Analytical Models for Certain Guideway Irregularities

Abstract

The design and construction of a guideway for ground transportation vehicles involve compromises between the desired smoothness and the necessary sacrifices in regard to expense and time to achieve it. The objective of this paper is to derive and analyze equations for guideway roughness spectra in order to obtain design and construction criteria understandable by contractors. Although there are many sources of guideway irregularities that should be considered in the final version of the design specifications, this paper concentrates on a design criterion for minimizing the degree of necessary natural terrain alteration by means of filling or leveling. In addition, a model is derived that defines the significance of random alignment errors caused by either surveying inaccuracies or foundation settlement. The results are applicable to either at-grade or elevated guideways and to either vertical or lateral irregularities. Typical results based on an idealized vehicle suspension system and typical ride comfort criteria reveal that the absolute upper bound on permissible profile elevation variations varies between 1.39 cm and 21.09 cm.