My two rail layout has Microscale Code 148 everywhere. Looking at the track from a distance, if not laid perfectly you can see a "wiggle or two" on every straight section. What I did to eliminate this was to obtain a exactly STRAIGHT piece of metal about 3 ft long with a width of exactly 1-1/4 inches. I called a local steel company and asked if they had any of that size in stock that I could buy from them. The person on the other end of the phone asked me if a 3/8 inch high (thick) piece would work, and I told him "Yes". He told me that the piece would be in their scrap bucket next to their front office receptionist's desk, and to just come in and pick it up, no charge. The metal piece "snaps" into place between the rails, and when I laid the track it was perfectly straight. I also made sure that cross level of each track had no more than a 1/8 inch variation in any 36 inches. Since that time I have had to shim the track in spots due to movement/shrinkage of the 1/2 inch plywood (good one side) on a few of my tables, but the layout has been operated "a lot" since late 2002 with no significant problems. The track is on cork roadbed. By way of info, it is not necessary to make each rail "even". My track sections are "close" but not exactly even due to curves.
I hope this is useful.
