3.1 Active Lighting and Rider Conspicuity

Improving bicyclist conspicuity is intended to make bicyclists more visible to motorists and to allow motorists more opportunity to see and avoid collisions with bicyclists. A common contributing factor for crashes involving bicyclists in the roadway is the failure of the driver to notice the bicyclist, particularly at night. White or light-colored clothing, long a recommended solution, does little to improve conspicuity at night (Raborn et al., 2008, Strategy F2). A study of bicyclists admitted to hospitals from bicycling injuries suggested that white upper body clothing may provide a protective effect for motor vehicle collisions during daylight hours (Hagel et al., 2014).

New bicycles must be sold with reflectors meeting the CPSC requirements. The reflectors may improve a bicycle’s night-time visibility when they are illuminated by motor vehicle lights approaching from behind. Active bicycle lighting requires the user turn it on/off to activate it versus a passive light (reflector). Active bicycle lighting can also be critical for the detection of bicyclists coming toward the path of a motor vehicle, because the bicyclist is outside the vehicle’s headlight beam until the last moment (Raborn et al., 2008). In most States and jurisdictions, bicycles ridden after dark are required by law to have active white front lights and most States also require red rear reflectors or active lights. White in front and red in rear is meant to replicate the lighting used in motorized vehicles. 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. Efforts to increase enforcement of laws requiring use of lights is needed to maximize use (Raborn et al., 2008). Communications and outreach to the general public and LEOs about State and local laws regarding the use of active bicycle lighting (and other conspicuity aids) should be provided. However, a study from Australia found the use of a bicycle light alone, whether static or flashing, did not enhance the conspicuity of the bicyclist among study drivers, so additional measures to improve conspicuity (such as clothing or reflective leg straps) may be needed (Wood et al., 2012).

Most bicycles do not come equipped with permanently mounted lighting (Osberg et al., 1998). Newer mounting devices may, however, make it easy to attach or remove lights as needed. Many currently available lights may also be easily switched from continuously lit to flashing modes. Batteries also last much longer with LED lighting, increasing convenience.

Additional materials attached to bicyclists or their bikes can increase rider conspicuity day or night. For daytime, bright-colored or fluorescent clothing, including shirts, vests, caps, etc., make the bicyclist more noticeable. In low-light conditions (e.g., rain, fog) and at night, the same items can have retroreflective (reflects light back toward the original source of light) materials incorporated in them, to make the bicyclist more visible and identifiable from much greater distances. Retroreflective bicycle tires, and now frames, are also available. Another product to increase visibility include bright neon tubes designed to be mounted on the bicycle frame, where they cast a bright, broad pattern of light onto the roadway, creating the illusion of a vehicle much wider than a bicycle. Lower cost stickers to put on rims (or cyclist extremities) and other parts of the bike are also available. Pedal reflectors are another option and may help drivers identify cyclists and estimate their speeds based on pedal rotations, though further research is needed. Lights also may be applied to helmets or backpacks to make the rider more conspicuous to other vehicles. Other emerging active lighting technologies may also enhance conspicuity of nighttime cyclists when used. Lights or retroreflective material attached to moving extremities (i.e., wrists and ankles) can create the perception of human movement and increase cyclist visibility (Koo & Huang, 2015; Karsch et al., 2012). A study of the effectiveness of different configurations of flashing lights on bicyclists’ joints found that lights placed on the lower body (hips, knees, and ankles) were the most effective in increasing bicyclist visibility (Koo & Huang, 2015). See also the Pedestrian Safety chapter, Section 4.3 on pedestrian conspicuity measures for more information.

Use: Most States have laws requiring use of active lights and reflectors on bikes ridden at night. There are no data on how frequently active lighting is used among those who bicycle after dark, but bicyclists involved in collisions at night appear to use lights infrequently. Use of bicycle reflectors is thought to be higher since they come pre-attached to bicycles at purchase, but these may be removed, or broken, after purchase, so use is not guaranteed. Nearly three-fourths of U.S. survey respondents who reported having ridden in the dark reported they took some measures, either using a bike headlight or reflective/fluorescent gear or clothing, to make themselves more visible (Schroeder & Wilbur, 2013).

Most, if not all, athletic shoes contain some retroreflective material. Some athletic clothing also has retroreflective material. Bicycle helmets may have retroreflective elements. Some bicyclists may be seen wearing additional retroreflective materials, such as vests, jackets, arm bands, or rear-mounted reflective triangles located under their bicycle seats.

Effectiveness: A Cochrane review of studies of pedestrian and bicycle conspicuity aids concluded that “fluorescent materials in yellow, red, and orange improved driver detection during the day ...” (Kwan & Mapstone, 2004). Even low-beam headlights can illuminate figures wearing florescent materials hundreds of feet away, much farther than figures wearing normal clothing (Zegeer et al., 2004, Strategy B5; Raborn et al., 2008, Strategy F2). One study among a cohort of riders who had participated in a large mass bicycle event found results suggesting that consistent use of fluorescent colors provides a protective effect against crashes and injuries (Thornley et al., 2008).

A small Australian study found that bicyclist clothing such as vests and ankle and knee reflectors significantly affected conspicuity, enabling drivers to react to bicyclists from further away than when the bicyclists wore only vests or no reflective material at all (Wood et al., 2012). Younger drivers detected and responded to bicyclists more often and from further distances than older drivers. In a year-long Danish study (Lahrmann, Madsen, & Olesen, 2018; Lahrmann, Madsen, Olesen, et al., 2018), researchers gave running lights to 1,845 bicycle riders (compared to 2,000 riders in the control group), and fluorescent yellow jackets to 3,402 riders (compared to 3,391 riders in the control group). Over the course of the trial, the treatment groups self-reported fewer multi-party personal injury events than their control groups (38% fewer for the running light group, and 47% fewer for the yellow jacket group after accounting for response bias). The group with the yellow jackets also reported 55% fewer accidents with motor vehicles than the control group (Lahrmann, Madsen, Olesen, et al., 2018). When sorted in half based on jacket usage rate, the multi-party personal injury event rate for the higher jacket usage group was 53% lower, while there was no significant difference between the lower jacket usage group and the jacket control group.

A study of bicyclists admitted to hospital emergency departments in Edmonton and Calgary, Canada, did not find a significant protective effect for using head- or tail lights, for retroreflective upper body clothing, nor for other reflective items for nighttime crashes. However, the sample size was small, and there was no apparent control for the riding environment or type of ambient/street lighting available (Hagel et al., 2014). A set of four on-road studies performed in Italy on a closed-circuit track found that relative detection performance of bicyclists with ECE/ONU 104 reflective tape applied to left and right posterior forks, seat post, and rear reflector was significantly better than the control condition (no reflective material; Costa et al., 2017). This difference was maintained under a variety of environment conditions (darkness with street lighting, darkness with no street lighting, and darkness with rain). However, further research is still needed to assess the effects of  types of conspicuity aids under different road environments and ambient and supplemental light conditions.

Another challenge is getting bicyclists to wear retro-reflective materials and use proper lighting and other conspicuity aids routinely (and appropriately). It is possible to obtain widespread use of lighting. Osberg et al. (1998) found nearly half of nighttime bicyclists in Paris used active lighting, compared to just 14% of Boston bicyclists, reflecting differences in laws, public health priorities, and perceived risk.

Evidence is unavailable about the effectiveness of  conspicuity promotional measures, or of laws requiring use of active lighting at increasing use. Raborn et al. (2008) suggest that increased enforcement of laws enhanced by coordinated communications and outreach efforts could heighten awareness among cyclists of the need for using proper lighting and the benefits of retroreflective materials at enhancing conspicuity. Logic suggests that if bicyclists are more noticeable, the frequency and severity of crashes would likely be reduced. With this goal in mind, certain local LEAs are engaging in community outreach and handing out bicycle safety lights rather than ticketing bicyclists.

Costs: Moderate costs are involved for communications and outreach and for law enforcement training to enforce active lighting laws. Conspicuity-enhancing gear, such as retroreflective wrist and ankle straps, or small active front and back lights, are sometimes distributed for free as part of school and community educational efforts. Additional costs for such materials are modest.

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 and/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. See Section 3.3 for more on enforcement and available resources.