Rail Profile - History

History

Early rails were used on horse drawn wagonways, originally with wooden rails, but from the 1760s using strap-iron rails, which consisted of thin strips of cast iron fixed onto wooden rails. These rails were too fragile to carry heavy loads, but because the initial construction cost was less, this method was sometimes used to quickly build an inexpensive rail line. Strap rails sometimes separated from the wooden base and speared into the floor of the carriages above, creating what was referred to as a "snake head". However, the long-term expense involved in frequent maintenance outweighed any savings.

These were superseded by cast iron rails that were flanged (i.e. 'L' shaped) and with the wagon wheels flat. An early proponent of this design was Benjamin Outram. His partner William Jessop had pioneered the use of "edge rails" in 1789 where the wheels were flanged and, over time it was realised that this combination worked better.

The earliest of these in general use were the so-called cast iron fishbelly rails from their shape. Rails made from cast iron were brittle and broke easily. They could only be made in short lengths which would soon become uneven. John Birkinshaw's 1820 patent, as rolling techniques improved, introduced wrought iron in longer lengths, replaced cast iron and contributed significantly to the explosive growth of railroads in the period 1825-40. The cross-section varied widely from one line to another, but were of three basic types as shown in the diagram. The parallel cross-section which developed in later years was referred to as Bullhead.

Meanwhile, in May 1831, the first flanged T rail (also called T-section) arrived in America from Britain and was laid into the Pennsylvania Railroad by Camden and Amboy Railroad. They were also used by Charles Vignoles in Britain.

The first steel rails were made in 1857 by Robert Forester Mushet, who laid them at Derby station in England. Steel is a much stronger material, which steadily replaced iron for use on railway rail and allowed much longer lengths of rails to be rolled.

The American Railway Engineering Association (AREA) and the American Society for Testing Materials (ASTM) specified carbon, manganese, silicon and phosphorus content for steel rails. Tensile strength increases with carbon content, while ductility decreases. AREA and ASTM specified 0.55 to 0.77 percent carbon in 70-to-90-pound-per-yard (34.7 to 44.6 kg/m) rail, 0.67 to 0.80 percent in rail weights from 90 to 120 pounds per yard (44.6 to 59.5 kg/m), and 0.69 to 0.82 percent for heavier rails. Manganese increases strength and resistance to abrasion. AREA and ASTM specified 0.6 to 0.9 percent manganese in 70 to 90 pound rail and 0.7 to 1 percent in heavier rails. Silicon is preferentially oxidised by oxygen and is added to reduce the formation of weakening metal oxides in the rail rolling and casting procedures. AREA and ASTM specified 0.1 to 0.23 percent silicon. Phosphorus and sulfur are impurities causing brittle rail with reduced impact-resistance. AREA and ASTM specified maximum phosphorus concentration of 0.04 percent.

The use of welded rather than jointed track began in around the 1940s and had become widespread by the 1960s.