I started to use the Screen Moulding for ties but decided they were too wide to match the width of the metal ties on O gauge tubular track. The width matches the base of the metal tie, but to wide to match the top of the tie. I bought 1/4" X 1/2" Basswood that comes in 24" lengths. Paint flat black with cheap spray paint, then cut into 2-1/4" length to match the Lionel metal ties. Paint again to get the bare cut ends.
Here is a area of my layout with ties added but have not placed ballast yet.
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Here is same area of layout showing a few of the Screen Moulding ties I used to add control rails and a uncouple magnet to the track. The cut-out is for my 97 Coal Elevator.
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Same area with Coal elevator in place. Note that there are 4 wood ties between the metal ties. I have decided that 3 ties looks better.
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A close up of track area while I was experimenting with Ties and Ballast. This section of track is the K-Line Tubular track that came in 36 inch lengths and had the metal ties spaced at 2-1/2 inches. I don't know if this track is available anymore.
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Here is area of my layout after adding ballast
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Steve