For decades, underground highways in Southern California were a frustrated commuter's fantasy -- too costly, too hard to build and, given the wealth of land, not necessary.
But Los Angeles is in its 18th year as the nation's most congested metropolis, freeways have little or no space for new lanes and traffic experts are running out of time-shaving options.
For The Record
Los Angeles Times Tuesday September 20, 2005 Home Edition Main News Part A Page 2 National Desk 1 inches; 45 words Type of Material: Correction
Tunnel map -- A map with a story in Sunday's Section A about proposed tunnel projects in Southern California showed California Highway 39 connecting with California 2, the Angeles Crest Highway. California 39 is closed about three miles short of California 2 because of landslides.
So civic leaders are joining engineers to consider burrowing the longest highway tunnels in America.
"Tunnels," said Wolfgang Roth, a geotechnical engineer working on one possible project in the Antelope Valley, "may finally have their day."
Three massive projects are under study in Southern California, each dwarfing any of the nation's 337 underground roadways, including the 2.6-mile tunnel in Boston's infamous "Big Dig," the most costly public works project in U.S. history:
* Congress recently approved $2.4 million to study a five-mile, $2-billion tunnel that would help link the Long Beach and Foothill freeways in Pasadena and South Pasadena, and keep 100,000 cars a day off city streets.
* For Orange and Riverside counties, Congress set aside $16 million to study a 12-mile tunnel that would connect fast-growing commuter towns in the Inland Empire to jobs on the coastal plain. Buried beneath Cleveland National Forest and projected to cost from $3.5 billion to $5 billion, it would be the second-longest in the world -- after a 15.2-mile project in Norway.
* A complex of tunnels and surface highways under study by the city of Palmdale would slice 23 miles directly though the San Gabriel Mountains from the Antelope Valley to Glendale, cutting the commute in half. It could cost $3.1 billion or more.
While some policy makers remain skeptical, others say engineering breakthroughs in Europe and Japan have made tunnels faster to build and more affordable -- especially where real estate prices have pushed the cost of new freeways skyward.
"The technology has evolved, so tunnels are becoming truly competitive alternatives," said Mark Pisano, executive director of the Southern California Assn. of Governments.
Giant tunnel-boring machines can drill quickly through the earth, cutting holes 45 feet in diameter. "If the hard rock stands up nice, the boring machine eats right through," said Roth. "Even with the fractured hard rock, as the machine advances, you stabilize the tunnel walls with rock bolts or 'shotcrete,' " he said, using the futuristic term for sprayed concrete.
