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This paper describes a human factors simulation study of the decision making behavior of drivers attempting to avoid nonrecurring congestion by diverting to alternate routes with the aid of in-vehicle navigation systems. This study is the first phase of a two part project in which the second phase will apply the driver behavior data to a simulation model analysis of traffic flow. The object of the driver behavior experiment was to compare the effect of various experimental navigation systems on driver route diversion and alternate route selection. The experimental navigation system configurations included three map based systems with varying amounts of situation information and a non map based route guidance system. The overall study results indicated that navigation system characteristics can have a significant effect on driver diversion behavior, with better systems allowing more anticipation of traffic congestion.

This paper describes a laboratory simulation study of driver reaction to in-vehicle navigation systems. The study included a pre-test questionnaire on demographic background and commuting behavior, simulation testing of navigation decision making, and a post-test questionnaire on navigation behavior and reactions to in-vehicle navigation systems and the laboratory simulation. A total of 277 subjects, both male and female, were employed over a wide range of ages. Test subjects were assigned to one of four navigation system groups or a no-system control group for the purpose of comparing system performance. The simulation task required subjects to experience a commuting ‘drive’ on a Southern California freeway route and minimize trip time by diverting off the main route to avoid congestion. Subjects were given orientation and training on the simulation and their navigation system condition, and were motivated by rewards and penalties to minimize trip time.

Real time man-in-the-loop simulation can be used in a variety of research, testing and training roles where safety, efficiency and/or economy are important. Simulation can allow complete control and uniformity over driving conditions and permit analysis of a range of vehicle and driver behavior variables. Simulation complexity and fidelity requirements will vary depending on application requirements. This paper reviews past and current driving simulation development efforts and applications. Simulation requirements are assessed relative to various applications, including vehicle handling, driver behavior, training, licensing and fitness for duty testing.

A Grade Severity Rating System (GSRS) was developed as a means for reducing the incidence and severity of truck accidents on downgrades. The ultimate result is a roadside sign at the top of each hill. The sign is tailored to the individual hill and gives a recommended maximum speed (to be held constant for the entire grade descent) for each of several truck weight ranges. This concept represents a major step forward in terms of grade descent safety because it tells the driver what to do directly, rather than giving him information which still requires evaluation under different loading conditions.

This paper describes the results of a test program to evaluate various roadway disturbances present in the driving environment. The specific objectives were to pare down the list of possible roadway disturbances to the worst cases, identify handling problem areas, find meaningful response parameters and compare responses of different vehicles which might influence the results. The program provided an accident data analysis, survey questionnaire results and full scale test results which found the pavement/shoulder dropoff (requiring an edge climb maneuver) to be the most severe and most likely disturbance to result in lane exceedance. This occurs when the vehicle is scrubbing one set of tires on the shoulder edge (or encountering the edge at too shallow an angle for climb), thereby climb), thereby requiring the driver to apply a large steering deflection to get the car to climb back onto the pavement. In this case the vehicle will “spin out” if the speed is high enough.

Results of a study to analyze and correlate handling-related driver/vehicle system response and performance data are reported. Steering control tasks involving maneuvers and disturbance regulation are emphasized. Correlations between vehicle handling parameters, objective measures, and subjective rating data have been made. These have lead to the tentative definition of values of steering gain and effective yaw time constant which are preferred for satisfactory handling qualities and performance for passenger automobiles.