Ditch Design


Ditch Design is the calculation of the surfaces in surface group 4.XX connecting the shoulder to the terrain surface. In the Road Design module, you can select between different methods to perform this calculation.

Normal Ditch

Normal ditch design can be done from any of the following:

When a surface in the surface group (+/-4) is shown for the first time it is a Normal surface.

Advanced Ditch

Advanced Ditch design can be carried out using any of the following ways:

In the above three procedures, in order to carry out advanced ditch design, one of the +/-4.XX surfaces are being changed from Normal to Advanced by pressing the button Advanced of the dialog box Road Surfaces.


Absolute means that the elevation of the advanced surface is given for at least two profiles between two breaks.

Relative to Vertical Alignment

In the dialog box, the method is called Relative Longitudinal Profile, but the value in the column is the depth below the vertical alignment.

Relative to Planum

When Planum is calculated to an intersection with the advanced 4.xx surface, this method may be used.

The value defined is the depth from the end point of the Planum to the bottom of the ditch.

Relative to Terrain

Using this method, a ditch may be calculated in both formations (cut and fill).

Minimum Depth

It secures a minimum depth on the ditch when using Relative to Terrain. In a cut, the value for Relative to Terrain could result in having no ditch surface and this function secures a minimum depth on the ditch.

Insert Proposal

The function is available via right-clicking on the surface group for Ditch. It is only available when the ditch is in 'Advanced mode'.

Use this function to design ditches using different methods in cut and fill.

In this dialog box, values for the advanced ditch surface are to be defined and values for other ditch surfaces can also be defined.


Define the section of the road model, for which this function is being adopted.

Advanced Surface

The surface for which this function is activated (shortcut menu) will be displayed in this field.


Normal Ditch design or Advanced Ditch design can be carried out by defining the suitable column of this table.

Other surfaces

Other surfaces of the ditch group can be defined in this table.


Note: In Insert Proposal cut/fill intervals and depths are calculated using the values of the other Road surfaces. So if any Road surface is changed Insert Proposal must be called again.

Rounded Ditch

A new type of ditch has been used in larger road projects. The shoulder and the ditch are rounded so an off-road drive not necessarily would result in a rolling vehicle. To do this calculation several 4.x surfaces must be specified.

Next topic: Macro