Vulnerable Road User Safety After Wales’s Default 20 mph Reform: Implications for Sustainable Mobility

Safe walking and cycling are part of sustainable mobility, but aggregate collision totals do not show whether speed policies reach vulnerable road users (VRUs). Wales reduced the default speed limit on restricted roads from 30 to 20 mph in September 2023. To avoid mechanical reclassification after the reform, roads posted at either 20 or 30 mph were pooled. A 2022Q1–2025Q4 panel compared 22 Welsh and 289 English local authorities using Poisson and ordinary least squares (OLS) fixed-effects models, supplemented by policy-level and spatial analyses. Combined pedestrian and cyclist casualties declined by 19.4% in the Poisson model and 26.0% when the OLS coefficient was scaled to the Welsh pre-reform mean. Poisson reductions were 22.2% for pedestrians, 25.7% for child VRUs and 14.8% for those killed or seriously injured; corresponding OLS outcomes survived false discovery rate control. The police-force placebo yielded a two-sided p value of 0.086. School-context estimates did not survive multiplicity adjustment, while current road status provided descriptive rather than segment-level causal evidence. Mean speed declined by 3.56 mph at 42 selected sites. The findings indicate lower recorded casualties among groups central to active travel. They do not establish lower risk per journey or isolate all Wales-specific changes, but they support transparent monitoring of whether sustainable transport policies reach vulnerable groups.