The implementation of a national journey-time system presents considerable technological, financial, and environmental challenges, but its potential returns are much greater. Drawing on experience from the development of the Trafficmaster national monitoring system in the UK, this article outlines how low-cost, high-performance image-capture systems could collect the live link travel times across a road network. A travel-time system is typically operated by a roads administration authority, transport department, local authority, motorway operator, or a travel-time information provider such as Trafficmaster. The usual requirements for a `local' travel-time system are to inform drivers about local traffic conditions, provide data for designing new road systems, or supply before-and-after comparisons for road projects. As soon as a network system has become operational, the comparison of real-time and reference data can be used as the basis for several enhanced road-user services. Trafficmaster's passive target flow measurement (PTFM) system, using vehicle licence plate recognition, uses a vehicle subsampling method to reduce the quantity of data that must be transmitted by each site. It could provide personal route planning where time of day, origin, and required destination time would all be considered.
Abstract