Lower speeds approved in Tennessee's Hamilton County; others likely to follow

| 2/8/2005

Tennessee’s transportation director has approved the first of a handful of requests to reduce speed limits in urban areas for large trucks and other vehicles as a way to fight air pollution. Currently, all vehicles are allowed to drive 70 mph.

Gerald Nicely, commissioner of the Tennessee Department of Transportation, announced the authorization for posting 55-mph speed limit signs for large trucks in Hamilton County at a press conference Feb. 8 in Chattanooga. All other vehicles would have new limits of 65 mph.

About 57 miles of interstate will be affected by the speed limit changes. A section of U.S. 27 that runs about 17 miles will also have lower speeds posted.

“After studying the issue we believe that lowering the speed limit for large trucks will make a difference in air quality for Hamilton County,” Nicely said. “A study conducted by the Federal Highway Administration shows that reducing truck speed limits by 10 mph can reduce the nitrogen oxide emission factor by approximately 18 percent or more per truck. If we get reductions anywhere close to that level in Hamilton County it will be worth it.”

Truckers in Hamilton County won’t see the new limit posted until early summer, Nicely said. The speed limit for automobiles will also be reduced at that time.

“The reason for reducing the speed of cars as well as trucks is to lessen the difference between the rates at which the two types of vehicles will be traveling.”

Chattanooga Mayor Bob Corker and Hamilton County Mayor Claude Ramsey requested the change in truck speeds.

Shelby County is likely next in line for the lower limits. Similar requests from Knox and Davidson counties also await action.

Officials in the state’s largest cities hope the slower traffic will help their areas meet new federal air-quality standards for ozone pollution.

All of Tennessee’s largest metropolitan areas failed last year to meet the new air standards. Failure to develop plans to clean up the air by 2007 could result in an end to industrial expansion and large cuts in federal highway funding for the area.

Shelby County Mayor A.C. Wharton requested the lower limit in a letter sent to Nicely last summer. The Tennessee Air Pollution Control Board and Metropolitan Planning Organization backed the change.

The city of Chattanooga and Hamilton County have also requested TDOT to authorize confining trucks to the right lanes.

TDOT spokeswoman Kim Keelor said the department was continuing to consider the proposal.

“We may be announcing something about that later this year,” she said.

The speed limit and lane changes do not require state legislative approval.

– By Keith Goble, state legislative editor