The man behind the wheel of a tanker truck hauling thousands of gallons of gas that exploded and brought down one of Northern California's most traveled highways had a long criminal rap sheet. But he still got a license.

The fiery crash has thrown a spotlight on the limits of anti-terrorism rules that may not prevent people with checkered backgrounds from hauling hazardous materials on highways.

The issue surfaced after the explosion and intense fire from driver James Mosqueda's tanker crash Sunday that caused the collapse of a busy Bay Area highway overpass.

Mosqueda, 51, cleared an FBI criminal history check and an intelligence review from the U.S. Transportation Security Administration.

The TSA said the checks aren't designed to identify people with Mosqueda's type of record, which includes a two-year prison term for a 1996 heroin conviction and other arrests but no terror charges.

"We're looking for terrorists," spokeswoman Andrea McCauley said Tuesday. "We're looking for people who would be involved in terrorist activities — that's the scope."

On Tuesday, demolition crews finished clearing the charred debris and hundreds of thousands of commuters settled into taking buses or subways to work — unless they could work from home. It was clear the highway collapse was impeding traffic, but rush-hour slowdowns didn't turn into the gridlock authorities had feared.

Investigators believe Mosqueda might have been speeding at the time of the crash, but they do not believe drugs or alcohol were factors in the accident.

Joe Come, program director for motorcarrier safety for the U.S Department of Transportation Inspector General's Office, said the crash raises a broader issue.

"There's a general question of how hard do you want to make it for people to get a commercial driver's license or anything else that can affect public safety," Come said. "Do we hold them to the same standard as airline pilots?"

Family and friends said Mosqueda, who remains hospitalized with second-degree burns, has been sober for a decade, is active in his church and works as a drug and alcohol counselor with a Hispanic health organization.

But an industry expert questioned rules that allowed someone with Mosqueda's background to operate a truck loaded with more than 8,000 gallons of gasoline.

"He is unemployable because of (his) past record. That would be our recommendation right off the bat," said Darryl Tolentino, managing director of Fleetwatch Systems Inc., which performs driver background checks for trucking companies.

A study commissioned in 2005 by the American Trucking Associations predicted the industry will be short by more than 100,000 drivers by 2014 and placed partial blame on the government's more stringent security and safety regulations enacted after the Sept. 11 attacks.

The U.S. Department of Transportation Inspector General's Office recently found that between 1998 and 2003, investigators uncovered schemes in 23 states in which commercial trucking companies were helping drivers fraudulently obtain licenses.

An investigation last year by the Dallas Morning News turned up evidence that truckers were being recruited at Texas prisons and that convicted felons are behind the wheel in hundreds of truck crashes in the state each year.

Nationwide, a study prepared for Congress in 2005 said thousands of felons are involved in commercial truck crashes annually.

"A family driving on the highway and looking at a gasoline tanker truck out the window assumes that driver has met the highest standards," said California Assemblyman Pedro Nava, a Democrat who chairs both the Assembly Transportation Committee and the Joint Committee on Emergency Services and Homeland Security. "We now know that's not the case."

Nava met Monday with California Highway Patrol officials at the crash site and plans to meet with officials from the state's Department of Motor Vehicles and the trucking industry to strengthen requirements for drivers.