Influence of road lighting on cyclist numbers and safety


Cycling to be a viable and safe travel option at all times of the day if it is to meet the needs of an increasingly 24-hour modern society. Darkness produces a significant drop in the number of people cycling, compared with the same time of day but in daylight. Public lighting may encourage people to cycle when it turns dark, by giving them greater reassurance of being seen by drivers and by making it easier to see potential hazards in their path. We examined the size of the reduction in cyclists after-dark at 48 locations in Birmingham, UK. We calculated odds ratios to account for effects of time of day and time of year on the number of people cycling. This compares the ratio of cyclists in the same hour of the day but in daylight or dark conditions to the ratio of cyclists over the same periods of the year but in an hour when the light condition does not change. A larger odds ratio indicates a bigger reduction in cyclist numbers due to darkness. Odds ratios at each of the 48 locations in Birmingham were compared against the relative brightness of the road or path at those locations, estimated from night time aerial images. Results showed an escarpment-plateau relationship between brightness and odds ratio. A small initial increase in brightness produced a significant reduction in the negative impact of darkness on cycling rates. This effect plateaued, with further increases in brightness having little impact on cycling rates after-dark. These results suggest minimal levels of lighting could encourage more people to cycle after-dark.

CIE 29th Session
Washington DC, USA