A Nifty Device to Stop Cars From Driving Too Close to Bikes

Maybe your state is one of the more than two dozen around the U.S. with what is known as a three-foot passing law—a provision that requires drivers to give people on bikes at least that much clearance when passing them on the road. (Pennsylvania calls for a more generous four feet.) But are these laws enforceable? Or are they just an empty promise of safety?

One police officer in Chattanooga, Tennessee, wanted to find a way to give the law in his jurisdiction some meaning. Officer Robert Simmons, who has been with the city’s department for 12 years and on full-time bike patrol for seven, came up with an idea for a device that can measure and record the distance between a bike and a car.