Masking of front turn signals by headlamps in combination with other front lamps

Abstract

Previous studies have shown that the visibility of a front turn signal is decreased if a headlamp is located near the turn signal. Consequently, both the US and ECE regulations require the turn signals to be more intense in such situations. However, it is unclear how adjacent light sources affect suprathreshold aspects, such as conspicuity. The present field study was designed to examine the effects of several factors on the night-time conspicuity of front turn signals. Specifically of interest were the effects of the number, luminous intensity, and spatial arrangement (including spacing) of the potentially interfering lamps. The following are the main findings: (1) The conspicuity of a turn signal was significantly lower when it was separated from a 1000 cd low-beam headlamp by 50 mm rather than 100 mm (centre-to-edge). A 200 cd turn signal at 100 mm was equal in conspicuity to a 288 cd turn signal at 50 mm. This effect is smaller than the effects obtained in previous studies using threshold-visibility paradigms. (2) Adding a second masking light source, at the same 50-mm spacing as the first masking light source, significantly influenced the conspicuity of the turn signal. The effect of the second masking source can be compensated for by an increase in the turn signal intensity corresponding to 8.5% of the intensity of the second masking source. (3) The conspicuity of the turn signal was unaffected by the spatial arrangement of two masking light sources.

Get full access to this article

View all access options for this article.

References

Kahnemann, D. Method, findings, and theory in studies of visual masking. Psychological Bulletin 1968; 70: 404-425.

Mortimer RG , Olson PL. Variables influencing the attention-getting quality of automobile front-turn signals. Traffic Safety Research Review 1966; 10: 83-88.

SAE (Society of Automotive Engineers) . Headlamp-turn signal spacing (Appendix: Front turn signal to headlamp spacing observations) SAE Information Report 1221. Warrendale, PA: Author, 1978.

Alferdinck JWAM , Varkevisser J. Conspicuity of the front direction indicator in combination with a D1 headlamp Report IZF 1991 C-20. Soesterberg, The Netherlands: TNO Institute for Perception, 1991.

Palmer J , Kantowitz B. Daytime running lights and turn signal masking Report DOT HS 808 221. Washington, DC: National Highway Traffic Safety Administration, 1994.

Kirkpatrick M , Baker CC , Heasly CC. A study of daytime running light design factors Report DOT HS 807 193. Washington, DC: National Highway Traffic Safety Administration, 1987.

Office of the Federal Register FMVSS (Federal Motor Vehicle Safety Standard) 108 (Lamps, reflective devices, and associated equipment). 49 Code of Federal Regulations, Part 571.108. Washington, DC: US Government Printing Office, 1999.

ECE (Economic Commission of Europe) Regulation No. 6 (Uniform provisions concerning the approval of direction indicators for motor vehicles and their trailers). Agreement concerning the adoption of uniform conditions of approval and reciprocal recognition of approval for motor vehicle equipment and parts. Geneva: United Nations, 1993.

Sivak M , Flannagan MJ , Budnik EA , Flannagan CC , Kojima S. The locations of headlamps and driver eye positions in vehicles sold in the US. Ergonomics 1997; 40: 872-878.

10.

Huey R , Decker D , Lyons R. Driver perception of just-noticeable differences of automotive signal lamp intensities Report DOT HS 808 209. Washington, DC: National Highway Traffic Safety Administration, 1994.

11.

Sayer JR , Flannagan MJ , Sivak M , Kojima S , Flannagan CC. Just noticeable differences for low-beam headlamp intensities Report UMTRI- 97-4. Ann Arbor, MI: The University of Michigan Transportation Research Institute, 1997.