SAFETY ON THE ROAD AT NIGHT: (3) AIDS TO THE DRIVER AT NIGHT

The author describes the features affecting visual acuity and how they influence driving. Road lighting is discussed and examples are given of factors governing road surface luminance. The relationship between skid resistance and luminance factor is examined. There is a tendency for roads with high luminance factors when dry to be slippery when wet. The characteristics of different designs of headlamps are explained, and the contrasting effect of their use on lit and unlit roads is illustrated. The problem of glare from road surfaces and oncoming headlamps is discussed. Several possible solutions are suggested including polarised light which appears to be too costly. The operation and advantages of an 'autodim' fully automatic dimmed system are explained. For abstracts of parts 1, 2 and 4, see IRRD abstracts nos. 222951-2, and 222954. /TRRL/