@article{ref1,
title="Illumination requirements for roadway visual tasks",
journal="Highway Research Board bulletin",
year="1960",
author="Blackwell, H. Richard and Pritchard, B. S. and Schwab, Richard N.",
volume="255",
number="",
pages="117-127",
abstract="Illumination data are presented for two roadway visual tasks: Seeing a mannequin and a black dog at various distances down the roadway with a variety of luminaire types and pavement surfaces. All measurements were made under an illuminative geometry that is representative of generally accepted practice in the country. Data suggest that: (1) 1.90 ft-candles of horizontal illumination are required for adequate visibility of the targets when they appear in the driving lane 200 ft ahead, (2) 5.7 ft-candles for the same targets to be adequately visible at the same distance when they appear in the curb lane, (3) 9 ft-candles if the targets must be seen 300 ft ahead, and (4) 48 ft-candles for 400-ft visibility in the driving lane. Moreover, these data reveal that there are visual tasks in night driving that are so difficult that they require interior levels of illumination.<p />",
language="",
issn="0073-2206",
doi="",
url="http://dx.doi.org/"
}