Reason number one is curves. The old layout had too many curves, had curves that were too sharp and had S curves that were too close together. The first pictures below are from the Rochelle Subdivision. Quite of few people really like the pictures and I have to admit they look pretty good. To be honest, though, this is one area of the layout that I did not like because, while the curves may be photogenic, it in no way represents what the Union Pacific looks like in Northern Illinois. There just are not S curves like that in Northern Illinois.
Being a pretty flat region, there are a lot of straight aways in Northern Illinois. Any curves are very broad and the S curves that do exits look much more like the picture below from the Geneva Subdivision.
One of the main reasons to start over was to build a layout without any peninsulas with their 180 degree turn back curves and the resultant sharp S curves. The Geneva Subdivision not only does not have any 180 degree turns, the 90 degree curves it does contain have 36" minimum radius. These standards are very important in order to capture the flat, straightness of Northern Illinois.
Reason number two for starting over was to get more topographical relief around the Rochelle Railroad Park. On the Rochelle Sub, I put the Railroad Park area on a flat piece of plywood. While Northern Illinois is flat, its not flat as a board. Below is the Railroad Park on the Rochelle Sub. As you can see, the ground from the pavilion to the tracks is flat as a board. This always bothered me.
This time, I made cut outs in the plywood between the pavilion and the tracks so that I could model some relief in that area. As you can see below, the area is not nearly as flat and, in my opinion, looks more realistic.
A couple of major improvements for the new layout, but just a small part of the large number of reasons for starting over. I'll be posting more reasons in the near future.