The report describes the equipment used, measurement technique and results from a survey of light output from all obligatory signalling lamps of 452 vehicles of all types from cars to articulated HGV's. The aim of dipped headlamps, and their light output both towards the footway and towards an oncoming driver, were also measured. The vehicles surveyed were randomly selected and measured at the side of the road during daytime in the South of England. They were measured with the engine idling, both before and after cleaning. The light output from dipped headlamps was also measured with and without allowing for incorrect aim. The headlamp mounting height and driver's eye height were also recorded. Light outputs of signalling lamps compare poorly with Type Approval values, half of them being less than the minimum standard for manufacture even after cleaning. None was brighter than the maximum standard. Although illumination from headlights is better than in 1971, it could be improved, as the aim of headlamps is very bad, and is worse than in 1981. Only about 1 headlamp in 15 complies with the British Standard for headlamp aim. Vehicles over 3 years old were no better than vehicles less than 3 years old. Rear fog lights on articulated vehicles are a particular concern. A quarter of these vehicles had none fitted, on the other 70 vehicles 28 lights were not working, and of the 102 lights fitted and working only 10 reached the Type Approval minimum. Stoplights on heavy goods vehicles (rigid and articulated) are also very poor, with 80 and 90per cent respectively below the Type Approval minimum (even after cleaning). (A)
Abstract