Overall, active lighting improves detection and recognition of bicyclists by motorists. In a controlled trial experiment, Danish researchers found that flashing lights used during daylight hours decreased the number of daytime bicyclist crashes during the experiment time period (Madsen et al., 2013). Absent safe infrastructure, bicyclist safety on public roads after dark is affected by a variety of factors inherent to the transportation system. Motorists may underestimate their visual limitations in darkness and fail to adjust their own speeds appropriately. Changes in vision during twilight hours and at night, headlamp glare, and age-related decline in visual function are among the challenges to bicyclist detection faced by motorists (Tyrrell et al., 2016; Wood et al., 2014). Detection may also be affected by driver expectations for seeing people on bicycles in the road environment, potentially related to the Safety in Numbers effect (Elvik, 2017; Tin Tin et al., 2015). Crashes after dark are also influenced by driver factors such as fatigue and alcohol consumption (Tyrell et al., 2016). Unfortunately, it is unlikely that any form of conspicuity can overcome the challenge of driver distraction (Szubski et al., 2019).
Most States have laws requiring use of active lights and reflectors on bikes ridden at night. Some State laws have specific requirements for the power of the light, i.e., ability to see the light at a certain distance of feet ahead. Some laws, such as in Oregon, require bicycle lighting not only at night, but also in other less than favorable conditions.
There is no data on how frequently active lighting is used among those who bicycle after dark. Nearly three-fourths of U.S. survey respondents who reported having ridden in the dark indicated they took some measures, either using a bike headlight or reflective/fluorescent gear or clothing, to make themselves more visible (Schroeder & Wilbur, 2013).
Evidence is unavailable about the effectiveness of laws requiring use of active lighting at increasing use. There is some indication that active visibility aids, such as lights, improve detection more effectively than passive visibility aids (Kwan & Mapstone, 2009).
Moderate costs are involved for communications and outreach and for law enforcement training to enforce active lighting laws.
Time to Implement:
Brochures and flyers for a bicycle safety education campaign highlighting conspicuity can be created quickly. Often an extra line or two about rider conspicuity can be added to existing educational material or reinforced at community events. Several months can be taken up by designing, producing, and implementing the communications and outreach and law enforcement training for enforcing active lighting laws.