Simplified Track Evaluation for Low-Speed, Low-Traffic Railroad Lines

The development of a railroad track–evaluation computer program called TRACK is described, and its application is summarized. TRACK was created to provide a simple tool to help determine the need for track rehabilitation. The program assesses the track’s vertical load–carrying capability and shows some relative effects of track improvements or deterioration. The evaluation is based on five equations that provide values for rail bending stress, tie bending stress, tie reaction, ballast surface stress, and subgrade surface stress. This information is important for initial design, rehabilitation planning, and basic track evaluation, but has not always been readily available in an easy-to-use format. Although the evaluation method in TRACK is simplified, it illustrates the complex interaction among the main track components—namely, that a change in one component affects the others. TRACK automatically selects values for equation variables from information about track characteristics and types of cars handled; the program then solves the equation. Calculated stresses are displayed beside suggested limiting values for the track. The basic approach is that if none of the four main track components (i.e., rail, ties, ballast, and subgrade) are overstressed, the track structure is considered suitable for the given traffic loading. TRACK is intended for low-speed, low-traffic railroad lines—those with conventional wood-tie track, with either jointed or welded rail, on which traffic is less than approximately 5 to 8 million gross tons per year, with maximum speeds of 25 to 30 mph.