|
Abstract
|
Vehicle headlamps do not provide adequate seeing distances in night driving conditions in which fixed (street) lighting is not provided. This may partly account for the greater accident rate at night than in daytime. Therefore, there is a need for improved vehicle headlighting.
This paper describes an integrated approach toward the investigation of various problems that detract from the effectiveness of current headlighting and the development of experimental and analytical procedures that can be used to develop improved vehicle headlighting systems.
Studies were conducted of a number of factors which affect the aim of headlamps, including the ability of persons in the service trade to aim lamps, the effectiveness of factory aim, the effects of vehicle service and of vehicle loading on headlamp aim. In this way the major factors that contribute to poor aiming of headlamps were discerned.
Since numerous testing procedures are currently being used to evaluate the effectiveness of headlamp beams which make it difficult to generalize findings from one procedure to another, effort was devoted toward the development of an acceptable field testing method. A dynamic field test method, using driver subjects, was devised, including the development of suitable vision targets. Test-retest reliability of the approach was about 0.97. The procedure was used to determine visibility distances, in night driving, for various headlamp beams, as well as to provide basic data for the development of an analytical model to predict seeing distances.
An analytical model was developed and verified against the field test data, and found to provide a valid means of predicting seeing distances in a variety of test conditions, including different headlamp beams. The use of the model is illustrated by showing the effects of the aim of headlamps, as well as comparisons between different meeting beams, including comparisons between the present U.S. and European beams and a proposed mid beam.
It is found that the mid beam concept will provide increased seeing distances for drivers in the lane being traveled and to the right of the lane when meeting another vehicle on a two-lane road and on divided highways. A procedure for the development of an appropriate control/display configuration for switching between low, mid and high beams is also described.
It is believed that the use of these tools will assist lighting engineers in the development of improved vehicle headlighting systems.
Language: en |