Is This America’s Most Daunting Infrastructure Obstacle?
Downtown Los Angeles with the San Gabriel Mountains in the distance. Doc Searls / Flickr via CC BY 2.0
In order to realize its ambitious high-speed rail dreams, California must first conquer the San Gabriel Mountains. And that's easier said than done.
If you’re traveling by train out of Los Angeles Union Station and head north toward the Mojave Desert and Central Valley, you have to snake your way through the San Gabriel Mountains via the San Fernando Tunnel and Soledad Canyon on the way up to Palmdale. The challenging topography makes it fairly slow going.
That route, originally built by the Southern Pacific Railroad in the 1870s, is certainly not the most direct way through as the crow flies. And unfortunately, trains can’t fly over the San Gabriel Mountains, which host a handful of peaks between 8,000 feet and 10,000 feet above sea level.
But California’s ambitious high-speed rail project connecting Los Angeles with San Francisco, which broke ground earlier this year near Fresno, will have to figure out a way to traverse the San Gabriel Mountains in order to allow high speeds needed for bullet trains.
This weekend, the Los Angeles Times splashed some cold water on the high-speed rail project, examining some of the financial and physical realities of the state’s massively expensive long-term transportation investment, currently priced at $68 billion.
An analysis by the newspaper “indicates that the deadline and budget targets will almost certainly be missed—and that the state has underestimated the challenges ahead, particularly completing the tunneling on time.”
This isn’t the first time the Times and critics of California’s high-speed rail project have questioned the budget projections and construction timetable. And it’s fairly normal for big-ticket transportation projects to have ballooning budgets and fluid timelines.
So what’s new? The Times’ report takes a very careful look at the topographical challenges confronting “the most ambitious tunneling project in the nation’s history.”
The California High Speed Rail Authority is considering different tunneling alignments through the San Gabriel Mountains that provide a far more direct route for trains heading in and out of the Los Angeles area. An earlier envisioned rail route along the State Route 14 freeway corridor, which traverses the mountains, is facing community opposition.
Depending on the various options under consideration, about 20 miles of tunnels might be needed to cross the San Gabriel Mountains, including one tunnel that’s 13.8 miles long, according to the Times. (Farther north, about 16 additional miles of tunnels will be needed to cross the Tehachapi Mountains between the Mojave Desert and the Central Valley.)
But the geology of the San Gabriel Mountains is incredibly complex and includes two major seismic fault lines (the San Andreas and San Gabriel faults), plenty of secondary fault lines and two tectonic plates (the North American and Pacific plates).
According to the Los Angeles Times:
A 2012 report by Parsons Brinckerhoff, obtained by The Times, warned the rail authority that the "seismotectonic complexity ... may be unprecedented" and that the rail route would be crossing faults classified as "hazardous."
The faults, changes in rock types and shattered rock cause many headaches, sometimes requiring changes in cutter heads. Doing so means stopping the machines while technicians crawl to the front to manually swap out as many as 40 to 60 cutter heads. A full swap of cutter heads can take an eight-hour shift, the engineers said.
Shattered rock causes additional problems in supporting the overhead formations, requiring workers to bore 10-foot-long holes into the ceiling and insert rock bolts that knit together blocks that weigh tons.
Long story short: Even in ideal construction conditions, the San Gabriel Mountains are poised to become the most daunting tunneling challenge American engineers will ever face. And California authorities say they're up for the challenge.
All this makes some of New York City’s biggest and expensive infrastructure projects—including East Side Access and the future replacement of Amtrak’s Hudson River tunnels in and out of Pennsylvania Station—seem like child’s play, along with previous infamous budget- and timeline-busting megaprojects, like Boston’s Big Dig.
These days, the biggest obstacles in the way of transportation investments are financial in nature. But in California, the biggest obstacle for the state’s high-speed rail dreams might end up being the cost of extremely difficult geology.
Stay tuned …
(Top image by Doc Searls / Flickr via CC BY 2.0)
Michael Grass is Executive Editor of Government Executive’s Route Fifty.
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