More than 40% of the nations vehicle miles traveled (VMT) occur on the arterial roadway network, which makes up less than 12% of the nations lane mileage. Because of the importance of the arterial system, more attention is being paid to developing techniques for monitoring arterial conditions and providing better traffic management and traveler information capabilities. Surveillance using loop detectors (or other point-based data collection systems) associated with traffic signals can be one way to develop an arterial monitoring system. In addition, with the prevalence of transit buses operating on arterials, and the development of more advance bus dispatch systems that include global positioning systems and real-time communications capabilities, attention is turning to the possible use of buses as probe vehicles along arterials. In the Portland, Oregon metropolitan region, research is underway to extract arterial performance measures from traffic signal system detectors and from buses acting as probe vehicles. This paper describes the techniques developed for constructing the shape of the congested regime in time and space along a key arterial corridor, using both signal system detectors and bus automatic vehicle location data. Congestion monitoring can be performed using each data source separately; however this paper demonstrates the value of combining the two data sources for improved congestion monitoring and travel time estimation. Future research will include expansion of these techniques to other corridors, the use of higher resolution, real-time transit AVL data, and on-line implementation of an arterial travel time information system.
Abstract