The effect of police enforcement on road traffic accidents

The primary goal of this thesis is to investigate the effectiveness of police enforcement on Road Traffic Accidents; specifically, ‘Does police enforcement activity have any real effect on levels of Killed and Seriously Injured road traffic accidents?' Data relating to forty one Police Force Areas in England and Wales was analysed by means of Zero Truncated Poisson regression, Cluster Analysis and Multilevel Modelling. Enforcement measures available to the police, for which data is available in this report, range from Prosecutions and Fixed Penalty Notices to Written Warnings and Vehicle Defect Rectification Notices. Results from the Zero Truncated Poisson regression models have significant effects (P < .05), in relation to both contemporary and lagged Annual data and contemporary Quarterly data, for all proxy variables except Prosecutions. Significant effects (P < .05) are also found for Fixed Penalty Notices lagged by two quarters, Vehicle Defect Rectification Notices and speeding related Fixed Penalty Notices lagged by one quarter. Results from Cluster Analysis verify the trend linking increased police enforcement with decreasing KSI rates. Clusters derived from population based KSI rates are more clearly defined than those using Vehicle kilometres travelled based KSI rates. Multilevel modelling found significant fixed effects (P < .05) for Fixed Penalty Notices and speeding related Fixed Penalty Notices in relation to both derived and regional clusters, linking an increase in enforcement to a decrease in the overall KSI rate. There would seem to be little doubt, based on the findings of this report, that higher levels of police enforcement, as measured here, lead to decreasing numbers of KSI accidents.