The monumental task of building California's bullet train will require punching 36 miles of tunnels through the geologically complex mountains north of Los Angeles.
Crews will have to cross the tectonic boundary that separates the North American and Pacific plates, boring through a jumble of fractured rock formations and a maze of earthquake faults, some of which are not mapped.
It will be the most ambitious tunneling project in the nation's history.
State officials say the tunnels will be finished by 2022 — along with 300 miles of track, dozens of bridges or viaducts, high-voltage electrical systems, a maintenance plant and as many as six stations. Doing so will meet a commitment to begin carrying passengers between Burbank and Merced in the first phase of the $68-billion high-speed rail link between Los Angeles and San Francisco.
However, a Times analysis of project documents, as well as interviews with scientists, engineers and construction experts, 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.
But Bent Flyvbjerg, a University of Oxford business professor and a leading expert on megaproject risk, said the lagging schedule, litigation, growing costs and permit delays arising so early in construction are warning signs that even more delays and higher costs are coming.
"You have an 80% to 90% probability of a cost overrun on a project like this," Flyvbjerg said. "Once cost increases start, they are likely to continue."
Flyvbjerg's research found that high-speed rail projects around the world experience an average of 45% cost growth, though 100% increases occur in some cases.
Although the state hopes to correct some of its early setbacks, the odds are stacked high against it, said Robert Bea, a member of the National Academy of Engineering and a pioneer in civil engineering risk analysis.
"You can never make up an early cost increase," Bea said. "It just gets worse. I have never seen it go the other way in 60 years."