Mid Atlantic Region
Delaware uses a real elevation method to set road elevations. This method sometimes requires the use of extra segments. This has the benefit of an enhanced look in the Live Map, and, more importantly, makes it easier to close a bridge or tunnel without affecting traffic to nearby homes and businesses.
Freeways are considered to be "Ground Level," except where they cross another freeway. And then that segment is adjusted accordingly. The only other exception to this are the downtown tunnels. Also, do not increase elevation on segments that go over bridges. If there is no other segment going under it, it should be Ground.
In general, all freeways should have an elevation of ground. Roads running over or under the freeways will have an elevation of +1 or -1. Where two freeways cross, the overpass should generally have +1 elevation. More complicated junctions may need more complicated treatment; apply the principal of "freeway defines ground level whenever possible" and keep elevations as sensible as possible. Remember that this region is not very hilly.