Beginning in early summer, the Tennessee Department of Transportation will lower speed limits for commercial trucks to 55 mph in Memphis and surrounding Shelby County, a change that affects 106 miles of interstate, including Interstates 40, 55 and 240.
The speed limit for automobiles will be reduced simultaneously, to 65 mph on interstates and other controlled-access highways.
The state announced in February that the same reduction will take effect this summer in Hamilton County, including Chattanooga.
The Tennessee Trucking Association likes the idea of lowered limits but wishes the change were uniform. “This is purely a safety issue,” said Dave Huneryager, the association’s president and CEO. “We have a longstanding policy of wanting a uniform 55 mph limit for all vehicles.”
The reduced speeds will bring the Memphis area into compliance with the U.S. Environmental Protection Agency’s Clean Air Initiative, the department said.
“Reducing truck speed limits by 10 mph can reduce the nitrogen oxide emission factor by approximately 18 percent or more per truck,” said Gerald Nicely, transportation commissioner. “If we get reductions anywhere close to that level in Shelby County, it will be worth it.”
The reduced speeds will reduce emissions by 3.1 tons a day by 2006, said Bob Rogers of the Shelby County Health Department.