Early Knoxville Police Department data following a recent bicycle-safety campaign is showing that use of new technology to raise awareness of Tennessee’s three-foot passing law has actually changed driving behaviors.

State and local law require drivers to maintain a minimum three-foot distance when passing bicyclists.

Data collected in 2018 showed 30 percent of bicycle fatalities nationwide involved a motor vehicle overtaking a bicyclist, according to the National Highway Traffic Safety Administration’s Fatality Analysis Reporting System. 

“In Knoxville, 12 percent of these bicycle-related crashes occurred when the rider was struck from behind,” said Ellen Zavisca, Principal Planner with Knoxville-Knox County Planning.

In fall 2018, Knoxville launched the “Minimum Three in Tennessee” bike-safety campaign, aimed at making Knoxville’s streets safer for bicyclists. Officials, including KPD, hoped to educate drivers to watch out for bicyclists and pass them safely. 

Key to the program’s success was KPD’s use of a new tool to determine how Knoxville drivers were actually adhering to the law. Ultrasonic devices, known as C3FT (pronounced “see three feet”), measure the distance in inches between a bike and passing cars, alerting officers when the gap is less than 36 inches or three feet.

The devices are bicycle-mounted electronic systems designed to detect, capture and display the proximity of passing vehicles to bicyclists. 

The equipment was funded through a research effort by NHTSA, and Bike Walk Knoxville helped secure Knoxville’s part in the national study. KPD was able to keep the devices as part of study, and they are deployed as needed for specific enforcement. Grand Rapids, Michigan, was the other city selected to participate in the project. 

KPD officers identified heavily used bicycle routes in the test program, which ended in December 2018. They gave a two-week warning before issuing any citations for violations of the Three Foot Law.

“The Knoxville Police Department was honored to be one of the cities selected for the Safe Cycling Initiative by means of the measuring device for enforcement of the three-foot safe passing distance law,” said KPD Lt. Sammy Shaffer, part of the Homeland Security Patrol Division. “Through the campaign, we had the opportunity to educate many motorists and cyclists on laws and safe riding practices.” 

In addition to KPD’s bicyclists, six civilian volunteers who ride regularly in Knoxville also collected data before and during the enforcement campaign. Their bikes were equipped with a version of the C3FT device that captures the passing distance of vehicles but doesn’t display that distance. They rode solely to collect data for the study, not as part of the enforcement effort, said Zavisca. 

While the national study of Knoxville’s public awareness campaign has not yet been published, Zavisca says data collected by KPD officers is promising: 

• The average passing distance has increased; 
• The number of dangerous passes has decreased; and 
• The ultrasonic devices have helped enforce the Three Foot Law.

“We can prevent our family members, friends and neighbors from being hurt or even killed in crashes if we show more patience and pay more attention while traveling our city’s streets,” Zavisca said.
For the second time, Knoxville was named a “Bronze Bicycle Friendly Community” in 2018 by the League of American Bicyclists.

Zavisca tracks pedestrian and bicycle crashes in the Knoxville region and will be looking to see if the enforcement had an actual effect on crashes. 

“All of us – whether we drive, walk or bike – are just trying to get where we’re going safely,” Zavisca said. “This research was one piece of our efforts to make Knoxville’s streets safer for everyone. It was an opportunity to raise awareness with drivers that people riding bicycles can be anywhere. It’s easy to pass them safely if you drive with awareness, take a breath, wait until it’s safe and then pass with caution.”

Additional information about the program, including a video that demonstrates the technology, is available online at http://www.knoxvilletn.gov/min3tn.