Difference between reported crash time and speed disturbances in urban signalized intersections: a case study in Fortaleza-Brazil

Abstract

The advent of new technologies for monitoring and controlling traffic allows the development of more robust road safety studies, based on the collection of disaggregated traffic data at intervals of 1 to 15 minutes or even in real time. However, in order to relate the crashes to their precursor conditions, applying this type of data requires a better knowledge on the accuracy of crash reported times. This work aims to present an analysis between the reported times of crashes and disturbances in the traffic flow conditions in urban signalized intersections in Fortaleza, Brazil. Vehicle flow disturbances were detected from speed oscillations by using an algorithm based on comparing speeds between “typical” and “crash” conditions and by validating the detections with visual analysis. The results of investigating 291 crashes showed an average difference of 20 minutes (sd = 23 min) between the reported time of crash and the occurrence of the speed disturbance. This is an indication that, while developing road safety disaggregated analyses, one should examine the database accuracy regarding the crash reported time.

Keywords

• Road safety
• Speed disturbance
• Reported crash time
• Crash time estimation