Ok. I see that the images appear in-line and don't have their file names. Ignore the 2 small examples - they just show when we do exactly the same thing to a small set of contours it works as advertised. Subset of the same site model.
The larger images - if you look a Model - exist.jpg you can see the modifying poly's (red) and the Grade Limit boundary (also red). The existing site model has orange majors (5m) and grey minors (1m).
Model - propose.jpg is the result.
In the proposed model, looking from left to right, it's almost as though instead of grading evenly from the 1st modifier to the 2nd, VW leaves a hunk of the original terrain in the middle and then tries to make good. The higher modifiers are better, I guess because at this stage there's little original material between contour modifiers, but there's still a bit of the same messiness going on.
In the early trials we drew the Grade Limit poly from contour to contour ie intersecting each contour with a vertex. This version uses a simplified poly. Result pretty much the same.
In the interim we've manually adjusted the original model so we can work the overall design, but this doesn't give us eg cut/fill volumes, or a fast way to tweak the reshaping in response to the developing design.
Any light you can throw on matters very, very gratefully received.
Thanks: t