An introduction of indicator variable to develop a new logic for incident detection algorithm

This study is performed to propose a new variable named an indicator that can easily detect the incident on freeways. To verify the usefulness of indicator for detecting the incident, 3 indicators of the flow, speed, and occupancy are built and they are compared with incident records. Even though there is a time lag due to an accumulation period, the stochastic natures of traffic variables can be resolved and it appears more stable traffic pattern than when the traffic variables are directly used. This makes it possible to easily find the threshold that an incident can be declared. If the value of the speed indicator is greater than the threshold, it can be judged that the incident may happen around the station. In this study it is appropriate to decide the thresholds that are -0.4 for 2-minute accumulation period or -0.3 for 5-minute accumulation period.