Calculation Warning in the Corridor Template View

In order for an area (and subsequent material volume) to be calculated between a surface and corridor (or between two or more corridors surfaces representing subgrades), the extents of the lower surface must intersect with the upper surface to form a closed shape.

If you see this error message, "Area calculations may be incorrect.", in the Corridor Template View's graphic pane, the extents of the surface and corridor do not intersect. Therefore, the missing data was estimated in order to form the intersection. The area calculates using this estimated shape is likely to be inaccurate. You should try to supply a more complete surface or corridor. At the very least, check the area calculations carefully before relying on them.

Here are conceptual scenarios that illustrate the issue:


Key
		Surface with one edge node indicated.
		Corridor template with both edge nodes indicated.
		Estimated connection to the projection up from the lower corridor template or surface.
		Portion where area can be calculated properly because the vertical projections from the corridor template intersects with the template or surface above it.
		Portion where area calculation may be inaccurate because the surface or corridor shape has been estimated.
	Vertical projection up from template or surface edge/extents.
	Vertical projection up from subgrade template that does not intersect with the template above it.
In this example, the projections up from the corridor template edges/extents properly intersect the edges/extents of other templates and the existing surface. The area (and subsequent volume) calculations are accurate.
In this example, the projection up from the corridor template edges/extents do not intersect the edges/extents of the existing surface. In order to calculate an area, horizontal extensions have been added to the surface to intersect with the projection of the corridor template. Because the shape of the surface has been estimated, the area (and subsequent volume) calculations may not be accurate.
In this example, a hole has been created in the existing surface by adding a surface boundary, thereby masking the surface topography in the hole. In order to calculate an area, the masked topography has been accounted for (the original shape of the surface is honored), even though it may not reflect the intended shape of the surface. Because the shape of the surface has been estimated, the area (and subsequent volume) calculations may not be accurate.
In this example, multiple corridor sugbgrade templates have been created. The projection up from each subrgrade must intersect the area above it. The left edge/extent of the second template does not intersect the edge/extent of the template above it. No area (or subsequent volume) can be calculated in the white space between the two templates or the template and the surface.