9.5 Arc

An arc describes a road reference line with constant curvature.

Figure 28. Road geometry described by an arc

Figure 28 shows the concept of an arc.

Elements in UML model

<arc> element

In ASAM OpenDRIVE, an arc is represented by the <arc> element within the <geometry> element.

UML class: t_road_planView_geometry_arc
XML tag:   <arc>

Arcs describe road reference lines with constant curvature.

Table 20. Attributes of the <arc> element
Name	Type	Use	Unit	Description
`curvature`	double	required	1/m	Constant curvature throughout the element. Positive curvature: left curve (counter-clockwise motion) Negative curvature: right curve (clockwise motion)

XML example

<planView>
    <geometry s="3.6612031746270386e+00"
              x="-4.6416930098385274e+00"
              y="4.3409250448366459e+00"
              hdg="5.2962250374496271e+00"
              length="9.1954178989066371e+00">
        <arc curvature="-1.2698412698412698e-01"/>
    </geometry>
</planView>

Rules

The following rules apply to arcs:

@curvature should not be zero.

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