About Railway

This topic provides information about the railway structure.

Unlike road design, there is no normal slope applied to the railway surface, the drainage being done through the ballast.

The railway profile contains the following parts:

Railway profile

Top.

Head.

Web.

Foot.

Railway top is the highest point on the railway head.

Railway surface

Railway surface width can be symmetrical or not. It is the sum of sleeper length and left/right ballast shoulder widths.

Track width is the distance between the two rail tops, center to center (L distance).

Track gauge is the distance between the inner face of rail heads.

Rail surface offset is the distance between the rail top and the railway surface. This distance is measured along the direction normal to the line joining the two rail tops. Notice that this distance may be different from the rail height.

Sleeper length is the tie length.

Left ballast shoulder width.

Railway Subgrade Surface.

Alignment is equidistant to the two rail tops in tangent sections.

Railway surface.

Railway section in a curved section

Inner rail is the rail among the two rails of a track that is inside the curve.

Track width/2.

Track width/2.

Cant is the distance measured along the Z-axis between the two rail tops (yellow dot on the tops) in a curve section. In a tangent section it is considered that the Cant is null.

Horizontal. Most of the time, the inner rail is horizontally aligned with the alignment in the curve section whilst the outer rail is above the horizontal axis.

Alignment. In curved section, the rail tops are superelevated compared to the horizontal line going through the alignment. Different pivot methods are proposed to control the rotation of railway curved sections.