This paper describes the industry-relevant basic research focus of the Michigan IVHS Program in the last two years, with an emphasis on the linkage among the various projects related to anticipatory route guidance. Future direction of this research focus will also be discussed.
The critical test for Advanced Traveler Information Systems (ATIS) is whether an individual driver with an appropriately equipped vehicle will get intelligent and safe advice on traffic diversion from his originally chosen route after a congestion-causing incident is detected and verified. Such advice should take into account not only current traffic conditions but also anticipated delay that may occur before the driver reaches his destination. Therefore, the Michigan IVHS research on traffic modeling and route optimization has focused on anticipatory route guidance. The anticipatory guidance system routes the vehicles by minimizing time-dependent link costs incurred by the driver. A novel dynamic programming approach has been used to take advantage of the time-dependent characteristics of the minimal travel-time solution to reduce computation load.
The computation of routes is accomplished in the vehicle so that the driver will have complete and private control of not only the objective function, but also the constraints, in the computation for his optimum route. The information to be provided from the infrastructure is a set of anticipated link costs, updated periodically, to reflect current system demand and unexpected traffic incidents. Preliminary analysis has suggested that, to minimize communication load, under certain conditions, all link costs (not just exceptional ones) should be transmitted and appropriate data compression techniques should be used.
Since diversion recommendations are generated within the vehicle, no matter where the vehicle happens to be, these recommendations may arise after the driver has passed the location for safe maneuver to divert. Human factors research has been conducted to assess the safe distance before the junction for recommended diversion that should be allowed for safe diversion. This safe distance would depend on the driver characteristics, as well as on the vehicle and road characteristics (including the lane location). The guidance system should be designed so that only safe diversion advice will be given to the driver.
Extension of research on anticipatory route guidance includes 1) the projection of link costs through traffic modeling and simulation, 2) inclusion of multiple transportation modes, and 3) coordination with traffic light controls. The research strategy is to generate practical guidelines for ATIS product development, which can be upgraded incrementally as additional research results become available, and as component costs change.