Spur siding using MTH O-54 RealTrax Turnout - Help with track layout

Not an expert, by any means, but I think the answer to your question depends on:

1. what radius partial curve you use to swing back parallel to the main line off the curved side of the switch, and

2. how many little fitter pieces you choose to insert between the switch curve and the partial curve used to swing back parallel.

Chuck

You need a full 54" curve piece to make the spur parallel to the main track. If you don't add a piece of straight track between the turnout and the curve, you end up with an "S" curve. The center track to center track distance appears to be about 7.25". If you add a 5" straight piece, C2C increases to about 9.75" and a 10" straight makes it about 12.25".

Exactly what I was looking for.

I forgot to show you the difference if you switch to 72's; 5.5", 7.25" and 9.25". I should also say that I don't know enough about the wisdom of using one group of another, a lot depends on speed and the size of your rolling stock.

This information is very helpful.

DoubleDAZ

What would the spacing be for O-54 turnout and a 4.25 inch straight?

I would expect about 9 inches on centerline?

Right around 9.5".

DoubleDAZ

What would the spacing be for O-54 turnout and a 3.5 inch straight section?

I would expect close to 9 inches on centerline?

It's going to be just under 9 inches. If you took .75 away from 9.50 Maybe round 8 and 3/4 inch.

It's just over 9", but these measurements are me eyeballing it using the Measure-Gen tool in RR-Track.  It's not as simple as subtracting the .75 difference between the 3.50 and 4.25 tracks though because this piece of track is on an angle. You're moving the spur OVER .75", but UP something less. Also, the shorter the piece used, the less it negates the "S" curve and long rolling stock may still have problems negotiating things depending on speed.

This siding is intended for shorter cars and diesel switchers. I use O-72 turnouts and curves everywhere else on the mainline.

I needed the 9 inch center-to-center spacing to match other tracks on the layout.