Helmet Use Among E-Bike, Pedal Bike, and E-Scooter Riders in Canberra: Observational and Quasi-Experimental Signage Intervention Study (Phases 1 and 2) [Protocol]

ABSTRACT Background Helmet use is a proven safety measure that reduces the risk of head injury among cyclists and e-scooter riders. Despite legal requirements for pedal bikes and e-bikes in Australia, compliance varies, particularly among users of electric vehicles. The growing popularity of e-bikes and e-scooters in urban areas presents new public health challenges, yet observational data on helmet use, behavioural determinants, and the effectiveness of safety interventions remain limited. Aim Phases 1 and 2 aim to assess helmet use among e-bike, pedal bike, and e-scooter riders in Canberra, and evaluate the impact of health-benefit and legal-penalty signage on compliance. Methods This study employs a multi-phase, quasi-experimental observational design across three urban bike paths in Canberra. Phase 1 (Baseline): Helmet use will be recorded via discreet video surveillance, capturing vehicle type, estimated age group, gender presentation, and weather conditions. Phase 2 (Intervention): Two sites will receive signage emphasising either safety benefits or legal penalties, while a third site serves as a control; post-intervention observations will assess changes in helmet compliance. Expected Results Baseline helmet use is expected to be higher among pedal bike riders than e-bike and e-scooter riders. Signage interventions are anticipated to increase compliance, with potential variation by message type, vehicle type, and rider demographics. Trial Registration Australian and New Zealand Clinical Trials Registry (ANZCTR) [ACTRN12626000245392]