WASHINGTON -- America's largest carrier association says it's is "extremely perplexed" that the Department of Transportation would agree to reopen its hours-of-service rules after years of improving truck safety statistics.

In a letter to Transportation Secretary Ray LaHood this week, ATA President and CEO Bill Graves said DOT's decision "creates uncertainty for trucking companies, their drivers and their customers, and is wholly unwarranted given the consistent and significant highway safety improvements made by the trucking industry under the current rules."

The letter is in response to the DOT's agreement with the Teamsters and Public Citizen to turn back the clock on hours-of-service and reconsider the rules that have been in place since 2004.

The groups announced that the DOT under the Obama administration will redraft new regulations within nine months and publish a new final rule in 21 months.

"As officials have pointed out on many occasions, both the available scientific research and the safety data provide a strong and substantial basis for retaining the existing HOS rules," Graves continued in his letter.

In fact, Graves argues that a new rule will "wreak havoc with trucking company operations, increasing freight transportation costs while destabilizing the trucking industry which is critically important to our nation’s economy" and will also “sow confusion within the trucking, shipping and enforcement communities, creating more uncertainty in very uncertain times."

While even ATA has some difficulties with at least one element of the current rules, he said "they do strike a good balance between promoting alertness, reducing driver fatigue and providing the trucking industry with the operational flexibility it needs."