A California congressman will introduce legislation Wednesday to allow commercial truck drivers under the age of 21 to operate in interstate commerce through their involvement in an "apprenticeship" program overseen by seasoned commercial drivers.

The legislation, to be introduced by Rep. Duncan Hunter (R), would establish sequential probationary periods during which drivers between ages 18 and 21 would be required to meet progressive competency requirements, and to hit specific safety benchmarks. Under-21 drivers would be accompanied by an experienced commercial driver's license (CDL) holder during all driving hours and would operate trucks equipped with advanced safety features and technology. Those who complete the program would be allowed to drive commercial trucks in interstate commerce on their own, according to the legislation.

Currently, states issue CDLs to driver applicants once they turn 18 and allow them to operate within the state where their license is issued. However, they cannot cross state lines until they turn 21. Efforts were unsuccessful to include language in the 2015 federal transport funding bill to allow strictly enforced pilot programs between neighboring states.

The trucking industry faces a shortage of qualified drivers that is only expected to get worse. A survey last October of 1500 motor carriers and drivers found that the driver shortage was the industry's most critical issue and that allowing drivers under the of 21 to operate in interstate commerce was the most effective remedy for attracting more drivers, as well as younger ones. About 1 on 4 truck drivers are 55 years or older and nearing retirement. However, carrier interests maintain that by forcing drivers to wait until 21 to operate rigs in interstate commerce, the federal government is creating an incentive for high school graduates who might not go right on to college to choose other professions.

Adding to the industry's frustration is that a driver under 21 who, for example, is licensed in California can drive the 500 miles from Los Angeles to San Francisco, but cannot drive from San Francisco to Reno, Nev., a distance of only 218 miles.

In a related development, the American Trucking Associations (ATA) said today that the driver turnover rate at truckload carriers fell in the final three months of 2017, but that the rate stayed higher than in the previous year.

According to ATA's "Trucking Activity Report," the annualized driver turnover rate at large truckload fleets - those with more than $30 million in revenue - fell seven points to 88 percent in the fourth quarter. It was the first time the rate had dipped below 90 percent since the first quarter of 2017. Driver turnover at small truckload fleets fell four points to 80 percent.

ATA Chief Economist Bob Costello said stronger freight demand may have encouraged drivers to stay with their fleets because they were making more money without having to jump to another carrier. In addition, many fleets either implemented or announced driver pay increases last quarter, which may have kept drivers in their current seats, Costello said.

However, the turnover rate at large and small fleets was 14 points higher than in the fourth quarter of 2016, and Costello said last quarter's decline may be a one-quarter blip. The driver market "remains tight and the driver shortage remains a real concern for fleets and the industry," he said. "If the economic climate continues to improve, I expect both turnover and driver shortage concerns to rise in the near future."