Sinkage Halts Subway Work

Subway tunneling beneath the Hollywood Freeway was temporarily halted Tuesday while transit engineers attempted to determine what has caused three spots to sink slightly more than a level permitted by Caltrans.

Metropolitan Transportation Authority officials characterized the problem near Universal City as a minor setback. The officials said at a news conference they should be able to quickly determine the cause of sinkages and make corrections.

“This is not a serious situation,” said Charles Stark, MTA project manager. “We’ll hopefully have it resolved in a day or so. There are no structural problems or any possibility of structural problems on this freeway.”

Caltrans permit engineer Ray Hinton said he wanted to “assure motorists that the freeway is absolutely safe.”

Three of the 200 points surveyed on the edge of the freeway near Lankershim Boulevard have slightly exceeded the 3.5-inch subsidence limit Caltrans set in a permit to the MTA, transit officials said. None of the spots exceed 3.8 inches of subsidence. Each of the spots is about the circumference of an automobile, officials said.

The average settlement of all 200 points is about 1 inch, MTA officials say.

Ahmad Habibian, manager of technical services for the American Society of Civil Engineers, said the Caltrans limits are merely “warning lights.”

“The threshold is always set at a very comfortable level,” he said. “It doesn’t mean that there’s a serious problem. It’s quite possible the problem can be rectified quickly.”

But state Sen. Tom Hayden, a frequent critic of the MTA subway project, called Tuesday for an independent assessment by the federal government into why the Hollywood Freeway has sunk much more than originally anticipated.

Hayden said in a statement released from Sacramento that “the MTA is so obsessed with rushing this project along regardless of any other considerations because they want to make it irreversible before the courts can rule on whether they have violated environmental laws.

“The MTA promised the public, federal government and its own board that this would never happen again,” Hayden said. “Well, it’s happening again, and it will continue to happen until new leadership stops this reckless, runaway gravy train to Universal Studios.”

MTA board member and Los Angeles County Supervisor Mike Antonovich, another subway critic, said the latest problems confirm his belief that the transportation agency ought to stop digging and instead build a light-rail system along the Hollywood and Ventura freeways.

“This should send a wake-up call to the mayor and other subway supporters that this project needs to be stopped and brought out of the ground,” Antonovich said.

Excavation in the San Fernando Valley’s loose, sandy soil has been plagued by sinkage problems. Contractors have attempted to firm up the ground ahead of digging machines by injecting it with an epoxy-like substance called chemical grout. But the expensive, time-consuming measure has met with limited success.

The first signs of excessive surface settlement occurred last year after a tunnel-boring machine had dug just 200 feet south of Chandler Boulevard. Work stopped for months while the machine was modified and $19 million in chemical grout was ordered, sending the cost of the contract soaring by almost 25%.

On March 11, tunneling under Lankershim stopped again for 10 days of intensive grouting after the floor of the El Sombrero nightclub sank 15 inches. Tunneling stopped again last Thursday for 24 hours for extra grouting after Lankershim sank half an inch in front of a First Interstate Bank high-rise. Dozens of other businesses along the street reported have had sinkage problems.

The MTA has publicly denied that its tunneling is responsible for the settlement while it has privately accused its digging contractor, Obayashi Corp., of causing the problems, according to documents obtained by The Times. Obayashi engineers, in turn, have said in internal documents that blame for the sinkage lies with the MTA, The Times has learned.

The MTA is digging the Valley extension of its Metro Rail subway system in two parts: Last year, it began to dig two tunnels south from Chandler Boulevard to Universal City under Lankershim Boulevard. This year, it began to tunnel south from Universal City to Hollywood--a route that will take it deep under the Santa Monica Mountains and popular Runyon Canyon Park.