Comparative analysis of six commercially available AVL systems

Technical assessments of six commercially available AVL systems have been performed. Among the system features included in the study were the positioning accuracy, the communication links, the central computer requirements for possible fleet sizes, and environmental factors such as road conditions which influence performance. For all AVL techniques, a position estimation accuracy has been performed based upon the individual features of each method. The AVL methods examined contain various error sources which have been combined in the analyses in models appropriate to each system. The instantaneous position estimation error thereby derived has been used to form a time-expanded vehicle position error which includes the effect of discontinuous sampling of vehicle data either by a vehicle-mounted position monitor or a central control station. Positioning accuracy data exist for most of the six AVL technologies. These data have been used for comparison with the analytical error models. Results of the experimental and theoretical comparisons are presented and discussed.