"We're not seeing any cracking," he said. "I'm very pleased with how well this bridge held up."

To aid in the repair effort, Gov. Arnold Schwarzenegger declared a state of emergency for Los Angeles County, allowing the possibility of state aid to local authorities. Two men and an infant died in the accident, and their bodies had not been identified Sunday night. Authorities said 10 people were hospitalized, none with critical injuries, and 10 others had run out of the tunnel uninjured. The remainder of those in the 31 vehicles were unaccounted for. Investigators said they did not believe that anyone else had died.

Some truckers familiar with the 550-foot-long tunnel where the accident occurred said it has long had a reputation for being dangerous. Javier Pablo, 37, of La Mirada, who hauls cargo out of the Port of Los Angeles, described it as dimly lit and particularly dangerous after a rainstorm, which was the situation Friday evening.

"You don't know what's going on inside that tunnel until you are inside, but everyone keeps going," he said. Other truckers made similar complaints in e-mails to The Times, and also said there was a blind curve inside the structure.

Caltrans' Failing said it was the first he had heard of any problems with the tunnel. He added that any dangers might be the result of risky driving rather than poor design. Still, he said he had ordered an analysis of accident rates to see if the tunnel has a pattern of problems.

The tunnel, built in the 1970s, is part of a four-mile-long, two-lane bypass around the intersection with the 14 Freeway. Trucks continuing on I-5 are required to use the bypass, but automobile drivers sometimes opt to use it as well.

Interstate 5 handles a significant portion of the truck traffic up and down the West Coast, from Mexico to Canada. The portion around Santa Clarita handles 225,000 vehicles a day, including many trucks going in and out of the ports of Los Angeles and Long Beach.

Most port traffic is hauled by railroads, however, and port officials said they did not expect the closure to harm trade.

"We don't foresee any significant problems from this," said Mike Zampa, a spokesman for shipper APL, which is run by Singapore-based Neptune Orient Lines.

Still, others considered the accident a warning. They warn that shippers throughout the nation are trying to squeeze larger and larger amounts of cargo to and from ports through thin bottlenecks caused by tunnels, bridges and other barriers. They worry that accidents such as this will occur with increasing frequency.

"We are setting ourselves up for a potential logjam," said Aaron Ellis, a spokesman for the Alexandria, Va.-based American Assn. of Port Authorities, which represents more than 140 public ports throughout North America, Latin America and the Caribbean.

The freeway closure had an immediate effect on some businesses.

Attendance at Six Flags Magic Mountain in Valencia was down about a third from the resort's usual pre-Halloween "Fright Fest" crowds, spokeswoman Susan Carpenter said.

"This is the only artery in and out of the valley here and it's having an impact on us," she said.

The story was different at the Fairfield Inn in Santa Clarita, a 66-room hotel that was filled with stranded travelers Friday and Saturday nights.

"It's an unfortunate situation, but a lot of people had no choice but to wait it out," said manager Jonathan Robles. Most guests are now gone, he said, armed with alternative directions supplied by the hotel.

Sean and Sheri Maxwell, who live within sight of Magic Mountain, spent Sunday cobbling together an alternative plan that would allow Sheri to reach her job in Sherman Oaks today and ensure child care for their two young children.

Before the announcement came that southbound freeway lanes would reopen, they decided that Sheri, 39, a physical therapist, would head south Sunday night to her mother's home in Arleta. She packed enough clothes for five nights just in case she couldn't return home.

"She doesn't show up, people don't get treated," Sean Maxwell said of his wife's work.