Costs and benefits of vision-based, wide-area detection in freeway applications

Wide-area detection systems (WADS) through video image processing is gaining worldwide acceptance as a proven technology for IVHS, as well as a preferred emerging technology for replacing loops in many practical situations. This technology has been tested and validated in many real-life applications. The advantages and sophistication of WADS are easily realized at intersections where the large number of detectors and need for wide-area measurements lead to up-front cost justification; this is not so obvious on freeways because of sparse detection and current lack of widespread WADS applications. In this article, a direct comparison of loops versus WADS is made, assuming that WADS is only being used as a direct replacement of loops. Even when ignoring intangible benefits, it is demonstrated that when an economic analysis is performed, WADS can be substantially more cost effective than loops. Intangible benefits include stopped vehicle and incident detectors, automatic extraction of measures of effectiveness and performance measurement, wide-area detection, continuous visual performance verification, accurate speed measurement through vehicle tracking, surveillance at minimal incremental cost, and others.