Goals and Objectives, and Business Case, which is a decision-making framework that will be used to help identify and evaluate potential Link21 projects. Early work also included a Market Analysis, which was completed in 2021 and was the most detailed and comprehensive travel analysis ever performed for the 21-county Northern California Megaregion

In early 2022, Link21 transitioned from Phase 0: Program Definition into Phase 1: Concept Identification. This transition marks a major milestone for Link21. We’ve accomplished a lot in the first two years of the Program. Learn more about the the engagement opportunities that occurred during Phase 0. 

Phase 1 began in 2022. Phase 1 is focused on exploring and assessing potential concepts for a new crossing of the San Francisco Bay as well as other key service and supporting infrastructure improvements for both BART and Capitol Corridor.

Concepts are informed by stakeholder and public input, the Market Analysis, ongoing technical studies, service planning, ridership modeling, and an environmental assessment of community constraints and opportunities. Throughout Phase 1, concepts will continue to be assessed to understand benefits and tradeoffs as Link21 explores options to meet Program goals and desired service improvements.

By the end of Phase 1 in early 2024, the Link21 Team will recommend what project(s) will move forward into environmental planning in Phase 2.

Learn more about Phase 1 planning activities in our Phase 1 Guide.

Phase 2 is estimated to begin in 2024. In Phase 2, Link21 will advance and develop individual projects. BART and Capitol Corridor — with input from partner agencies and the public — will identify and prioritize project alternatives that should be taken to the design and construction phase. Other agencies or jurisdictions may take responsibility for delivering related project(s) and improvements.

Phase 2 will include a detailed environmental analysis. The public's contributions, opinions, and feedback will continue to shape and guide the project(s). 

Phase 3 is estimated to begin in 2029. Final engineering and design will be completed for the project(s). Each project will then be constructed, tested and commissioned, and made ready for service. 

All phases are dependent on available funding. BART and Capitol Corridor will continue to identify funding sources and work to secure the support and funding needed to bring the full Link21 vision to reality.