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Column: Improvements in traffic flow are thanks to road geometry
Rudi Kiefer

In Lumpkin County, the intersection of Ga. 115 (Dahlonega Highway) and Ga. 52 at Copper Mines Road used to be a constant bottleneck. Vehicles would sit idling, then inching forward one car length at a time to await their turn at the 4-way stop. Things changed when the Georgia Department of Transportation (GDOT) redesigned the intersection into a roundabout, a.k.a. traffic circle. Now, traffic flows smoothly and hardly anybody needs to stop anymore. The old argument “Americans don’t know these and can’t handle them” has been disproved on this route to Dahlonega.

A similar stop-and-go spot exists in Habersham County at Ga. 105 (Cannon Bridge Road) and Ga. 115, leading to Helen. The GDOT is currently accepting online input for the plan to lose the 4-way stop there too and replace it with a roundabout. It is encouraging to see the shift in thinking among traffic engineers. It makes more sense to design for traffic to flow, not to stop it at every intersection. 

In Hall County, home of countless 4-way stops, the same road geometry that’s been popular in Europe for decades is taking hold. At Sardis Road and Ledan Extension, a roundabout makes crossing the intersection easy. In Flowery Branch, Lights Ferry Road intersects Mitchell Street the same way.

Besides easing traffic flow, roundabouts also benefit the environment by eliminating needless stops and start-ups. Accelerating from a full stop uses a lot of gas and produces emissions that we can live without. Maybe some day we will even see a redesign of that goofy intersection in Clarkesville where Ga. 385 meets Washington and East Louise Streets. Motorists are forced to make it through multiple stop signs and a traffic light, while a roundabout could eliminate all that. 

Another aspect of road geometry is apparent on curvy country roads. The turns are banked toward the outside of the curve, requiring a firm grip on the steering wheel. But if you look at a race track, they lean inward, allowing cars to pass through them faster and with less effort. It seems at first like the country roads have it wrong, but leaning a curve to its outside allows rainwater to disperse. An inward-banked curve tends to funnel water. Not a concern on a controlled racing circuit, but with 24/7 traffic on public roads, engineering is choosing the lesser evil.

Rudi Kiefer, Ph.D., is a professor at Brenau University, teaching physical and health sciences on Brenau’s Georgia campuses and in China. His column appears Sundays and at