Curved Track Sections Question

[smquitadamo]

Are curve track sections (i.e. 0-72)  relatively the same in terms of the layout geometry ? 

Specifically is the track section length the same regardless of which brand I am using?   For example - is an 0-72 curve the same physical length whether or not I am using RealTrax, FasTrack, ScaleTrax, Atlas, etc...??

Note: I am NOT looking to interconnect various tracks from different manufacturers... my question is a by-product of some layout software that does not include the track manufacturer I plan to use.

Thanks - Scott Q

[wjstix]

It should work out the same to the extent that each brand would allow you to do a 36"R curve of 90, 180, 270, or a complete 360 degree / 72" diameter circle, regardless of the number of pieces needed. If each company used the same number of pieces per circle (like say all needed 16 pieces to make a full 72" circle) the geometry couldn't be too different.

[phillyreading]

If you are talking about space needed for a layout using 072 curves, it will matter as to which brand of track you use. Lionel's Fastrac has an outer edge of plastic and that needs to be taken into account when planning. GarGraves 072 track might be closer to 074.25 inches for a full circle. Lionel's tubular track in 072 is about 72 inches for a full circle. Geometry can be affected also by mixing brands of tubular track, as not all curves are produced with the same amount of track or rail length being used. K-Line's 042 curves and Lionel's 042 curves are not always the same even in tubular track, there can be a quarter inch differance in geometry of a circle.

The best advice is to measure a full circle laid out end to end, before installing it onto the layout.

I have some experiance with H.O. track and it seems that H.O. has more of a standard that is held to for track geometry and switch sizes.

Lee F.

[lionelsoni]

No.

I have examples of two Lionel O27=profile O54 tracks that are not the same as each other and not the same as the K-Line O54 that I use on my layout.  The Lionel radii (to the center rail) are 25.75 and  27 inches.  The K-Line is 26.375.  That's quite a variety.

I standardized with K-Line O27 (which is the same for all manufacturers), O42, O54, and O72, and Marx O34; so I had to scramble when K-Line went out of business to get a lifetime reserve of their track.

Here is how to measure the radius even if you have only one curved section on hand:

Measure the chord of a curved section, in a straight line from one end to the other of the center rail.  Multiply that number by half the cosecant of half the angle that the section turns.  The result is the radius to the center rail.

For example, O42 has 12 sections in a complete circle; so each section turns through 30 degrees.  Therefore you multiply by half the cosecant of 15 degrees, or 1.931852.  (For 8 sections in a circle, multiply by 1.306563; and for 16 sections, by 2.562915.)

The more careful you are measuring to the exact center of the end of the center rail, the more accurate your result will be.