Ballast and Subgrade Requirements Study: Railroad Track Substructure - Design and Performance Practices

摘要

Earth materials - i.e., soil and rock - form the substructure (ballast, subballast, and subgrade) of all railroad track. In this report, the most suitable technology and design criteria as related to design of the substructure are identified based on a review of current track substructure design procedures employed in the United States and foreign countries. A primary emphasis has been placed on identifying an approach for rational design of track to support vertical, lateral, and longitudinal loads. Principal design parameters and available analytic and empirical design procedures are discussed.