Citation

Taignidis I, Kanellaidis G. J. Transp. Eng. 2001; 127(4): 275-282.

Copyright

(Copyright © 2001, American Society of Civil Engineers)

DOI

unavailable

PMID

unavailable

Abstract

Required stopping sight distance (SSD), used to calculate the minimum rate of vertical curvature or the minimum length of a crest vertical curve (CVC), is usually calculated on the assumption that the grade of the braking section is zero (G = 0). This assumption is not the worst case and may lead to the selection of a CVC on which there is a segment with SSD restriction. On each CVC there are braking sections on one or both directions of travel, on which average grade is negative (G less than 0). In the present paper a method for calculating required SSD, partly or wholly on a CVC, is developed, using the average grade over the braking distance. In addition, a computer program is compiled for calculating the value of the required SSD for all driver positions before or on a CVC. An SSD profile is drawn and it is proven that, for a significant length of the CVC, the required SSD is greater than the value used for calculating the minimum value of the rate of vertical curvature.