page_title: Rail profile
section_title: North America
hierarchical_section_title: Rail profile / Rail weights and sizes / North America
caption_attribution_description: English: Cross-Section of Standard Rail, one hundred pounds to the yard, as used on the Pennsylvania Railroad in the 1890s.
context_page_description: The rail profile is the cross sectional shape of a railway rail, perpendicular to its length.
  Early rails were made of wood, cast iron or wrought iron. All modern rails are hot rolled steel with a cross section approximate to an I-beam, but asymmetric about a horizontal axis. The head is profiled to resist wear and to give a good ride, and the foot profiled to suit the fixing system.
  Unlike some other uses of iron and steel, railway rails are subject to very high stresses and are made of very high quality steel. It took many decades to improve the quality of the materials, including the change from iron to steel. Minor flaws in the steel that may pose no problems in other applications can lead to broken rails and dangerous derailments when used on railway tracks.
  By and large, the heavier the rails and the rest of the trackwork, the heavier and faster the trains these tracks can carry.
  Rails represent a substantial fraction of the cost of a railway line. Only a small number of rail sizes are made by steelworks at one time, so a railway must choose the nearest suitable size.
context_section_description: The American Society of Civil Engineers (or ASCE) specified rail profiles in 1893 for 5 lb/yd (2.5 kg/m) increments from 40 to 100 lb/yd (19.8 to 49.6 kg/m). Height of rail equaled width of foot for each ASCE tee-rail weight; and the profiles specified fixed proportion of weight in head, web and foot of 42%, 21% and 37%, respectively. ASCE 90 lb/yd (44.6 kg/m) profile was adequate; but heavier weights were less satisfactory. In 1909, the American Railway Association (or ARA) specified standard profiles for 10 lb/yd (4.96 kg/m) increments from 60 to 100 lb/yd (29.8 to 49.6 kg/m). The American Railway Engineering Association (or AREA) specified standard profiles for 100 lb/yd (49.6 kg/m), 110 lb/yd (54.6 kg/m) and 120 lb/yd (59.5 kg/m) rails in 1919, for 130 lb/yd (64.5 kg/m) and 140 lb/yd (69.4 kg/m) rails in 1920, and for 150 lb/yd (74.4 kg/m) rails in 1924. The trend was to increase rail height/foot-width ratio and strengthen the web. Disadvantages of the narrower foot were overcome through use of tie plates. AREA recommendations reduced the relative weight of rail head down to 36%, while alternative profiles reduced head weight to 33% in heavier weight rails. Attention was also focused on improved fillet radii to reduce stress concentration at the web junction with the head. AREA recommended the ARA 90 lb/yd (44.6 kg/m) profile. Old ASCE rails of lighter weight remained in use, and satisfied the limited demand for light rail for a few decades. AREA merged into the American Railway Engineering and Maintenance-of-Way Association in 1997. By the mid-20th century, most rail production was medium heavy (112 to 119 lb/yd or 55.6 to 59.0 kg/m) and heavy (127 to 140 lb/yd or 63.0 to 69.4 kg/m). Sizes under 100 lb/yd (49.6 kg/m) rail are usually for lighter duty freight, low use trackage, or light rail. Track using 100 to 120 lb/yd (49.6 to 59.5 kg/m) rail is for lower speed freight branch lines or rapid transit (for example, most of the New York City Subway system track is constructed with 100 lb/yd (49.6 kg/m) rail). Main line track is usually built with 130 lb/yd (64.5 kg/m) rail or heavier. Some common North American rail sizes include:
  75 lb/yd (37.2 kg/m) (ASCE)
  80 lb/yd (39.7 kg/m) (Dudley) New York Central Railroad
  85 lb/yd (42.2 kg/m) (ASCE)
  90 lb/yd (44.6 kg/m) (ARA)
  100 lb/yd (49.6 kg/m) (AREA)
  105 lb/yd (52.1 kg/m) (Dudley) New York Central Railroad
  112 lb/yd (55.6 kg/m) (KCSC)
  115 lb/yd (57.0 kg/m) (AREA)
  119 lb/yd (59.0 kg/m) Colorado Fuel and Iron
  127 lb/yd (63.0 kg/m) (Dudley) New York Central Railroad
  132 lb/yd (65.5 kg/m) (AREA)
  133 lb/yd (66.0 kg/m) (AREA)
  136 lb/yd (67.5 kg/m) Colorado Fuel and Iron
  140 lb/yd (69.4 kg/m) (AREA)
  141 lb/yd (69.9 kg/m) (produced by Nippon (Japan))
  155 lb/yd (76.9 kg/m) (no longer in production) Pennsylvania Railroad
  Some common North American crane rail sizes include:
  12 lb/yd (5.95 kg/m)
  20 lb/yd (9.9 kg/m)
  25 lb/yd (12.4 kg/m)
  30 lb/yd (14.9 kg/m)
  40 lb/yd (19.8 kg/m)
  60 lb/yd (29.8 kg/m)
  80 lb/yd (39.7 kg/m)
  85 lb/yd (42.2 kg/m)
  104 lb/yd (51.6 kg/m)
  105 lb/yd (52.1 kg/m)
  135 lb/yd (67 kg/m)
  171 lb/yd (84.8 kg/m)
  175 lb/yd (86.8 kg/m)
caption: Cross-section drawing showing measurements in Imperial units for 100 lb/yd (49.6 kg/m) rail used in the United States, c. 1890s
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