Oakland, Calif. ? Tough anti-terrorism rules designed to limit who can transport hazardous materials on highways don’t prevent people with checkered backgrounds from becoming truckers, experts and regulators acknowledged Tuesday.

Those rules are aimed at weeding out terrorists, not necessarily other criminals, a spokeswoman for the U.S. Transportation Security Administration said.

The issue surfaced after the explosion and intense fire from driver James Mosqueda’s gasoline tanker Sunday caused the collapse of a busy Bay Area highway overpass. Mosqueda, 51, cleared an FBI criminal history check and an intelligence review from the TSA despite a history of criminal convictions.

On Tuesday, demolition crews finished clearing the charred debris, and hundreds of thousands of commuters settled into new routines on bus routes, subways or just working from home. It was clear the highway collapse was impeding traffic, but rush-hour slowdowns didn’t turn into the gridlock authorities had feared.

The TSA concedes that its screening rules are contributing to a growing trucker shortage, but a spokeswoman 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.

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.

“We’re looking for terrorists,” spokeswoman Andrea McCauley said. “We’re looking for people who would be involved in terrorist activities – that’s the scope.”

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 their drivers fraudulently obtain licenses.

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, D-Santa Barbara, 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.”