Small Layout, Track radius/engine compatability

[Law Dawg 86]

I am a novice . I am planning a small 4x8 layout with 2 concentric circles with crossovers. I am going to use 22 &  18 curve. Can I use an Athearn SD50 unit with these curves? Do I use 3/4 or 1/2 inch plywood. I am going to use EZ connect track, so do I need any sound insulation for the track like cork?

[ABC]

Six axle diesels are not the best idea on 18" radius curves, and may derail in the curves, uncouple, and probably would have some overhang. Usually with six axle (3 on each truck) diesels it is best to stick to a minimum radius of 22".

[zachary4179]

see i have to use a 24" and a 36" for my engion becus  thay have 8 whills on them so  yea the biger rades the better