How Roundabouts Help Lower Carbon Emissions

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CARMEL, Ind. — It’s getting harder and harder to run a stoplight here, because there are fewer and fewer of them around. Every year, at intersections throughout this thriving city, traffic lights and stop signs have disappeared, replaced with roundabouts.

Lots and lots of roundabouts.

There is a roundabout decorated with the local high school mascot, a greyhound and another with giant steel flowers. A three-mile stretch of Carmel’s Main Street has 11 roundabouts alone. The roundabout that locals perhaps prize the most features box hedges and a three-tier bronze fountain made in France. In 2016, it was named “International Roundabout of the Year” by no less than the U.K. Roundabout Appreciation Society, which, according to the Carmel mayor, Jim Brainard, is largely made up of “three guys in a pub.” (Their actual membership is six. But, still.)

Carmel, a city of 102,000 north of Indianapolis, has 140 roundabouts, with over a dozen still to come. No American city has more. The main reason is safety; compared with regular intersections, roundabouts significantly reduce injuries and deaths.

But there’s also a climate benefit.

Because modern roundabouts don’t have red lights where cars sit and idle, they don’t burn as much gasoline. While there are few studies, the former city engineer for Carmel, Mike McBride, estimates that each roundabout saves about 20,000 gallons of fuel annually, causing the cars of Carmel to emit nearly 30 fewer tons of planet-heating carbon emissions a year. And U.S. highway officials broadly agree that roundabouts reduce tailpipe emissions.

They also don’t need electricity, and, unlike stoplights, keep functioning after bad storms — a bonus in these meteorologically turbulent times.

“Modern roundabouts are the most sustainable and resilient intersections around,” said Ken Sides, chairman of the roundabout committee at the Institute of Transportation Engineers.

The reason that Carmel has so many roundabouts is Mr. Brainard, the city’s seven-term Republican mayor.

Mr. Brainard first encountered roundabouts in the 1980s, when he studied at the University of Oxford and became taken with European traffic flow. After getting elected mayor in 1995, he asked a consultant to look into building a roundabout in Carmel. The consultant refused, saying they were dangerous and pointing to an effort in Massachusetts to remove them.

ImageMayor Jim Brainard of Carmel at the Hoagy Carmichael roundabout. “People love them here,” he said of the circles. “You couldn’t take one out.”
Mayor Jim Brainard of Carmel at the Hoagy Carmichael roundabout. “People love them here,” he said of the circles. “You couldn’t take one out.”

But Mr. Brainard discovered that the consultant was confusing roundabouts with rotaries, or large traffic circles, which are bigger, arguably scarier and include Dupont Circle in Washington and Place Charles de Gaulle, the multilane beast around the Arc de Triomphe in Paris.

Modern roundabouts, by comparison, are compact, with lower speed limits, traffic yields rather than stops and generally fewer lanes. Unlike traffic circles where cars enter at 90-degree angles, traffic flows into modern roundabouts at a smaller angle, drastically cutting the chances of getting T-boned. Well-designed ones are also more friendly to pedestrians and cyclists. In 1997, Mr. Brainard oversaw the building of a roundabout on the city’s outskirts and added another two the following year. Locals, initially skeptical, warmed to them: They alleviated rush hour backlogs and stops. Within a decade, the city had close to 50, and doubled the number again over the next ten years.

“Now we can’t live without them,” said Becky Blystone, a preschool teacher who also works at All Things Carmel, a souvenir shop on Main Street that sells roundabout-themed tchotchkes like drink cozies and playing cards.

Outsiders took notice. In 2011, CNN did a segment, and the International Roundabout Conference came to town (topics, according to Mr. Brainard, included entrance and exit angles and sightlines).

The city fanned the hype, issuing publications like “Roundabout Carmel: Highlighting City of Carmel Roundabouts from 1997 to 2010” (it features a “dogbone” shaped roundabout highway interchange dubbed the greenest in the country) and a glossy coffee table book, written by Mr. Brainard, called “Carmel: ‘Round about Right.” It also celebrates National Roundabouts Week, which this year included trivia nights and Wear Your Roundabout Shirt to Work Day.

“People love them here,” Mr. Brainard said during a recent tour of Carmel in his hybrid Ford Escape. “You couldn’t take one out.”

Not everyone is a fan.

“I hate them,” said Corey Hill, a call center director from nearby Avon who said he often gets stuck behind confused out-of-towners.

Bill Greenman, operations manager at a restaurant downtown, said local sentiment often varied by mood. “If you’re having a wonderful day, you’ll probably just ignore them,” he said. “If you’re having a bad day in traffic, you’ll probably blame it on roundabouts.”

Having greener intersections dovetails with Mr. Brainard’s climate mitigation efforts. He was among the thousands of leaders who pledged to uphold the Paris climate agreement when former President Donald J. Trump announced the American pullout in 2017. Carmel’s city vehicles are either hybrid or run by biofuels, green spaces sown with native plants have exploded in number and size, and solar panels help fuel the city’s water treatment and sewage plants. Under Mr. Brainard’s watch, the city has also added bike paths, taken out traffic lanes, widened sidewalks and increased walkability, all in an effort to get people out of their cars.

“We need to do everything we can about carbon emissions and the climate change issue,” Mr. Brainard said.

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Jackson Circle in Carmel has box hedges and a three tier bronze fountain and was named “International Roundabout of the Year” in 2016.
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A roundabout at Old Meridian Street and North Pennsylvania Avenue in Carmel, with a sculpture by Arlon Bayliss titled “Grace, Love and Joy.”
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A double-tear or “dogbone” roundabout at Keystone Parkway and 116th.
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“Beacon Bloom,” an installation, also by Mr. Bayliss, at the roundabout at 96th Street and Westfield Boulevard.

Carbon emissions per roundabout are highly dependent on location, construction, volume and time of day: A study of two roundabouts in Mississippi found a 56 percent decrease in carbon dioxide emissions; another calculated cumulative decreases at six roundabouts of between 16 percent and 59 percent. Carmel’s estimates are just that — the city engineer used calculations based on a study from Virginia. But overall, the Federal Highway Administration has found roundabouts cause fewer emissions compared to signalized intersections, and said the difference can be “significant.”

“Just imagine a post-Sandy, post-Katrina or post-Andrew world where recovery funds were put to work building resilient, sustainable modern roundabouts instead of rebuilding fragile, polluting signalized intersections,” Mr. Sides, the traffic engineer, said.

The United States has been slow to adopt modern roundabouts, though that is changing somewhat. By one count, they now number about 7,900 countrywide, with hundreds added each year. Still, hesitation remains.

Mr. McBride, who, as Carmel’s city engineer for 13 years, oversaw the construction of nearly 80 roundabouts, said roundabout-curious municipal leaders often asked how to win over the public.

“You can spit out fact-based data, but at the end of the day most of the general population is scared of things that are new and different,” Mr. McBride said.

Roundabouts put decision making in the hands of drivers, unlike much of the U.S. roadway system, which, Mr. McBride said, “doesn’t put a lot of faith in the driver to make choices.”

“They’re used to being told what to do at every turn,” he said.

More than half of all serious crashes happen at intersections, according to the Federal Highway Administration, which has been pushing the construction of modern roundabouts for 20 years and provides funding for them through highway safety, congestion mitigation and air quality improvement programs.

In the course of promoting roundabouts, Mr. Brainard visited Sarasota, Fla., in 2009, where he said he was met with a roomful of angry people. Among their fears: roundabouts were bad for pedestrians and would cause uneven wear on tires. But Mr. Brainard’s spiel about Carmel’s experiences evidently hit home. Sarasota now has a dozen roundabouts, with another in construction and five more planned, and just this year won the Innovative Roundabout of Merit Award.

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Roundabout-themed merchandise at All Things Carmel. The mayor has also put out a glossy coffee table book called “Carmel: ‘Round about Right.”

Locally, there’s been scrutiny. In 2019, an Indianapolis Star investigation undercut Mr. Brainard’s assertions that roundabouts were safer and more cost effective, reporting that, after Carmel transitioned to roundabouts, collision rates had jumped. Mr. Brainard disputed their findings, saying the Star hadn’t accounted for Carmel’s population explosion: The number of people living there had quadrupled since he took office, with daytime visitors adding to the load. A recent study of Carmel’s roundabouts by the Insurance Institute of Highway Safety found that injury crashes were reduced by nearly half at 64 roundabouts in Carmel, and even more at the more elaborate, dogbone-shaped interchanges.

Andrea Bill, associate director of the Traffic Operations and Safety Laboratory at the University of Wisconsin-Madison said roundabouts sometimes led to more fender-benders and sideswipes, but saved people from paying a greater price.

“The thing I say to people is ‘would you prefer an ambulance or tow truck?'” Ms. Bill said. “Most people would say a tow truck.”

Still, roundabouts take some getting used to. To that end, Carmel has published tips on its website, along with a roundabout map, and distributed hand-held plastic fans adorned with a roundabout diagram and instructions about where to yield (upon entering), what formation to drive in (staggered), and whether to stop (do not).

Driving Carmel’s roundabouts on a recent fall day, a driver from Brooklyn found herself taken with all the dipsy-doodling that the cars of Carmel must do. There was something merry in all this going around, akin perhaps to dancing around the maypole, albeit in multi-ton vehicles that can cause injury or death. But to that point, vehicular fatalities in Carmel, according to a city study, are strikingly low; the city logged 1.9 traffic deaths per 100,000 people in 2020. In Columbus, Indiana, an hour or so south, it was 20.8. (In 2019, the national average was 11.)

Ms. Blystone said people who visit the All Things Carmel shop often come in differing opinions about the local roundabouts.

For those who struggle, she said she offers the same advice. Take your time. And if they’re in doubt, just go around again.

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