What is a vertical alignment in tcpMDT and what files does it generate?

It is defined as a set of vertical alignments that make up the final design of a road, involving distances from the origin and absolute elevations. The application uses files with the extension .RAS to store this information.

In TcpMDT, the vertical alignment file is defined as a text file in ASCII format with the extension .RAS. This file stores the information of the vertical alignments that make up the final design of a road.

Data Structure

The content of the file consists of a series of lines, where each line represents a vertex or node of the vertical alignment. According to the examples and the application's editing panels, each line is composed of five main fields or columns separated by spaces:

1. Distance from origin (Station): Indicates the station point of the vertex.

2. Elevation: Represents the elevation or absolute height of the vertex.

3. Kv or Radius: Defines the parameter of the parabolic curve. If the curve is parabolic, the Kv (parabola parameter) is indicated; if it is circular, the Radius of the arc is indicated.

4. Tangent: It is the length in orthogonal projection of the half-branch onto the alignments.

5. Arrow: Represents the maximum ordinate at the vertex.

Format Example

In a typical .RAS file, the initial and final points usually have values of Kv, tangent, and arrow set to 0.000, since there is no curve at the ends. A snippet of the file would look like this:

0.000 237.952 0.000 0.000 0.000
20.000 237.700 455.685 20.000 0.439
420.000 197.548 4041.270 40.000 0.198
...
2528.405 69.846 0.000 0.000 0.000

(Source:)

Additional Considerations

• Types of curves: The format supports both parabolic and circular curves.

• Symmetry: In parabolic vertical alignments, vertices can be symmetrical (equal tangents) or asymmetrical (where the Kv and entry tangent differ from the exit ones). Although the standard list shows a single column for tangent and Kv, the application internally manages data for asymmetrical curves, allowing different Kv and tangents for each branch.