SIOUX FALLS, S.D. (KELO) — The city of Sioux Falls installed its first roundabout in about 2008 and its working on its fifth.
The circular multiple lane turning options are often considered an option to replace traffic signals as the city reviews street projects, said engineer Andy Berg.
But roundabouts aren’t always the best fit on every street.
Take Veterans Parkway for example.
The parkway has multiple traffic lights on the section from the intersection with Arrowhead Parkway south to the intersection with 57th Street.
“On Veterans Parkway, the traffic volume is way past (allowing for a) roundabout,” said Heath Hoftiezer, a traffic engineer for the city. “Veterans Parkway is a planned regional principal arterial road.”
Roundabouts are not suited for Veterans Parkway but they are suited for the intersection of Southeastern and 69th Street.
And there is a roundabout “planned in conjunction with Veterans at Western and 95th Street near the Harrisburg School,” Berg said.
The city is building a new roundabout on a section of 33rd Street just east of Veterans Parkway.
“I would say we’d never rule it out,” Berg said of at least considering a roundabout. Even an older, well established street could someday get a roundabout.
But the same rules and needs apply whether its a roundabout on a new street or an old street.
The traffic volume must fit a roundabout and there needs to be enough space.
“The biggest challenges with roundabouts, new and retrofit are the right of ways,” Berg said. “They take more right of way (space).”
“Roundabout lanes are 16 to 18 feet wide,” Hoftiezer said. “Turning vehicles take up much more space so the lanes are bigger.”
Roundabouts also allow for turning trucks and trailers. When trucks turn, the trailer will follow using the lane apron designed for that purpose, Hoftiezer said.
The city has installed and will consider roundabouts for multiple reasons.
“One of the biggest benefits is there are fewer conflict points than with regular traffic signals,” Hoftiezer sad.
Conflict points are potential crash points.
Roundabouts are safer in terms of the types of crashes.
“(Crashes) are a lot less harmful,” Hoftiezer said. Crashes tend to be rear end or sideswipe crashes, he said.
From a sustainability standpoint, “We are not using electricity of signal equipment,” Hoftiezer said.
The city also had reduced maintenance. Hoftiezer said it costs about $5,000 a year to maintain a traffic signal.
Traffic also moves more efficiently in locations where roundabouts are appropriate.
Public acceptance has increased since the city installed its first roundabout roughly 14 years ago.
Hoftiezer said data from the Federal Highway Administration shows that when roundabouts are first installed only 10% to 20% of drivers support them. Once they are in place, 80% to 90% support them, he said.
“Over the past year, we’ve gotten quite a few letters asking why we don’t have more roundabouts,” Hoftiezer said. “Ten years ago we would have not gotten that kind of feedback.”
“Sometimes the request to put on in is not a good fit,” Berg said of a location. “Just because someone has asked for it, it doesn’t mean we can put on in.”