The California High Speed Rail Authority voted June 27 to approve a route and certify the environmental review of a $22.6 billion section of the passenger rail network that links the cities of Palmdale and Burbank in Los Angeles County. With the approval, 463 miles of the planned line from San Francisco to Los Angeles have been cleared, and only a relatively small portion between Los Angeles and Anaheim is still awaiting environmental approval.
The preferred alternative for the Palmdale-Burbank segment is a 38.3-mile route known as SR14A, which includes four tunneled sections totaling 27.9 miles. The tunnels would carry trains under areas such as the Angeles National Forest and the San Gabriel Mountains National Monument to minimize impacts on communities and habitats. Using tunnels also helps avoid tight turns and steep grades that would slow operating speeds, said Christine Inouye, the HSR Authority’s chief strategic delivery engineer during the authority’s board meeting. This segment of the high-speed rail route would be completely grade-separated, allowing trains to reach a maximum speed of 220 mph.
The segment would have an operational travel time of about 17 minutes, compared to an hour by car, according to LaDonna DiCamillo, CHRA’s Southern California regional director. The approval is “a major milestone in connecting San Francisco to Los Angeles in less than three hours,” said agency CEO Brian Kelly. “It’s also transformative for Los Angeles County, connecting Palmdale to Burbank in a way that’s never been possible before.”
Map courtesy of the California High Speed Rail AuthorityAccording to Inouye, the planned tunnel segments include two double-drilled sections that run 13.2 miles and 12.4 miles respectively. Two shorter tunnel segments can be constructed with cut and cover or sequential excavation. The route would also include about 1.5 miles of elevated sections, including a viaduct over the Santa Clara River and the Metrolink commuter line.
Authority board members and public commenters raised questions about the safety of the tunnels with seismic activity in the area. Sarah Wilson, an engineer who provides expert tunneling services to the authority, said preliminary plans call for tunnels to be built to support up to 6.5 feet of movement, with tunnel lining along the entire its length, in addition to fault chambers in the fault zones.
In addition, the authority plans to use an earthquake early warning system that would automatically activate the train’s brakes before an earthquake, Wilson said. A similar system used in Japan prevented derailments during a magnitude 9.1 earthquake in 2011.
Construction of the Palmdale-Burbank segment is expected to take about seven years, after design and procurement.
In addition to being part of California’s larger high-speed rail network, the segment would connect with other modes of transportation at both ends. To the north, the Palmdale Transportation Center station would provide connections to commuter bus and Metrolink service, and potentially to the future Brightline West high-speed rail to Las Vegas via the proposed High Desert Corridor project between Palmdale and Victor Valley. In Burbank, the station would be located next to the Hollywood Burbank Airport and provide access to two Metrolink lines and other transportation.
Work is currently underway on 119 miles of the line in the Central Valley. Authority officials expect to complete the environmental review of the Los Angeles-Anaheim segment next year.
