Background: Pedestrians and cyclists account for nearly one in three of all road users killed and seriously injured in road traffic crashes. Late detection of other road users is one of the basic driver failures responsible for collisions. Aids to improve pedestrians and cyclist visibility have been used to avert potential collisions. However, the impact of these strategies on drivers' responses, and on pedestrian and cyclist safety is unknown. Objectives: 1. To quantify the effect of visibility aids versus no visibility aids, and of different visibility aids on the occurrence of pedestrian and cyclist-motor vehicle collisions and injuries. 2. To quantify the effect of visibility aids versus no visibility aids, and of different visibility aids on drivers' detection and recognition responses. Search strategy: Searches were not restricted by date, language or publication status. All electronic databases were searched from date of inception to the most recent date available. We searched CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE (Ovid SP), TRANSPORT (to 2007/06), PsycINFO (Ovid SP), PsycEXTRA (Ovid SP), ISI Web of Science: Social Sciences Citation Index (SSCI) and ISI Web of Science: Conference Proceedings Citation Index- Science (CPCI-S). We searched the reference lists of included trials, contacted authors and searched the websites of relevant transport research organisations. The searches were last updated in May 2009. Selection criteria: 1. Randomised controlled trials and controlled before-and-after studies of the effect of visibility aids on the occurrence of pedestrian and cyclist-motor collisions and injuries. 2. Randomised controlled trials of the effect of visibility aids on drivers' detection and recognition responses. This included trials where the order of presentation of visibility aids was randomised or balanced using a Latin Square design. Data collection and analysis: Two authors independently screened records, extracted data and assessed trial quality. Main results: We found no trials assessing the effect of visibility aids on pedestrian and cyclist-motor vehicle collisions and injuries. To date we have identified 42 trials assessing the effect of visibility aids on drivers' responses. Fluorescent materials in yellow, red and orange colours improve detection and recognition in the daytime. For night-time visibility, lamps, flashing lights and retroreflective materials in red and yellow colours increase detection and recognition. Retroreflective materials enhance recognition, in particular when arranged in a 'biomotion' configuration, taking advantage of the motion from a pedestrian's limbs. Substantial heterogeneity between and within the trials limited the possibility for meta-analysis. Summary statistics and descriptive summaries of the outcomes were presented for individual trials when appropriate. Authors' conclusions: Visibility aids have the potential to increase visibility and enable drivers to detect pedestrians and cyclists earlier. Biomotion markings, which highlight the movement and form of the pedestrian, showed evidence of improving pedestrians' conspicuity at night. Public acceptability of various effective strategies which improve visibility would merit further development. However, the effect of visibility aids on pedestrian and cyclist safety remains unknown. A cluster randomised controlled trial involving large communities may provide an answer to this question. It would, however, be a challenging trial to conduct. Studies that collect data of road traffic injuries relating to the use of visibility aids also warrant consideration.
- *Bicycling [injuries]
- Accidents, traffic [mortality; *prevention & control]
- Protective devices
- Time factors