Why Is a Heat Order Necessary?
The trackage that VRE trains operate on consists of continuous welded rail. Rails come from the welding plant in strings one-quarter mile long. Once the quarter-mile rails are laid in the track, the ends are welded to each other to create strings of rail that are truly continuous. This eliminates the “clickety-clack” of traditional 39-foot rails. Welded rail results in a smoother ride with less maintenance. Steel rails slowly expand and contract as temperatures rise and fall. In fact, an 1800-foot length of rail will expand almost one foot with an 80-degree change in temperature! Before welded rail, expansion was absorbed by a small gap (joints) between the rails every 39 feet. With welded rail the normal tendency to expand must be constrained internally by securing the rail. Careful engineering measures, including heating the rail, are taken when rail is installed to account for rail expansion and contraction. The ties, rock ballast, and rail anchors, which hold the rail longitudinall
