This is a simple reference guide intended for use when designing and building custom layouts. If you have a particular locomotive or two in mind for your layout, this guide can tell you the minimum size your turntables need to be, and therefore how much space you must allocate for them.

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 (and for, like, realism stuff).

This section provides turntable lengths for single unit locomotives only. For example, the Steam Flyer length does not include the required length for the tender. For this information, see the following section.

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

This section provides turntable lengths for multiple-unit locomotives. For example, the Steam Flyer length takes into account the required length for the tender. All unit pairings are listed for convenience.

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 BigBoy + Berk Tender: 13

Steam Challenger + BigBoy Tender: 12

Steam Flyer + Tender: 7

Steam Ka + Tender: 9