Curved Turnout Question....

[ljudice]

Doing some trackwork and it would be wonderful if I could convince myself that the following is at least plausible:

-   branch diverts from mainline at curved switch
-   branch is on outer, wider radius leg
-   main is on inner



Technically this is Peco Code 55 - the inner is 24"  and the outer even wider and operationally it is bulletproof.
I have mocked the thing up and it looks right.

Just need your thoughts...

[PGE_Modeller]

Yes, your situation is entirely plausible as there are definitely instances in prototype railroading where the main track is the "curved" or "divergent" route through a regular turnout and the spur (or branch) is the "straight" route.   

The example which comes immediately to mind for me was on the Pacific Great Eastern in Squamish, BC.  About 1 1/2 miles North of Squamish Dock, the main track took the "divergent" route through a #9 turnout while the South leg of a wye continued on the straight route following the old Howe Sound, Pemberton Valley & Northern track alignment.  In such as case, the turnout is in the "normal" position when aligned for the "divergent" route and is in the "reverse" position when aligned for the "straight" route.

Cheers,

[Denver Road Doug]

Yes, even though the design guys may insist otherwise, this is not that uncommon in real life.   If you're using a #5 or an otherwise problematic turnout then I'd say I might rethink some things, but those Peco's should be solid.

[ljudice]

Thanks guys...

Just checked and the inside curve is 18" not 24" so I think I'm re-engineering this....

[nkalanaga]

Unless your established minimum radius is greater than 18 inches it should still work. 

[ljudice]

Unless your established minimum radius is greater than 18 inches it should still work.

That's the problem, I am strictly sticking to 24".   I actually have found a way around this already though....

- Lou

[crrcoal]

Entirely plausible. Remember you're modeling coal country so anything goes.

[nstars]

The preferred situation in real life would be to have the mainline use the curve with the widest outside radius as the smaller inside radius could  result in a reduced track speed and main lines tend to have higher track speeds than branches. However, there are more than enough situations where local circumstances have resulted in a different situation. I know a situation where the diverging route through the turnout is designed for 100 miles/h and the straight line for 60.

Marc

[randgust]

You will see it, but not very often on a high-speed/tonnage main line, and never in a current main line design.   I've seen some designs go through some relatively absurd handstands to avoid that situation.   If it was 'current day' CSX or NS or UP or BNSF, on a main, they'd never do it.  You'd see the switch moved back to the nearest tangent, throw in a diverging turnout to the switch, and run it parallel for a quarter mile if they had to.  And it is funny sometimes, because they wouldn't think twice about running (or even backing) a train through a crossover between mains with the same switch geometry.

But I can also send you half a dozen shots of switches on curves, and at least a couple where the 'main' takes the diverging route, usually with an appropriate speed restriction in place.   A lot more common in the past and on shortline/industrial situations.   Usually the issue is that the switch just gets beat to pieces if there's much traffic over it.   

[basementcalling]

You will see it, but not very often on a high-speed/tonnage main line, and never in a current main line design.   I've seen some designs go through some relatively absurd handstands to avoid that situation.   If it was 'current day' CSX or NS or UP or BNSF, on a main, they'd never do it.  You'd see the switch moved back to the nearest tangent, throw in a diverging turnout to the switch, and run it parallel for a quarter mile if they had to.  And it is funny sometimes, because they wouldn't think twice about running (or even backing) a train through a crossover between mains with the same switch geometry.

But I can also send you half a dozen shots of switches on curves, and at least a couple where the 'main' takes the diverging route, usually with an appropriate speed restriction in place.   A lot more common in the past and on shortline/industrial situations.   Usually the issue is that the switch just gets beat to pieces if there's much traffic over it.

True that, but the prototypes have almost unlimited space to set their geometry the way they need compared to our layouts. There is no operational reason why the existing arrangement would not work for currently available N scale rolling stock and engines. Peco turnouts are about as close to bullet proof as we have when properly installed. I've never seen any cars or engines properly in gauge have any trouble with the curved leg of one of those.

Relax.

[Rossford Yard]

I had several spots where the main was the Peco inside curve on a curved turnout.  On one spot, a BNSF guy came to help and insisted that the main (on the branch line no less) go through a  straight turnout, and it may have been correct, but it didn't look right.  Those Peco curves do allow some great looking free flow track patterns.

I say we have to make some compromises for both aesthetics and space issues in N, so go for it.  18" is sure big enough radius.

[ljudice]

I think this falls easily into the prototype for anything rule...

I've pretty much discarded the idea though (although not because of the curve) - I am trying to keep the mainline to 24" curves or above if at all possible and I had mismeasured the Peco curved switch at 24 instead of 18.

But the bigger thing is I've realigned this branch to more naturally fit in with the watercourse that is planned for the right side of the mainline....

-ljj

[nkalanaga]

Good!  It's always nice when something can be changed to both make the builder happier AND be more prototypical.