Roundabouts are eating (slowly!) the suburbs

Hillsboro, Va., recently added roundabouts at both ends of the city to improve the flow of commuters heading from West Virginia to DC
Hillsboro, Virginia, recently added roundabouts at both ends of the city to improve the flow of commuters heading from West Virginia to DC (Michael S. Williamson/The Washington Post)

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A quiet spin-off revolution is sweeping through suburban America. And it could have gone on, unmeasured and unnoticed, if it weren’t for Lee Rodegerdts.

As it turns out, the good folks at the US Bureau of Transportation Statistics don’t track the nation’s roundabouts, roundabouts, or traffic circles. In fact, no federal agency does. Instead, that heavy responsibility has fallen, for a quarter of a century, on the modest shoulders of Rodegerdts, an engineer and talented amateur photographer and pianist in Portland, Oregon.

In the late 1990s, the unassuming but stealthily hilarious Rodegerdts was recruited by the Federal Highway Administration to write the book on roundabouts. The result was “Roundabouts: an informative guide”. In the course of his investigation, Rodegerdts was surprised to discover that no one was aware of the new intersections that were proliferating across the country.

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So he started counting. And he kept counting, through another edition of the guide, through dozens of roundabout conferences and conspiracies, through roundabout research projects, and through countless actual roundabout construction designs. His count soon migrated online, where he still spends his free time reviewing submissions from a small army of enthusiastic roundabout hobbyists, checking out new roundabouts and figuring out their construction dates using published reports and historic satellite photos.

When Rodegerdts started, he counted around 300 roundabouts across the country. Barely 25 years later, it counts about 9,000. And that doesn’t include more than 160 roundabouts or more than 700 traffic calming circles (which are very different from roundabouts).

Compared to the hundreds of thousands of normal intersections that dot the American landscape, governed by stop signs and traffic lights, roundabouts are rare beasts. But unlike drivers who frequently confuse and annoy, roundabouts are closing in fast.

“People doubted that we could keep up,” Rodegerdts told us. “But so far I think we’ve done it.”

The modern roundabout is based on a geometric design that forces traffic to slow down, plus a simple innovation born in Britain in the 1960s: the rule that people already in the circle have the right to step. At traditional traffic circles and roundabouts, which still lurk in many East Coast cities, traffic moves faster and vehicles already in the roundabout often must yield to newcomers.

In the United States, the first roundabouts were often built in larger cities. In general, our analysis shows, they are more likely to be built in well-educated, high-income cities. These days, the fastest growth is in the suburbs and rural areas.

“It’s very difficult to fit roundabouts into our dense urban environment,” Rodegerdts said. “And so most of the roundabouts have been coming into either completely new subdivisions or are modifications of existing intersections, often suburban or rural.”

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Why add a roundabout, you might ask. Because roundabouts offer impressive safety improvements. Overall, a roundabout will reduce fatal crashes by 90 percent and reduce all car crash injuries by at least 75 percent, even if it accommodates a higher volume of cars.

At a two-way rural stop, the gains can be even more dramatic. A roundabout can reduce all traffic injuries, both fatal and non-fatal, by nearly 90 percent. After all, it’s nearly impossible to drive through a roundabout at 60 miles per hour and hit a minivan, which is all too common at typical rural intersections.

“That’s the beauty of the roundabout,” Rodegerdts told us. “It’s the geometry. It’s the curves that are doing the work. And not rely on a traffic control device as the only thing keeping you from crashing at high speed.”

So which state is the most indirect? Florida has the most roundabouts, but it also has the third largest population in the nation. Nebraska has the most roundabouts per person, but they’re spread over one of the sparsest (and often most scenic) road networks in the country. Per highway mile, Maryland emerges as the champion of roundabouts.

City rankings, on the other hand, are almost pointlessly easy. Almost any way you slice the data, the upscale Indianapolis suburb of Carmel ranks as the indirect capital of the nation. And, like the Rodegerdts’ database, Carmel’s roundabout network is largely the work of a visionary man, in this case, seven-term Republican mayor and celebrity niche roundabout developer Jim Brainard.

A lawyer by training, Brainard’s experience with roundabouts when he took office in 1996 consisted of having seen several in the UK. But those modern intersections made an impression, and when his constituents demanded a safer, more walkable city, he thought he had a solution.

Roundabouts were becoming rarer in the United States back then. As one of the highest income and most educated cities in the country, Carmel was fertile ground for traffic innovation. Still, it took some effort and a weekend research trip to Purdue University to convince the skeptical city engineer. (More than a hundred intersections later, Brainard said, that one-time skeptic has become a coveted leader in roundabout engineering and a commanding general in the roundabout revolution.)

Most roundabout-curious cities and counties have moved cautiously, but Brainard is achieving the traffic-signless holy grail of roundabout revolutionaries through sheer force of will and a bit of carefully structured public debt.

Brainard’s attitude is that if Paris can build a world-class roundabout-infused urban area on a flat piece of unspectacular but fertile ground, then so can Carmel (pronounced CAR-mull). He is careful but bold, he speaks of his goals in terms of time, referring to European empires and monarchs while explaining the need to build infrastructure that will last for the next thousand years.

And monarch is almost a fitting job description for Brainard right now. Carmel became a city in 1976, when White Flight began to swell it and other suburbs. Brainard has now served longer than any other mayor in city history combined (a fun fact we borrowed from Indianapolis Star columnist James Briggs). In that time, Brainard saw the city grow from 38,000 to more than 100,000.

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As mayor, he has built more than 140 roundabouts, reducing traffic fatalities so drastically that the local fire department rarely uses its Jaws of Life extraction tools. But the traffic circles are just one pillar in Brainard’s grand plan to build a dense, European-style city in central Indiana. To that end, he’s also added winding, leafy pathways and a resplendent concert hall that hosts everything from performances by the Carmel Symphony Orchestra to Michael Bolton’s holiday specials.

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Roundabouts are a linchpin in Brainard’s vision of a pedestrian center. that’s not alone because they are often more pedestrian-friendly, but because they can reduce pollution and allow designers to accommodate more traffic in a smaller space. On a key stretch of its main north-south thoroughfare, Carmel replaced five lanes of traffic with just two lanes and multiple roundabouts. Green spaces and sidewalks have sprung up where those lanes used to be, and the total traffic flow on the highway has actually increased.

In all of Carmel, there are only nine regular stoplights left, Brainard said. And by the time he leaves office next year, the city will be on track for just one. Ironically, as a nearby plaque notes, it is the site of one of the first automatic traffic lights in the United States. And now, at least in Carmel, it will be the last.

“It’s in the middle of the little downtown that’s been there forever, and there are buildings on all four corners, so that’s the one that’s going to stay,” Brainard said, explaining that there simply isn’t room for a roundabout there.

But “it’s pretty safe,” the mayor assured us. “You can’t drive fast in that area.”

Why? Because, she said, “We put a roundabout at each end!”

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