The role of innovative visibility aids on e-scooter riders’ conspicuity in daylight

• Contrasting colours were used to enhance e-scooter rider visibility for drivers. • Detection time was lower with contrasting colours on both the e-scooter and rider. • Conspicuity ratings were higher for e-scooters with contrasting aids than grey clothes. • Contrasting visibility aids can reduce accidents from poor e-scooter visibility. This study explores how different visibility aids of contrasting colours could enhance the e-scooter riders’ conspicuity under daylight conditions. With the rise in popularity of shared e-scooter services, an increase in incidents involving e-scooter riders and motorized counterparts was noticed. 48 licensed drivers (mean age = 24.6 years) detected the e-scooter riders in the videos and images featuring a simulated urban road environment in daylight, while performing a secondary task (n-back). The time to detect standing and moving e-scooter riders and subjective conspicuity ratings were assessed in three visibility aid conditions: Control (grey clothes and grey backpack), Patterned Jacket (jacket and backpack with checkerboard black and yellow pattern) and Wheels-Backpack (yellow stripes on the e-scooter wheels and on a dark backpack). Improved detectability was observed for e-scooter riders in the Wheels-Backpack condition, resulting in a minimum 168 ms increase in detection time compared to other two conditions. In terms of conspicuity ratings, participants gave higher scores to riders wearing Wheels-Backpack and Patterned Jacket (6.02 and 6.31, respectively, on a Likert 10-point scale), with no significant difference between them. Detection from videos or images showed similar effects. For all of these analyses, Bonferroni post-hoc tests followed a Repeated-measures ANOVA. Distributing contrasting colours across the e-scooter and the rider enhanced their daylight conspicuity better than when contrasting colours were located on the riders’ upper body. However, drivers did not realise that these two visibility aids were not equal in terms of conspicuity benefits.