Rail profile

The rail profile is the cross sectional shape of a railway rail, perpendicular to the length of the rail.

Early rails were made of wood, cast iron or wrought iron. All modern rails are hot rolled steel of a specific cross sectional profile. Typically the cross section (profile) approximates an I-beam but is asymmetric about a horizontal axis (however see grooved rail below). The head is profiled to resist wear and to give a good ride, the foot is 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.