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

BSMART helps the Chattanooga police give the local three-foot passing law some teeth.

Courtesy Chattanooga Police Department

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.

“I thought, I wish there was a data-driven way, like a radar gun,” says Simmons. “This is what I want to build; this is what we need to prove it in court.”

Simmons had been thinking a lot about how to prevent deaths like that of David Meek, a leader in Chattanooga’s biking community who was killed in 2009 when a truck driver drove close enough to hook Meek’s saddlebag, dragging him under the wheels. “That resonated in my head,” says Simmons. “I didn’t act on it—was just a thought in my head that we have to do something about this.”

Then Chattanooga got a new mayor, Andy Berke, and a new police chief, both of whom were receptive to suggestions about improving safety for people on bikes. In discussions with the chief, Simmons got the go-ahead to see if he could come up with a way to enforce Tennessee’s three-foot law.

Chattanooga calls the result BSMART (its technical name is the C3FT Device). Developed by Codaxus, an engineering firm in Austin, Texas, the handlebar-mounted device measures the distance of passing vehicles with ultrasonic waves. The bike-car gap is then shown on a large digital display, and when a car comes closer than 36 inches, BSMART beeps—alerting an officer to a violation. Paired with a GoPro camera, the device both detects and records a car’s proximity to a bike.

“It’s easy to use,” says Simmons. “It doesn’t distract me. I just ride along until it starts beeping.”

(Courtesy Chattanooga Police Department)

Simmons got the device, which was actually paid for by a local bike advocacy group called Friends of Outdoor Chattanooga, on May 17. He has only used it consistently for a couple of weeks so far, sometimes while in full uniform and sometimes in plainclothes, working with other officers in marked cars to conduct the pursuit. He he has already pulled over about 25 drivers. (No surprise to learn that drivers give him a wider berth when he’s in uniform.)

He hasn’t written any citations yet, preferring to give warnings to those drivers who get too close. A lot of them, says Simmons, don’t know about the law. “The device has allowed me to interact with those who commit the violation and do some education,” he says. “A lot of people don’t know and have trouble judging three feet themselves.”

Simmons says if he gets attitude from a driver, or if the person behind the wheel doesn’t seem receptive to the information, he’ll write a ticket. He’s already worked out an arrangement with a judge who says he’ll try to sentence offenders to a Bicycling 101 course. The class imparts the rules of the road that apply to bicycles and includes a group bike ride to show participants how it feels to travel the streets of Chattanooga on two wheels.

For Mayor Berke, improving conditions for people on bikes is part of a larger effort to diversify transportation options in his city and improve quality of life for everyone. “Everybody deserves to be safe on the streets, whether they’re traveling by car, by foot, or by bicycle,” says Berke. “We’re using innovative technology to build stronger neighborhoods. If you think about what makes a neighborhood great, it’s seeing that multimodal transportation occurring. People getting out of cars, talking to each other.”

Simmons says the city has already received inquiries from at least 10 other police departments about getting their own devices, as well as some bike advocacy groups. “It’s a device that’s really needed,” says Simmons. “Hopefully it’ll keep going and we’ll save some lives.”

About the Author

  • Sarah Goodyear
    Sarah Goodyear is a Brooklyn-based contributing writer to CityLab. She's written about cities for a variety of publications, including Grist and Streetsblog.