Authors: Gang-Len Chang & Kyeong-Pyo Kang
Date: Aug. 1, 2005
This project presents the evaluation results of three ITS technologies offered by system providers for improving operational efficiency and traffic safety at highway work zones. The first is an integration of variable message signs (VMS) and sensors that function to guide traffic approaching the work zone via dynamic late merge (DLM) operations. Observations of the day-to-day traffic patterns over the work zone under DLM control clearly indicate that such a control system has the potential to significantly increase the work zone throughput, reduce the queue length, and vehicle delay if all sensors and VMS are placed at proper locations.
The second technology is a travel time prediction system that employs traffic data from sensors to project the travel time from a set of given origins to the target destination. The field test results from the highway segment along EB I-70 from MD 32 to I-695 reveal that prediction of travel times under moderate and stable traffic conditions is likely to yield an acceptable level of reliability. However, much remains to be improved for achieving reliable prediction of travel times under congested and unstable traffic flows.
The third target technology under evaluation is a license plate recognition (LPR) system that computes the travel time between an O-D pair based on the entry and exit times of a matched license plate number. The performance of the LPR system on the I-95 testing site shows that the employed technology for LPR cannot yield a sufficient level of license recognition rate for reliable estimation of travel times unless the target highway segment is under congested traffic conditions and vehicles are moving under relatively slow speeds. Besides, the LPRS may not be a cost-effective system for use in local arterials with a large percentage of turning flows, which often causes the LPRS to have a low match rate.