How do roundabouts work?
There seems to be a local trend toward roundabouts. Do statistics show that cities with lots of roundabouts have fewer traffic accidents?
That was the question posed to us by a reader of The Telegraph through Macon Me Curious, a new project of the Center for Collaborative Journalism in partnership with The Telegraph and GPB Macon.
Roundabouts decrease the number of “conflict points” at any given traditional, two-way stop intersection from 32 points to eight, said Tyler Peek, a district traffic engineer for the Georgia Department of Transportation.
“Conflict points are where you have the potential for a crash to occur. Now, that doesn’t mean a crash will occur or is prone to occur. The opportunity exists because of the way the intersection is set up, because you’ve got multiple directions of travel, and depending on the intersection, you have multiple ways in which you can turn and navigate,” Peek said.
Take the College and Oglethorpe streets roundabout for example. Prior to the roundabout installation in 2014, there were five to six right-angle collisions a year, according to Macon-Bibb County Traffic Engineering.
“Since the roundabout has been built, we haven’t had any right-angle collisions,” said Macon-Bibb traffic engineer Nigel Floyd.
Right now, in Macon-Bibb there are roundabouts at College and Oglethorpe streets, Eisenhower Parkway and Holly Lane, and Thomaston and Lamar roads. A mini-roundabout also exists at Arkwright Road, Bass Road and Ga. 87.
Roundabouts are popping up in cities nationwide.
“It’s a national trend. Roundabouts are prevalent all over Europe. I guess the Federal Highway Administration is now adopting roundabouts in the United States. So, a lot of communities are implementing roundabouts just because of their safety features,” Floyd said.
In Georgia, locations for roundabouts are chosen once the transportation department has conducted a traffic engineering study.
“These studies are a very comprehensive analysis that looks at multiple factors of an intersection, traffic data, crash data, roadway geometry, land use and right of way,” Peek said.
But before conducting the study, the Georgia Department of Transportation must learn of a problem intersection through a local government contacting them or a request from the general public.
“The request for the study, or the idea that we need to do something at a location, can come from a variety of sources, but it all still funnels through that traffic engineering study process where we vet out what options are worth pursuing and which ones are not a really good fit,” Peek said.
Besides improving the safety of an intersection, Peek said roundabouts also improve the efficiency at particularly congested areas by allowing cars to continue moving instead of completely stopping.
There can be drawbacks.
“Although you have pedestrian crossings there, you don’t have a stop feature as you would with the traffic light. At a traffic light, you have stop conditions for pedestrians to cross the street and you have signals. At a roundabout, you don’t have that. You can put what they call red flashing beacons or pedestrian warning signals, but you don’t have an actual stop condition,” Floyd said.
Also, not everyone knows how to properly drive a roundabout.
“When we first started implementing them, a lot of people were confused on how to use them and thought they wouldn’t probably work. But I think since we’ve got roundabouts in and people are driving them, I think people feel safer going through an intersection rather than going through a traffic signal,” Floyd said.
In addition to the four roundabouts in Macon-Bibb, the Georgia Department of Transportation has identified two more roundabout projects.
One of those is where Pio Nono Avenue, Broadway and Houston Avenue merge and flow toward Houston Road. The other is downtown by the Navicent Health main campus at the intersection of Pine, Forsyth and Spring streets.
“You’re coming into the city right in downtown Macon and going right into the hospital. We felt like that was a good place. Plus, it’s a five-leg intersection there, and you can take those five legs and do a roundabout there pretty easily,” Floyd said.
Do you have a question you want answered? What are you curious about? Let us know at macon.com/curious.