Can We Fight Carbon Emissions With Roundabout Intersections?

The U.S. city of Carmel, Indiana (population: 102,000) has 140 roundabouts, "with over a dozen still to come," reports the New York Times. (Alternate URL here.) "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, which means the cars of Carmel emit many fewer tons of planet-heating carbon emissions each 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... 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... [V]ehicular 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.) The Times points out other advantages - they can also be more friendly to pedestrians and cyclists, and alleviate rush-hour backups. But Carmel's former city engineer just argues it's an improvement over an older roadway system which "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."

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