HID car headlights and road safety : a state-of-the-art report on high-pressure gas-discharge lamps with an examination of the application of UV radiation and polarised light.

This report is the English version of IRRD 860391 (see C 1630). This report firstly offers an overview of observation in vehicle lighting. To see and be seen are important considerations in this regard. The paper describes the function and types of application of the front dipped headlight. Subsequently, the technical lighting aspects of high-intensity discharge (HID) lamps which have an influence on road safety are described. Due to the intense light produced by HID lamps and the presence of ultraviolet (UV) radiation, two possible areas of application are described: (1) polarised light and (2) the use of fluorescent material to enhance the visibility of objects. The health hazard presented by UV radiation is not ignored, however. The light emission of a dipped light beam as stipulated by ECE regulation R20 is dealt with extensively. The paper also presents the results of study into HID lamps in the United States and European research through EUREKA 'VEDELIS'. It is concluded that: (i) the proposed light emission of the dipped light beam for HID lamps is higher than the current ECE standard for virtually all measurement parameters; and (ii) the orientation of the light beam emission should pay greater attention to the position of vulnerable road users.