ANALYSIS OF TRAIN DRAG IN VARIOUS CONFIGURATIONS OF LONG TUNNEL

Designers of long rail tunnels in many parts of the world are presently hampered by the scarcity of information allowing a prediction of train drag. Such data are vital to the optimum choice of tunnel configuration, and particularly the cross-sectional dimensions, because of its bearing on train power requirement, traction energy costs and the temperature conditions of the tunnel environment. The paper describes a relatively unsophisticated theory which predicts overall mean values of aerodynamic drag for various combinations of train and tunnel types. Where possible, comparisons are made with other experimental and theoretical data. An important part of the paper then discusses the trends arising from the results, and in particular the implications that these have on the decision-making process for a particular railway tunnel requirement.