Citation

Balachandra M, Dais JL. Highw. Res. Rec. 1973; 432: 12-24.

Copyright

(Copyright © 1973, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

An analytical method is proposed for the design of guideway elements subject to jerk and acceleration limits. The method generalizes the limits on lateral jerk and acceleration familiar in highway design to the fore-aft and vertical modes. It is proposed that, under combinations of these modes, the magnitudes of the jerk and effective acceleration vectors must be limited. Equations describing the level of discomfort are derived for both constant and variable-speed motion along horizontal and vertical curves. The equations explicitly include the effect of superelevation. A four-spiral switch for use in a personalized rapid transit system is analyzed in detail. It is found that a length reduction of more than 25 percent is possible by using superelevation. A right angle turn composed of two spirals and a circular arc is detailed. It is found that the use of superelevation can reduce the magnitudes of the effective jerk and acceleration vectors by more than 50 percent. Finally, a four-spiral grade change is detailed. Discomfort is investigated and compared for constant speed and zero fore-aft thrust motion. It is shown that the usual analytical approach that includes only the centripetal component of acceleration and jerk can lead to considerable error in predicting discomfort.

Language: en

Keywords

HIGHWAY TRAFFIC CONTROL; HIGHWAY ENGINEERING