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About Link21

Link21 is an Integrated Rail Network for Northern California

Link21 is a long-range transportation program sponsored by the San Francisco Bay Area Rapid Transit District (BART) and the Capitol Corridor Joint Powers Authority (Capitol Corridor) to transform the passenger rail network serving the 21-county Northern California Megaregion, which includes the greater San Francisco Bay Area, the Monterey Bay area, the Sacramento area, and the Northern San Joaquin Valley. 

Link21 will make it more convenient for people to take BART and Regional Rail (commuter, intercity, and high-speed) throughout the Megaregion. The Link21 integrated rail system will:


ENABLE fast, frequent, reliable, safe, and accessible rail service


INCREASE connections between affordable housing and high-quality jobs

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IMPROVE air quality by creating viable alternatives to driving


ENHANCE Northern California's livability, economic competitiveness, and environment


MEET the future travel demands of Northern California’s growing, diverse population

During the Link21 Program development process, BART and Capitol Corridor will work with partners to identify and prioritize a number of major projects needed to create this integrated rail network. Key investments will connect, build upon, and improve Northern California's existing passenger rail service.

Link21 Will Include a New Transbay Rail Crossing

For decades, transportation leaders have recognized the need for a new transbay rail crossing between Oakland and San Francisco. The existing transbay corridor includes BART, the San Francisco-Oakland Bay Bridge, buses, and ferry service.

The existing transbay corridor is currently the most congested corridor in the Northern California Megaregion — and one of the most congested corridors in the United States.

Regional Rail does not currently cross the Bay in this corridor. However, there are many Regional Rail riders with destinations across the Bay who would benefit from a direct rail connection.

Prior to the pandemic, BART trains were frequently overcrowded. Any major disruption to service negatively impacted travelers regionwide.

Therefore, at the core of the Link21 Program is a new transbay rail crossing project between Oakland and San Francisco. The project will provide one or more passenger rail services across the Bay.

In addition to the new transbay rail crossing, the Link21 Program will include many other projects to improve the reliability, frequency, capacity, and hours of service for Northern California's rail network.

Why Link21 and Why Now?

Northern California's population is projected to reach 16 million by 2050. Looking beyond the pandemic, travel demands across the region are still expected to increase sharply in coming decades. Without changes, traffic congestion and overcrowding will worsen, threatening Northern California's status as one of the most economically productive region in the country.

The benefits of Link21 extend far beyond the San Francisco Bay Area. Link21 will facilitate new connections and open up more possibilities for business and leisure travelers. The new rail crossing could allow for many more direct trips on rail and enable other rail projects in the region to serve even more travelers.