tcpMDT

Calculate earthwork (platform)

Updated on 4 June 2026 tcpMDT Leer en español

Calculates the earthwork for a platform drawn on a CAD layer: obtains the cut and fill volumes (interior area and slopes), draws the 3D contact polyline where the slope meets the natural terrain, and creates the platform surface as a .sup file.

This is the non-interactive equivalent of the MDT command "Platform by elevation" (SUP_MT_COTA_EXP). It can operate with a fixed elevation or by automatically searching for the balance elevation (where cut ≈ fill).

Critical prerequisites: 1. An active TIN surface (.sup) must exist in the MDT drawing. Use Query active surface information to verify this. 2. A closed polyline with at least 3 vertices must be drawn on the layer specified in layer_name. This polyline defines the platform perimeter in plan.

Parameters

Parameter	Type	Required	Default	Description
`layer_name`	text	Yes	—	Name of the CAD layer containing the platform polyline. It must be closed and have at least 3 vertices.
`elevation`	number (m)	No	Suggested mean elevation	Uniform platform elevation in metres. If omitted without `optimize`, the assistant returns the mean terrain elevation as a suggestion. Mutually exclusive with `optimize`.
`cut_slope`	number (H:V)	No	0.667	Cut slope expressed as H:V ratio. Example: `0.667` = 0.667 m horizontal per 1 m vertical (slope 2:3). Must be > 0.
`fill_slope`	number (H:V)	No	1.5	Fill slope expressed as H:V ratio. Example: `1.5` = 1.5 m horizontal per 1 m vertical (slope 3:2). Must be > 0.
`cell_size`	number (m)	No	1.0	Cell size for volume integration. Smaller values give more precision at the cost of longer computation time.
`optimize`	boolean	No	`false`	If `true`, automatically searches for the balance elevation (cut ≈ fill) using binary search between the minimum and maximum terrain elevations within the polygon. Mutually exclusive with `elevation`.

Result

The following are created in the drawing:

3D contact polyline: the line where the platform slope intersects the natural terrain.
Platform surface .sup file: saved in the DWG folder.

The assistant returns: applied elevation (or optimal if optimize=true), terrain elevations within the platform (min/mean/max), cut volume (m³), fill volume (m³), net volume, platform area (m²), slope area (m²) and number of contact polyline vertices.

Tip: If you do not know the platform elevation, use optimize=true to automatically find the balance elevation. This minimises total earthwork and is a good starting point for design.

Typical slopes: Cut in rock: H:V ≈ 0.25. Cut in medium soil: 0.5–1.0. Standard fill: 1.5 (3H:2V). Fill in flood-prone areas: 2.0 or more.

Example prompts

You can ask the assistant things like:

Calculate the earthwork for the platform on layer EXP at elevation 530 metres
Calculate the volumes for platform EXP and find the balance elevation for me
Earthwork for layer EXPLANADA with cut slope 1:1 and fill 1.5:1
Calculate the platform on layer PLATAFORMA at elevation 245 with a cell size of 0.5 metres
How much cut and fill does the platform on layer PARCELA at elevation 100 have?
Optimise the platform elevation on layer EXP to minimise earthwork