Roundabout called a success
By Mike O'Neal: Staff Writer
Chattanooga's first traffic roundabout just outside the Bachman Tubes through Missionary Ridge has been such a success that similar circles may be installed elsewhere around town, traffic officials say.
"I'm always looking for improvements to the traffic system," said John Van Winkle, the city's traffic engineer. "Now, I find myself looking at other intersections to see if a roundabout would work there."
The roundabout at the tunnels between Chattanooga and East Ridge is designed to control vehicles' flow on a high-traffic thoroughfare. Brainerd has had a few traffic circles to control speeding for years, including ones on Old Mission Road near the Brainerd Golf Course and on Chickasaw Road in Shawnee Park. The traffic circles are not as elaborate as roundabouts.
Tennessee Valley Authority officials have proposed a pair of roundabouts where Access Road, Lake Resort Drive and the ramps from Highway 153 meet at the Chickamauga Dam, engineers said.
Delays have been alleviated for the more than 20,000 vehicles passing through the Bachman Tubes daily, officials said. No accidents have been reported since the roundabout opened Sept. 26, 2001, according to Becky Roberts with the traffic engineer's office. During the first six months of 2001 four accidents were reported at that intersection, she said.
The major benefits of a roundabout are shorter delays, increased traffic capacity, improved safety and improved aesthetics, according to the National Cooperative Highway Research Program.
Optimally, traffic in a roundabout never lurches along in a stop-and-start cycle of traffic lights and stop signs, according to engineers. Instead, it flows in a never-ending yield/merge pattern. Operating on the "yield to traffic in the circle" rule, drivers slow as they approach the roundabout, bear to the right, yield to traffic on their left, travel counter-clockwise and signal their intention to exit.
The circular roadways are cheaper to build and maintain than intersections with right angles and traffic lights, according to engineers.
Mr. Van Winkle said another economic benefit is long-term maintenance of a traffic signal is eliminated. And if crashes occur at a roundabout, they are usually sideswipe accidents, which are far less serious than head-on or right-angle impact accidents, according to engineers.
Mr. Van Winkle said public pressure to improve the intersection of Shallowford and Jenkins roads is building. An April 1 traffic count there showed 18,615 vehicles traveled through that intersection, he said. Traffic at the intersection now is controlled by four-way-stop signs, and during the traffic count as many as 90 cars were backed up on eastbound Shallowford Road during peak hours, officials said.
State approval would be required before any design changes to the intersection could be made, officials said.
Preliminary designs for a Shallowford/Jenkins roundabout show right-of-way acquisition would be minimal and a roundabout could handle the traffic volume without added lanes and a signal light, officials said.
"I'm convinced a roundabout would work," Mr. Van Winkle said. "I'm anxious to see it built."
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