# 8.7.2.3 IfcAlignmentVerticalSegmentTypeEnum

## 8.7.2.3.1 Semantic definition

The IfcAlignmentVerticalSegmentTypeEnum indicates the type of a segment of a vertical alignment segment (IfcAlignmentVerticalSegment).

Used Symbols and their meaning

References to EN 13803/2017

EN 13803/2017 covers "Track alignment design parameters". As such it is not fully compatible with definitions for IFC Alignment. Therefore rail specific terms like track have been replaced with more general terms also applicable to road design.

Referenced content of EN 13803/2017 "Table 2 - Elements for vertical alignment" has been modified as follows:

Vertical curve, parabola: Derivative of gradient with respect to chainage is constant
Generalized: Derivative of gradient with respect to horizontal projection of alignment is constant

Vertical curve, circular: Derivative of vertical angle with respect to sloping length along the track is constant
Generalized: Derivative of vertical angle with respect to 3D arc length along the alignment is constant

EN13803 clause 3.5: Chainage: longitudinal distance along the horizontal projection of the track centre line.

## 8.7.2.3.3 Formal representation

TYPE IfcAlignmentVerticalSegmentTypeEnum = ENUMERATION OF
(CIRCULARARC
,CLOTHOID
END_TYPE;