Frequently Asked Questions

Link21 is a Program of system improvements for BART and Regional Rail (including commuter, intercity, and high-speed) that will transform the Northern California Megaregion’s passenger rail network into a faster, more integrated system, providing safe, efficient, equitable, and affordable travel for all types of trips. Other partner agencies in the Megaregion are also implementing rail projects that will contribute to this transformation.

The Program will include a new transbay rail crossing between Oakland and San Francisco. The new crossing will improve travel and quality of life in the Megaregion.

Link21 builds off of years of research, planning documents, and studies. The Program plays a critical role in rail planning for the Megaregion and will implement components of the California State Rail Plan. Recognized as an anchor program in the Metropolitan Transportation Commission's Plan Bay Area 2050, Link21 is working closely with the California State Transportation Agency (CalSTA) and other partners to transform passenger rail in Northern California.

Link21 aims to create better connections, improve ease of travel, promote sustainability, support the Megaregion’s economy, and advance equity.

In Link21's planning phase, we’ll identify what projects and facilities are needed for Link21. Schedule details will be refined and updated as the Program progresses. Where possible, Link21 aims to plan and deliver benefits by 2040. Associated projects vital for the Link21 network will likely be fully operational before then. 

Link21 will study options to improve passenger rail service for many areas within the Northern California Megaregion. While specific locations have not yet been determined, the Link21 Program will include a new transbay rail crossing between Oakland and San Francisco. Link21 is using four building blocks to help identify where Link21 improvements can be the most effective: markets, service, infrastructure, and train technology.

Northern California's population is projected to reach 14.9 million by 2050 (up from 12.2 million in 2015). Travel demands across the Megaregion are expected to increase sharply in the coming decades. Without improving our public transportation system, traffic congestion and overcrowding will worsen, pollution will reduce air quality, transit will be strained, and economic stagnancy will diminish our quality of life. These challenges restrict residents' ability to forge a path to a vibrant future.

The inability of the existing transportation network, in particular the transbay corridor, to meet the needs of the 21-county Megaregion leaves many residents struggling to live affordably and within easy reach of work, school, shopping, and recreation.

Link21 will help alleviate many of the transportation challenges that residents of Northern California face daily. As the Megaregion continues to grow, Link21 will be an important part of a sustainable transportation network to tie communities and economies together. The Program will benefit generations to come.
 

Link21 is sponsored by the San Francisco Bay Area Rapid Transit District (BART) and the Capitol Corridor Joint Powers Authority (CCJPA) in close collaboration with the California State Transportation Agency (CalSTA) and other agency partners. The Link21 Program is building upon previous planning work and regularly engages key stakeholders to build an integrated passenger rail network, as envisioned by the California State Rail Plan.

BART and Capitol Corridor have the resources, expertise, and leadership necessary to bring this transformational megaproject to fruition. Because BART is a member agency to Capitol Corridor, these two agencies are primed to collaborate effectively and efficiently.

BART is the primary way that people move across the San Francisco Bay during peak commute hours. BART’s 2016 voter-approved Measure RR provided funding to begin the study and development of Link21. 

Capitol Corridor Joint Powers Authority’s (Capitol Corridor) role in the Link21 Program is to provide a regional and intercity rail perspective to the Program as well as support the implementation of the California State Rail Plan. The California State Transportation Agency (CalSTA) is Capitol Corridor's funding partner for this Program. Other rail operators in our region are also active partners in the Link21 Program.

A popular trip on Capitol Corridor is travel between Sacramento and San Francisco, which currently requires riders to transfer to a bus in Emeryville or to BART in Richmond. Having to transfer makes the trip slower and less convenient for travelers. A new transbay passenger rail crossing between Oakland and San Francisco could allow for a seamless ride between Sacramento and San Francisco.

Solutions that improve both San Francisco Bay Area Rapid Transit (BART) and Regional Rail (including commuter, intercity, and high-speed rail) will likely be the most impactful in addressing the Northern California Megaregion's long-term transportation challenges.

A second transbay crossing is an important solution to reducing congestion throughout the transbay corridor and may also enable expanded BART service hours and other possible system projects. 

In addition, a new transbay passenger rail crossing will facilitate new connections between rail systems that are currently separate. For example, passengers from points along the Peninsula could more easily and quickly travel by rail to the East Bay, Sacramento Area, or Northern San Joaquin Valley. Providing Regional Rail access across the Bay could attract riders throughout the Megaregion and reduce vehicle congestion.

Link21 is a multiyear, multiphase program of passenger rail projects. The Link21 Program will identify potential projects throughout the 21-county Northern California Megaregion that will improve the passenger rail network. One key project within the Link21 Program will be a new transbay rail crossing between Oakland and San Francisco.

Within the Link21 Program, "Regional Rail" refers to commuter (e.g. Caltrain, Altamont Corridor Express [ACE], Sonoma-Marin Area Rail Transit [SMART]), intercity (e.g. Capitol Corridor and San Joaquins), and high-speed rail (e.g. California High-Speed Rail) service and operators.

Regional Rail and BART have unique networks that serve different areas throughout the Megaregion. They also run on different tracks. "Gauge" refers to the width between the rails. While Regional Rail uses standard gauge, the most common gauge of North America, BART's unique gauge requires separate infrastructure.

The current BART fleet is electric, except for the BART-to-Antioch extension trains. Regional Rail systems currently use diesel-powered trains. However, passenger rail in California will be converting to zero-emission trains in the next 15 years. These modern, environmentally-friendly vehicles will help pave the way for a new frontier of public transportation.

The Northern California Megaregion is a 21-county area covering the San Francisco Bay, Monterey Bay, Northern San Joaquin Valley, and Sacramento regional areas. These 21 counties increasingly face shared transportation, housing, environmental, and economic challenges. Taking a megaregional approach helps the Link21 Team identify the most comprehensive and effective solutions.

Counties in the Megaregion are:

• Monterey Bay Area: Monterey, San Benito, Santa Cruz
• Northern San Joaquin Valley Area: Merced, San Joaquin, Stanislaus
• Sacramento Area: El Dorado, Placer, Sacramento, Sutter, Yolo, Yuba
• San Francisco Bay Area: Alameda, Contra Costa, Marin, Napa, San Mateo, San Francisco, Santa Clara, Solano, Sonoma

The transbay corridor refers to the cross-Bay travel routes between Oakland and San Francisco. This includes the existing BART Transbay Tube, Oakland-San Francisco Bay Bridge, and the San Francisco Bay Ferry. The transbay corridor has some of the highest vehicle congestion and transit crowding in the Megaregion.

For Link21, the term "priority populations" refers to census tracts in the Megaregion that experience high levels of inequitable outcomes. Priority populations will be emphasized in Link21's planning work.

Link21's priority populations definition was developed in collaboration with community members through the Program's community co-creation process. Identifying and integrating the needs of priority populations into the Program is part of Link21's commitment to equity. 

The Link21 Program is revisiting and refining the definition of priority populations based on input from communities, experts, and through its community co-creation process.

The new transbay rail crossing will be located in the transbay corridor between Oakland and San Francisco and connect many communities beyond the East Bay. Possible locations are still under study and will be open for public feedback.

The existing transbay corridor is a critical chokepoint for all forms of transportation, including BART. The California Department of Transportation and the Metropolitan Transportation Commission have both rated the transbay corridor as the most congested corridor in the region due to roadway and transit congestion. Other plans, such as the California State Rail Plan and the Metropolitan Transportation Commission's Plan Bay Area 2050, indicate that a new rail crossing is the best way to provide more capacity and meet the travel demands of the Megaregion.

Creating a new transbay rail crossing, with associated improvements, is likely to be one of the first major projects within Link21 because addressing this chokepoint and gap first will increase the effectiveness of any future Link21 projects.

Every alternative we analyze will include a new transbay passenger rail crossing between Oakland and San Francisco. Prior work, such as the Metropolitan Transportation Commission’s (MTC) Plan Bay Area 2050, Crossing Study, Horizon, and Core Capacity Transit Study, as well as the 2018 California State Rail Plan, identifies a crossing in this location as key for improving the Northern California Megaregion’s transportation network.

The new transbay crossing will address our biggest bottleneck and have cascading benefits throughout the Megaregion. Other crossings may be considered by other rail projects but are not part of the Link21 Program.

Key System trains used to connect to the Bay Bridge from an elevated terminal in San Francisco, with moderate grades to the bridge. The Link21 Program needs to connect to locations deep underground in San Francisco and Oakland, which would create long, gradual ascents to the existing Bay Bridge. Link21 trains would need several miles of trenches and elevated ramps through the dense urban environment to get trains up to the level required to clear the shipping channel. We consider connecting to an underground crossing more feasible and acceptable.

The Link21 Team studied the possibility of a dual configuration for BART and Regional Rail. Solutions to that incompatibility have been explored but produce undesirable outcomes, including unacceptable permanent impacts in San Francisco due to longer approaches on Regional Rail trains. BART and Regional Rail use different track gauges, which creates a number of issues around the two modes sharing an underground structure. There are also safety issues if BART and Regional Rail trains run together, as they have significantly different weights and meet different crashworthiness standards. 

To provide seamless service, the Link21 Team is only considering systems that will be interoperable with either BART or Regional Rail operators. Learn more about Link21 train technology and interoperability.

Link21 will include a new transbay passenger rail crossing between Oakland and San Francisco. Improvements are needed at the core of the system (the transbay corridor) to be able to support better service systemwide and for generations to come. A new crossing will unlock the potential to improve rail travel in the Megaregion by facilitating new connections on either side of the crossing. Link21 is also taking into consideration the other many passenger rail improvement projects already planned or underway in the Megaregion.

Link21 is a program supported by the public and backed by data. When voters approved BART’s Measure RR bond and Metropolitan Transportation Commission's (MTC) Regional Measure 3, they mandated that funds support the development of a second transbay crossing.  

BART's Measure RR and Regional Measure 3 were both developed with extensive community and regional planning input. 

Analysis and public outreach from recent efforts like MTC’s Plan Bay Area 2050, the Bay Crossings Study, Horizons, Core Capacity Transit Study, and San Francisco’s ConnectSF have also shown the public's desire for transformative investments in BART and Regional Rail (including commuter, intercity, and high-speed rail), particularly through the transbay corridor.

The Metropolitan Transportation Commission's Crossings: Transformative Investments for an Uncertain Future study demonstrates that the most cost-effective and sustainable way to address transbay congestion is through new BART and Regional Rail infrastructure (including commuter, intercity, and high-speed rail).

Through passenger rail improvements, Link21 will advance state and national climate goals and is one of the top-ranked transit projects for regional greenhouse gas reduction. Train travel is a sustainable and green form of transportation and has the potential to reduce vehicle miles traveled by up to 4.8 million per day by 2050. A rail crossing will be able to carry many times more people than an auto crossing.

Light rail is a great solution to transportation challenges in more local settings. However, at a megaregional scale, options like BART and Regional Rail (including commuter, intercity, and high-speed rail) provide capacity and speed that better meet the needs of long-distance riders. Additionally, light rail does not satisfy our programmatic requirement for interoperability with the existing BART and Regional Rail networks. 

Link21 will look at all passenger rail systems within the Megaregion as part of an integrated network. However, specific system improvements will focus on compatibility with BART and Regional Rail.

BART and Regional Rail have the ability to move larger numbers of people more quickly and serve longer-distance trips than buses and ferries. Additionally, under Measure RR, Link21 is mandated to address Northern California's passenger rail network.

However, Plan Bay Area 2050 includes important improvements to bus and ferry systems, and Link21 will complement these efforts. Major investment in BART and Regional Rail (including commuter, intercity, and high-speed rail) is also necessary to help address our transportation challenges in the long term.

MTC’s Core Capacity Transit Study considered bus and ferry improvements. In the study, MTC noted that, while buses and ferries do provide modest increases in transbay capacity, they do not provide the capacity needed to meet long-term demand. MTC’s Crossings: Transformative Investments for an Uncertain Future study also concluded BART and Regional Rail are the most effective long-term solutions.  

Capitol Corridor and other train systems share tracks with freight. Link21 is exploring the possibility of adding tracks to separate these systems and provide a more seamless passenger experience. In cases where separate tracks may not be possible, Link21 will be proactively working with freight operators to eliminate or reduce disruptions to service.

Link21 is planning for sleek, fast, electric trains that will reduce greenhouse gas emissions. Train technology will be compatible with current BART technology or with current Regional Rail technology.

California High-Speed Rail Authority (CHSRA) is a separate project that is expected to terminate at the Salesforce Transit Center in San Francisco. Link21 is not a statewide system requiring the infrastructure for high-speed rail, however the Program will certainly improve connections to other high-speed rail networks. Link21 looks forward to partnering with other agencies to connect the Megaregion with fast, efficient, and affordable passenger rail service.

Link21 will provide a variety of benefits to people moving throughout the Northern California Megaregion. Possible benefits include:

• Faster travel times
• Fewer transfers
• Reduced crowding
• Longer service hours
• More frequent service

A new transbay rail crossing for Regional Rail (including commuter, intercity, and high-speed rail) could also provide direct service by train to more parts of the Megaregion.

Due to its size and geographic reach, Link21 has the potential to bring many positive changes to the Northern California Megaregion. Benefits outside of transportation include reducing greenhouse gas emissions, helping to address housing issues, and encouraging the spread of economic and social prosperity through all 21 counties.

Because BART and Capitol Corridor are transit agencies, they are working closely with partners in state, regional, and local government organizations to make sure these benefits can be realized.

Link21 has conducted a detailed Market Analysis and is collecting public input for the entire Northern California Megaregion to determine where the Program will yield the most benefits. Specific locations have not yet been determined and infrastructure will not be built in most communities. However, there will be direct and indirect cascading benefits areas all around the Megaregion, even if infrastructure is not built in those areas.

A key project in the Link21 Program is a new transbay passenger rail crossing between Oakland and San Francisco to address the most congested corridor in the Megaregion and increase the effectiveness of any future Link21 projects.

Passenger rail investments in any area will have a ripple effect across the Megaregion, generating $145 billion in economic benefits, 377,000 jobs, and enabling future passenger rail improvements, according to a 2020 report by the American Public Transportation Association (APTA).

The decision of which agencies will oversee the construction of Link21 will be decided later as the Program progresses and individual projects are identified. The Link21 Program will create many high-quality construction jobs for residents of the Northern California Megaregion.

Current (2021) estimates indicate that the Link21 Program will generate 377,000 job-years (a job-year is defined as one job for a one-year duration) and $145 billion in ripple economic benefits for the Northern California Megaregion. 

Link21 does not want fares to be a barrier to riders using the rail system; however, any changes to transit fares will require a collaborative effort among the different operators in the Megaregion. Link21 will join the Metropolitan Transportation Commission and other partner agencies that have been considering the issue of affordable fares.

A major benefit from Link21 may be the ability to provide extended hours on BART and Regional Rail (including commuter, intercity, and high-speed rail). The Link21 Team is currently evaluating what improvements are needed to allow for extended service hours, especially on BART.

Link21 supports our partners’ initiatives to create transit-oriented communities (TOC) to catalyze economic prosperity, access to jobs and housing, and equitable land use for the Northern California Megaregion's residents.

BART and Capitol Corridor have programs in place to promote TOC. By working with local jurisdictions early on, they will begin planning, designing, and creating vibrant, equitable, and transit-oriented communities in those areas around Link21 improvements. They will also seek to avoid negative impacts on local communities as part of Link21’s commitment to equity.

Link21 will provide a variety of benefits to people moving throughout the Northern California Megaregion. Possible benefits include:

• Faster travel times
• Fewer transfers
• Reduced crowding
• Longer service hours
• More frequent service
• More reliable service
• Access for marginalized neighborhoods
• Clean and green service

Comprehensive cost estimates to bring Link21 from design to construction have not yet been developed.

Program development work accounts for around 3-5% of the total cost and is funded by BART's voter-approved Measure RR bond, The Metropolitan Transportation Commission's (MTC) Regional Measure 3, and the California State Transportation Agency (CalSTA), administered by Capitol Corridor. This includes planning and engineering, engagement and outreach, travel demand and land use, and environmental review, all of which contribute to Link21’s goal of a more efficient, equitable, and sustainable passenger rail network in Northern California. 

Preliminary estimates for the new transbay crossing are provided in the MTC's Plan Bay Area 2050, listed at $29 billion (2040 dollars). This amount is subject to change as the development of program alternatives allows for a more detailed estimate.
 

The study and development of Link21, including the new transbay crossing project, is funded by BART's voter-approved Measure RR bond. The Metropolitan Transportation Commission (MTC) has also earmarked funds from Regional Measure 3 for the project and the California State Transportation Agency (CalSTA) provides annual funds for the Program, administered by Capitol Corridor. The Link21 Team is working to identify additional funding sources to carry the Program into future phases.

Link21 is committed to advancing equity as a core component of our evaluation framework, market analysis, and public outreach. The Program's Goals and Objectives will be evaluated using metrics that center equity.

Link21 is partnering with priority populations that have been harmed and neglected by past transit projects through a community co-creation process. Link21's equity work aims to contribute to advancements in access to jobs, housing, education, health, and safety.

The Program will revisit and refine its equity strategy based on input from the public, experts, other agencies, and through its community co-creation process.
 

Equity is a central and core principle of Link21, which will integrate equity goals and concepts throughout the Program.  

The Link21 Team felt that having a separate equity goal could "silo" it and therefore diminish the importance of including equity as a fundamental and integral part of the entire Program. 

The Link21 Goals and Objectives will be evaluated using quantitative metrics that consider equity, allowing a thorough consideration of equity through all analyses. Communities throughout the Megaregion shaped and supported this approach through Link21's co-creation effort.

A program of this magnitude can be a catalyst for transformative land use policy changes, creating an opportunity for our cities, counties, and state to address the biggest problems facing the Northern California Megaregion.

By working with local jurisdictions early on, we will begin planning, designing, and creating vibrant, equitable, and transit-oriented communities in those areas around Link21 improvements. We will also seek to avoid negative impacts on local communities.  

We are using a Business Case process to develop and evaluate a shortlist of alternatives that maximize public benefits, economic benefits, financial viability, and deliverability.

One or more preferred alternatives may be carried into the CEQA/NEPA environmental process that will culminate in environmental review of a final preferred alternative. Extensive public outreach will be conducted during the Business Case and environmental review to ensure that people have ample opportunity to provide input. 

Link21 is using a Business Case process to help screen and evaluate program and project alternatives to ensure that only the most beneficial and feasible possibilities are brought to environmental review.

Performing this more in-depth screening up front will help limit the number of alternatives that go through the detailed analysis required for environmental review, which saves taxpayers money. In addition, it builds in public input right from the start.  
 

Our partners from transit, funding, regulatory, city, and county agencies are valued stakeholders as we develop Link21. We meet regularly with an expanding group of partners to get their input on Link21. 

As the Link21 Program evolves and specific projects are defined, other agencies may take on additional responsibilities in the development and delivery of this transformational rail program.

The initial list of program alternatives will be developed with information from three sources: existing studies, the Link21 Market Analysis, and public input. 
 

Public input is essential to Link21. We look forward to receiving your input on the direction of the Link21 Program. 

The Link21 Team is following state and local health mandates related to the COVID-19 pandemic. We hope to be able to get out and meet you face-to-face. In the meantime, keep an eye on this website and social media channels for opportunities to weigh in and get involved. You can also use our comment form or leave a voicemail at 855-905-Link (5465).

Intensive public outreach began in 2021 and will continue through all phases of Link21. Please sign up to stay informed or get involved.

Link21 is a generational investment that will provide benefits far into the future. Careful work in planning, environmental analysis, design, and construction will ensure that Link21 meets the needs of the Northern California.

There are many planning and engineering challenges inherent in implementing such a large program, requiring full consideration of how projects might affect megaregional communities and the environment.

It's possible that Link21 will be able to implement some projects before 2040. Link21 will be considering innovative delivery methods, alternative financing mechanisms, and phasing. These opportunities will emerge as the Program progresses.

The Link21 Team reviewed a range of possible post-pandemic travel patterns, including the possibility that more people will be working from home.

The Link21 Market Analysis addresses the potential long-term impact of COVID-19 on travel patterns by modeling future scenarios with different assumptions for population, jobs, telecommuting, and travel growth.

Early data on the pandemic shows that more people are moving to less expensive parts of the Northern California Megaregion. As population spreads more evenly across the 21 counties, it becomes more important for people to have fast, convenient, and environmentally friendly ways to see family and friends, visit cultural and recreational centers, and access health care, jobs, and education.

Even in the face of the pandemic, the Metropolitan Transportation Commission (MTC) considers Link21 an important program for the Bay Area. MTC adopted Plan Bay Area 2050 on October 21, 2021, which includes Link21.

The decision to construct Link21 project(s) will not be made for several years. This gives BART and Capitol Corridor time to continue to understand and integrate new travel patterns into the Link21 Program.

BART and Capitol Corridor are both working daily to address the challenges of COVID-19. At the same time, BART and Capitol Corridor understand that they must also continue to plan for the future. The public agrees.

Link21 is a voter-approved program. In a June 2020 survey of residents across the Northern California Megaregion, 79% of voters said that even as we deal with the impact of the COVID-19 pandemic, we still need to develop plans to help fix our Megaregion’s long-term challenges with traffic and transportation. This result held in each area of the Megaregion and across demographic splits. 

The funds that support Link21 are dedicated for use on capital projects and cannot be used to fund operations. Therefore, planning work on Link21 can move forward without impacting the operating budgets of our region’s transit operators. 

An improved passenger rail network will provide convenient alternatives to driving, and, therefore, improve air quality and reduce pollution caused by cars. Link21 will advance state and national climate goals and is one of the top-ranked transit projects for regional greenhouse gas reduction, according to the Metropolitan Transportation Commission's study Plan Bay Area 2050.

Link21 recognizes that sea level rise over the next century could have major implications for the region’s rail transportation network and the communities that network serves. Resiliency to the effects of extreme weather and sea level rise is one of Link21's Goals and Objectives.

Link21 assumes, consistent with regional plans such as Plan Bay Area, that communities in the megaregion vulnerable to sea level rise will be protected through a comprehensive approach. When recommending improvements to the passenger rail system, we will analyze potential sea level rise impacts and identify project-specific designs and actions to increase resilience wherever feasible.