To the average tourist, Carmel, Indiana (pop. 91,065) is a sterling Midwestern suburb. It’s been put on several Best Place to Live lists in recent years and has seen its population grow by more than 10,000 since the 2010 Census. But before the city’s recent achievements, it had a history innovative thinking. Carmel was one of the first cities to install a stop-and-go traffic light back in 1924. These days, however, Carmel’s in a debate over a different type of traffic sorter: the roundabout.

Boasting 105 roundabouts over its 47 square miles, Carmel may as well be America’s roundabout kingdom. The Indianapolis suburb had 105 roundabouts, according to the mayor’s office, and plans for at least 30 more roundabouts are in place. When construction is completed on all of Carmel’s proposed 140 roundabouts, that’ll mark one loop for every 650 Carmel residents.

To Mayor James Brainard, the man responsible for Carmel’s roundabout bloom, the traffic circles are a no-brainer.

“Anytime you can do that and make rather easy changes and save lives, it makes a huge difference to the community,” he tells Inverse.

While traveling in Europe he fell in love with the roundabout’s elegant shape and its positive impact.

“I quickly learned that the use of roundabouts was not only good for traffic safety and traffic flow,” Brainard says, “but that they had less of a negative impact on the quality of the air, in contrast to gas engines idling at red lights and engines revving when traffic begins to move again after coming to a complete stop.”

After he was elected in 1996, Brainard set about making his circular dreams a reality — but not without some resistance. Though an estimated 5,000 roundabouts have cropped up across the United States, many Americans remain skeptical of the circle. And new research on bike safety in roundabouts — coupled with what looks like England’s 180 on its original concept — has only brought the roundabout under increased scrutiny.

Frank Blackmore roundabout magic England UK design transportation
This 'magic' roundabout within a roundabout was constructed according to the designs of British inventor Frank Blackmore in the early 1970s.

Who Invented the Modern Roundabout?

But before there was James Brainard, there was Frank Blackmore. A Royal Air Force pilot in World War II, Blackmore joined England’s Transport Research Laboratory in 1960 and set about solving the empire’s traffic problems. It was at the transportation think tank that Blackmore developed the idea of the roundabout.

“His interest became an obsession, and family holidays were regularly punctuated with stops at intersections while he took photos from every possible vantage point,” The Guardian wrote of Blackmore after his death in 2008. “These trips were documented with photographs, not of his children or beauty spots, but of cars, junctions and road signs.”

In the 1970s, Blackmore’s first roundabout designs were realized in the multi-ringed behemoths in Swinton and Hempstead, England. The projects sparked controversy — in fact, they still do — but more were constructed. Today, there are an estimated 26,000 roundabouts in use in the UK and 32,000 in France.

Unlike streets that were haphazardly made to encircle existing fountains or statutes, modern roundabouts are carefully crafted to control traffic. For starters, a good roundabout has controls the approach of all vehicles according to “Roundabouts: Myths & Facts,” a report by Mark Doctor of the Federal Highways Administration. Crucially, modern roundabouts have just perfect geometry to reduce the speed of traffic to a max of 30 miles per hour.

conflict points Department of Transit roundabout intersection urban planning
A traditional intersection has 32 "conflict points,' while a modern roundabout has only eight.

Fewer “Conflict Points”

These factors — the angle and speed of traffic — led to swift declines in accidents. In geometric terms, roundabouts simply have fewer “conflict points.” Where a traditional two-way intersection has 32 places for cars to collide, a modern roundabout only has eight points for conflict.

And this math plays out on the road. Though many drivers are more fearful entering a roundabout than a regular intersection — and experience a corresponding 12 percent increase in accidents at new loops — the type of accident is changed, largely for the better.

Because cars in a roundabout are all moving in the same direction, instead of squaring off at an intersection, head-on collisions are all but eliminated. That’s led to a 38 percent drop in injuries and a staggering 90 percent plummet in fatal crashes. While side-swipes may rise — and insurance premiums along with them — these incidents don’t typically kill.

Motorists aren’t the only ones who benefit from this streamlining, either. Instead of having to “look both ways as you cross the street,” at a roundabout, pedestrians only have to focus on a single traffic flow, making them safer for just about everyone.

An elevated roundabout in the Netherlands, just for bicycles.
An elevated roundabout in the Netherlands, just for bicycles.

Circles and Cyclists May Not Mix

It was safety stats like these that allowed modern traffic circles to hop the pond and find a home in cities like Carmel. But in recent years, many English cities have been paving over their roundabouts, in part because of the damage this design seems to pose to cyclists.

While the statistics about driver safety may still ring true, a 2008 study in the journal Accident Analysis & Prevention found that turning a traffic signal into a roundabout actually increased a cyclist’s risk of injury by 27 percent. Reduced speeds can reduce damage, but even helmet-wearing cyclists aren’t totally protected from the full force of a car going 25 miles an hour. This study isn’t the last word, of course, and many cities continue to report improved safety for cyclists in roundabouts over traditional intersections, but this and other concerning data has been enough to spur some urban planners to reconsider.

“There is a tendency for motorists at roundabouts to look through cyclists while watching for other motor vehicles, hence the frequency of ‘SMIDSY’ (Sorry, mate, I didn’t see you) collisions,” The Guardian reported in a 2015 about diverging American and British attitudes toward roundabouts.

One solution, suggested in that same piece from The Guardian, was to set up traffic lights in the roundabout, which would require breaking before both entering and exiting. Alternatively, priority could be given to cyclists, as is done with many Dutch roundabouts in bike-loving the Netherlands. Or, they could have taken a page from the Dutch city, Eindhoven, which went and built an elevated roundabout just for cyclists.

And yet many Brits have decided to bypass these opportunities, citing the money and space such improvements would require. While the vast majority of the UK’s 26,000 roundabouts will probably remain intact, many islanders have decided to turn their backs on the nation’s hooped history.

Positive Results, But Far From a Panacea

Whether Carmel will stand by its roundabouts in the long run remains to be seen. Right now, Mayor Brainard reportedly plans to build an additional 28 roundabouts by 2018 as part of that final 140 roundabout goal. But it’s possible many Indianans will one day find, just as the British did, that some intersections are better served by a more linear design.

Christine Scales, a city-county councillor representing neighboring Indianapolis, which shares more than a few roads with Carmel, tells Inverse that some intersections are just better without a roundabout.

Carmel Indiana Indianapolis map drive time suburb city roundabouts urban planning design
The suburb of Carmel, Indiana is about a 30 minute drive from the state capital Indianapolis, Indiana.

“I have no opposition to roundabouts when their location is considered in a judicious manner,” Scales says. And yet she opposes Carmel’s mayor in his attempted expansion of the roundabout program. “I believe he has convinced himself of the safety of roundabouts, as well as their benefit of enhancing traffic flow,” she says. “[But] because he does not appear to evaluate each intersection as to the cost-benefit of replacing a traditional intersection, he has run into some problems.”

Still, as many English cities make a U-turn on roundabouts and American cities continue their slow and steady road redevelopment, Brainard keeps pushing for his ambitious roundabout plans to be realized. While Carmel, Indiana’s streets may not be universally beloved, the otherwise innocuous suburb is destined to be America’s roundabout kingdom for years to come.

Photos via Reddit, Department of Transit, Eindhoven City Council , Google Maps (1, 2), Wikipedia