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Cost of San Francisco Downtown Rail Extension Swells to $8.2B

Written by Annie GausPublished Oct. 27, 2023 • 7:00am
A cross-section rendering shows where The Portal station would end at Salesforce Transit Center. | Transbay Joint Powers Authority

A planned Downtown San Francisco rail extension called The Portal is about to get much more expensive, according to an estimate presented at a regional transit meeting Wednesday. 

The proposed rail tunnel is intended to connect Caltrain—and future high-speed trains—at the Fourth and King streets station to the massive new Salesforce Transit Center. Project costs have ballooned from $6.5 billion to a staggering $8.25 billion since October 2022, according to the Metropolitan Transportation Commission. 

The cost increase is attributed to a mix of factors, including inflation, expanding project timelines and a risk assessment from the Federal Transit Administration that determined that the prior cost estimate was unrealistic, according to John Goodwin, a spokesperson for the Metropolitan Transportation Commission. 

“With all of these factors, you’re seeing some whopping projected cost increases, not just for The Portal, but for other projects in the Bay Area,” he said. 

Lily Madjus Wu, a spokesperson for the Transbay Joint Powers Authority, which is primarily responsible for the rail extension project, said that the organization has asked the federal government to fund roughly half of the project costs, which will amount to up to 2 miles of construction. 

Wu added that $729 million of the cost increase is attributed to a request that the federal government credit the costs of a train box at the terminal that has already been built. 

The authority is eyeing 2025 to begin heavy civil engineering and tunnel work for The Portal, she said. 

A document presented at the Metropolitan Transportation Commission’s Wednesday meeting noted that “adjusted escalation rates, project schedules, labor and materials cost increases, and financing costs” have spiked the project's sticker price. 

The Portal, formerly called the Downtown Rail Extension, is viewed by transit boosters as a linchpin of a regional transit system that will eventually unite Caltrain, San Francisco’s bus system and high-speed rail.

Transit projects across the country are competing for federal infrastructure dollars, and a lack of certainty about the amount and timing of funding can also tack on additional project costs, Goodwin added. 

Caltrain didn’t immediately respond to a request for comment. 

The Downtown Rail Extension has been decades in the making, and its estimated cost has increased multiple times in recent years. In 2016, the cost of the rail extension was estimated at $3.9 billion

In 2022, the rail extension was rebranded as The Portal to “generate excitement” about the project, according to the Transbay Joint Powers Authority. 

“People understood the sci-fi connection to the name and mark [logo] and felt it would help convey that this project is future forward,” authority documents said. 

The Transbay Joint Powers Authority said at the time that the rail extension would bring “California’s statewide high-speed rail service into Downtown San Francisco at the TJPA multimodal facility, Salesforce Transit Center, which currently connects nine transit systems (found within and around) to eight Bay Area counties.”

Annie Gaus can be reached at

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