Vehicle Reidentification and Travel Time Measurement Using Loop Detector Speed Traps

1 This dissertation presents a vehicle reidentification algorithm for consecutive detector stations on a freeway, whereby a vehicle measurement made at a downstream detector station is matched with the vehicle's corresponding measurement at an upstream station. The algorithm should improve freeway surveillance by measuring the actual vehicle travel times; these are simply the differences in the times that each (matched) vehicle arrives to the upstream and downstream stations. Thus, it will be possible to quantify conditions between widely spaced detector stations rather than assuming that the local conditions measured at a single station are representative of an extended link between stations. The method is developed using vehicle lengths measured at dual loop speed traps. These detectors are quite common, often placed at half mile spacings or less on urban freeways. The proposed approach is a milestone in highway research because no previous work uses the existing detector infrastructure to match vehicle measurements between detector stations. The work is also transferable to other detector technologies Abstract 2 capable of extracting a reproducible vehicle measurement, i.e., a vehicle signature, such as video image processing. The contribution to the field of traffic surveillance should prove to be significant since the vehicle reidentification algorithms will allow the study of travel time applications (e.g., incident detection and dynamic trip assignment) without deploying an expensive detection system. This will enable cost-benefit analysis before investing in a new detection system. If travel time measurement proves to be beneficial, the system could be deployed using speed traps, or the algorithms could be transferred to emerging detector technologies with better measurement resolution. The methodology should prove beneficial for research purposes as well, by yielding better insight into traffic dynamics between widely spaced detector stations.