# 8.7.2.1 IfcAlignmentCantSegmentTypeEnum

## 8.7.2.1.1 Semantic definition

The IfcAlignmentCantSegmentTypeEnum indicates the type of a segment of a cant alignment segment (IfcAlignmentCantSegment).

Cant is defined as the amount by which one running rail is raised above the other running rail, in a track cross section.

For 3D modeling both the cant value and the cant angle (bank angle, lateral angle, cross slope angle) are relevant.

The relation between cant value D, Railhead distance b and cant angle ψ is shown below.

$$\displaylines { \psi = \arcsin \frac{D}{b} \\ \sin \psi \approx \psi \approx \tan \psi }$$

### 8.7.2.1.1.1 Cant variation in high performance transition bends

While for combinations of horizontal clothoids and linear cant transitions the extension along the base line differs in some cases, curvature transition and cant transition for high performance horizontal transition bends are expected to have the same start position and end position. In some regulations the same linear extension requirement is mandatory for high performance transition bends.

Whether the cant variation is defined by the same base formula as the curvature of the corresponding horizontal high performance transition bend or by a linear ramp also might differ between regulations.

## 8.7.2.1.3 Formal representation

TYPE IfcAlignmentCantSegmentTypeEnum = ENUMERATION OF
(BLOSSCURVE
,CONSTANTCANT
,COSINECURVE
,HELMERTCURVE
,LINEARTRANSITION
,SINECURVE
,VIENNESEBEND);
END_TYPE;