Street lighting for preventing road traffic injuries

Background Road traffic crashes are a major cause of death and injury, especially in low and middle-income countries. It is estimated that road traffic injuries will have risen from ninth to third in world disease burden rankings by 2020, accounting for 2.3 million deaths globally. Street lighting has been suggested as a relatively low cost intervention with the potential to prevent traffic crashes. Objectives To assess the effects of street lighting on injuries caused by road traffic crashes. Search strategy We searched the Cochrane Injuries Group's Specialised Register, CENTRAL, MEDLINE, EMBASE, TRANSPORT, Australian Transport Index. We also searched the Internet and checked reference lists of relevant papers. The search was not restricted by language or publication status. The searches were conducted to October 2008. Selection criteria Randomised controlled trials, non-randomised controlled trials and controlled before-after studies, comparing new street lighting with unlit roads, or improved street lighting with the pre-existing lighting level. Data collection and analysis Two authors screened search results, extracted data, assessed risk of bias and analysed the data. Main results We found 16 controlled before-after studies of street lighting, all reporting crash data, of which 14 contributed data to the meta-analysis. Seven trials included a designated control site, the other nine collected data at one site with the daytime data being used as the control. The methodological quality of the trials was generally poor. Three trials compared street lighting with an area control on total crashes; pooled rate ratio (RR) = 0.45 (95% Confidence Interval (CI) 0.29 to 0.69). Two trials compared street lighting with an area control on total injury crashes (all severities); RR = 0.78 (95% CI 0.63 to 0.97). No trials compared the number of fatal crashes with an area control. Ten trials compared street lighting with a day time control on total crashes; pooled RR = 0.68 (95% CI 0.56 to 0.83). Five trials compared street lighting with a day time control on total injury crashes; pooled RR = 0.68 (95% CI 0.59 to 0.79). Three trials compared street lighting with a day time control on fatal crashes; pooled RR = 0.33 (95% CI 0.17 to 0.66). Authors' conclusions The results from this systematic review suggests that street lighting may prevent road traffic crashes, injuries and fatalities. However, further well designed studies are needed to determine the effectiveness of street lighting in middle and low-income countries.