As congestion increases, transportation agencies are seeking regional travel time data to determine exactly when, how, and where congestion affects freight mobility. Concurrently, a number of regional intelligent transportation systems (ITS) are incorporating various technologies to improve transportation system efficiency. This research explored the ability of these ITS devices to be used as tools for developing useful historical, and perhaps real-time, traffic flow information.
Regional transponder systems have required the installation of a series of readers at weigh stations in ports, along freeways, and at the Washington/British Columbia border. By linking data from these readers, it was possible to anonymously track individual, transponder-equipped trucks and to develop corridor-level travel time information. However, the research found that it is important to have an adequate number of data points between readers to identify non-congestion related stops. Another portion of this research tested five GPS devices in trucks. The research found that the GPS data transmitted by cellular technology from these vehicles can provide much of the facility performance information desired by roadway agencies. However, obtaining sufficient amounts of these data in a cost effective manner will be difficult. A third source of ITS data that was explored was WSDOT’s extensive loop-based freeway surveillance and control system.
The output from of each of the ITS devices analyzed in this research presented differing pictures (versions) of freight flow performance for the same stretch of roadway. In addition, ITS data often covered different (and non-contiguous) roadway segments and systems or geographic areas. The result of this wide amount of variety was an integration task that was far more complex then initially expected.
Overall, the study found that the integration of data from the entire range of ITS devices potentially offers both a more complete and more accurate overall description of freight and truck flows.