State eyes roundabouts for 31 intersections

January 7, 2012

The city of Carmel may be the roundabout capital of the United States, but the Indiana Department of Transportation has ambitious plans of its own for the European-style traffic fixtures.

INDOT has identified 31 intersections statewide for roundabout construction over the next five years, including a dozen in the metro area.

That’s less than half of Carmel’s 70-plus roundabouts—but a tenfold increase from the three roundabouts INDOT has today. The first was opened to traffic in Valparaiso nearly four years ago.

roundabouts Twin roundabouts on State Road 32, east of Noblesville, were INDOT’s second and third statewide. (IBJ Photo/ Perry Reichanadter)

Then, last year, a pair of roundabouts was completed east of Noblesville where State Road 32 intersects with Union Chapel Road and with nearby Promise Road.

“It’s a big jump from three to 30 roundabouts,” said INDOT Commissioner Michael Cline. “It’s a little bit of a cultural shift for us.”

Driving the change is safety, Cline said.

An Insurance Institute for Highway Safety study found that roundabouts reduced crashes 40 percent and injury crashes 80 percent.

INDOT’s own, limited experience with roundabouts isn’t quite so impressive, at least not yet.

Two years after building a roundabout at State Road 130 in Valparaiso, total crashes had fallen 6 percent. The number of injury crashes at the location is down 65 percent, according to the agency’s LaPorte District.

Slower and steady

The underlying reason for fewer injuries is the reduction in high-speed collisions.

“You have fender-benders rather than T-bones,” Cline said.

“It’s all about speed,” said Carmel Mayor James Brainard.

While slowing traffic, roundabouts generally maintain flow rather than halting traffic entirely as with a traffic signal or stop sign. That portends reduced fuel consumption and less air pollution. Eliminating traffic lights also reduces electricity use, which can run $1,000 a year at some intersections.

As such, local and state governments in some cases have been able to lasso federal Congestion Mitigation and Air Quality Improvement Program funds to pay for construction. Many of these grants are in the range of $150,000 to $300,000, said Lori Miser, executive director of the Indianapolis Metropolitan Planning Organization.

roundabout mapA relatively simple roundabout can cost $400,000 to build, according to INDOT, after factoring in time-intensive work such as relocating utility lines. Construction costs can be similar to building a conventional, traffic-signal-controlled intersection, according to some state highway departments that have studied the issue. Carmel’s Department of Engineering says roundabouts can be built for $125,000 less than a traffic-signal intersection. Whatever the case, the real savings would appear to be long term through the elimination of traffic signal maintenance.

INDOT engineers estimate the 31 roundabouts planned statewide will cost a total of $26 million to build.

In some locations, Brainard said, roundabouts require only 1/10th the land of conventional configurations. That means spending less money to acquire private property.

Most of INDOT’s planned roundabouts in central Indiana are part of its reconstruction to interstate standards of U.S. 31, through Carmel and Westfield.

The eight roundabouts planned won’t sit atop U.S. 31, per se. Rather, they’re slated for ramps tying into the highway at Rangeline Road and at 131st, 136th and 161st streets.

Other roundabouts INDOT plans in the metro area include one at State Road 144 and Kitchen Road, in Morgan County, later this year. In 2015, two roundabouts are planned on S.R. 267 in Hendricks County—replacing traffic signals at the intersection with Township Line Road and another at County Road 150S.

INDOT is using roundabouts on some new-terrain roadways as well, including a 200-foot roundabout being built just east of Interstate 65, near Lafayette, where the existing S.R. 25 will connect to the new S.R. 25 Hoosier Heartland Highway.

Cline noted that roundabouts aren’t without critics, including some who argue that they’re inappropriate for roads heavily traveled by semi trucks. That concern can be addressed by constructing aprons in the roundabout to accommodate trucks whose drivers miscalculate the turn, he said.

“There aren’t a lot of places where you couldn’t do it,” Cline said of a roundabout.

Where a roundabout might be a tricky proposition is in locations with high traffic volume, say somewhere north of 35,000 to 40,000 vehicles a day, Brainard said.

The roundabout-minded mayor recently took heat from merchants for Carmel’s plan to add roundabouts as part of the reconfiguration of the busy intersection of East 96th Street and Keystone Avenue.

Carmel officials point out they’re not planning to plop down a roundabout in the intersection, however. Rather, Carmel wants to raise Keystone over 96th Street, with motorists accessing 96th via ramps that would lead down to two roundabouts that would replace existing traffic lights.

Still, some businesses at the intersection complain the configuration could be confusing to customers and lead to accidents. Carmel says the twin roundabouts on 96th would take up less space, which the city might otherwise need from merchants. They also claim the design would improve the flow of traffic at the congested intersection.

Indianapolis planning roundabouts

Despite some reservations about roundabouts, their use is growing.

The Indianapolis Department of Public Works plans to build its first modern roundabouts (Monument Circle has been around since the 1800s) in 2013, on Edgewood Avenue at McFarland Avenue and at Gray Road, said DPW spokeswoman Kara Brooks. The project is federally funded.

Meanwhile, the city is considering other locations, including Five Points Road at Thompson Road, German Church Road at 42nd and 46th streets, and Springmill Road at 91st Street.

“The Department of Public Works now looks at sustainable construction and design as a part of all proposed road projects. That includes the use of roundabouts,” said Marc Lotter, spokesman for Mayor Greg Ballard.

He said Ballard believes each project should be evaluated on an individual basis, “based on the impact of traffic flow, environmental concerns and cost.”

INDOT’s Cline said a number of cities and towns in the state often follow INDOT’s lead. He predicted some of them will now look more seriously at roundabouts, which the traffic engineer dubs as “superior devices.”

INDOT has incorporated the roundabout into its design manual referenced by numerous local governments, noted Craig Parks, project development director at engineering firm American Structurepoint.

The Indianapolis firm, which helped design six roundabouts for Carmel in the Keystone Avenue corridor, has seen growing interest among its municipal clients, including the cities of Evansville and Fort Wayne. The latter hired the firm nearly a decade ago to design a roundabout for the northeastern Indiana city.

Closer to home, Fishers and Noblesville have also been keen to embrace roundabouts, Parks noted. Avon, Plainfield and Westfield have also climbed onboard the emerging trend, Miser said.

Brainard’s crew in Carmel has attracted national attention for that city’s prolific use of the traffic features. Last May, the Transportation Research Board conducted the third International Conference on Roundabouts in Carmel, which drew a number of international transportation engineers.•


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