Light Levels for Parking Facilities Based on Empirical Evaluation of Visual Performance and User Perceptions

Light levels recommended for parking facilities should be backed by empirical research that accounts for all users. In the current study, pedestrians’ and drivers’ visual performance and their perceptions of safety, comfort, and visibility were evaluated at a parking garage and at parking lots with asphalt and concrete pavements under three light source types (high-pressure sodium luminaire, 3000 K light emitting diode [LED] luminaire, and 5000 K LED luminaire) and at multiple light levels. Visual performance involved facial and hand recognition, wheel stop detection, detection of a side-facing pedestrian, and detection of a vehicle backing up from a parking spot. Perceptions of safety, comfort, and visibility were assessed by means of a questionnaire. Results showed that in the parking garage, an increase in light level beyond 10 lux of average horizontal pavement illuminance did not result in a statistically significant increase in visual performance or perceptions of safety, comfort, and visibility. For parking lots of asphalt and concrete pavements, this plateauing was observed at the 2 lux light level. No statistical differences were observed between the light source types for the visual performance tasks, but the perceptions of safety, comfort, and visibility were highest for the 5000 K LED luminaires.