The Downtown Rail Extension (DTX), also known as The Portal project, will eventually connect 11 Bay Area transit systems.
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Right below the Grand Hall of the Salesforce Transit Center and stretching for several blocks, Speaker Emerita Nancy Pelosi and other leaders got a glimpse of the future.
"It's about the future. It will take some time," said Speaker Emerita Pelosi.
The 80,000-square foot area will be the concourse level with shops in the future.
Further below is where Fourth Street Caltrain station will connect with the Salesforce Transit Center. And, it'll eventually also be where you can catch high-speed rail.
"It's a big deal!" said Mayor London Breed.
Plans for The Portal will move forward thanks to one huge gift from the federal government.
"$3.4 billion," said Mayor Breed.
RELATED: CA to receive $6 billion federal investment for high-speed rail projects
CA to receive $6B federal investment for high-speed rail projects
"Yes, today is cause for celebration," said Speaker Emerita Pelosi.
"The total budget is $8.4 billion (for The Portal) which includes the train box that was built several years ago," said Jeff Gee, Chair of the Transbay Joint Powers Authority Board of Directors. "The $3.4 billion that the federal government just committed is huge. It brings us to two-thirds funded for this project."
The Transbay Joint Powers Authority says The Portal project will bring together key modes of transportation in the future.
"This project brings Caltrain from Fourth and King all the way to Downtown San Francisco and right behind it, California High-Speed Rail," said Gee.
The high-speed rail project is projected to cost $106 billion, according to the California High-Speed Rail Authority.
Critics say the bullet train project faces a nearly $7 billion shortfall to finish the Central Valley segment. And the project also needs about $100 billion to connect San Francisco and Los Angeles by the high-speed rail system.
RELATED: Another $100 billion needed to complete California's bullet train project
Supporters remain confident.
"High-speed rail is really starting in California, so take pride in that," said Speaker Emerita Pelosi. "When we show and demonstrate this giant step forward, then it's easier to attract more resources to get the job done."
"The key is to get it done sooner because time is not free. Every time a year passes, the costs keep going up. We just need to break ground," said Gee.