Incorporating Incident Data into a Freeway Data Archive for Improved Performance Measurement

The Portland Oregon Transportation Archive Listing (PORTAL) archives high resolution traffic data including speed, volume, and occupancy collected from 500 freeway loop detectors in the Portland metropolitan area. PORTAL currently provides measures related to total congestion that occurs on the freeway network, but cannot presently distinguish between recurrent and non-recurrent congestion effects. In response to the need to make such a distinction, the objective of this paper is to describe the incorporation of freeway incident data received from the Oregon Department of Transportation (ODOT) into PORTAL. ODOT’s freeway incident database includes information about vehicle crashes and stalls, debris on the road, construction and other random events. The paper demonstrates how users can view incident data associated with a particular time frame and location. For example, a user analyzing data from a particular day will be able to immediately access associated incident data so the user can determine if the traffic pattern is related to an incident. In addition, freeway incident performance metrics will be described, including tracking of incident trends over time and location and numbers of incidents by incident type. Finally, the paper will describe how comparing incidents with weather data archived in the PORTAL database can be used to determine how weather has influenced incidents. The above-described incident performance metrics are useful to traffic researchers and practitioners and may contribute to incident-reduction measures in the Portland area.