Some Measures for Improving Night Visibility at Highway Intersections

Report No: 77-R44

Published in 1977

About the report:

Through selected case studies, this report illustrates how the inadequate visibility of road signs and pavement markings at night contributes to wrong-way driving. A concept termed "keg of legibility" for visibility at night has been developed by the author to delineate the limits of night visibility under low beam headlights. The report discusses the application of the keg of legibility to the placement of signs, markings, and additional devices that can be used to help inform the motorist who is to negotiate a four-lane divided highway and to guide him through the intersection. Cases of poor road geometrics are cited to emphasize the need for such information and guidance.

Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.


  • N. K. Vaswani

Last updated: January 28, 2024

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