Why in the world did they ---

[TimTRH]

 So - I was working on the ole layout, doing some changes, pulled out the 90 xing, and messed with a 60. (This is all O tubular, but the question can go to any brand) I happened to double check the 60 degree, and said - oh - wow - its 10 inches long - no worries. Then I thought about this title in my mind, for a "why is it" and/or "why dont they" post. For example -

Why is it that the Lionel 90 degree crossing was made 8.3 inches long, but they didnt make us an 8.3 inch piece to even out the other side?

Why is it that MTH Realtrax made the O42 switch 11 inches long, but they never made either an 11" straight, nor a 9" straight again to even up the other side of the loop, etc. (the O54 is 13.5", again - no 6.5" exists)

Even in HO, ATLAS made the #4 switch tons of years ago, but NEVER has made a curve piece of track to bring the diverging route back to parallel with the main.

Those are just a few that i thot' of - I am sure there are a lot more:)

[Andrew Falconer]

Why did the people at Atlas O make an almost complete track system, but they left out a few things such as the Two Track Mainline diamond crossing for 90 degrees, 60 degrees, snd 45 degrees. It is very hard to cut and rejoin the single track corssings to make a real two tracks crossing one track diamond.

 

Andrew

[lionelsoni]

I believe that the crossings were sized for figure-8 layouts.  I posted these three ways to make figure-8s with 45-degree curves in a recent topic::

The tightest uses 7 curved sections for each loop and a 45-degree crossing to connect them.  To do that, the crossing needs to fit in place of a curved section in each loop, as Bruce noted.  The length of the straight paths through the crossing are 10.355 inches for O27 and 11.716 for O31.  Lionel calls their crossings 10 1/4 and 11 3/4, which are .005 short and .034 long, respectively.

The next tightest uses 6 curved sections per loop and a 90-degree crossing, with 4 straight sections on the arms of the crossing.  The length of the straight paths through the crossing are 7.322 and 8.284.  Lionel calls their crossings 7 3/8 and 8 5/16, which are .053 and .028 short, respectively.

It is also possible to make a figure-eight with 5 curved sections in each loop and a 45-degree crossing, with 3 straight sections on each arm of the crossing.  However, the regular 45-degree crossing won't work here.  Instead, you would need one with the same lengths as the 90-degree crossing, that is, 7.322 and 8.284. 

[Anonymous]

I don't know for certain, but didn't MTH make 4.5 inch straights? 4.5 x 2 = 9...

I know Atlas has a lot of different lenghts for just this reason.

[TimTRH]

 The MTH piece is 4.25" x 2 = 8.5" The better solution that probably gets used is a 5" and a 4.25" which will give you 9.25 " which is less forced play then the 8.5" would require.

Atlas HO # 4 switches are 12.5 degree diverge route, trust me I did HO a lotta years, ya have ta cut a piece of 19"r curve at 12.5 degrees to get the route back to parallel again. The 1/3 piece that they have made for years is only 10 degrees, 2.5 degrees off.

Most of these facts hit the hardest when one is using a PC program (I use RR Track) to work up layout designs. 

I think that Fastrack may have covered it the best, with Atlas O next or even with Fastrack.