Interpretation ID: aiam2595
3396 Alma Street
Lynwood
CA 90262;
Dear Mr. Green: Your letter of April 8, 1977, to the President of the United State concerning the need for improved motor vehicle headlamp standards has been referred to this office for consideration and reply.; We have received considerable information regarding the effects o foreign and domestic motor vehicle headlighting equipment, including engineering papers and test data on 'selective yellow' headlamps. All information concluded that filtering of headlamps to produce yellow reduces the photometric intensity of the lamp, thereby reducing the actual seeing distance. Some vehicle operators subjectively concluded they can see further with yellow headlamps, but objective seeing distance tests with specific target characteristics and distances indicate a loss of seeing distance.; It is also true that while the original intent in using yello headlamps was to reduce the glare from oncoming vehicle headlamps, our current test data indicates that a yellow light does not reduce glare. The white light is, therefore considered safer and is the basis for requiring white light in Federal Motor Vehicle Safety Standard No. 108 (copy enclosed).; Although this lighting standard is generally in accordance wit standards developed and published by the Society of Automotive Engineers, it does not specifically require sealed-beam headlamps. However, it does require headlamps which are designed to be aimed properly when installed in prealigned mechanical assemblies. The lamp itself may be sealed-beam (filament is enclosed only by the lamp shell in an inert atmosphere) or it may be a halogen lamp (filament is surrounded by a small envelope containing a halogen gas). Specifically, the halogen-bulb headlamp is legal if incorporated into an otherwise legal motor vehicle headlamp.; I trust the foregoing is fully responsive to your inquiry. Sincerely, E. T. Driver, Director, Office of Crash Avoidance, Moto Vehicle Programs;