OAKLAND, Calif. – As transportation officials braced for massive gridlock during today’s commute after the collapse of a key connector ramp near the San Francisco-Oakland Bay Bridge early Sunday,

Gov. Arnold Schwarzenegger declared a state of emergency and authorized free public transit rides to help people get to work.

The ramp that connects Interstate 80 to eastbound Interstate 580 collapsed after a speeding tanker truck with 8,600 gallons of gasoline slammed into a guard rail, sparking an explosion and intense fire, according to the California Highway Patrol.

Tons of steel, concrete and asphalt blanketed part of the westbound Interstate 80 to Interstate 880 ramp that the truck was on when it crashed.

The part of the heavily-traveled MacArthur Maze where the collapse occurred will be closed for weeks, if not months, causing the worst traffic disruption in the Bay Area for commuters since the 1989 Loma Prieta earthquake.

CHP officer Trent Cross said that aftr the crash, James Mosqueda, 51, of Woodland, Calif., the driver of the tanker truck, crawled out of the passenger window, walked down the ramp to a gas station and took a taxi to a hospital. He was later taken to a San Francisco hospital for treatment of burns to his face and neck.

Mosqueda reportedly had been licensed to drive the truck for 10 months.

He works for the South San Francisco-based Sabek transportation company, and is being treated for second-degree burns to his face and neck.

“If this had happened during weekday commute times, we would have had a very ugly incident on our hands,” Cross said, adding that it was fortunate that no one was killed or seriously injured in the accident or subsequent collapse of the ramp. “The bridge is replaceable. A life is not,” he said.

It is too early to know what charges, if any, Mosquedo or his company might face, according to California Highway Patrol Commissioner Mike Brown. He said that the driver was coming from Contra Costa County but he would not say at an afternoon news conference where the driver was headed.

“He was fresh on his route,” Brown said, adding that there is little information available because the “investigation is only hours old.”

By the time CHP officers arrived at the scene, Mosqueda was already gone. Oakland fire crews fought the 2,000-degree blaze until shortly before 6 a.m.

The crash sparked a series of explosions on the lower portion of the ramp where Mosqueda was driving from westbound Interstate 80 to southbound Interstate 880. The intense heat melted the steel screws on the upper deck of the ramp, which was built in the 1950s.

Although the collapse has closed the ramp, motorists can continue to use Interstate 80 to get to and from San Francisco over the bridge.

On an average weekday, about 45,000 vehicles typically drive over the ramp that collapsed, according to Caltrans director Will Kempton. An estimated 35,000 cars drive over the lower bridge each day.

Ordinarily, it isn’t that easy to knock down a freeway. But the fireball apparently erupted precisely at the Achilles’ heel of the skyway – the underside of the pier where all of the supporting steel girders are bare and unprotected by concrete or anything else, according to Berkeley civil engineering professor Abolhassan Astaneh-Asl.

“I think this was really the perfect fire, tragically,” he said.

The freeway collapsed more or less for the same reasons that the World Trade Center towers did on Sept. 11, 2001. The steel supports were baked at, and probably beyond, 1,000 degrees Fahrenheit, the point at which steel turns to rubber, said Astaneh, who studied the WTC collapse for the National Science Foundation and also studied the MacArthur Maze after the 1989 Loma Prieta earthquake.

“It’s not to say the steel melted. Some portions may have melted, but the steel got soft, like rubber,” he said. “When steel gets that warm, it loses its strength and cannot carry its load any more.”

Caltrans has not yet checked the support columns to make sure they are still viable. Agency spokeswoman Lauren Wonder said the agency has demolition contractors ready to remove the damaged roadway, but that she could not say how long it might take to rebuild the ramps.

Kempton said that Caltrans officials are rushing to prepare an emergency proclamation, which he expected the governor to sign early in the week. The declaration would allow the Federal Highway Administration to reimburse Caltrans for the cost of repairing the ramp.

“This is not going to be a cheap process,” Kempton said, noting that bridge engineers were already working on the design efforts.

Kempton said state contracting rules have already been suspended to speed up the rebuilding. The rules normally require a competitive bidding process for public works projects.

While he would not offer any kind of time frame for repairing the ramp, he said that it would be a quicker turnaround than in 1989, when the Cypress Freeway collapsed during the Loma Prieta quake and the Bay Bridge was closed for a month. Unlike then, when several roads were closed, Sunday’s bridge failure is relatively isolated and can be addressed immediately.

State transportation officials advised motorists to take public transportation into and out of San Francisco. Oakland and San Francisco police will put extra officers on surface streets to help ease problems and congestion in the days to come.

San Francisco Mayor Gavin Newsom said Sunday he was in contact with the Schwarzenegger administration and already there are plans to “fast-track” reconstruction of the collapsed portion of the roadway.

“We’re all going to do what we can to fast-track reconstruction of the site,” he said. “We also are going to work with the labor parties, they understand the urgency.”

Newsom said the governor’s office is looking at the model used by then-Gov. Pete Wilson to reconstruct damage caused by the 1994 Northridge earthquake that closed Interstate 5 north of the San Fernando Valley.

“Unquestionably this will be one of the more problematic commutes in recent memory,” he said, speaking about the short-term impact.

It is too early to assess the economic impact from the crash, Newsom said, but he noted San Francisco’s population nearly doubles during the workday. And even with fast-track rebuilding, he warned, “These things do not happen overnight.

“And so there’s going to be a lot of disruption and a lot of effort to redirect people on a more permanent basis.”

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