Horizontal Alignment

Menu: Civil / Start / Alignments / Raw alignment

The Horizontal Alignment Tab represents the alignment's behavior in the XY plane, defining how curves and straight segments connect. When a horizontal curve is calculated, this tab becomes the default view when selecting an alignment.

In a horizontal alignment, all arc elements are tangential to adjacent segments, ensuring smooth transitions. If a curve's radius is positive, it turns clockwise; if negative, it turns counterclockwise.

1. Key Features of the Horizontal Alignment Tab

✔ Manages alignment geometry in the XY plane
✔ Supports different element types – Lines, Arcs, Spirals, and Spiral-Arc-Spiral combinations
✔ Allows direct modification of horizontal curves
✔ Enables manual picking of polylines for alignment creation
✔ Provides a structured table for reviewing alignment parameters

📌 Example:
An alignment starts with a straight segment, followed by an arc starting at chaining 1830.776 with a radius of 800m that turns counterclockwise and ends at chaining 2290.102.

2. Horizontal Alignment Table – Column Descriptions

Column	Description
No	Sequential number in the current alignment.
Chaining	The stationing (chaining) of the current point.
Eq.Ch.	A fixed value that replaces the chaining value (used for adjustments but does not affect point position).
Name	Point number from the descriptive file.
X	X coordinate of the alignment point.
Y	Y coordinate of the alignment point.
PCode	PCode associated with the point.
Element	Defines the segment type (Line, Arc, Spiral, Symmetric Spiral, or End).
Param.Hor.Curve	View-only field displaying horizontal curve parameters.

🔹 Editing Alignments Directly:

Users can modify the alignment structure by changing the element type, allowing for dynamic adjustments in alignment design.
Non-tangent curves can be introduced to create complex road geometries.

3. Element Type Options for Horizontal Alignments

Element Type	Description	Defining Parameters
Line	A straight segment in the alignment.	Next point, direction in degrees, or segment length.
Arc	A curved segment.	Center point, midpoint, radius, chord + direction, or tangent direction + point.
Spiral	A transition curve used for smooth entry into an arc.	Minimum radius of curvature, spiral length, or tangent direction + point.
Symmetric Spiral	A spiral-arc-spiral combination for smooth entry and exit into arcs.	Minimum radius of curvature, spiral length.

4. Best Practices for Managing Horizontal Alignments

✔ Ensure tangent continuity between lines and arcs for smoother transitions.
✔ Use spirals for safe and progressive entry/exit into curves.
✔ Modify horizontal alignment parameters directly when refining an alignment.
✔ Check alignment radius to ensure compliance with design standards.
✔ Use the polyline selection tool for quick alignment definition from existing geometries.

🚀 Optimize Horizontal Alignments for Roads, Railways, and Infrastructure!

With dynamic element types, direct curve editing, and advanced alignment tools, VisionLidar’s Civil Module provides powerful capabilities for horizontal alignment design and refinement. 📏🚆🏗️