Motorist Passing Bicyclist Laws
The purpose of bicyclist passing laws is to require motor vehicle drivers to overtake people on bicycles with a legally defined minimum amount of clearance space between the vehicle and the cyclist. This helps to reduce the likelihood of a sideswipe, and to reduce the chance of a close encounter that could potentially destabilize or divert the course of a bicyclist and cause a crash. Given the high rate of crashes that occur when the driver of a motor vehicle passes a person on a bicycle, it is important to tackle this motorist-bicyclist interaction. However, the research has shown mixed results from current implementations of motorist passing laws.
As of September 2021 there were 35 States and the District of Columbia known to have enacted bicyclist passing laws requiring drivers to leave a space of 3 feet or more when passing cyclists (National Conference of State Legislatures [NCSL], 2022). Pennsylvania and New Jersey require at least 4 feet for passing, and South Dakota requires at least 3 feet for roads with a speed limit of 35 mph or less and at least 6 feet for roads with a speed limit greater than 35 mph. North Carolina requires at least 2 feet for passing and permits passing a bicyclist in a no-passing zone if the motorist leaves a clearance of at least 4 feet. Delaware, Kentucky, Nevada, Oklahoma, and Washington require the motorist to change lanes to pass a cyclist on roads with lanes in the same direction. Eight other States have laws requiring motorists to pass at a safe distance and speed but are usually not more specific.
There is some empirical data suggesting that these laws may change driver behavior. A naturalistic observational study of driver passing behavior in Michigan measured vehicle passing distance in five jurisdictions having 3 feet (1 city), 5 feet (3 cities), and no enacted (1 city) passing laws (Van Houten et al., 2018). The results showed that drivers maintained a significantly greater separation distance when they overtook bicyclists in sites with 5-feet laws, compared to sites with 3-feet or no law. Roadway infrastructure also influences passing behaviors. Roads with paved shoulders, wider roads, and greater number of lanes were associated with greater separations between drivers and bicyclists. Shared use lanes led to closer passing, as did passing situations with larger vehicles. Research by Mackenzie and Evans confirm the finding that road environment influences motorist passing distances (Evans et al., 2018; Mackenzie et al., 2019). In an evaluation of a passing law enacted in Baltimore, Maryland, Love et al. (2012) similarly found that environmental and social factors such as lane width, bicycle infrastructure, cyclist identity, and street type influenced passing distance. The study reported low compliance with the passing law and little to no enforcement of the law by area police. The authors concluded that interventions such as driver education, signage, enforcement, and bicycle infrastructure changes (such as bike lanes and Complete Streets designs) are needed to influence driving behavior and to increase motorist compliance with the motorist passing law. An evaluation of HVE campaigns in two cities showed that concentrated education and outreach coupled with enforcement resulted in higher average passing distances and a decrease in violations of the passing laws (Blomberg et al., 2022).
Bicycle passing laws can be difficult to enforce because it is a challenge to measure the exact distance between bikes and vehicles. Police in Chattanooga and Austin use devices called C3FTs, a handlebar mounted ultrasonic device, to measure when a vehicle passes a police bicycle with less than 3 feet of distance (Davis, 2017; Goodyear, 2015). Devices such as these can offer valuable, accurate information to help make passing laws enforceable.
It is unclear whether motorist passing laws lead to a reduction in crashes. An analysis of 18,534 bicyclist fatalities from 1990 to 2014 in the United States failed to find any significant safety effect for bicyclists in States where Motorist Passing laws were implemented (Nehiba, 2018). A study looking at the impacts of bicyclist safety laws on crashes identified an association between safe passing laws and a reduction in crashes, but authors noted that the crash reduction effect was temporary. Current research has not been able to determine why such laws do not produce lasting safety improvements (Jackson et al., 2021).
Van Houten et al. (2018) note that no research has been conducted on public education around motorist overtaking laws and regulations. In addition, no studies around motorist passing laws have examined the question of speed while passing.
Moderate costs could be incurred for informing and educating the public and providing training for enforcement personnel.
Time to Implement:
A bicyclist passing law can be implemented as soon as the law is enacted.
 A trademarked name meaning “see 3 feet” manufactured by Codaxus LLC, Austin, Texas.