ANALYSIS OF CORRELATION BETWEEN ARTERIAL TRAVEL TIME AND DETECTOR DATA FROM SIMULATION AND FIELD STUDIES

Abstract

The effectiveness of control strategies applied to alleviate traffic congestion depends heavily on the accuracy and credibility of the data sources used. Among data sources now available, loop detector systems can provide large quantities of high-quality data. The feasibility of using detector data to improve the performance of advanced traveler information systems functions, such as arterial travel time estimation, is examined. The relationships between travel times and flow/occupancy information are assessed using simulation techniques and field data. A common study area is used for both types of experiments. The NETSIM model was selected as the best simulation tool available. Recent enhancements of the model, expected to be incorporated in its next release allow for the simulation of surveillance detector information such as vehicle counts, percentage occupancy values, and average spot speed. Several experiments are performed to incorporate variations in entry flows and turning movement percentages, as well as the randomness of traffic phenomena. Besides the simulation experiments, field studies are carried out as part of a validation effort. These studies include on-site travel time data collection and concurrent detector output consideration for detectorized links in the study area. The explanatory analysis presented indicates that both approaches support the following conclusions: (a) travel time is independent from both flow and occupancy under conditions of low traffic demand, and (b) generalized regression equations can be fitted for certain ranges of occupancies to properly model the relationships between travel time and detector data.