Interface - The Journal of Wheel/Rail Interaction

124-POUND RAIL

Examining 124-Pound Rail
By Jude O. Igwemezie, Ph.D. • April, 2008

North American Shortline railroads are under pressure to interchange and carry more and heavier axle loads. Many of these shortlines are only a few miles long and are privately owned and operated. They do not have the resources that would allow them to upgrade their track structure to the level of the major railroads.

From a track infrastructure viewpoint, most of these railroads need to better distribute vehicle loads to the track structure and, most significantly, the ties. This would normally require: 1) a rail with a section modulus that is greater than that of the current 115-pound rail section. 2) Rail with a bigger ball would be required to make the economics worth while. 3) Since 115-pound rail has a 5-1/2-inch base, the existing tie plates and rail anchors would have to be changed, since rail that satisfies conditions 1 and 2 would likely have a 6-inch wide base.

Analysis performed by BC Rail in 1993, indicated that the cost of replacing tie plates and rail anchors in order to accommodate a change from rail with a 5½-inch base to one with a 6-inch base would cost an additional $68,000 per mile of track (1). Today, that cost would be significantly higher. Accordingly, BC Rail convinced Corus, a European rail manufacturer, to roll a 124-pound rail section, which incorporated a 136-pound head section and a 115-pound web and 5 1/2-inch base.

Applied Rail Research Technologies Inc. performed Finite Element stress Analysis (FEA) to compare 115-, 119-, and 124-pound rail sections, each of which has a 5 1/2-inch base, in order to determine the 124-pound rail section’s ability to handle increasing axle loads, and its applicability to the North American shortline / regional rail industry.

The three rail sections and pertinent geometrical data are shown in Figure 1. Numerous Linear Elastic 3-D Finite Element Analyses (FEA) were performed on 115-, 119- and 124-pound rails at different levels of wear. A new cross section and two worn sections representing 1/2inch of vertical wear, and combined 1/2-inch vertical and 1/2-inch gauge-face wear were considered for each rail. The physical properties of the rails are shown in Table 1.

Structural System
A 3-D section of each rail was discretized into 4- to 8-node, 3-D solid elements mesh. Since the contact area between the wheel and rail is about the size of a dime, a finer mesh was used in the head near the area of the applied load. A more coarse mesh was used in the rest of the rail section (see Figure 2). The same meshing technique was used for the worn sections. A rail length of 76 inches was used in each model.

Boundary conditions were imposed at all of the nodes to simulate appropriate restraints, supports and symmetry. On the cross section at the end of the rail where the load was applied, symmetry was utilized and the longitudinal movements were restrained. All movements were restrained at the other end of the rail.

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