Simulation of Railroad Hump Yard Activities With Emphasis on the Configuration of the Classification Yard

Abstract

The railroad transportation system is composed of three main components of elements: the roadway of track, the vehicle, and the terminal. The "batch" nature of railroad transport increases the relative importance of the terminal as a key in the system. The railroad classification yard, the most important of the various terminal types, has been neglected from the standpoint of planning and development.

The objective of this study was to undertake the development of a generalized yard model by which "sketch" planning and design can be accomplished. Emphasis throughout the study was placed on hump yards.

A literature review and extensive discussions and correspondence with yard planners and managers provided the basis for defining the activities within the yard. Although the yard is basically a queueing system, the serial nature of the queues, as well as the problems presented by the queue of downstream processing occupying the work station of upstream activities, prevented an analysis using queueing based solutions. A simulation model was utilized to produce performance curves for a base case yard facility. Yard performance was defined in terms of the delay encountered by cars moving through the facility. Delay slope values were calculated which represent the time required to process a car beyond the minimum processing time as a function of traffic volume.

The results of the analysis indicate the effect of the various design and operating parameters on the performance of the facility. A methodology is developed to predict changes in performance for any change in the operating and design parameters. Multiple modifications can also be investigated using this technique.