Removal of Topsoil and Vegetation

Use this dialog to define how the finishing surfaces for the road surface should be constructed when removing topsoil and vegetation.

Where to Find the Dialog

In the toolbox, select SFI Properties..., go to the Road Body tab, and open the Substructure table.

Vegetation and topsoil are often weak materials and are therefore usually removed during road construction, for example, in low embankments and sloping side terrain. The topsoil layer is normally scraped off (and preserved) when the material can be used to cover slopes and earth grading surfaces.

Vegetation and topsoil layers can be described as separate strata in the terrain model. See the section on strata for more details.

Sections

Removal of topsoil and vegetation is specified with From profile - To profile. There is no limit to the number of sections (intervals). If there is a gap between two sections, nothing is done in that area.

Design

The finishing surfaces can be designed in three different ways (A in the figures = topsoil/vegetation layer):

Method 1: Embankment extension, normal cut

Method 2: Embankment extension, vertical cut

Method 3: Vertical embankment, vertical cut

You can also choose different designs depending on whether you are in a cut or fill. The cut design is used if surface 4.01 or the one inside is under a good layer (soil or rock).

Forced Removal

If No, you must specify the criteria for removing topsoil and vegetation.

One of the following criteria must be met:

• Embankment height

Topsoil and vegetation are removed if any of the heights (under the left and right shoulder edge and under the centerline) are below the given value.

• Slope

Topsoil and vegetation are removed if the average terrain slope between the embankment foot on the right and left side, or between the embankment foot and the top of the cut, is steeper than the given value (given as a ratio).

Combination of Topsoil/Vegetation and Mass Replacement

Removal of topsoil and vegetation has much in common with mass replacement. In a profile where both topsoil/vegetation and replacement masses are present, there are several possible combinations. Designs 1 and 2 can be combined freely, while design 3 must be applied to both topsoil/vegetation and mass replacement.

Combination 1-1. A = Topsoil/vegetation layer, B = Replacement mass

Combination 2-2. A = Topsoil/vegetation layer, B = Replacement mass

Combination 1-2. A = Topsoil/vegetation layer, B = Replacement mass

Combination 2-1. A = Topsoil/vegetation layer, B = Replacement mass

Combination 3-3. A = Topsoil/vegetation layer, B = Replacement mass

VIPS Import

The import reads the contents of the VIPS table: Removal of topsoil and vegetation.