Bay Area link a big, pricey job

145-mile segment already $13B short, and rugged terrain poses problems

California’s High-speed Rail Authority is forging ahead with plans to bring the state’s bullet train to the Bay Area.

But the authority doesn’t have the $13 billion officials say they’ll need to build the key 145-mile segment of the system connecting Silicon Valley with the Central Valley. And will that even be enough?

The project’s route cuts through the core of San Jose, the Bay Area’s largest city, and the rugged coastal mountains east of Gilroy. It includes am

bitious plans for long twin tunnels beneath the Pacheco Pass that must cross an active seismic fault and contend with tricky geological conditions that could stop tunneling machines in their tracks.

Those factors make construction of the new rail line far more complex than other sections of the project now being built in the Central Valley, which have been beset by years of delays and exploding budgets.

While the authority tries to find money to pay for the project, it’s continuing the long process of designing and planning the socalled Valley-to-valley segment. The authority identified its preferred route last fall, and late last month released a massive environmental impact report for the segment. Next the public will weigh in.

“We certainly see this as another big milestone in getting high-speed rail finished in California,” said Boris Lipkin, the Northern California regional director of the High-speed Rail Authority.

Still, Lipkin acknowledged, “We will need additional funding to actually build this part of the system.”

The Valley-to-valley segment begins where trains traveling south from San Francisco on tracks shared with Caltrain cross Scott Boulevard in Santa Clara.

The route that authority staffers recommend for the segment continues to use Caltrain’s tracks to travel through San Jose and south to Gilroy. The authority is also considering other routes that would involve building a separate viaduct through San Jose. Those options would save the highspeed trains some time but would come at enormous expense and disruption in the city. The rail authority’s board will make the final decision on which route to use in the summer of 2021.

Once trains pass a planned downtown Gilroy stop, they will gradually curve east toward the Diablo Range, eventually passing through a 1.5-mile tunnel near Casa de Fruta.

Trains will emerge briefly before entering the 13.5-mile tunnel through the Pacheco Pass, where plans call for them to travel at their top speeds of over 200 mph. The segment ends northeast of Los Banos, just before passengers enter the intersection of rail lines traveling south toward Los Angeles and north to Merced.

The long Pacheco Pass tunnel — which the rail authority estimates will cost $5.5 billion to build — concerns Darrel Cowan, a professor in the University of Washington’s Department of Earth and Space Sciences who studied the geology of the Diablo Range as a Stanford PH.D. student.

The mountains aren’t made up of just one material, Cowan said. Instead, they’re a chaotic mix of shale studded with much harder chunks of metamorphic rock, he said, ranging in size “from a baseball up to my house or a car.”

Think of those metamorphic rocks like the nuts embedded in a fruitcake, or chocolate chips in cookie dough, but exponentially bigger and harder — maybe several times larger than the tunnel-boring machine that will try to drill through them.

“You’re drilling through soft shale, and then you run into a huge block,” Cowan said.

“It’s going to be very hard to predict,” he added, meaning the rail system’s engineers will need to extensively study the area’s geology to determine what their machines will run into — and what they’ll do if they get stuck.

As the tunnel passes north of the San Luis Reservoir, it will have to contend with another potential problem: the Ortigalita Fault, which runs up the east side of the Diablo Range.

High-speed Rail Authority officials say their engineers are extensively studying the range’s geology and the fault zone as they plan and design the Pacheco Pass tunnel, which will have an early detection system to automatically slow or stop trains during an earthquake. Lipkin, the authority’s regional director, said planners are also taking lessons learned from other tunnels in seismically active areas of California and Japan.

The estimated cost for finishing the high-speed rail line between San Francisco and Los Angeles now sits at $80.3 billion, far more than the $45 billion the authority predicted when voters approved the system in 2008.

Despite statewide coronavirus lockdown orders that limited work on other projects, construction has continued on the bullet train’s first 119-mile segment — running from Merced to Bakersfield along viaducts that tower over Highway 99 in the Central Valley. The HSR authority hopes to begin offering service on that section before the end of the decade.

Meanwhile the authority is working to plan, design and fund the rest of the system in chunks, until it eventually reaches California’s economic powerhouses in the Bay Area and Los Angeles. Those “bookend” projects won’t be easy or cheap — in addition to the 15 total miles of new tunnels east of Gilroy, the rail authority will need to tunnel another 35 miles through mountains in Southern California for trains to eventually reach Los Angeles.

The authority’s optimistic timelines aim to have trains zipping between San Francisco and Bakersfield by 2031, with service to Los Angeles in 2033.

Members of the public will be able to learn more about the Valley-to-valley project and offer their comments at a series of open houses — their formats shifted from in-person events to webinars as a result of the coronavirus — on May 11, 14 and 18.

“This is the critical path and the necessary steps for us to be able to build the system, ultimately, and get from San Francisco to Los Angeles,” Lipkin said.