Hi Kevin,
You are correct that the red box indicates that the software isn't happy with the value you have typed. If you get this problem you can hover over the box and a tool-tip should appear telling you what it is that the software doesn't like. For the batter angles you can go to a steepest batter angle of 1:0.01 which is about 0.5° from vertical.
Now the obvious question is why you can't you type in a batter of zero, which as you say should give the vertical slope that you want.
The straightforward answer is that
Kubla Cubed doesn't currently support
totally vertical slopes. There are various technical reasons which are related to the triangular prism calculation engine we use to calculate volumes. This is the most accurate way to calculate earthworks volumes, but also throws up quite a range of technical challenges for our programmers that simpler methods don't have.
...And to be honest, we've never prioritised resolving this issue before now, because we've never come across an example where very steep slopes aren't good enough in practice.
However, as it happens we have recently been doing R&D into allowing vertical slopes, because I think it is difficult for users to understand why they can't do this. Our principle has always been to make this software as intuitive as possible, so we're working of fixing this and I believe vertical slopes will be possible in an update this year.
Leo
