Tracking Police Responses to “Hot” Vehicle Alerts: Automatic Number Plate Recognition and the Cambridge Crime Harm Index

Abstract

Research Question Are selective decisions to dispatch police cars for interception of vehicles identified by 'live alerts' from fixed cameras using an Automatic Number Plate Recognition (ANPR) database associated with the highest levels of harm across all live alerts? Data This study examined 70.3 million vehicle registration marks read by Fixed ANPR cameras in the West Midlands Police area in April 2015, from which 12,581 live alerts were generated with many repeats, for 1488 unique vehicles identified. A random sample of 210 of these unique alerts was drawn for detailed analysis. Methods Cambridge Crime Harm Index values were applied to each of the 210 cases in the sample, with mean values computed and contrasted for alerts generating dispatched responses vs. no dispatch, interceptions vs. no interceptions and consequences imposed on drivers vs. no consequences. Findings The mean Cambridge Crime Harm Index (CCHI) value of the alerts leading to a dispatched response was 58% lower (59 CCHI days vs. 141) than the value of alerts not leading to a dispatch. The harm level of alert dispatches leading to interception was 57% lower (67 vs. 107 CCHI days) than those not intercepted. The harm level of interceptions leading to consequences was 57% lower (46 vs. 106 CCHI days). Conclusions While resource limitations may affect these outcomes, there is great potential value in creating an automated CCHI calculator to inform the professional