American Trucking Associations says the Federal Motor Carrier Safety Administration's new definition of a "tank vehicle" is too expansive and needs to be changed.

FMCSA made the change last year in a rule that tightened its standards for commercial driver's license testing, and created new commercial learner's permit.

The agency defined a tank vehicle as one designed to transport any liquid or gaseous material in tanks that are either permanently or temporarily attached to the chassis and are rated at more than 119 gallons and aggregated to 1,000 gallons or more. A flatbed carrying empty tanks rated at 1,000 gallons or more is not considered a tank carrier.

This definition includes vehicle that "are manifestly not tank vehicles," ATA said in a Feb. 22 letter to FMCSA Administrator Anne Ferro.

It includes, for example, dry van trailers hauling empty or filled cylinders and intermediate bulk containers designed for liquids and gases, ATA said.

The problem is that under the new definition these types of shipments trigger the need for a tank endorsement on the driver's commercial license. This affects many private fleets but large less-than-truckload carriers are especially hard hit, ATA said.

"These motor carriers do not know in advance what types of containers will be moving on shipments between their terminals," the association said in its letter to Ferro. "Obtaining this endorsement is burdensome, requiring additional training, time off work and substantial costs and fees."

There is no precise estimate of how many drivers will be affected, but just the two largest pickup and delivery carriers have close to 200,000 drivers who handle such loads, ATA said.

ATA asked the agency to revise the definition to preserve safety but exclude vehicles "that are patently not tank trucks."

The revision should say that a tank endorsement should be required for any tank over 1,000 gallons, and for vehicles with permanently attached tanks bigger than 119 gallons with an aggregate capacity of more than 1,000 gallons, ATA said. It should clarify that a permanent tank is emptied while on the truck, rather than being offloaded.

States have until July 2014 to adopt the new definition, but according to a bulletin from the South Carolina Trucking Association some states already have made the change and are enforcing the new definition. SCTA cited Louisiana, which has begun citing drivers but will not levy any fines until March.