Road‌ ‌lighting‌ ‌for‌ ‌pedestrian‌ ‌reassurance:‌ ‌consideration‌ ‌of‌ ‌methods‌ ‌and‌ ‌new‌ ‌metrics‌

One reason for installing road lighting in subsidiary roads is to enhance pedestrian reassurance after dark. Low reassurance has been associated with poor mental health, social isolation and lower active walking. However, despite numerous studies, it remains unclear if there are optimal lighting characteristics for pedestrian reassurance.
Two field studies were carried out in the city of Sheffield in the UK. Field study 1 was designed to examine the day-dark approach proposed by Boyce et al. 2000, which uses evaluations of reassurance in the daytime as well as after dark, rather than after-dark only. Thus, this study had 24 participants, rating 10 test locations in daytime and after-dark, using a survey. It also considered the development of a composite evaluation item to characterise reassurance rather than rely on the response to a single question.
The results of field study 1 suggested that reassurance was better characterised by minimum illuminance and uniformity than by mean illuminance, the usually considered metric, but that was not an apriori hypothesis of field study 1. Therefore, Field study 2 was carried out with an expanded sample (35 participants) and a set of locations (16 roads) to test that hypothesis and also to consider the association between reassurance and three types of illuminances referred to in lighting guidance - horizontal, hemispherical, and semi-cylindrical. Results of Field Study 2 suggest the minimum horizontal illuminance and hemispherical mean illuminance are more relevant than horizontal mean illuminance for pedestrian reassurance.
Finally, some consideration to methodological matters is given, such as the impact in findings of asking participants to imagine after-dark settings and the validity of subjective assessments of lighting. Responses to an item regarding the perceived risk at night were analysed. These analyses suggested that asking participants to imagine an after-dark scenario might promote lower perceptions of safety. Also, the association of subjective evaluations of the lighting were analysed against the lighting metrics and reassurance appraisals resulting from study 1 and 2. Findings suggest that the perceived quality of lighting, in both studies, is associated with the recorded significant illuminances of each study.