Hi Razor,
Consider yourself volunteered !
The splines I have made so far are 50m deep (but height adjustable, so the ground height can be anything less than 50m, relative) they are 5m wide at the top, which can either be "buried" or visible - as in the screenshot, these measurements are just the ones I came up with when I got the idea and it's not a big job to make different sizes BUT most of the work is in the textures. I have also done an inner corner asset (wood) and some "floor" assets, one of the "floors" is a spline but the rest are fixed size for performance considerations, in combination they should cover most requirements. It's your sort of feedback I'm looking for to make these assets fit for purpose and I'm completely open to ideas.
If you would like to try out some of the assets then PM me your email address and I will send a CDP to you in the next couple of days. I'm concentrating on my road assets at the moment but developing the edges and related stuff (I call them MR or Model Railway assets) would be a welcome change from the road asset "production line" !
Cheers
Chris