Research Released by NHTSA on 3-Foot-Passing Law Enforcement

In 2018, the City of Knoxville and nonprofit organization Bike Walk Knoxville partnered with the National Highway Traffic Safety Administration (NHTSA) and TPO to conduct a study. The research focused on educating drivers and protecting the lives of bicyclists in Knoxville. The full study was released earlier this month.

Tennessee law and City of Knoxville ordinance require that drivers who are passing bicyclists give at least 3 feet of space. One challenge is making sure drivers are aware of the safety requirement, and another is enforcing the law to help keep people riding bicycles safe.

As part of this study, officers from the Knoxville Police Department outfitted their bicycles with technology to measure and record the distance of passing vehicles. They used these bicycles for a high-visibility enforcement campaign in which drivers who passed too closely were pulled over and given either warnings or citations.

Bike Walk Knoxville helped to recruit many of the civilian bicyclists who participated in the research. They rode in Knoxville for several months prior to the enforcement campaign with equipment on their bikes to collect data on passing distances. The information they collected helped to measure how driver behavior changed after the enforcement campaign.

The NHTSA researchers found that after the enforcement campaign, the average passing distance of drivers increased, and the share of drivers who passed within that dangerous 3-foot zone decreased.

For more information on this research, visit To see the report, visit the TPO’s page dedicated to bicycling and walking studies.