Expert prioritization of safety measures to address low-noise risks of electric vehicles: A Delphi study focused on vulnerable road users

OBJECTIVES: To establish expert consensus on the prioritization of evidence-informed safety measures for the low-noise risks of electric vehicles (EVs), and to specify consensus positions on acoustic and non-acoustic countermeasures that complement existing acoustic vehicle alerting system (AVAS) mandates. METHODS: A three-round Delphi study with 17 multidisciplinary experts (mean 17.5 years of professional experience, including a blind pedestrian expert) rated 24 items on 7-point Likert scales, and one item on a 10-point scale. Consensus required a mean absolute deviation (MAD) of 1.0 or less. The process was conducted face-to-face, so the results represent negotiated expert judgment. RESULTS: Experts agreed that low-noise EVs pose a heightened, stratified risk for vulnerable road users (VRUs), especially children, older adults and blind pedestrians (Median = 6.0; MAD = 0.2). The strongest consensus supported awareness and education campaigns (Median = 7.0; MAD = 0.1) and research into non-acoustic, system-level measures such as pedestrian detection (Median = 6.0; MAD = 0.1). Experts agreed that AVAS should sound while reversing (Median = 7.0; MAD = 0.1), not while idling (Median = 1.0; MAD = 0.6), and should vary with speed (Median = 7.0; MAD = 0.4). They recommended operation below 30 km/h, with ambient-noise adaptation, rather than only below 20 km/h as currently mandated. Simulating a combustion-engine sound, preventing driver disablement and using AVAS as a pedestrian-detection system received only moderate support (Median = 5.0; MAD = 0.5 to 0.8). Experts also identified ergonomic and psychosocial benefits of low-noise, low-vibration EVs for fleet workers. CONCLUSIONS: Negotiated expert consensus favors two near-term priorities: multi-stakeholder awareness and reeducation programmes, and selective, adaptive acoustic alerts below 30 km/h. Pedestrian detection and driver-alert systems are a promising longer-term complement that requires real-world validation before wider adoption. Findings reflect a Southern European urban context and require validation in other settings.