THE DEVELOPMENT OF ANALYTICAL MODELS FOR RAILROAD TRACK DYNAMICS

ABSTRACT A renewed interest during the past decade in high-speed rail transportation has underlined a need for better understanding of the dynamic interaction between vehicle and track. Speeds in excess of 100 miles per hour tax the presently-used rail-tie-ballast track structure in terms of long-term stability and required track accuracy. Hence the investigation of improved structures with better dynamic response characteristics and greater stability has followed in the wake of improved high-speed railcar design. This paper presents some recent developments in analytical modeling of railroad track structures for the study of vehicle-track dynamic interaction by computer simulation. A technique for describing the track structure, which is a complex distributed-parameter system, as a lumped-parameter model of one or more degrees of freedom is developed; and the use of this model to generate both the “on-car” and “trackside” response is examined. Field measurements taken on mainline track of several North American railroads are used to evaluate the accuracy and define the necessary modifications of the computer model. Predictions of better overall system response and long-term stability from this computer model have aided in the preliminary design of several new track structures which are currently undergoing field evaluation.