Caltrain San Francisco Railyards Redevelopment: Timeline, Housing, Transit Impact

This article takes a look at Prologis and Caltrain’s early-stage plan for the 18.63-acre Caltrain San Francisco Railyards at 4th and King in SoMa. They want to turn it into a dense, mixed-use neighborhood.

The proposal pictures a huge transit hub, tall new buildings, and long stretches of open space. All of that could change how people live, work, and get around the Bay Area.

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If you’re reading from Marin County—San Rafael, Mill Valley, Novato, Sausalito—this plan hints at bigger regional shifts. Housing, jobs, and transit could all ripple out to places like Larkspur and Corte Madera as projects like this move forward.

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What the plan envisions for the Caltrain Railyards

Prologis and Caltrain’s joint venture sketches out 7–8 million square feet of new development. That includes about 4 million square feet of office space and around 2,500 housing units.

There are two main options on paper—“Maximum Commercial” and “Maximum Residential.” But the developers say they’re after a more balanced mix to serve both workers and residents across the Bay Area, including Marin commuters heading into San Francisco.

Most new buildings would stand 350 to 600 feet tall, with a signature 850-foot tower at 4th and King above a new Caltrain station.
There’s a planned transit facility with more than four acres of public open space.
Pedestrian promenades, parks, and retail-lined streets aim to make the district walkable and connected.
For financing, private and institutional money would fund the buildings, while public sources would cover infrastructure and transit improvements.
The first phase would bring about 2.5 million square feet of development around 4th and 7th Streets, as platforms and tracks get moved to make way for early towers on Block 1.

Prologis and Caltrain talk a lot about community engagement and ongoing work with the City of San Francisco, neighborhood groups, and agencies like the Office of Economic and Workforce Development. Even though the site is in SoMa, the ripple effects could definitely reach Marin County towns, especially as planners weigh growth, housing costs, and transit access for places from San Anselmo to Tiburon.

Transit, infrastructure, and the regional timeline

The plan features a major transit center anchored by a new Caltrain station. There’s also over four acres of public open space and a network of pedestrian-friendly streets.

It all depends on finishing the Transbay Joint Powers Authority’s Portal Project and building a new off-site rail storage and maintenance facility. They expect rail service to keep running during construction.

Early construction would move the 4th Street platforms and tracks, opening up Block 1 for the first towers and about 2.5 million square feet of new development around 4th and 7th Streets.

The full build-out could take 15–20 years, depending on financing, permits, and coordination with state and city agencies.
They’re aiming to break ground in 2029, with the whole project possibly wrapping up by 2041 or 2042.
Construction will happen in phases to keep rail service going the whole time.

Marin County perspective: watching from San Rafael, Mill Valley, and beyond

Marin communities keep a close eye on the SF railyards plan. Local leaders in San Rafael, Novato, and Tiburon are weighing how regional growth fits with traffic, housing, and infrastructure funding.

This project signals a shift toward transit-oriented development. That kind of change could ripple out, affecting everything from Larkspur’s ferry to Corte Madera’s shopping corridors.

Community engagement is still key. Residents across Marin—from Fairfax to Sausalito—are going to see more ongoing dialogue as city and state agencies work together with local stakeholders.

There are new opportunities for Marin workers to live closer to jobs in San Francisco and commute by Caltrain.
This could shake up housing supply and affordability across the North Bay as regional demand changes.
Marin businesses near cross-county corridors and transit hubs might see economic benefits, too.

If all goes as planned, groundbreaking could happen by 2029. Development would then roll out in phases into the early 2040s.

For folks living in Marin—commuters, business owners, or just curious neighbors—this project could really shape the regional conversation. The Bay Area’s push for a more transit-focused future is something Marin will feel, whether you’re in San Rafael, Sausalito, or somewhere in between.

Here is the source article for this story: Deep Dive Into Caltrain’s San Francisco Railyards Redevelopment

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Joe Harris is the founder of MarinCountyVisitor.com, a comprehensive online resource inspired by his passion for Marin County's natural beauty, diverse communities, and rich cultural offerings. Combining his love for exploration with his intimate local knowledge, Joe curates an authentic guide to the area featuring guides on Marin County Cities, Things to Do, and Places to Stay. Follow Joe on Facebook, Twitter, and Instagram.