It's supposed to make the air cleaner and help Sullivan County meet federal environmental guidelines.
The Sullivan County Commission voted last May to ask TDOT to lower the speed limit for trucks to 10 mph less than the speed limit for other vehicles.
A statement issued Wednesday by TDOT says signs with the new speed limits will begin to be posted next week.
According to TDOT:
•The new signs will display a reduced speed limit for commercial trucks, taking the speed limit to 55 mph from 70 mph.
•The speed limit for other vehicles will also be reduced to 65 mph instead of 70 mph.
•Installation of the new speed limit signs will begin on Monday, weather permitting.
•There are 18 speed limit signs being installed - along with several other signs showing "reduced speed ahead."
•The speed reduction area will begin along Interstate 81 at the Washington County line and continue to the Virginia state line at Bristol - for a total of 22.1 miles.
•The speed reduction area will also include Interstate 26 beginning at Kingsport and including a 2.5-mile portion of State Route 137 (US 23) that is part of the controlled access highway at the start of I-26 to the Washington County line - for a total of 12.5 miles.
•The Tennessee Highway Patrol will be issuing warnings rather than citations the first two weeks the new speed limits are in effect in order to allow motorists time to adjust to the reduced speeds.
The Kingsport Metropolitan Planning Organization asked the County Commission to seek the speed limit change from TDOT. The goal: reduce vehicle emissions, thereby improving air quality, with the goal of bringing Sullivan County into attainment with the Environmental Protection Agency's federal air quality health standard for ozone. Sullivan County and portions of the East Tennessee Valley are currently categorized by the EPA as non-attainment areas.
"County governments are looking at ways to improve air quality to meet EPA standards," said TDOT Chief of Environment and Planning Ed Cole. "A study conducted by the Federal Highway Administration shows that reducing truck speed limits by 10 miles per hour can reduce the nitrogen oxide emission factor by approximately 18 percent or more per truck. If we get reductions anywhere close to that level it will be worth it."
"According to studies by the Tennessee Department of Environment and Conservation's Division of Air Pollution Control, reduction of interstate truck speed limits is among the most effective measures we can take to assure the Tri-Cities attains and maintains attainment with the National Ambient Air Quality Standard for ground-level ozone," said Bill Sorah, chairman of the Ozone Action Partnership for Northeast Tennessee. "This action fits in with our Early Action Compact with EPA, which has allowed our counties to avoid classification as non-attainment. Non-attainment is a label we want to avoid. Not only would it mean our air quality does not meet the standards, but it would also create an impediment to economic development."
A Federal Highway Administration analysis of reduced truck speeds and its effect on emission rates can be found in the TDOT media room at www.tn.gov/tdot/mediaroom/docs/2005/emission_reductions.pdf.
Before they voted on the issue last year, county commissioners were told it might mean more cars hitting more trucks. But it might mean fewer trucks hitting cars.
Proponents of the proposal, speaking on behalf of the Ozone Action Partnership, said transportation officials think making trucks go 10 mph slower than cars would be "a wash" on safety because it will mean "more car onto truck, but less truck onto car and less sideswipes."
Supporters also said better air quality could help promote economic development in the county.
County Commissioner Joe Herron said the county's status as a non-attainment area for ground-level ozone had kept some businesses from locating here in recent months.