Roundabouts becoming part of driving landscape to improve safety, reduce travel time

A roundabout coming to the intersection of Mad River and West Alex Bell roads in Washington Twp. is the first constructed by Montgomery County, but the circular intersection idea has been gaining steam in other communities locally and nationwide.

Communities have been installing roundabouts to reduce congestion and travel time, decrease potential vehicle conflicts at intersections and greatly reduce severe crashes that can result from right angle-type collisions at high speeds in a conventional intersection, according to the Montgomery County Engineer’s Office.

On average, roundabouts reduce crashes by 35%, injuries by 76% and deaths/fatalities by 90%, according to Montgomery County Engineer Paul Gruner.

“In the case of the Mad River/Alex Bell Roundabout, the level of service improves from (an) ‘F’ to ‘A’ (grade), compared with a signalized intersection improvement from ‘F’ to ‘B,’” Gruner told this news outlet. “Those comparisons are based upon peak-hour traffic. In the off-peak hours, traffic in the roundabout will be constantly moving, whereas with a signal, one direction would always be stopped.”

The new roundabout, which opened today, cost $280,000 for engineering, $370,000 for right of way and $970,000 for construction, according to MCEO. Ninety percent of construction costs were paid from federal safety money and 10 percent from the Ohio Public Works Commission, Gruner said.

Putting in a traffic signal there would have been more costly because that would have required the widening “all legs of the intersection back a distance,” he said.

The intersection had 40 crashes in a 3-year period, he said, with 19 of them being injury crashes, “which is pretty unusual for intersection crashes,” Gruner said.

The county will get another roundabout next year as the Montgomery County Transportation Improvement District launches construction on Dog Leg Road where it intersects with Jackson Road/Union Airpark Boulevard. There are four roundabouts in Greene County with four in the works, eight in Warren County with another six planned, three in Miami County and 30 in Butler County with six on the way, according to the engineer’s office in each area.

That includes roundabouts carried out by the state, counties, cities and townships, but not roundabouts developers built as part of a residential, industrial or commercial projects.

Roundabouts have become increasingly popular in Ohio and nationwide due to their successful performance history, officials said.

Greene County Engineer Stephanie Goff said roundabouts are more efficient than traditional intersections and less expensive to operate than traditional intersections with traffic signals. They also calm traffic and are “the single most effective road design in reducing the rate of crashes and crash severity.”

“Drivers must slow down and maintain slower speeds to navigate a roundabout,” Goff said. “If a crash does occur, they are less severe because they are at slower speeds and not angle and left turn crashes, which account of 65% of fatal crashes at traditional intersections.”

Modern roundabouts are the Butler County Engineer’s Office’s “number one tool in the toolbox” for making intersections safer, according to BCEO spokeswoman Betsy Horton

“We found early success with the effectiveness of modern roundabout intersections and have increasingly utilized the approach as our “go-to” solution for problem intersections with reductions of 100 percent in fatal crashes, 83 percent in injury crashes, and 61 percent in total crashes, Horton said. “Single-lane roundabouts are safer because they have fewer conflict points and slower speeds with 30 percent more capacity than a signalized intersection.”

While other parts of the nation have been quick to embrace roundabouts, not all local counties and communities have been able to do so, officials told this news outlet.

Montgomery County has “a significant part” of its land area occupied by municipalities, many of which are already fully developed, Gruner said.

“That means that areas around the intersections are constrained by homes or businesses that make the acquisition of land for a roundabout difficult,” he said “Also, the Montgomery County Engineer’s Office is responsible for 525 bridges, the most of any county in the state. That means that we need to devote a higher percentage of our revenue to bridges than some other counties.”

In contrast, he said, counties like Warren and Butler are rapidly developing with new growth, and have Tax Increment Financing districts to provide funding for road improvements along with available land for the right of way needed, Gruner said.

Goff said the Greene County Engineer’s Office is seeing a shift in area counties, including her own, “as you see changes in leadership occurring, education of the traveling public occurring and drivers getting more familiar with them.”

“I do believe many of our predecessors were hesitant about them,” Goff said. “I personally have always been a fan and proponent of roundabouts.”

Troy in Miami County has two roundabouts, the most recent of which opened at the intersection of McKaig Avenue and South Dorset Street in 2019, according to Troy Titterington, the city’s service and safety director

“It was a four-way red flashing light stop and go,” Titterington said. “With the Troy Christian Schools right there, the movements were very slow and inefficient. A lot of frustration for drivers and backups were routine. There weren’t many accidents but the roundabout has made traffic movement much, much smoother.”

Warren County Engineer Neil Tunison said cost of construction and right-of-way acquisition are the two main factors his office has not pursued roundabouts more aggressively.

“It’s certainly not due to push-back from the public,” Tunison said. “We have six in design or planning in areas where we have congestion and motorists are glad to hear they are coming. Constructing them is a matter of need and then finding the funding. It’s the same with any roadway or bridge improvement.”

In addition, most roundabouts require “significant real estate” to install, which is expensive and could result in the need to take property in developed areas, possibly displacing home owners, he said.

Plus, as stewards of limited public funding, the “new” technology may be something that designers are taking a wait-and-see attitude before “jumping onto the roundabout bandwagon,” Huelskamp said.

But roundabouts can perturb motorists who are unfamiliar with or intimidated by them, officials said.

The majority of the engineers contacted for this report said that education is the greatest tool they have toward helping motorists learn how to navigate roundabouts and regularly make information on how to drive them available via websites and social media.

Montgomery County Engineer’s Office is providing information on roundabouts and how to drive them at A MCEO video at illustrates how to navigate a single-lane roundabout.

Huelskamp said he has seen some signing that appears to help motorists who still have trouble with roundabouts, but ultimately, “time” is the solution for people getting used to a new configuration.

Carmel, Indiana, a city of about 100,000 people approximately two hours west of Dayton, opened its first roundabout in 1997. Now it has 144 of them, three of which opened in the last few weeks, with four on the way, according to Jim Brainard, who has been mayor there since 1996.

Roundabouts, he said, create “substantial safety.” Carmel’s fatality rate is at two per 100,000 people annually as opposed to the U.S. average traffic fatality rate of about 12 per 100,000 people, Brainard said.

The city is converting all its stoplights to roundabouts, except for one in an older part of town that isn’t big enough to do it, he said.

Creation of a roundabout at an intersection with no signalized intersection is a minimum of $500,000 less than installing traffic lights and is far more efficient than adding lanes, Brainard said.

“All they’re doing … is creating a bigger parking lot to get more cars through the green cycle of the light,” he said. “A roundabout moves about 50% more cars per hour, so we don’t have to widen all those lanes.”


  • When approaching a roundabout, slow down. Roundabouts are designed for low speeds around 20 to 30 mph.
  • Yield to the cars in the roundabout. They have the right of way.
  • Look to your left and enter the circle by turning right when there is a safe gap in traffic.
  • Keep moving when you’re in the roundabout. All U.S. roundabouts are one-way: counterclockwise.
  • Exit right when you see your turn.

SOURCE: Montgomery County Engineer’s Office

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