I know that our insiders have said that the changes in concept art for Slinky are due to budget cuts. And I don't doubt that at all. But could the elimination of the trenches be partly caused by the ground itself? I know very little about this sort of thing, but if the water table is too high in that area, couldn't it be that having a trench would cause more problems in the long run? (keeping water from seeping in, draining any rain that gets in, etc.) If I remember correctly, they did some test drillings in this area a few months ago. Perhaps they found the ground unsuitable for permanent "dry" trenches.
There is an underpass in my town that goes under some train tracks, and it is near impossible for them to keep the bottom from pooling water and slush/ice.