A Short Study of Seeing Distance

This paper describes a computer based study of seeing distance for automobile headlamps. The study extends an experiment in which subjects determined the presence of a target and the identity of the target, while driving. The results of the study show that values of seeing distance for the task of identifying a target in addition to determining its presence while driving the vehicle are lower than values of seeing distance when a driver only needs to determine the presence of a target. The study also includes an analysis of the effect on seeing distance of horizontal misaim which suggests that additional refinement in the specifications of beam patterns would be necessary before horizontal aim adjustment hardware could be eliminated. An approach for developing beam pattern specifications, based on determining intensity requirements for meeting such needs as pedestrian protection and glare reduction, is also suggested.