A stylist was just starting her shift at a salon in Kansas City, Missouri, when a car smashed through the storefront window and landed in the waiting area a few feet away.

Such crashes were so common along 31st Street that business owners regularly texted one another photos showing the damage caused by vehicles speeding along the four-lane road lined with shops, bars and restaurants, which drivers used as a shortcut between major highways.

“A wide road makes people think, ‘We’ll just drive as fast as we want on it,’ ” said Ryan Ferrell, who owns the property housing the salon, a bookstore and apartments above.

When concrete sidewalk barriers didn’t work, Ferrell and other business leaders campaigned to put the street on a “road diet.”

Removing lanes has been a tool that many cities have used for years to calm traffic, despite resistance from some Republican governors. President Donald Trump’s administration doesn’t like it either.

Federal transportation officials once heralded road diets for cutting crashes by 19% to 47%, but criteria for an upcoming round of road safety grants say projects aimed at “reducing lane capacity” should be considered “less favorably,” the administration said.

Forcing travelers into more constrained spaces “can lead to crashes, erratic maneuvers, and a false sense of security that puts everyone at risk,” the U.S. Department of Transportation said in an email to The Associated Press.

Kansas City saved some money when it converted 31st Street in 2022 because a gas line was going in anyway. It reopened with one lane in each direction instead of two, a shared turn lane near the intersections with signals, better pedestrian crossings and protected on-street parking spaces.

Bobby Evans, an urban planner at the Mid-America Regional Council who has worked on Kansas City’s road diets, calls the strategy “a smashing success” and one of the most effective tools at reducing speed, crashes and injuries.

Numerous other cities have credited road diets with improving safety.

Philadelphia cited a 19% drop in injury crashes. Portland, Oregon, saw a decline of more than 70% in vehicles traveling at least 10 mph over the speed limit. The average speed in Fort Lauderdale, Florida, fell by 5 mph on some roads within months.

But Jay Beeber, executive director for policy at the National Motorists Association, an advocacy organization for drivers, said most road diets represent an ill-advised effort to force vehicles off the road. The number of vehicles may decline on dieted roads, but then surrounding roads have to absorb the traffic, he said. “Those cars have to go somewhere,” he said. “Cars are like water. They seek their own level.”

Trump’s transportation department also cited delivery and emergency vehicles among its concerns.

When University of Iowa researchers surveyed first-responders in Cedar Rapids, their study published last year found no noticeable difference in response time when a road diet was in place.

“The road diet didn’t cause a level of congestion that slowed them down,” said Cara Hamann, an associate professor of epidemiology who co-authored the study.