Visibility of Two-Wheelers Approaching Left-Turning Vehicles Compared with Other Hazards Under Nighttime Conditions at Urban Signalized Intersections

Abstract

In the past, researchers have investigated ways to increase the conspicuity of two-wheelers (i.e., motorcycles, mopeds, scooters, and other motorized vehicles) under daytime conditions. However, only a few researchers have analyzed their conspicuity under nighttime conditions. The aim of this study was to evaluate the visibility of two-wheelers encountered by left-turning motorists at urban intersections under nighttime conditions, and compare them with other hazards. A low-fidelity simulator was used to collect data and perform evaluations. The simulator presented a series of videos from a motorist’s perspective, while a passenger vehicle was positioned in the permitted left-turn lane at a signalized intersection. During each video the study participants were instructed to determine whether a left-turn maneuver was safe under the given set of nighttime traffic conditions. The response times for 30 participants were recorded and totaled 627 responses. The observed response times to a two-wheeler were not different from the response times to a passenger vehicle with two headlights. However, the response times were significantly shorter than the times to recognize no hazard or a two-wheeler with no headlight. The conspicuity issues that pertain to two-wheelers in daytime and nighttime conditions were not observed to be the same. Further, the same treatments proposed for two-wheelers in daytime conditions may not be as beneficial or even needed during nighttime driving.