Road lighting for pedestrian reassurance: an investigation of methods and optimal illuminance

After dark, road lighting fulfils a primary need of pedestrians by helping them feel reassured that it is safe to walk. Guidelines are essential for providing road lighting that is suitable and efficient for its purpose. However, the basis of current lighting standards is unknown. This thesis aims to provide credible evidence for optimal illuminance for pedestrian reassurance, and in doing so to question the methods used to establish that threshold.
Three experiments were conducted, being field studies in Sheffield, UK. Experiment 1 was a pilot study to investigate one aspect of the day-dark method - the time of day for the daylight evaluations; daylight evaluations were conducted once at around midday and once in the evening at the same time of day as after-dark evaluations, using the biannual daylight savings clock change. Experiment 2, then used the day-dark method with a larger sample of participants and locations to investigate the relationship between pedestrian reassurance and illuminance, and the difference in reassurance evaluations given by solo and accompanied participants. Experiment 3 used travel count of pedestrian numbers in daylight and after dark at the same locations used in Experiment 2, to explore an objective method for measuring pedestrian reassurance.
The results of Experiment 1 suggested that the effect of time of day of daylight evaluations on the day-dark difference was of little practical significance. The results from Experiment 2 revealed that roads with higher mean illuminance had smaller day-dark differences, suggesting enhanced pedestrian reassurance. An optimal mean illuminance of approximately 7.2 lx for a day-dark difference of 0.5 was suggested. The differences in reassurance between solo and group evaluations were negligible. Experiment 3 results indicated that darkness had a deterrence effect on pedestrian traffic. Odds ratio determined using these data were consistent with reassurance ratings obtained in Experiment 2.