Create a Circular Arc by 2 Tangents and Distance

Description

Create a circular arc segment using the tangent bearings and optionally trim the tangents to the created arc.

Access

Home / Tools / Create / Line or Alignment / Circular Arc / 2 Tangents and Distance

Requirements

Solve Module.

Controls

Control	Description
Name	Type a name for the generated line or alignment, or click to increment to the next available name.
Tangent In	If the Trim intersection checkbox is cleared, input the reference line representing the entry tangent. selected, input the line or alignment segment representing the entry tangent.
Tangent Out	If the Trim intersection checkbox is cleared, input the reference line representing the exit tangent. selected, input the line segment representing the exit tangent.
Distance	Select one of the following methods to input the length of the arc. Arc Distance - Input the arc distance. Chord Distance - Input the chord distance. External Distance - Input the distance. Middle Ordinate - Input the distance. Radius - Input the radius. Tangent Distance - Input the tangent distance.
3D circular arc	Do one of the following: Select the checkbox to create the arc in 3 dimensions. Clear the checkbox to exclude the vertices heights from the arc calculations.
Trim Intersection	Do one of the following: Select the checkbox to trim the tangent where the arc intersects with the tangents. Clear the checkbox to retain the full tangent line after creation of the arc. Note: The Tangent In and Tangent Out may be cleared to enable input in the required format.
Join into object	Do one of the following: Select the checkbox to insert the created arc into the existing Tangent In line Clear the checkbox to create a new line for the created arc. Note: Available when Trim intersection is selected.

Notes

Select or clear the Trim intersection checkbox prior to inputting the tangents.
If the Trim intersection checkbox is selected:
- Define the tangents as line segments rather than the start and end vertex of a reference line.
- No solution will be found if the arc extends beyond the end of the tangent, or if the tangent lines cannot be trimmed.
If tangent lines intersect at a location other than the tangent line start or end points the direction of the tangent is important to determine the required solution.
- The end of the line or alignment closest to the mouse cursor is considered the start vertex and determines the direction of the tangent.
- Ensure the reference lines or segments are picked so that the tangents direction is towards the intersections point.
When creating a line, the tangents must be line objects. When creating an alignment the tangents must be alignment objects.
Click the Components tab prior to clicking OK to view the values computed for the arc.
Click Solve to preview the circular arc.
Click OK to create the arc and optionally trim the tangent and insert the circular arc into the line or alignment.
If the 3D circular arc checkbox is cleared:
- Distances input are interpreted as 2 dimensional distances.
- Heights are not used to compute the arc components.
- Lines or alignments will display as a circular arcs in the Plan view.
- Vertices heights are used to display the curve in 3D view.
When creating an alignment, this tool is available providing the horizontal design standard in the create options is configured to 'None'.

Possible errors

Error	Description	Possible Solution
The computation has no solution.	An arc could not be computed within the given constraints.	Ensure the following: The two tangents intersect. If 3D circular arc is selected the lines must intersect in 3 dimensions. If the Trim intersection checkbox is selected ensure that the tangents physically extend far enough so that the created arc intersects with the tangents. The distance is not too large or too small for the tangents. If the two tangents physically intersect at a location other than the tangent lines start or end points, the location of the mouse cursor when the tangents are picked, ensures the tangent directions are towards the intersection point.