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Double Slip Turnouts VS Double Crossovers

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Double Slip Turnouts VS Double Crossovers
Posted by alloboard on Monday, April 19, 2010 8:57 PM

 I've seen these at New York Penn Station

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Posted by cowman on Monday, April 19, 2010 9:34 PM

Did you have a question about them?  I've losts posts in the middle of typing them at times. 

They both exist, double slip conserves space, but all traffic must pass over one point.  A double crossover allows double track operations (meets and passes) and also changing tracks from either direction.

Have fun,

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Posted by cx500 on Monday, April 19, 2010 11:43 PM

 In real life, the railroads hated both of them.  But sometimes they were a necessary evil and this is particularly true of a throat of a passenger station where movement between any pair of tracks might happen, and parallel moves were also desired.  To do it with normal turnouts and crossovers would put the other end of the interlocking out in the suburbs.  In model form we are faced with similar limited space so they are in theory over-represented.

One look at the complexity of a double slip will reveal its complexity.  All those movable points need to be bought, assembled, interlocked and maintained.  They are tricky to build in model form; the full size versions are just the same.

A double crossover is more tolerable, but it still requires four frogs where the two crossing tracks intersect.  Frogs are expensive, and the frog points require regular maintenance to repair damage from the wheel treads hitting them (the banging noise you hear).  If you can separate the two crossovers you have just saved four frogs.

John

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Posted by ATLANTIC CENTRAL on Tuesday, April 20, 2010 6:08 AM

cx500

 In real life, the railroads hated both of them.  But sometimes they were a necessary evil and this is particularly true of a throat of a passenger station where movement between any pair of tracks might happen, and parallel moves were also desired.  To do it with normal turnouts and crossovers would put the other end of the interlocking out in the suburbs.  In model form we are faced with similar limited space so they are in theory over-represented.

One look at the complexity of a double slip will reveal its complexity.  All those movable points need to be bought, assembled, interlocked and maintained.  They are tricky to build in model form; the full size versions are just the same.

A double crossover is more tolerable, but it still requires four frogs where the two crossing tracks intersect.  Frogs are expensive, and the frog points require regular maintenance to repair damage from the wheel treads hitting them (the banging noise you hear).  If you can separate the two crossovers you have just saved four frogs.

John

I will second John on this, real railroads here in North America avoid such trackwork unless they have no choice. And when they did/do use it, it is always in some yard/terminal situation where a track crew is ALWAYS readily available to keep it working. Such trackage would virtually never be found on the main line or awy from urban areas.

Even in urban areas, two single crossovers will be used if there is room, for all these same reasons, cost, maintenance and safety.

Just like the real railroads, I avoid them on my layout.

Sheldon

    

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Posted by richhotrain on Tuesday, April 20, 2010 6:23 AM

When I built my first layout, I created a double mainline with a crossover between Track 1 (outer) and Track 2 (inner) and a turnout off Track 2 to access my yard. When the guys at my LHS looked at a diagram that I had drawn, they noted that the combined crossover and turnout created a sharp S that could cause derailments, and they suggested a double slip as an alternative to ease the angle from Track 1 into the yard.

Here is a great photo of a double slip in operation:

http://en.wikipedia.org/wiki/File:Double_slip_at_Munich_central.jpg

As far as a double crossover goes, I use one at the throat of the tracks feeding into and out of my passenger train station.  It is nothing more than two pair of turnouts positioned to form an X pattern.  It is a real space saver  but, again, poses difficulties for trains crossing from one track to another.

Rich

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Posted by BRAKIE on Tuesday, April 20, 2010 9:09 AM

Talking about switch complexs!

 

http://www.columbusrailroads.com/pom-feb2007.htm

Larry

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Posted by Paul3 on Tuesday, April 20, 2010 9:58 AM

When the 28 tracks of South Station in Boston, MA were laid out in 1899, it had 26 4-motor No. 8 Double Slips in the yard throat (a 4-motor double slip has not only moving switch points, but moving frogs as well).  There were two complete yard ladders from both the Southeast (Old Colony RR lines to Plymouth, Middleboro, et al) and the Southwest (NYNH&H lines to New York City, Hartford, Cape Cod and B&A to Albany).  That's four ladders, IOW.  South Station's yard throat was arranged such that it allowed up to 8 train movements at the same time through the entire terminal.  When finished, it was the busiest railroad terminal in the USA, and held that title for a while, possibly through the end of World War I.

Today, South Station has 13 tracks (due to the Post Office having some of the original land) and far less double slips.  The entire plant was rebuilt and turned slightly back in the mid-1980's so that each track is approx. the same length.  The old South Station layout had some tracks that were only 4 cars long while others were 16 cars.  The new layout has every track able to handle an 8-car train, plus some longer tracks, too.  There is some talk of the US Post Office leaving their site at South Station and allowing the State to buy it for more tracks...but it's still early.

There were no double crossovers (called "scissors") in South Station's old layout.

Paul A. Cutler III

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Posted by UP 4-12-2 on Tuesday, April 20, 2010 10:31 AM

ATLANTIC CENTRAL

I will second John on this, real railroads here in North America avoid such trackwork unless they have no choice. And when they did/do use it, it is always in some yard/terminal situation where a track crew is ALWAYS readily available to keep it working. Such trackage would virtually never be found on the main line or awy from urban areas.

Sheldon

Sorry Sheldon, you are incorrect here.

Leavittsburg, Ohio, where the Erie Railroad Mainline (two tracks) crossed a B&O (I believe) mainline is one well-documented location where double slip turnouts were used in a mainline setting.

My friend Rich Cox and I made a trip there in the late winter of 1992 to see the turnouts, but he had failed to adequately read the caption in his Morning Sun book that stated the double slip turnouts had been removed in the late 1970's.

However, we were able to see the locations where the (two) double slip turnouts had been.

Rich was planning to model that location in HO scale, however, subsequently changed to Canadian railroading interests.

In the model world, the Peco double slip turnouts work very well.  I have used them.  They will sometimes catch unsprung lead and/or trailing trucks on steam engines.  Adding springs to the offending lead or trailing truck solves the problem.

John

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Posted by tomikawaTT on Tuesday, April 20, 2010 11:23 AM

There was (and most probably still is) one rural station on the rather busy JNR (now JR-East) Chu-o Hon Sen where every one of the 100+ daily trains had to pass over a double slip switch.  Down (away from Tokyo) trains which actually stopped there had to use both curved routes of that double slip, plus the straight route that WASN'T the main through track.  Stopping Up trains used one curved route, while non-stops just ran right straight through.  To add to the fun, that DSS was located at one 'corner' of an asymmetrical scissors crossover.

The problem was that there was very little space between a bridge abutment and a tunnel portal, and there HAD to be a way to make meets and passes there on the single track route.  The solution was to build a switchback station.  The main (Up to Down) entered from the lower right and ran on a perfect tangent across the DSS, across the diamond crossover and then the straight side of the turnout with its headblock ties just outside the tunnel portal.  The curved side of that tunnel-portal turnout led to the Up platform track, on the uphill side of the island platform.  The track on the valley side of the platform ran through the other straight route of the DSS to a dead-end spur used only to allow trains that stopped there to either back into (Down trains) or back out of (Up trains) the platform tracks.  Up trains backing from the platform to the spur used the non-mainline route through the scissors.

Theoretically, three trains could get into the clear to allow a non-stop train to run through - but the movement would have to be choreographed like a ballet (or a sliding block puzzle.)

I like the idea so much that I'm planning to incorporate it into my mountain-climbing short line - which will have heavy traffic, but nowhere near as much as the prototype.

Chuck (Modeling Central Japan in September, 1964)

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Posted by cx500 on Tuesday, April 20, 2010 12:27 PM

UP 4-12-2

ATLANTIC CENTRAL

I will second John on this, real railroads here in North America avoid such trackwork unless they have no choice. And when they did/do use it, it is always in some yard/terminal situation where a track crew is ALWAYS readily available to keep it working. Such trackage would virtually never be found on the main line or awy from urban areas.

Sheldon

Sorry Sheldon, you are incorrect here.

Leavittsburg, Ohio, where the Erie Railroad Mainline (two tracks) crossed a B&O (I believe) mainline is one well-documented location where double slip turnouts were used in a mainline setting.

My friend Rich Cox and I made a trip there in the late winter of 1992 to see the turnouts, but he had failed to adequately read the caption in his Morning Sun book that stated the double slip turnouts had been removed in the late 1970's.

However, we were able to see the locations where the (two) double slip turnouts had been.

.......

John

 

A couple of comments.  Sheldon did not say never, he said virtually never.  On the railroad exceptions to the general rule always seem to have occurred.  You will notice that your cited example has been removed, probably followed by the opening of a bottle of champagne by the local roadmaster.  Was one line abandoned, or did the double slip get replaced by a pair of facing point turnouts?  A No.11 double slip at the hump in Toronto made an elegant layout on paper, but the designer said he was the target of regular complaints for years after.  Eventually the local track crew squeezed in a pair of facing point No.9 turnouts instead.

Perhaps I should also mention that as well as single slip and double slip turnouts, another related design was a diamond crossing with movable point frogs for the center pair.  These would be used where the crossing angle of two lines was very shallow, I'm guessing about 6 degrees or less.

I have now attached a photo of the lines of double slips at Toronto Union Station.  If you look over to the far side where the double slip ladders intersect, you can just make out examples of the movable point frogs diamond.  I am sure that there must be at least on example out in the wider world too.

John


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Posted by ATLANTIC CENTRAL on Tuesday, April 20, 2010 3:52 PM

John,

One exception proves nothing. Get all the track maps, from all the railroads IN NORTH AMERICA (europe is a different story just to be clear) - now, or in 1950, or 1920.

Add up all the slip switches and tell me what precentage are on mainlines or in rural areas. I'll bet a dollar to a dounut the ones on mainlines and/or in rural areas are less than 10%, likely even less than 5%.

I never said never, I did say vertually never, implying a very low percentage of exceptions.

And even your exception likely was near the home base of a track maintance crew, so they could keep a close eye on that trackage.

US railroads hate those things, they see them as a necessary evil of passenger terminals and other tight trackwork locations. In real life they are like boats and swimming pools, they just pits to throw money into.

And like the prototype, I avoid them on my layout as well.

Sheldon

    

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Posted by markpierce on Tuesday, April 20, 2010 4:16 PM

A friend once designed a track plan for my consideration.  The layout was to represent a rural area, yet the plan was filled with double-slip switches, three-way (lap) turnouts, and double crossovers.  I spent many hours to eventually eliminate all specialty trackwork using conventional, everyday turnouts as well as reconfiguring and reducing tracks.  The result was a far more prototypical look.

Mark

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Posted by UP 4-12-2 on Tuesday, April 20, 2010 11:39 PM

ATLANTIC CENTRAL

...And when they did/do use it, it is always in some yard/terminal situation where a track crew is ALWAYS readily available to keep it working. Such trackage would virtually never be found on the main line or awy from urban areas.Sheldon

I was responding to "always", regardless of what came after.

My understanding of always is that either something is "always" true, or it is not always true, period.

Leavittsburg appeared to be a fairly rural location when we were there, but I've never checked any official state DOT urban area maps on that issue.  My friend to this day is rather embarrassed we drove so far to see something that, had he read the caption, he would have known had been ripped out.

So the mention of Leavittsburg, OH, is a local train store joke, as my friend is now the sales manager.

At Leavittsburg, it appears they shifted the alignment and/or significantly widened the curve radius of the minor mainline and tied in at a location farther down the former Erie main rather than at the former double slip turnout location.  The  relocated line may also have been downgraded.

I don't need to buy all kinds of track maps I really can't afford.  At least one author commented that Leavittsburg was one of the very few, if not only, locations in the entire U.S. where double slip turnouts were used in a mainline situation.  However, it did exist, proving once again there is a prototype for nearly everything.

In my model railroad experience, I used a Peco 3-way turnout into a double slip turnout to save space on a yard ladder--and it worked pretty well.  However, I did learn to avoid special trackwork.  My entire mainline now has only three #6 turnouts on it (two in the preferred trailing point position to minimize trouble), with no provisions to add more.  Sometimes less is more, and I'm hoping my minimalist track arrangement will be offset by nice scenery instead--and my purpose is to run the largest motive power reasonably fast on heavy trains--so I just don't do switching, unless I'm breaking up a train.

Respectfully submitted--

John

One can never have too many articulateds (yes, I stole the quote)

 

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Posted by ATLANTIC CENTRAL on Wednesday, April 21, 2010 6:36 AM

 

UP 4-12-2

ATLANTIC CENTRAL

...And when they did/do use it, it is always in some yard/terminal situation where a track crew is ALWAYS readily available to keep it working. Such trackage would virtually never be found on the main line or awy from urban areas.Sheldon

I was responding to "always", regardless of what came after.

My understanding of always is that either something is "always" true, or it is not always true, period.

John, I understand, maybe I should have added "major junction or interlocking" to my discription, as "always" was refering to the need for careful and constant maintenence of such trackwork - as the rest of that sentence explained - sorrry if I was not clear about my meaning.

Sheldon

    

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Posted by railandsail on Saturday, December 08, 2018 11:22 PM

Like a slip switch, but not a single or double slip

 

cx500

Perhaps I should also mention that as well as single slip and double slip turnouts, another related design was a diamond crossing with movable point frogs for the center pair.  These would be used where the crossing angle of two lines was very shallow, I'm guessing about 6 degrees or less.

 

This is one of the first mentions I've seen of such a turnout. I think I have such an animal I first referred to as a single slip. It says 'Atlas' on the back  #NS4547, Made in Austria,...likely a Roco.

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Posted by gmpullman on Saturday, December 08, 2018 11:59 PM

railandsail
This is one of the first mentions I've seen of such a turnout.

The movable point frog is only part of a turnout or crossing. In the example of a crossing there is no turnout at all (i.e. no choice of diverging routes) the design of such a frog is to reduce impact wear at the point of the frog itself.

 Frog_Sprung by Edmund, on Flickr

Some are sprung, others have actuating levers connected to an operating mechanism, either levers in a tower or remote motor drives,

 Frog_Sprung_drawing (2016_08_17 08_08_12 UTC) by Edmund, on Flickr

Here is an example of a single-slip on the New York Central main east of Collinwood Yard in Cleveland, Ohio at BR Tower, MP 171.

 CP171_BRtower by Edmund, on Flickr

 

Another Double Slip only a few miles west of the BR photo. This one also on the New York Central main, track two, at QD Tower, Collinwood, Ohio:

 Collinwood_Yards by Edmund, on Flickr

Regards, Ed

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Posted by mvlandsw on Sunday, December 09, 2018 12:52 AM

The B&O had a double slip switch on the mainline on the bridge at Harpers Ferry.

The Union Pacific had a single slip switch on the main just west of the Topeka, Kansas depot where the Rock Island trains left their trackage rights on UP.

Mark Vinski

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Posted by NHTX on Wednesday, December 12, 2018 1:34 AM

     One of the earliest lessons I learned about railroading is there is no such thing as "never" or "always".  If you look long or hard enough, you will find that exception, out there, somewhere.  The mergers and trackage rights agreements have seen many diamond crossings replaced with two standard turnouts, points in the center, frogs out, forming a shallow X.  Same flexibility of routing as a double slip but the simplicity of two frogs and two sets of points.  Ease of maintenance and repair with readily available, common components.

     Although I know modelers usually gravitate toward the visually impressive, unless I were modeling a major urban passenger terminal, just like the prototype, no double crossovers or slips for me, for the same reasons.

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Posted by richhotrain on Wednesday, December 12, 2018 5:43 AM

NHTX

Although I know modelers usually gravitate toward the visually impressive, unless I were modeling a major urban passenger terminal, just like the prototype, no double crossovers or slips for me, for the same reasons.

Generally, I would agree with you. I suppose that there are some modelers out there who might install a double crossover or double slip because it looks cool. But the most valid reason for a modeler to install a double crossover or double slip is space, or the lack thereof. 

For example, on my current layout, I have a series of four double slips connecting four parallel mainline tracks. Why? Because the space required is far less with the four double slips than the space required to install 6 crossovers. In fact, I don't have the space to install 6 crossovers.

Rich 

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Posted by BRAKIE on Wednesday, December 12, 2018 8:12 AM

The real lesson is the railroads will use what ever it takes to get the job done including considering how many electric motors and switch heaters it will take and how often the frogs need replace.. If a double slip is cheaper that's what they will use..

Larry

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Posted by jeffhergert on Wednesday, December 12, 2018 10:21 AM

gmpullman

 

 
railandsail
This is one of the first mentions I've seen of such a turnout.

 

The movable point frog is only part of a turnout or crossing. In the example of a crossing there is no turnout at all (i.e. no choice of diverging routes) the design of such a frog is to reduce impact wear at the point of the frog itself.

 Frog_Sprung by Edmund, on Flickr

Some are sprung, others have actuating levers connected to an operating mechanism, either levers in a tower or remote motor drives,

 Frog_Sprung_drawing (2016_08_17 08_08_12 UTC) by Edmund, on Flickr

Here is an example of a single-slip on the New York Central main east of Collinwood Yard in Cleveland, Ohio at BR Tower, MP 171.

 CP171_BRtower by Edmund, on Flickr

 

Another Double Slip only a few miles west of the BR photo. This one also on the New York Central main, track two, at QD Tower, Collinwood, Ohio:

 Collinwood_Yards by Edmund, on Flickr

Regards, Ed

 

The diagram above is not a moveable point frog.  The frog point itself does not move.  The wing rail on the lesser used route moves, forced over by the wheel flange itself.  Once the wheel is clear, the spring closes the wing rail back into position.  

Jeff

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Posted by 7j43k on Wednesday, December 12, 2018 10:35 AM

Hmm.  Interesting direction, about the moveable frogs.

Here's a "real" moveable frog:

 

and the article which uses the photo:

 

https://en.wikipedia.org/wiki/Swingnose_crossing

 

Seems like the swingnose points would be a good choice if the routes were of equal use (as opposed to mainline and little used siding, which might indicate using a spring loaded wing rail).

 

Ed

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Posted by gmpullman on Thursday, December 13, 2018 12:49 AM

jeffhergert
The diagram above is not a moveable point frog.

Right. I mentioned that it was a spring rail frog. I didn't have the nice photo that the other Ed has. 

Thanks, Ed

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Posted by jeffhergert on Thursday, December 13, 2018 6:39 PM

7j43k

Hmm.  Interesting direction, about the moveable frogs.

Here's a "real" moveable frog:

 

and the article which uses the photo:

 

https://en.wikipedia.org/wiki/Swingnose_crossing

 

Seems like the swingnose points would be a good choice if the routes were of equal use (as opposed to mainline and little used siding, which might indicate using a spring loaded wing rail).

 

Ed

 

All the new high (40 MPH or higher) speed dual controlled turnouts UP has installed in my area now have the moveable point frogs.  They also have signs placed for train crews to remind them of the need to manually operate the frog when instructed to hand operate the turnouts.

Jeff

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Posted by OT Dean on Tuesday, December 25, 2018 12:27 AM

cx500

 In real life, the railroads hated both of them.  But sometimes they were a necessary evil and this is particularly true of a throat of a passenger station where movement between any pair of tracks might happen, and parallel moves were also desired.  To do it with normal turnouts and crossovers would put the other end of the interlocking out in the suburbs.  In model form we are faced with similar limited space so they are in theory over-represented.

One look at the complexity of a double slip will reveal its complexity.  All those movable points need to be bought, assembled, interlocked and maintained.  They are tricky to build in model form; the full size versions are just the same.

A double crossover is more tolerable, but it still requires four frogs where the two crossing tracks intersect.  Frogs are expensive, and the frog points require regular maintenance to repair damage from the wheel treads hitting them (the banging noise you hear).  If you can separate the two crossovers you have just saved four frogs.

John

 

When my brother worked for the Milwaukee Road, in the Muskego Yard, back in the early '50s, they had a double slip turnout at a busy point of the yard.  They called it a "Puzzle Switch" because it was so complicated--and they didn't like it, for the reasons given.  He said they hired him after only one trial shift because he was a model railroader and could tell which way a switch was lined, not something that comes easily to some, but he admitted that it took him longer to figure out the alignment than any other arrangement.

Merry Christmas and Happy Railroading in the New Year!

Deano

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Posted by rrinker on Wednesday, December 26, 2018 2:45 PM

 WHat's old is new again - back in the day, may tinplate turnouts had moveable frogs, as did the Tru-Scale HO ones. With no flange gap in the frog area, these turnouts with quite reliable, they just didn't resemble anything on the prototype. They still don't - a moveable frog turnout has two mechanisms, one for the points and one for the frog, they don;t rotate around some point in the closure rail area like the model ones.

                                         --Randy

 


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