http://trn.trains.com/Interactive/Photo%20of%20the%20Day.aspx?id=%7b955D6395-49E6-40C5-8A8D-36A5D6FAC8B8%7d
The link is to an Al Kalmbach photo from 1949 in Milwaukee, " beneath Milwaukee’s arched Wisconsin Avenue bridge." To the left of the locomotive there are some apparent switch points. Closer inspection reveals that this is no switch, but a mechanical crossing. Does anyone know if these were common back then? Is it a poor man's crossing? Perhaps the machine shop never got around to grinding some points at that angle. I see a tower nearby; maybe the points were interlocked and could only assume one of two positions. Otherwise, I see a recipe for derailment when a distracted switchman throws one of those sets of points the wrong way.
Does anyone know the story on this? Or more about such crossings in general?
Thanks,
Shooshie
Actually instead of calling it a poor mans crossing it should be considered a rich mans crossing. The moveable point crossings were for higher speeds. They were common when trains ran on fast schedules like the Hiawatha.
The interurban ,North Shore line also used them on the main line where they crossed the Milwaukee or the CNW.
Randy
Shooshie,
I can't open your link, but are you referring to one of these?
http://www.google.com/imgres?imgurl=http%3A%2F%2Fi155.photobucket.com%2Falbums%2Fs309%2Fmsibnsf%2FP1000581.jpg&imgrefurl=http%3A%2F%2Fwww.subchat.com%2Freadflat.asp%3FId%3D645350&docid=LkXkptBCPHMn0M&tbnid=kM8yAaeNK2UvJM%3A&w=973&h=1024&ei=cB9qU7e7CtCUyAT_m4LgCA&ved=0CAIQxiAwAA&iact=c
A common name for that is a “puzzle switch.” It is an actual crossing diamond for the crossing function, but it also has divergent capability.
Upon approach from any of the four directions, it offers a choice of crossing straight through or diverging into the other track.
Movable-point frogs are not common. Kensington Junction included several crossings where the South Shore crossed the IC main line to connect with the IC suburban line that were equipped with movable-point frogs. I haven't seen them anywhere else.
Double-slip (puzzle) switches can be found by the dozen in the approaches to any major passenger terminal. It would be quite unusual to see one by itself outside of a terminal area.
Actually and to my surprise , wilkapedia has a good explanation.
http://en.wikipedia.org/wiki/Switched_diamond#Switched_diamond
Not a slip switch for there is no divergent route and as was stated slip switches are LOW speed devices rarely found outside of terminals.
All major terminals in New York:: GCT, NYP, Hoboken, and Jamaica plus in many places along the subway systems employ slip and double slips switches. It is one of the major wonders many of Ridewithmehenry's first time riders remark about, in fact.
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It would be nice to see a picture of what the OP is referring to. I don't find any photo of a "switched diamond" online. There is a schematic in the Wikipedia link, and a photo of a switched frog. I assume that a switched diamond would have all four frogs that have a rotatable bridge section that lines up one route or the other. They would not have points, but just match rail end-to-end. I don't recall ever seeing one.
Edit: If you click open the link and then login as a magazine subscriber you can make the photo open, I can't put a hot link in that way.
You must be a magazine subscriber, but it is a puzzle switch in Milwaukee, the caption says at a point where an industrial line diverts from the pacific coast main, with a Milwaukee Road steam engine passing on an adjacent track.
Movable-point obtuse-angle frogs are very common as parts of slip switches. Less common as stand-alones in standard crossings, but hardly unknown.
Closed acute-angle frogs with spring-loaded wing rails are quite common.
CSSHEGEWISCH Movable-point frogs are not common. Kensington Junction included several crossings where the South Shore crossed the IC main line to connect with the IC suburban line that were equipped with movable-point frogs. I haven't seen them anywhere else. Double-slip (puzzle) switches can be found by the dozen in the approaches to any major passenger terminal. It would be quite unusual to see one by itself outside of a terminal area.
My favorite stand-alone double slip switch was at one corner of an asymmetric diamond crossover, at a place called Higashi-Shiojiri on the JNR's Chu-o Hon Sen. It was needed because there was a meet-pass signal box/station on a narrow ledge between a tunnel portal and the abutment of a bridge over a deep canyon. Over 100 trains a day were scheduled across it - every train that passed that point. The need (and the station) went away when a second tunnel was driven through for the down main track. The new Shiojiri tunnel is on a completely different alignment, and its eastern portal is a couple of kilometers away from the old tunnel.
Chuck
Nomenclature, definitions, terminology, geography, cultures and what we are talking about cause confusion. I looked at the Wikopedia article and I don't think it is describing switch styles but rather junctions, crossovers, turnouts, etc. as all diagrams except one are single lines depicting a single track. It is also based on English railroading rather than American. And it also negates what I described as slip and double slip switches and their uses. Instead they are showing different kinds of junctions, crossovers, turnouts and the respective interlocking. So, now that you know the picture is not of a switch but of an interlocking or junction or crossover, you can analyze it from a different perspective.
DwightBranch Edit: If you click open the link and then login as a magazine subscriber you can make the photo open, I can't put a hot link in that way. You must be a magazine subscriber, but it is a puzzle switch in Milwaukee, the caption says at a point where an industrial line diverts from the pacific coast main, with a Milwaukee Road steam engine passing on an adjacent track.
As far as I know there weren't any slip switches in Milwaukee on the Milwaukee road. The spot the OP is referring to is Grand Ave. interlocking.
I was able to bring up the picture without difficulty. Perhaps if I warmed up the link...http://trn.trains.com/Interactive/Photo%20of%20the%20Day.aspx?id=%7b955D6395-49E6-40C5-8A8D-36A5D6FAC8B8%7d
Another reason for such a crossing would be that the angle is too acute to assure a safe straight route across the other track. Batter a frog a little bit, and you could have problems. The crossing between Metra and UP at Western Avenue has a number of diamonds like this (as well as double-slip switches...definitely a different animal). I'll have to check again sometime and see whether it's only the UP's main tracks that have them (and not the tracks moving stuff to or from the coach yard to the station). At high speed or low speed, something like this would reduce the amount of wear in the vicinity of the frogs by eliminating the gap. This would be especially useful at a spot like this, where diamond replacement would cause a major disruption to traffic. (Again, though, the tracks do cross at a fairly sharp angle.)The premise would be the same as a movable-point frog on certain switches...although these switches permit higher speeds for the diverging routes, the frogs usually protect the main lines (where speed is not affected). What makes them higher-speed switches is the acuteness of the angle. I suspect that anything with a number higher than 20 would be likely to have a movable frog. And that would apply to switches or diamonds.
Carl
Railroader Emeritus (practiced railroading for 46 years--and in 2010 I finally got it right!)
CAACSCOCOM--I don't want to behave improperly, so I just won't behave at all. (SM)
CShaveRRI was able to bring up the picture without difficulty. Perhaps if I warmed up the link...http://trn.trains.com/Interactive/Photo%20of%20the%20Day.aspx?id=%7b955D6395-49E6-40C5-8A8D-36A5D6FAC8B8%7d
Nope, still "subscriber-only content" on my end.
but worked this time for me
but I am a TRAINS -and CLASSIC TRAINS subscriber
CSSHEGEWISCH Movable-point frogs are not common.
Movable-point frogs are not common.
Please help me out with terminology here.
What is a "movable-point frog" and how does it differ from a normal frog?
Rich
Alton Junction
A movable-point frog can croak while he hops.
All seriousness aside, a normal fixed-point frog is a solid casting that includes a gap in the rail tread to allow for passage of the wheel tread. A movable-point frog has several parts, one of which is a tread that can move in either direction to close the gap in the rail tread, allowing a smoother ride and less hammering action.
Perhaps some of the railroaders on this forum can explain this a bit better.
There's a much more recent shot of this location over on Trainorders.com today:
http://www.trainorders.com/discussion/read.php?4,3403496
richhotrainWhat is a "movable-point frog" and how does it differ from a normal frog?
BNSF installed a movable point frog in the interlocking in my old hometown of Toluca IL, along the ex- Santa Fe, west crossover (from south to north track using Santa Fe nomenclature). There are two frogs and sets of points on each crossover, but they had only installed one movable point frog (out of a total of four in the interlocking) at the time I was there. It looks sort of like a spring switch frog if you have seen one of those, only it is controlled by pipes radiating from the switch to the frog, sort of like a manual interlocking at a tower, so that when the switch points move, so does the point in the frog, making the rail the point is now part of continuous rather than with a one or so inch gap as in a normal frog. The result is just fantastic in terms of noise: it is much, much quieter, and I must imagine that the maintenance is reduced also.
On a side note, the east crossover was just a mess when I was there in the fall of 2012, one frog was in the mud, bolts were loose, etc. I think BNSF needs to pick up the maintenance there. I also noticed something I thought I would never see on that line: a contractor was welding in a section of rail, hard to believe they would let one of those guys out there, I wonder if BNSF is farming out their maintenance of way operations. If so, it is too bad, I would think they would want to keep it in house for accountability.
Moveable point frog
Standard Frog
Never too old to have a happy childhood!
Thanks guys for the explanations and photos of movable point frogs.
BaltACD Moveable point frog Standard Frog
The one I saw on BNSF was a bit different, but the point was like that. I notice in the photo of the movable point frog there aren't any guard rails on the outside rails, they seem to be part of the frog. The one I saw actually had guard rails like the bottom photo, elaborate things with narrow guard rails, unlike normal frogs which usually have guard rails made from normal rails bent to shape.
I hope that Kalmbach will forgive me, but for the sake of all those who cannot access the picture, I've copied it and put it in my dropbox so that we can have this conversation:
https://dl.dropboxusercontent.com/u/75122252/MilwaukeePoorMansCrossing.jpg
It's been so long that I don't remember how to turn that into a link using HTML, so forgive me also that you have to copy the URL physically, and paste it into your browser. Seems that we all have to be members, anyway, right? So it shouldn't be a problem for us to see this switch and talk about it.
This isn't a double-slip switch. I'd never have asked about such a thing. This looks like two back-to-back stub switches, until you realize that there are no alternate routes. You can only go straight through on the route on which you're approaching. BUT... the other points... er... stubs... have to be lined up or you'll go flying off into oblivion, taking the approaching trackwork with you.
So, some say it's a high-speed crossing. That's believable, but that doesn't look like a high-speed area. Were it in a cornfield in Iowa, yes, but not under a bridge in industrial Milwaukee. Still, it may be the truth. The westbound line (curve to the left) could be a high-speed route.
Sorry to be just now returning to the conversation, but I've been too busy for the past few days.
No, it's not a slip switch of any sort.
It doesn't have a movable frog. Ahhh!!! I just figured out how to insert photos in this forum. Sorry for not figuring out that it's just a matter of using the [ img ] and [ /img ] tags.
Anyway, you can see here that this is an unusual kind of crossing. Maybe high speed, but it sure doesn't look it. Looks to me that someone decided to delay the construction of a diamond, then forgot about it. It would have a pretty long frog/diamond length due to the shallow angles between the tracks, but that shouldn't be a problem. That's why it mystifies me. Why'd they make it this way? Or why'd they leave it this way?
For now, the best candidate seems to be the fast-crossing explanation. It would eliminate the diamond and the corresponding bump that invariably goes with diamonds. But it requires someone on duty 24/7 to be sure it's set right. I guess that's normal on railroads, anyway.
I'll bet some of you know the real story of this particular location. Tell us all, if you do!
DwightBranch, the purpose of the "guard" rails at a switch frog is more aptly put in the word "guide" rails. The frog theoretically allows an opening for a wheel flange to go a different way. The guide rail prevents that from happening by holding the other wheel as close to its designated path as possible. Of course, it would require a sudden lateral force for the flange ever to go the wrong way, but no doubt it happened.
The movable frog closes that gap, eliminating the need for the guide rails. This (the top photo) is truly a high-speed switch.
Actually and to my surprise , wilkapedia has a good explanation. http://en.wikipedia.org/wiki/Switched_diamond#Switched_diamond Not a slip switch for there is no divergent route and as was stated slip switches are LOW speed devices rarely found outside of terminals. Randy
That's not it. Notice that in the wikipedia diagram, only the frog area moves, that is, the inner X between two outer rails. This example on the Milwaukee looks like two switches, back to back. No frog. All movable points are on outer rails. There is no inner frog or diamond.
At first glance, I thought it was a pair of opposing stub switches, and I wondered why anyone would ever design them such that you were having to line up TWO pair of movable stubs, rather than the usual pair.
Then I noticed that there were no "slip" curves for the alternate routes. This was not a switch.
It's a crossing without a frog/diamond.
I hope that sheds some light on why I consider this a unique crossing.
Shooshie Actually and to my surprise , wilkapedia has a good explanation. http://en.wikipedia.org/wiki/Switched_diamond#Switched_diamond Not a slip switch for there is no divergent route and as was stated slip switches are LOW speed devices rarely found outside of terminals. Randy That's not it. Notice that in the wikipedia diagram, only the frog area moves, that is, the inner X between two outer rails. This example on the Milwaukee looks like two switches, back to back. No frog. All movable points are on outer rails. There is no inner frog or diamond. At first glance, I thought it was a pair of opposing stub switches, and I wondered why anyone would ever design them such that you were having to line up TWO pair of movable stubs, rather than the usual pair. Then I noticed that there were no "slip" curves for the alternate routes. This was not a switch. It's a crossing without a frog/diamond. I hope that sheds some light on why I consider this a unique crossing.
Just behind the tender of the steam locomotive is the Tower that controls this interlocking and provides the 24 hour supervision of it's operation. A signal maintainer would normally be stationed at the tower to perform all the required maintenance operations on a daylight Monday-Friday basis and being subject to call for any repairs required after those hours.
That is a very interesting track device detail. I am not sure how unique it is, but I have never seen a crossing like that before. As you say, it is actually two switches facing each other with no space between them. Each switch has its frog and two points. The frogs are not movable. I assume that the two switches are linked together, so when you line up for either direction of the crossing, both switches move simultaneously.
In the picture, the trailing points nearest the viewer are lined to the left, and the facing points are lined to the right. So the crossing is lined for the track coming out from under the gondola and curving to the left. When you "throw" the crossing, the near points move to the right, and the far points move to the left.
I assume that this design is necessitated or preferred due to the fact that both tracks in the crossing are curved. I don’t think it is based on a need for high speed.
From the photo, I cannot tell what the points look like. The gleam of the rails in the photo and the distance may just make them look like stub switches. Although as switches go, they turn out relatively sharply, so I am not sure how points might be configured to work there. A photo or plan detail of the points would be most interesting to see.
Is this switch owned by the CMSTP&P?
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