How roundabouts transformed Carmel

We made serious mistakes in planning and building suburbs in the 20th Century, which is why the New Urbanism movement began. For example, planners separated the integral uses of cities and towns, including live, work, play, civic functions, and parks, and put them in different locations. Traffic engineers abandoned the fine-grained network of streets used since the dawn of civilization in favor of a tree-like system that concentrated traffic on thoroughfares designed for fast-moving motor vehicles.

This approach was carried out in every metro area, creating a ubiquitous sprawl with the same look and problems. The scale of sprawl, estimated to cover 98 percent of metro areas, has made reform very difficult. Although many suburban retrofit projects have been built, they have made a small dent in the overall problem.

Yet no municipality has done more to reform its dysfunctional road network than a suburb north of Indianapolis called Carmel, Indiana. Public Square has reported on some of Carmel's development projects, here, here, and here.

But we haven’t covered, beyond passing mentions, Carmel’s most comprehensive reform—building 152 roundabouts throughout this suburban municipality of 100,000 people. Although roundabouts have been constructed all across the US, no place has come close to Carmel—the city has been called the “roundabout capital of the United States.” A great video series on Carmel has been put together by Rob Sanders, who goes by Road Guy Rob on YouTube. I will draw on that series and embed the videos below. (Disclosure: I have never been to Carmel. I have written about it, looked at plans, watched videos, and toured by Google Street View).

The roundabouts in Carmel are the brainchild of Jim Brainard, the city’s mayor from 1996 to 2021. Roundabouts are often controversial among urban designers, who question whether they are pedestrian-friendly compared to traditional intersections in cities and towns. Roundabouts allow cars to (mostly) keep moving without stopping, and the most walkable cities have very few of these intersection types. 

These objections have merit, yet roundabouts remain an important sprawl reform tool. Suburban street networks will not disappear in my lifetime, and probably several lifetimes after I am gone. Roundabouts slow traffic down to human-scale speeds without reducing throughput in automobile-oriented places. By human-scale speeds, I mean 20 mph or less. At such low speeds, pedestrians are much less likely to die if struck by an automobile. Cars also can stop way more quickly, pedestrians can make eye contact with drivers, and the built environment is far less threatening to people on foot. That, in turn, allows urban life to take root. (Historic street grids also slow traffic, but such systems are beyond challenging to recreate once a dendritic network has been fully established).

Carmel has built roundabouts throughout its 49 square miles to tame an automobile-oriented area and offer other mobility options while at the same time allowing cars to move freely. Cars are necessary in the American suburbs, and Carmel is no exception.

Brainard began his roundabout crusade before these traffic devices became popular in the US. Soon after he was elected, he saw them as an answer to morning and afternoon traffic jams around the high school. This first attempt failed to get council approval. When faced with a political roadblock for a new idea that is not a priority for other elected officials or constituents, most mayors would give up and move on. Brainard found a way around it instead. 

On a new road Carmel built in 1997, the mayor got two roundabouts built under the radar by calling them “a landscaping project involving circular intersections,” Sanders reports. “Once they saw the roundabouts up close, city council members conceded they looked pretty good and might save the city money in the long run,” he says. Because no US roundabout design standards existed then, the first roundabouts failed to slow traffic enough. So the city adjusted the geometry to ensure drivers would slow to 10-15 mph, making them very safe.

With each new roundabout built, city residents liked them better. “I couldn’t take a roundabout out today if I wanted to,” Brainard says.

Sanders reports that the roundabouts have allowed Carmel to reduce space for cars and give it to bicyclists. For example, five-lane suburban arterials can be converted to one lane in each direction with a road diet. 

Because the city has no stoplights now, traffic continues to move at a safer and more comfortable pace for bicyclists, who are given dedicated lanes. In the example Sanders cited, “the travel time to get to one end of the corridor to the other is about the same as it was when it was five lanes.”

Sanders explains how roundabouts prevent traffic from stacking up at intersections, avoiding the vicious circle of building more lanes, which reduces walkability and increases traffic, causing more congestion. He explains that by avoiding the “platooning” of vehicles, a road feels less busy while moving the same number of cars. Slower traffic generates a lot less noise. 

Driving in Carmel is easy, one resident reports. “When you live here you realize that you don’t have to stop, traffic just keeps flowing.” By removing all traffic lights, “Carmel unlocked random continuous flow throughout the city,” Sanders reports. Keeping drivers happy has reduced opposition to building mixed-use urbanism while giving residents transportation options.

A quarter century later, Carmel finally installed the pair of roundabouts first rejected around the high school. They keep traffic flowing under 20 mph—you hardly need a school traffic zone. Students cross at a mid-block location. When you are on the main arteries in Carmel, you can't drive for very long—a minute or two at most, before coming to a roundabout. Everywhere there would ordinarily be a traffic light, there is a roundabout. Once you leave the main thoroughfares, the side streets look like most other suburban communities. Downtown is impressive ... for a suburb that didn't have one until recently.

Road Guy Rob explains transportation planning better than anyone else on YouTube that I have seen, and he does so in a way that is entertaining and compatible with new urbanist ideas. Below are the titles and the links to Sanders’ videos on Carmel. The first is about a “peanut” roundabout that solved a traffic problem on a state highway in Carmel without demolishing houses, which would have been the case with the conventional solution. The second and third tell the story of the 152 roundabouts and how they enable bicycling. The final one covers Carmel’s approach to downtown development.