Global positioning systems (GPS) used for fleet management by trucking companies provide probe data that can support a truck performance-monitoringprogram. This paper discusses the steps taken to acquire fleet management data and then process those data so they can eventually be used for a network-based truck performance measures program. While other studies have evaluated truck travel by using GPS, they have used a limited number of project-specific and temporary devices that have collected frequent locationreads, permitting a fine-grained performance analysis of specific roadwaysegments. In contrast, this fleet management GPS data project involved infrequent reads but a relatively large number of different trucks with ongoing data collection. The most effective approach to obtaining the fleet management data was to purchase the data directly from GPS vendors. Because a performance measures program ultimately monitors trips generated by trucks as they travel between origins and destinations, an algorithm was developed to extract trip end information from the data. The large volume ofdata required automated processing without manual intervention. Because performance measures require travel times and speeds, it was also necessary to evaluate whether speed data from a large number of trucks could compensate for infrequent location reads. Spot speeds recorded by the trucks GPS devices were compared to speed data from roadway loops. The researchers concluded that spot speed data can indicate free flow conditions, but sufficient quantities of data are probably necessary to measure congested travel.
Samenvatting