Comparison of Detector Technologies for Travel Time Measurement Systems

Traffic management systems are in demand of accurate data sources in order to determine the actual traffic situation with high accuracy. Most current systems rely on local detectors which measure the traffic condition at one point on the road but new section detectors like travel time systems have become available which provide new and more accurate data of the traffic situation. Several technologies like automatic number plate recognition (ANPR) cameras, magnetic signatures or Bluetooth scanners can be used for travel time measurement via reidentification of vehicles. ANPR readers provide the best data for all systems with reidentification rates of more than 90%. Travel time systems based on magnetic detectors have often a lower cost but still provide highly accurate data for many applications. Bluetooth scanners are often the most affordable solution but the use is limited to highways or urban arterial roads with high traffic volume.