A decision support system for monitoring traffic by statistical control charts

Identification of critical traffic conditions based on analysis of traffic variables in a route allows the planners to react timely under such conditions. In this paper, a Decision Support System (DSS) is proposed to determine traffic condition in a route based on the data traffic variables received online in a route such as speed and flow. A knowledge based system is established, which consists of a series of rules (If-Then) to identify the critical traffic conditions when the traffic variables in a route decrease or increase as compared with the previous means, significantly. Statistical control charts are used to identify significant deviations of traffic variables from their means, which are usually caused by events such as accidents. The data for traffic variables, namely flow and speed in 60 hours was collected from one of the main highways of Tehran (Iran’s Capital) in peak hours (17 and 18). 35 observations were used to design control limits for two traffic variables, namely flow and speed and the remaining 25 observations were used to monitor traffic conditions in the future (execution of phase 2 of statistical control charts). The results of traffic monitoring in the intended route indicate that the decision support system has a good performance to identify critical traffic conditions.