Train Aerodynamics

Chapter 9

Ballast flight beneath trains

Abstract

This chapter considers the flight of ballast beneath trains, an issue that has emerged in recent years as train speeds have increased. It begins by considering the nature of the initiation of ballast movement and of the flight of ballast particles and the different effects caused by this phenomenon in different countries around the world. The flow beneath trains is then considered, based on the material presented in Chapter 5 but looking at those parameters that might be considered as particularly important to ballast movement – flow velocities and shear stresses near the ballast bed. A simple analysis of the different aerodynamic and mechanical forces on ballast stones is then presented, which highlights ...