Citation

Greenshields BD, Dickinson HC, Conner CN, Shelton WA. Highw. Res. Board Proc. 1935; 1935.

Copyright

(Copyright © 1935, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

The results of this investigation are based upon study of 7500 cars whose behavior was recorded by the photographic method described in volume 13, PROCEEDINGS, HIGHWAY RESEARCH BOARD. The study was confined largely to two-lane highways where the traffic density varied from 200 to 1300 vehicles per hours. The photographic data is discussed and the speed and spacing of motor vehicles is mathematically analyzed. It is concluded that the minimum requirements for safe passing under average traffic conditions are 10 to 11 sec. and from 1000 to 1600 ft. of clear roadway. Many drivers pass with less than safe distance available, evidently depending upon any approaching vehicle to give way or reduce speed to avoid collision.