Creating a Railway Subgrade Surface

Select a 3D alignment as input in the tree or 3D area.

Hover over the columns' header to display the tooltip that illustrates the location of each parameter on the section.

The Primary alignment box is filled in with its name. A Start section and an End section are automatically listed in the panel, with five parameters organized in columns. Hover over the columns' header to display the tooltip that illustrates the location of each parameter on the section.

By default, the parameters are locked: the value is retrieved from the business rules. And you cannot change it manually except by unlocking it, as described further below.

You retrieve five parameters for width, slope and transition length computation:

Vertical Offset: distance between the 3D alignment and the summit of the railway subgrade surface. It is a fixed value. The default Vertical Offset 0.5m.

The subgrade surface will be generated with two sections that have the same vertical offset value. You can widen the subgrade surface by specifying a new width value or by adding a new section.

The central alignment position on the vertical plane depends only on the primary alignment, left or right since you decide which alignment is primary or secondary. The central alignment of the subgrade surface is aligned vertically with the alignment. There is no horizontal offset.
Left and Right Width: The subgrade surface width is equally distributed on each side of the middle curve, except in curves where the widening is set on the outer side.
Left and Right Slope: Two slopes between the horizontal plane and the surface, with an angle rule. The default slope is 4%.

The Ballast option is selected by default. It has an impact on the width of the dual track subgrade surfaces. Another option Keep For Subgrade allows you to use the section as an input for the subgrade generation.

Optional: When the railway surface has two tracks, choose a second 3D alignment as input in the tree or 3D area.

Hover over the columns' header to display the tooltip that illustrates the location of each parameter on the section.

A central axis separates the left alignment and the right alignment. It will be generated as Crown summit edge under the Subgrade Surface feature node.

All the alignment specifications (speed, radius…) are based on the alignment selected as primary.

You obtain:

One surface for one or two alignments.
Three edges: Left, right edge and crown summit edges.

In the Rules area, choose a default design rule in the combo box, that should apply to the future railway alignment.

When no rule is defined in the Data Setup, the default business rule is retrieved from the script file stored in \resources\knowledge\scripts.

If you do not select any rules, the default tables or formulas are defined by the administrator in the initialization file, startup\Civil\AlignmentDesign\RailwayAlignmentDesignRules.xml, and they are used by default.

To customize the subgrade surface width, widening and transition length parameters, the administrator can set them in Data Setup.

The resource names are:

Subgrade Surface width and transition length
Subgrade Surface curve widening and transition length

Notes:

If one of these design rules is selected in the combo box, the cells of the Sections' table are filled in with the user-defined key parameters.
The width can be determined from following inputs:
- Design speed
- Railway track type (Mono or Dual)
- The ballast availability
Design rules are editable from Data Setup.

To add a section, click the Origin cell on the Add Section line and select

Point on alignment or an existing point on alignment.

Similarly you can remove or reorder sections along the alignment only when there are more than two sections in the list.

To edit a section parameter from the panel’s Sections table, click a cell and select Unlock.

Select a Destination Set for the subgrade surface.

The subgrade surface is generated under a subgrade surface set.

After relock, the parameter will automatically restitute the automatic value. By default, if no destination set already exists, a new one is created. You can also add a new one by clicking .