As Franklin County motorists find themselves driving in more circles via roundabouts, local experts continue to say the configurations are safer than signalized intersections and provide for better traffic flow.

Based on the most recent information from the Franklin County Engineer's Office, the county has about 50 roundabouts, with half of them constructed in the past five years, said W. Fritz Crosier, the county's chief deputy of engineering.

The county defines a modern roundabout as a one-way, circular intersection with yield control for all entering traffic. Vehicles circulate counter-clockwise at speeds around 20 miles per hour, with the lane use very similar to a typical four-way intersection, except for a slight circular adjustment.

Crosier said some central Ohio municipalities, such as Dublin, Gahanna, Grove City and Hilliard, maintain roundabouts, and the county engineer's office maintains six of the county's 50.

To his knowledge, Crosier said, the most recent roundabout was completed in 2018 on Smothers Road at Schott and Red Bank roads near Westerville, and the county has four more planned for construction in the next few years.

Those include Norton Road at Johnson Road in Pleasant Township; Morse Road at Kitzmiller Road and Clark State Road at Reynoldsburg-New Albany Road, both in Jefferson Township; and Morse Road at Babbitt Road in Plain Township.

Gahanna's experience

As part of Gahanna's Hamilton Road Central project that was completed in 2017, two roundabouts were built at Clark State Road and at the Northeast School on Hamilton Road. Both are south of where U.S. Route 62 crosses Hamilton.

Rob Priestas, Gahanna's director of public service and engineering, said the roundabouts are efficient and provide for constant movement of traffic.

"Prior to the roundabout installation, the intersection of Clark State Road and Hamilton Road experienced heavy congestion and backups," he said. "Since the completion of the roundabouts, there is very little delay and congestion experienced at this intersection."

Priestas said an average of one or two accidents per month is reported on the Hamilton Road roundabouts.

"The key is that the types of accidents experienced are minor property damage only and do not indicate or result in severe injury or death," he said.

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Priestas said the roundabout at Route 62 (known locally as Johnstown Road) and Morse Road was the first roundabout in Gahanna, though only a small portion is in the city's corporation limits. The rest is in Columbus and Plain Township, according to the county engineer's office.

Crosier said the county-maintained roundabout, constructed in 2007, was one of the first in Franklin County.

"In the first three full years of operation, from 2008 to 2010, there were approximately 125 crashes at the intersection, 10 of which involved injuries," he said. "The high number of crashes was most likely attributed to the fact that it was one of the first roundabouts in this part of Franklin County. Drivers were, generally, unfamiliar with roundabouts."

Crosier said it was a multilane roundabout on all four approaches, which is more complicated to navigate than a single-lane roundabout.

After additional analysis, he said, modifications were made to the roundabout from 2011 to 2013.

These modifications included converting the outside through lanes to exclusive right-turn lanes and reducing the number of lanes in the circle from two to one, Crosier said.

After implementing the modifications, the crashes decreased significantly, he said.

From 2015 to 2017, 21 crashes were recorded, with only two of these involving injuries, according to Crosier.

He said roundabouts warrant no specific requirements.

"They're just a good balance of increasing safety and still getting good capacity to the intersection," Crosier said. "They're safer than a traditionally signalized intersection."

Studies have shown roundabouts provide nearly an 80 percent reduction in injury accidents because the circular layout reduces the likelihood of head-on or broadside collisions, according to franklincountyengineer.org/roundabouts.

The county website notes other benefits of modern roundabouts include:

* A reduction in pollution and fuel use because there is less idle time for motorists.

* Slower speeds and fewer stops and starts result in less traffic noise.

* No expensive traffic signals to install or maintain.

Crosier said roundabouts also are safer than signalized intersections because of slower speeds.

"There's typically less property damage," he said. "They keep a continuous flow of traffic."

Carla Marable, communications director for Franklin County Engineer's Office, said the average cost of a modern single-lane roundabout can range from $1.8 million to $2 million.

"Historically, they are cheaper than signalized intersections; however, there are so many variables that could impact cost, we don't have an accurate cost comparison," she said.

Driver preparation

Crosier said types of roundabouts include single lanes; multilanes with one or more approaches having two or more lanes; and a newer type, the "turbo."

"'Turbo' is basically a multilane roundabout, and once you choose a lane, you don't have an option to change lanes once you're in the roundabout," he said. "I don't think it has been used in the U.S. yet. There's some interest in the future to use them."

Before Gahanna opened the two roundabouts on Hamilton Road, an interactive display was featured on the floor of Gahanna City Hall, 200 S. Hamilton Road, to allow individuals to simulate the driving experience of navigating a roundabout, Priestas said.

Based on feedback from active senior citizens, Gahanna's service department organized a hands-on roundabout training course at Headley Park, 1031 Challis Springs Drive. It included classroom instruction, followed by an opportunity to practice safe-driving techniques using golf carts.

"Our class roster had 23 seniors who participated in the training class," Priestas said. "Countless folks came into City Hall to look at the (interactive display), to better understand how to navigate the proposed roundabouts. We had many more campaigns besides the training class and (display) to help educate motorists on how to properly navigate roundabouts."

Crosier said Gahanna was aggressive with its outreach campaign for the roundabouts.

"Generally speaking, education is important with roundabouts," he said. "The single roundabout can be simple to understand. As you add lanes, more decisions are put on the driver. With more decisions, sometimes there's more opportunity for errors."

Crosier said he isn't sure where roundabouts gained their popularity, but Carmel, Indiana, a city north of Indianapolis, has more than 100 roundabouts.

"It's one of the most forward-thinking (cities)," he said. "In Wisconsin, there are quite a few there. I've been to roundabout-specific conferences. They seem to be in the forefront of the roundabout industry."

mkuhlman@thisweeknews.com

@ThisWeekMarla