Are headlight shields safe?

Press, 19 June 1986, Page 29

Are headlight shields safe?

Protective plastic headlight shields are prohibited in most European countries and the United States as well as others, although they are acceptable in New Zealand and Australia. Research undertaken by Melbourne-based Hella Manufacturing with Ford and General Motors in Australia tends to support the view of traffic authorities that do not countenance the use of the shields. The Australian tests have shown that not only do the shields reduce lighting efficiency by 10 per cent, but also that gravel impact, scratching, solvents and cleaning fluids can damage the shields and cause serious side effects. The shields also obstruct cooling air flow. In the case of small headlamps and driving lights that can cause cracked glasses, reflector discoloration, lamp distortion and premature bulb and bulbholder failure. The tests clearly demonstrated that refraction in scratches and indenta-

tions dispersed light, thereby reducing illumination as well as the cutoff line that should provide a driver with a visual fixing point when night driving.

Further, the shields can result in oncoming traffic being subjected to unwarranted glare while the driver of a car fitted with shields can expect to have to cope with “self glare” in adverse weather conditions. Dirt on the shields can reduce illumination to zero.

Beam misalignment is also probable because of the horizontal bend line in the shields.

Last year, the United States National Safety Administration rejected an application from a car manufacturer to fit plastic shields. Research is neverthless proceeding with a view to the production of more efficient shields. In the meantime, a lens which is resistant to scratching, the abrasive action of road grit, grime, and solvents has yet to reach the car accessory market.