WS Atkins Consultants Ltd has developed Idris technology as a solution to road toll payment enforcement problems, that is based on low-cost inductive loops that are easy to maintain. Idris algorithms process detector output in real time and generate a parametric description, including length and speed measurements, for each vehicle. This description can then be applied to identify and distinguish vehicles in different situations and manoeuvres. These advances provide dramatic improvement in data quality, achieving count error rates below 1 in 10,000 in free flow and 1 in 500 in congestion. Comprehensive trials have shown that Idris can separate vehicles and produce a trigger in all traffic and weather conditions. This article summarises the results at two test sites, including results during peak periods. The first site was used for preliminary evaluation of Idris' general vehicle separation capability and resulting count accuracy at all speeds including stationary, and regardless of the relative positions of vehicles in the toll lane. The second site was used for a set of controlled tests, to evaluate Idris' performance in classifying vehicles at various known speeds and separations, including stop-go traffic, and in other capabilities. The article also assesses the lessons learned, and discusses Idris applications.
Samenvatting