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Many traffic accident cases involve questions of driver visual perception. It is common for one or both sides to employ experts in such matters. These individuals often make use of reconstructions in an effort to arrive at an opinion concerning driver perception. While such reconstructions can be helpful, they can also be very misleading. The purpose of this report is to review basic information concerning visual perception, to lay a foundation for understanding how the visual system works under nighttime driving conditions. Applied research on night driving will be covered as well, with a particular focus on detecting conditions in the forward field. The report concludes with a section on problems that can degrade visual performance at night.

Frequency response methods are applied in developing an understanding of the influence of design parameters on the directional performance of commercial vehicle combinations employing full trailers. Transfer functions are used to describe the contributions of full trailers, trucks, and tractor-semitrailers to the rearward amplification between the lateral accelerations of the towing and last units in truck-full trailers, doubles, and triples combinations. These transfer functions show how forward velocity, distances from pintle hitches to center-of-gravity locations, and cornering coefficients influence rearward amplification.

A method for calculating the probability of wheel lock occurring during braking with passenger cars is presented. The method combines (1) the probability distribution of vehicle deceleration during braking, (2) the probability distribution of tire-road friction exhibited by the general road system, and (3) the braking efficiency level of the vehicle, to predict the probability of the occurrence of wheel lockup during a given braking event Results are presented employing the constituent probability data available in the open literature. These results predict that lockup events are very rare for typical drivers operating vehicles of 80% braking efficiency or better. As braking efficiency falls, the frequency of occurrence of lockup rises rapidly. At braking efficiency levels as low as 50%, typical drivers would experience lockup about once a month or once every 35 miles of travel on wet roads.

Physical prototypes of two forms of intelligent subsystems for increasing a truck driver’s ability to maintain stable operations with an articulated heavy-duty vehicle have been designed, constructed, and demonstrated. The two systems deal, respectively, with (1) quasi-steady-state rollover and (2) rearward amplification of lateral acceleration (especially in multi-articulated trailer combinations). Both forms of instability have been documented through prior research and both are known to influence the crash record. Results from testing show that both systems are viable from a technical point of view.

The goal of this study was to provide information about the frequency of installation and use of fog lamps. Two surveys were performed. In the first one, installation of fog lamps was estimated by a survey of parked vehicles in two iarge shopping centers. The second survey studied the usage of fog lamps during daytime and nighttime, under clear, rainy, or foggy conditions. In this survey, an observer in a moving vehicle noted the types of lamps that were energized on the fronts of oncoming vehicles, and whether fog lamps were installed at all. The main findings are: (1) The best estimate of the current frequency of installation of fog lamps in southeast Michigan is about 13%. (2) During daytime, the usage of fog lamps increased with deterioration in atmospheric conditions, with the usage reaching 50% of all installed fog lamps during moderate-to-heavy fog.

Suggestions for pictographic symbols for identifying automotive controls and displays were obtained from 32 drivers. A total of 142 symbol candidates were developed from these suggestions for 25 functions. Subsequently, 104 people at a driver licensing office ranked these candidates and corresponding symbols in ISO Standard 2575 from best to worst. The criterion was how well the candidates represented the functions of interest. Based on those data the authors recommend replacing the ISO symbols for the lighter, fog lights, hood release, master lighting switch, and temperature and continuing to seek alternatives for the front defrost, hazard, headlamp cleaner, high beam headlamps, unleaded fuel, parking lights, rear defrost, windshield washer, and windshield washer/wiper.

This study investigated levels of driver comfort and acceptance for an autonomous intelligent cruise control (AICC) system driven in an actual highway environment. Objective measures of driving performance and behavior are compared with participants' subjective assessments when operating under manual control, conventional cruise, and AICC. Included in the comparison are measures of driver velocity and braking behavior. Participants drove at slightly higher mean velocities under the manual condition as compared with AICC. Participants applied the brakes least frequently when driving manually. Participants rated the AICC system favorably for comfort, ease of use, and convenience. However, participants did express limited concerns associated with the use of AICC.

Vehicle motions can adversely affect the ability of a driver or occupant to quickly and accurately push control buttons located in many advanced vehicle control, navigation and communications systems. A pilot study was conducted using the U.S. Army Tank Automotive and Armaments Command (TACOM) Ride Motion Simulator (RMS) to assess the effects of vertical ride motion on the kinematics of reaching. The RMS was programmed to produce 0.5 g and 0.8 g peak-to-peak sinusoidal inputs at the seat-sitter interface over a range of frequencies. Two participants performed seated reaching tasks to locations typical of in-vehicle controls under static conditions and with single-frequency inputs between 0 and 10 Hz. The participants also held terminal reach postures during 0.5 to 32 Hz sine sweeps. Reach kinematics were recorded using a 10-camera VICON motion capture system. The effects of vertical ride motion on movement time, accuracy, and subjective responses were assessed.

A class of heavy truck vehicles, characterized primarily by high centers of gravity, was studied using analysis and computer simulation to identify and understand the relationship between directional and roll stability of such vehicles during steady turning maneuvers. Findings of the computer-based study suggest: (1) directional instability (yaw divergence) is possible for such vehicles during steady turning while operating at elevated speeds on horizontal road surfaces, (2) yaw divergence will lead to rollover in the absence of corrective steering action and/or reduced speed, and (3) the primary mechanism responsible for precipitating yaw divergent behavior in such vehicles is the nonlinear sensitivity of truck tire cornering stiffness to vertical load acting in combination with typical heavy truck fore/aft roll stiffness distributions. In addition, the influences of roadway superelevation and driver steering control as contributors to vehicle stabilization are examined and discussed.