Generally #7 through #10 are used in yards, at least in the transistion era, and hand operated switches in the main were #10, with siding switches #14-#16. Higher speed switches were #16 and above, up into #20 +.
On the UP main track in rule 251 double track territory the trailing point, hand lined crossovers were #10.
Dave H. Painted side goes up. My website : wnbranch.com
I walked through a very sharp turnout in the main yard at Woss on Vancouver Island 14 years ago because an old 2-8-2 was sitting just beyond it on a stub. As I got to the points, I shook my head, turned, and thought to myself, "There's just no way...."
I went back to the derelict steamer and took a closer look. Now I understood how and eight-coupled steamer of any size could have negotiated what I think was a real #6.
I believe that mains turnouts on the CPR leading to sidings in the Fraser Valley are actually #10's, or thereabouts, and most certainly not less than a #9. Higher speed turnouts, such as crossovers, are going to be in the #22+ range if I recall a conversation over on the trains.com forum many years ago...in fact, I think the number stated was a #25 or better.
DoughlessWith the discussion of turnouts, I've come to realize that our #4 through #10 frog models are actually close to what the prototype uses. Maybe we typically use one frog more severe in our situations than does the prototype.
I don't think that's correct. On some prototype double track mainlines, the crossovers from one track to another use like no. 20 turnouts.
With the discussion of turnouts, I've come to realize that our #4 through #10 frog models are actually close to what the prototype uses. Maybe we typically use one frog more severe in our situations than does the prototype.
This is important to me because my new more contemporary layout is being built with #8 and #6 frogs. With my tests, I thought the longer equipment looked a bit funny hanging over the turnout when traversing a #6 frog in a yard and spur, but that overhang might actually be quite common on real yards and spurs. I'm using #8s for the passing siding/runaround.
Of course, the actual mainline turning radius we use is much more compressed for our layouts compared to the prototype.
- Douglas
At Tower 55 in Ft Worth 30 years ago, a local car manufacturer was doing some compression testing on some new cars on one of the wye legs that was particularly sharp. They had a cut of cars with an engine on each end. Lets just say the test wasn't as successful as they had hoped.
An anecdote I picked up in my younger days was that a specific curve in Butler, PA was Pullman-Standard's de facto minimum curve. All outbound shipments moved from the Bessemer & Lake Erie to the PRR/PC/Conrail, which crossed perpendicularly. If something couldn't navigate the curve between the two, that represented a severe problem for Pullman. It wasn't considered a major problem until the initial R&D for the first 89 foot flats. Engineering calculation indicated that it was too tight for them, which proved true in initial tests. The underframe was reworked until the flats could make it in practice not just on paper.
It was about 340 feet or so.
The 1922 P&R MofW rule book had plans for split point switches down to a #3.
DoughlessInteresting table. As an aside, any ideas as to what "Stub Switch Length" means? I'm assuming its one of the three legs of the switch.
I believe it would refer to the "movable" portion of the rails at the stub end:
Stub_switch_crop by Edmund, on Flickr
So the "Stub Switch Length" would be measured from the last point of the anchored tie (where spikes end) following the dashed lines to the actual toe of the switch. Note the tie rods (T) to maintain gauge.
A switch refers only to the movable portion of a turnout.
Regards, Ed
Doughlessany ideas as to what "Stub Switch Length" means? I'm assuming its one of the three legs of the switch.
not sure. click the table, it's linked to the page I got it from and has some discussion of stub switches.
greg - Philadelphia & Reading / Reading
gregc looks like a #4 was prototypical
looks like a #4 was prototypical
Interesting table. As an aside, any ideas as to what "Stub Switch Length" means? I'm assuming its one of the three legs of the switch.
At 11 feet as a minimum, actually building the minimum seems laughably short for anything other than a 0-4-0. Which would relegate #4 switches to only the wharf-ish type of switch areas, if 11 feet means what I think it means. Maybe it means somehting else.
Maybe it means the minimum length beyond the frog the track should be before another track is joined to it, if they build the switch assembly as one piece.
Sharply curved frogs are not limited to just industrial trackage. Boston's South Station had #8s in the throat. One of the reasons the New Haven decided to buy their I-5 Hudsons was, the R class 4-8-2s repeatedly derailed on the throat, especially the double slips. I would not be surprised to find that many major terminals had throats laid out with #10 or sharper frogs because of cramped locations and maximum speeds not exceeding 15MPH.
Doughless I was going to start a new thread until I saw this one, so I'll embed my question here since I think both questions can be addressed. What is the typical minimum turnout frog# an industrial switching area might have? Not speaking of railroad policy absolute minimum, or the one off example, but as a general operating observation. Our models compress curve radius, or degrees, to where a typically broad radius on layout would actually be a tight radius in prototype general situations. Same holds true for turnouts. A #10 frog is very gentle for our models, but its my understanding its fairly severe for the prototype. But still, industrial areas or even modern industrial parks probably have turnouts with divergent degrees more severe than a #10, I'm thinking. We use #4's a lot on our layouts for industrial spurs, but is that too severe for a typical prototype turnout in an industrial area?
I was going to start a new thread until I saw this one, so I'll embed my question here since I think both questions can be addressed.
What is the typical minimum turnout frog# an industrial switching area might have?
Not speaking of railroad policy absolute minimum, or the one off example, but as a general operating observation.
Our models compress curve radius, or degrees, to where a typically broad radius on layout would actually be a tight radius in prototype general situations.
Same holds true for turnouts. A #10 frog is very gentle for our models, but its my understanding its fairly severe for the prototype.
But still, industrial areas or even modern industrial parks probably have turnouts with divergent degrees more severe than a #10, I'm thinking.
We use #4's a lot on our layouts for industrial spurs, but is that too severe for a typical prototype turnout in an industrial area?
I actually meaured a lot of frogs on some industrial trackage many years ago and found mostly #6 and #8's.
Sheldon
Nominally one limit on practical curvature is imposed by using solid wheel sets on freight equipment. Tread as well as flange wear then becomes a potential concern.
Remember that 'in practice' most model railroad curves are already wildly tighter than those AREMA would likely specify for other than sidings or industrial plant trackage.
Remember there are some curves to sharp for anything more then a end cab switcher.
On the PRR there was a scrap yard that had a very sharp curve.
How sharp?
We had to use idler cars to make a pickup or setout. Needless to say the flange squeal was loud.
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
Do you mean contemporary or if not, what time period?
As plant has improved and equipment gotten larger the standards have changed overtime.
gregc values for Reading steam locos
values for Reading steam locos
I believe B&O had a two-truck switcher that was specially modified to allow greater truck swivel (e.g. longer traction motor leads) for street-trackage curves in Baltimore -- those might be the 'tightest' general curves a regular engine might be expected to encounter in practice.
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What's the minimum curve radius for North American railways? Is it a solid standard? what's the typical turn radius for (edit: modern day) locomotives?
Building my first layout, 4x8 contemporary urban area in HO scale