Freight trucks travel northbound on Interstate 5 Highway on Sept. 3 in Tracy, Calif. (AP Photo/Godofredo A. Vásquez, file)

More than 550 commercial driving schools in the U.S. that train truckers and bus drivers must close after investigators found they employed unqualified instructors, failed to adequately test students and had other safety issues, the federal Transportation Department announced Wednesday.

The move marks the Trump Administration’s latest effort to improve safety in the trucking industry. And unlike its actions last fall to decertify up to 7,500 schools that included many defunct operations, this latest step is focused on active schools inspectors identified as having significant shortcomings in 1,426 site visits completed in December.

The department has been aggressively going after states that handed out commercial driver’s licenses to immigrants who shouldn’t have qualified for them ever since a fatal crash in August. A truck driver who Transportation Secretary Sean Duffy says wasn’t authorized to be in the U.S. made an illegal U-turn and caused a crash in Florida that killed three people. Other fatal crashes since then, including one in Indiana that killed four earlier this month, have only heightened concerns.

Duffy said 448 schools failed to meet basic safety standards. Inspectors found such deficiencies as employing unqualified instructors, failing to test students’ skills or teach them how to handle hazardous materials and using the wrong equipment to teach drivers. Another 109 schools removed themselves from the registry of schools when they learned inspections were planned.

“American families should have confidence that our school bus and truck drivers are following every letter of the law and that starts with receiving proper training before getting behind the wheel,” Duffy said.

The list of schools officials want to decertify now are generally smaller ones, including a number of programs run by school districts. Five of the bigger, more reputable schools represented by the national Commercial Vehicle Training Association were audited but those all passed.

Jeffery Burkhardt, chair of the national trucking schools group, said established schools welcome the enforcement effort to eliminate bad schools that aren’t meeting the standards. He said these audits mark the first time regulators have enforced the standards for driving schools that were passed in 2022.

“You know, the good players have no problem with it. Absolutely none,” said Burkhardt, who is also is senior director of operations at Ancora, which provides CDL training at colleges, community colleges and companies.

Another 97 schools are currently under investigation for compliance issues.

Part of the industry problem is that schools and trucking companies can essentially self certify themselves when they apply to begin operating, observers note, and questionable operations might not be caught until much later when the Federal Motor Carrier Safety Administration gets a chance to audit them.

It wasn’t immediately clear how many students were enrolled at these schools that are being decertified or how many graduated with questionable qualifications. A Transportation Department spokeswoman said officials may follow up on those graduates later. Burkhardt said that hopefully most of the unqualified drivers were weeded out before they got on the highway by the skills tests states administer before handing out commercial licenses.

There is steady demand for truck drivers because there is high turnover in the industry, and it has been difficult to attract enough drivers willing to spend days away from home delivering heavy loads. But there is some cushion in the industry right now because there are currently more drivers than needed in the midst of a 10% drop in shipments since 2022 owing to economic uncertainty. Nonetheless, many trucking companies still struggle to find enough well-qualified drivers with clean records.

Both the American Trucking Association and the Owner Operator Independent Drivers Association praised the decisive action to shut down “sham schools” that aren’t meeting basic safety standards.