A Methodology for the Analysis of ITS Impacts on Mobility, Air Quality, and Land Use

The Indiana Department of Transportation (INDOT) is currently implementing (or has implemented) several components of Intelligent Transportation Systems (ITS). This includes a mini Advanced Traffic Management Systems (ATMS) implemented on a three-mile stretch of the Borman Expressway to evaluate advanced non-intrusive sensor systems and the associated communication infrastructure for the installation of a full-scale ATMS on the 16-mile stretch of the Borman Expressway. Potential specific ITS technologies that are either being implemented or are being considered include pre-trip information, en-route information, variable message signs, and Hoosier Helpers. It is expected that the implementation of various ITS technologies on the Borman Expressway will result in improved traffic flow, lower travel times, higher average speeds, and improved safety and environment. This study evaluated the impacts of these ITS technologies on mobility, air quality, and safety on the Borman Expressway and its vicinity. 1) Mobility - The performance of various ITS components under normal and incident conditions for the Borman Expressway Evaluation Network were simulated and the results were compared with the corresponding scenarios in the absence of these technologies. The results suggest that the network can accommodate the vehicles that divert from the Borman Expressway, indicated by the decrease in the overall network average travel time with increase in market penetration of information. Hence, providing en-route route diversion information to some users can result in significant benefits in terms of travel time savings and congestion alleviation. 2) Air Quality - The performance of various ITS components under normal and incident conditions for the Borman Expressway Evaluation Network were simulated and the resulting HC, CO, and NOx emissions were compared with the emissions under a do-nothing scenario. The same network was used for air quality impact evaluation that was used for evaluating the mobility impacts of ITS. The results obtained from the simulation experiments indicated that significant improvement in air quality can be achieved by effective implementation of various ITS technologies under normal and incident conditions. One important trend observed from the results of these experiments was that the magnitude of reduction in mobile emissions was highest under incident conditions with link closure, and lowest under normal peak-hour conditions. 3) Safety - By testing the hypothesis that secondary crashes may take place as a direct result of primary incidents or traffic congestion, safety impacts were evaluated. Logistic regression modeling was used to predict the likelihood (risk) of a primary incident being followed by a secondary crash, using the “best” combination of primary incident characteristics. The resulting models suggested that the likelihood of a secondary crash occurring increases with an increase in the primary incident clearance time and with the involvement of a car, semi, or truck