Citation

Shepard FD. Transp. Res. Rec. 1979; 737: 93-95.

Copyright

(Copyright © 1979, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Traffic flow characteristics along a section of highway atop Aston Mountain, Virginia, were measured before and after the installation of pavement in set lights and low-level illumination lights to aid motorists during fog by improving highway delineation. After installation, daytime speeds decreased and nightime increased, with a significant increase in the variability of speeds day and night. While there was little difference in headway during the day, there was a decrease in nighttime headways after installation. This and the decrease in vehicle queueing indicates that motorists were using the inset lights for guidance rather than relying on car following, Also, the lateral placement of automobiles was farther from the right edge line after installation. While there was some concern that the system might promote a false sense of security leading to excessively increased speeds which leads to a greater probability of accidents, it is difficult to surmise what, if any increase in accident potential would result from the noted difference in traffic flow parameters, especially since there has been only one accident in fog conditions since installation.