All types of track bolts and nuts used by the various railroads and electric railways in the United States and Canada were studied by the committee, and it is their belief that the recommended dimensions are based on sound engineering design to meet existing conditions, present usage, and where possible, simplification of manufacture. Manufacturers of track bolts and nuts furnished data to the committee on sizes and types purchased over an extended period to determine the most generally used design. A program of static and torsion testing was conducted to establish the best engineering design, taking into account present-day joint bar designs, use of power wrenches, and other factors.

Tolerances for the heads, necks, and bodies of track bolts, and the dimensions of track bolt nuts are made adequate for good manufacturing practice with the thought in mind that manufacturers will use working gages to keep within the limits, and thus ensure that the product will pass the user’s inspection.