This report describes research into the estimation of the O/D throughput (number of vehicles travelling between two locations) using licence plate data collected using Automatic Number-Plate Recognition (ANPR) systems. The objectives were to recommend a method of estimating O/D throughput and its accuracy (confidence limits) and to recommend good practice for the implementation of the recommended method. The approach used was to collect information from a programme of video filming and measurements at six locations where ANPR systems were installed, and to study the effect of factors such as the traffic conditions and the vehicle characteristics on the accuracy of licence plates read and the number of plates matched. An analytical approach was also used, based on statistical theory, to inform the research by establishing theoretical relationships between the O/D throughput and number of plates matched. The final recommended method related the O/D throughput to the number of matches, the number of plates read at each site and a correction factor, to be derived from a validated reference set of data extracted from video filming. A free-standing document included as an appendix to the report details the recommended method and its implementation. (A)

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