Search Results

This study evaluated the relative effects of horizontal and vertical misaim of low-beam headlamps. The approach involved analyzing light-output matrices of 150 production low beams, manufactured for sale in the U.S., Europe, and Japan. The specific analysis involved computing, for 225 locations in the central part of each beam pattern, the ratios of nominal intensity and intensity for vertical and horizontal misaim of up to 1.5°. The ratios greater than 1 log unit were considered to be of practical significance in terms of changes in visual performance and discomfort glare, and those greater than 0.5 log unit of likely significance. Only changes relative to visual performance and glare under nominal aim were considered; absolute levels were not examined. Furthermore, simultaneous horizontal and vertical misaims were not considered.

We collected photometric data, concerning the simultaneous levels of rearview mirror glare and luminance of the forward scene, in order to characterize the night driving environment for rearview mirrors. An instrumented vehicle was used to collect photometric data for each combination of three road types (urban, expressway, and rural) with two pavement conditions (dry and wet). We then used these data to quantify the benefits of variable-reflectance rearview mirrors relative to (1) fixed-reflectance mirrors, and (2) two-level prism mirrors. The performance of the various types of mirrors was quantified in terms of a figure of merit. The figure of merit is simply the percentage of the time that all of three mirror-performance measures are met: (1) discomfort glare, (2) forward visibility, and (3) rearward visibility.

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.