Innovation That Matters

Sonar device keeps cars at a safe distance from cyclists


C3FT is a sonar device that is attached to a police biker's handlebars, to provide proof of drivers infringing on the three-foot zone.

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The three-foot rule, which is in place in 26 states across the US, requires cars to keep a safe distance between themselves and cyclists. If they fail to do so they can be issued with a ticket, which can lead to points on their license or monetary fines. But although there are a substantial number of cases — 500 in Florida last year — very few drivers are ever found guilty, because it has been difficult for police to judge and prove distances. Now, C3FT is a sonar device that can be attached to a police biker’s handlebars, and provide technological proof of drivers infringing the three-foot zone.


C3FT was created by Austin-based engineering firm Codaxus and will enable police departments to collect statistics about the law as well as enforce it. It uses an ultrasonic detector to take immediate distance measurement and transmits information on a numeric display. Buzzers and LED indicators go off automatically anytime a vehicle crosses the preset distance threshold. It also includes an optional video camera to record activity on the road or the display.


A prototype of the gadget was funded by the Friends of Outdoor Chattanooga charity and is currently being used in Chattanooga by the head of bike patrol Robert Simmons. The device enables Simmons to issues warning to drivers who get to close to his bike, and send problematic drivers on a Bicycling 101 course, which requires them to take a bike ride through the city to experience the dangers involved.

In Chattanooga, C3FT is primarily in use as an educational tool — ensuring more drivers know about the rule and its importance. Could every city be required to use this device?



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