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Technical Paper

Fog Lamps: Frequency of Installation and Nature of Use

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.
Technical Paper

Evaluation of the SAE J1735 Draft Proposal for a Harmonized Low-Beam Headlighting Pattern

This study evaluated the SAE J1735 Draft Proposal for a low-beam headlighting pattern in relation to the current standards in the U.S., Europe, and Japan. The approach consisted of the following steps: (1) identifying a set of 15 important visual performance functions (including seeing and glare) for low-beam headlamps; (2) defining the relevant geometry relative to the visual performance functions; (3) setting criterion values of illumination for each of the visual performance functions based on the available empirical data; and (4) evaluating the standards relative to the criterion values by using the worst-allowed-case approach (evaluating the minima specified by the standards for seeing functions, and the maxima for glare functions). The results indicate that the SAE J1735 Draft Proposal tended to require better performance than the current U.S., European, and Japanese standards.
Technical Paper

The Relative Importance of Horizontal and Vertical Aim of Low-Beam Headlamps

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.
Technical Paper

Quantifying the Benefits of Variable Reflectance Rearview Mirrors

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.
Technical Paper

Current ISO Automotive Symbols versus Alternatives - A Preference Study

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.
Technical Paper

A Survey of the Condition of Lighting Equipment on Vehicles in the United States

A nationwide survey was conducted of the condition of vehicle lighting equipment. Twenty different sites were visited and a total of nearly 1, 000 vehicles included in the sample. Headlamp aim and dirt levels were measured and the condition of marker and signal lamps noted. The results of the survey indicate that many vehicles have headlamps that are badly aimed. The condition of front and rear marker and signal lamps is generally good, with more than 98% of such units functioning. Side marker lights were in poorer shape, hut more than 90% of these were operating. Consistent differences were found between areas with and without vehicle inspection programs. It appears that such programs are effective in improving the condition of vehicle lighting systems.
Technical Paper

Market-Weighted Trends in the Design Attributes of Headlamps in the U.S.

This report provides updated information regarding the market-weighted prevalence of various headlamp design attributes in the U.S. and a summary of recent trends for these design attributes. The main findings were as follows: (1) there was a general transition from dual-filament light sources in 1997 to single-filament sources in 2007; (2) the preferred optics changed from lens-based in 1997 to mostly reflector-based optics in 2007; and (3) while mechanical aim was the most frequently specified aiming method in 1997, the 2007 sample made nearly exclusive use of visual/optical aiming (with visual/optical right side as the most common specific type).