Abstract:Identifying the “health problem” of traffic monitoring equipments is important to longterm performance of intelligent transportation system (ITS) application system.Based on statistical distribution analysis of plentiful traffic data archives,a quantitative method to seek the potential problem of traffic observations is proposed.Employing freeflow speed,a steady parameter of traffic flow,as a main indicator,parameters estimation,hypothesis test and confidence interval analysis are jointly used to determine the health condition of traffic detectors.The methodology is demonstrated through application to the historical and realtime data in the Advanced Traffic Management System of Shanghai urban expressway system,with validation by floating car measurement.