Track Gage Widening A Model Study
American Society of Civil Engineers
Occurrences of gage widening and rail overturning are of growing concern to the railroad industry. These problems occur at the interface between the rail and the tie, which is often considered to be the weakest point in conventional track structure. Consequently, a better understanding of the failure mechanisms and model of deformation associated with these problems can help the track engineer deal more effectively with these problems and improve the track structure. Recent examinations of these problems have shown that rail overturning, which is the extreme case of rail rotation and gage widening, are closely interrelated (6). In fact, gage widening can be defined as consisting of rail rotation combined with rail translation, which is the lateral displacement of the rail base relative to the ties. It can be observed that each of these two modes of deformation, rail rotation [rail roll (6)] and rail translation, can occur for the same type of loading environment. However, the relative magnitude of the deformation is dependent on the properties and conditions of the fasteners, tie plates, and ties. Consequently, the question arises as to whether, in fact, these problems are truly independent of each other, or whether they are in fact interdependent. The purpose of this paper is to present two simple models which represent the deformation mechanisms of gage widening and rail rotation. These models exhibit the essential features of the deformation mechanisms, and are amendable to exact solution. Consequently, they can be readily used to examine the general behavior characteristics of these two modes of deformation and their sensitivity to various loading combinations. Definition of Problem. -- The problem of gage widening occurs when the gage, measured 5/8 in. (0.016 m) below the top of the rail head, increases beyond the standard value for tangent track of 4 ft 8-1/2 in. (1.435 m). This deflection, at the rail head, can be due to rail translation, which is the rigid body displacement of the rail with respect to the tie, or to rail roll, which is the rotation of the rail section from the original "vertical" axis of the rail. Thus, rail translation can be considered to be the lateral deflection of the rail base with respect to the tie; rail roll can be considered to be the lateral deflection of the rail head with respect to the rail base; and gage widening can be considered to be the lateral deflection of the rail head with respect to the tie.
Gage widening, Rail overturning
Zarembski, A. M., & Rassasian, M., “Track Gage Widening A Model Study”, Transportation Engineering Journal, American Society of Civil Engineers, November 1979.