Prediction of nighttime driving visibility from laboratory data

The application of laboratory threshold visibility data to the subject of driving visibility with heat absorbing glass has been reviewed in an attempt to resolve excessive differences between calculated predictions and road test observations. New calculations are described that yield predicted losses of visibility distance due to the use of heat absorbing glass rather than regular glass in automobile windshields. The predicted losses agree satisfactorily with the observed losses for road tests, which average proximately 3%. The new calculations have made use of a revised visual exposure interval of ? sec corresponding with five visual fixational pauses per second and a new simulation model that assumes that the target-to-background contrast increases with reduced headlamp-to-target distance.