A simple list of the minimum turntable diameters for every vanilla locomotive in Rolling Line, to be used as a reference when building layouts with particular locomotives in mind.
Introduction
One thing to take into account is that the numbers listed in this guide are based on the minimum turntable size that the locomotive in question needs in order to be placed on said turntable. Some locomotives, such as the Steam JGR, may be able to use a smaller turntable than the number given, but this is not recommended.
In fact, I’d recommend that you make your turntables one unit larger than the numbers given, to give yourself a little extra leeway when driving the locomotive onto the turntable.
Turntable Lengths (Single Unit)
Commuter Sprinter: 6
Diesel AC44: 7
Diesel DA: 5
Diesel DG: 5 (Note: It technically fits but it really doesn’t. Definitely use 6.)
Diesel DX: 5
Diesel F7A: 5
Diesel NR: 7
Diesel U20C: 5
Electric V8: 8
Electric Side-Rod: 5
Rotary Plow: 5
Shunter DSJ: 4
Steam Berkshire: 6
Steam BigBoy: 8
Steam Challenger: 8
Steam Flyer: 4
Steam JGR: 3 (Note: Will spin on 2 if you’re very good at parking, but cannot be placed on 2.)
Steam Ka: 5
Turntable Lengths (Multiple Units)
Commuter Sprinter x2: 12
Diesel F7A + F7B: 10 (Note: Also valid for F7A + F7A. And F7B + F7B if you’re doing that for some reason.)
Rotary Plow + Tender: 9
Steam Berkshire + Tender: 11
Steam BigBoy + Tender: 13 (Note: It can fit on 12, but only if the tender is placed first.)
Steam Challenger + BigBoy Tender: 12
Steam Flyer + Tender: 7
Steam Ka + Tender: 9
Thanks to HuskyDynamics for his great guide, all credit to his effort. you can also read the original guide from Steam Community. enjoy the game.