Passenger Trains > Puzzle Switches from long ago and right now

Recently there was a discussion of "puzzle switches" also known as "double-slip switches". Here are two examples, one that sees lots of action every day, and one that's part of a railway museum.

1) The San Bernardino Metrolink switch--one of relatively few that are not in a big downtown station track layout. This one even has moveable point frogs for smoother passage. It's just west of the Mt. Vernon Viaduct; straight through is for the ML San Bernardino Line, with over 40 trains a day, Monday through Friday. Diverging to the upper left is what we used to call the "Short Way", bypassing the "B" yard and connecting to the former Third District to Riverside and points west; it's the route of the Inland Empire-Orange County ML service. I haven't been in San Berdoo for Amtrak 3 and 4 in a long time, but would guess that those trains use the Short Way and go diagonally through the switch to the BNSF main line off to the lower right.

2) This piece of "specialwork" is from the Pacific Electric 6th & Main terminal in downtown Los Angeles. About 50 years ago it was salvaged by Orange Empire Trolley Museum volunteers just befor the elevated terminal structure was demolished to make way for a new bus station. Unlike the ML-BNSF switch, this one is a single-point type, closer to streetcar line practice. Its main use is to provide a route for cars and locomotives coming out of Barn 2 (the Walter Abbenseth Car House) to reach the dual-gauge loop track. Diverging to the upper right goes to a display track, to center left goes to a storage track. For many years, what is now Orange Empire Railway Museum in Perris CA (oerm.org) was the only railway preservation facility with a puzzle switch, but now Seashore Trolley Museum has one near their visitor loading area.

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That track is still called the Short Way and Amtrak does not use it, only Metrolink.

Thanks for sharing.

OTG Wrote:
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> That track is still called the Short Way and
> Amtrak does not use it, only Metrolink.

Yep, it even its own, if extremely short, subdivision; Metrolink's Short Way Subdivision.

UP and Amtrak 35 and 36 used to use that all the time until Metrolink expanded! Also, how the hell could tower operators know how the hell to line switches like that in that type of complicated interlocking at big city terminals! I know it took a lot of practice and trial and error to figure that out!

I can only imagine the fun of having to hand line that thing...


Jeff

Easy, just line the route. And of all things the company that makes to silly 'cube' switch stand indicator with the cute arrow straight or to the side messed up their advertizing photos about three months ago in a magazine. Showed their cube with a straight ahead arrow on a switch obviously lined for the siding. So much for the advertizing department knowing anything. Always, always always - look at the points. Thats where you are going irregardless of the target . . . . or the little cube.

CDTX Wrote:
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> I can only imagine the fun of having to hand line
> that thing...
>
>
> Jeff

That happened once, and a Metrolink started down the BNSF for a short distance, oops!

ProAmtrak Wrote:
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> UP and Amtrak 35 and 36 used to use that all the
> time until Metrolink expanded! Also, how the hell
> could tower operators know how the hell to line
> switches like that in that type of complicated
> interlocking at big city terminals! I know it took
> a lot of practice and trial and error to figure
> that out!

each switch machine had a corresponding switch number ... in reality they're no different than a compact crossover ... complicated interlockings had routes on the model board with corresponding designations ... for example the train director would call out to the leverman ... need a route K 2 track to JO 4 track... with K beings a section the interlocking where the train will be entering the plant and JO being another section of the interlocking where the train will be exiting the plant ... the leverman would look up at the model board and use the levers associated with that route ... seasoned leverman could do it blindfolded ... these days with electronic dispatching and auto routing the disp locks the route by clicking the entrance route and the exiting route and the switches automatically line the switches for that routing



Edited 1 time(s). Last edit at 04/16/14 23:40 by Out_Of_Service.

Thanks for the explanation, but from a railfan's perspective, it can get perplexing, in fact my dad told me Mission Tower used to have switches that were like spaghetti!

in the first image there's a single slip switch in the background ... single slips are very rare ...

http://www.trainorders.com/discussion/read.php?2,3382682

OTG Wrote:
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> That track is still called the Short Way and
> Amtrak does not use it, only Metrolink.
>
> Thanks for sharing.


I used it on #4 about a year ago.

Yes, they'd use a matrix diagram? I am building a working interlocking on my model railroad with 40 levers (plus two for a train order signals). I don't have all the levers in place yet but based on the ones I've used so far I can understand how you could get to the point where you wouldn't have to refer to the matrix. I lined a route the other day from memory and a fellow railroader friend just shook his head. LOL

Out_Of_Service Wrote:
>
> each switch machine had a corresponding switch
> number ... in reality they're no different than a
> compact crossover ... complicated interlockings
> had routes on the model board with corresponding
> designations ... for example the train director
> would call out to the leverman ... need a route K
> 2 track to JO 4 track... with K beings a section
> the interlocking where the train will be entering
> the plant and LN being another section of the
> interlocking where the train will be exiting the
> plant ... the leverman would look up at the model
> board and use the levers associated with that
> route ... seasoned leverman could do it
> blindfolded ... these days with electronic
> dispatching and auto routing the disp locks the
> route by clicking the entrance route and the
> exiting route and the switches automatically line
> the switches for that routing

wabash2800 Wrote:
-------------------------------------------------------
> Yes, they'd use a matrix diagram? I am building a
> working interlocking on my model railroad with 40
> levers (plus two for a train order signals). I
> don't have all the levers in place yet but based
> on the ones I've used so far I can understand how
> you could get to the point where you wouldn't have
> to refer to the matrix. I lined a route the other
> day from memory and a fellow railroader friend
> just shook his head. LOL
>
> Out_Of_Service Wrote:
> >
> > each switch machine had a corresponding switch
> > number ... in reality they're no different than
> a
> > compact crossover ... complicated interlockings
> > had routes on the model board with
> corresponding
> > designations ... for example the train director
> > would call out to the leverman ... need a route
> K
> > 2 track to JO 4 track... with K beings a
> section
> > the interlocking where the train will be
> entering
> > the plant and JO being another section of the
> > interlocking where the train will be exiting
> the
> > plant ... the leverman would look up at the
> model
> > board and use the levers associated with that
> > route ... seasoned leverman could do it
> > blindfolded ... these days with electronic
> > dispatching and auto routing the disp locks the
> > route by clicking the entrance route and the
> > exiting route and the switches automatically
> line
> > the switches for that routing

wabash2800 Wrote:
-------------------------------------------------------
> Yes, they'd use a matrix diagram? I am building a
> working interlocking on my model railroad with 40
> levers (plus two for a train order signals). I
> don't have all the levers in place yet but based
> on the ones I've used so far I can understand how
> you could get to the point where you wouldn't have
> to refer to the matrix. I lined a route the other
> day from memory and a fellow railroader friend
> just shook his head. LOL

For a machince with individual levers (mechanical, electro-mechanical, electro-pneumatic, electric) rather than eNtrance eXit, there was a manipulation chart
http://zippy.cso.uiuc.edu/~roma/signal/images/Manipulation-chart.jpg that lists every possible route by endpoints and the levers for that route in the order that they must be pulled out of the machine. When learning a new tower, the new guy typically learns with all levers in the machine for every move. After a while, one gets used to what must be in the machine and what doesn't need to be in the mchine for a given route. After a while longer, is is possible to pull any lineup without the manipulation chart. Ultimately, it comes to working in the dark on 2d and 3d trick.

It doesn't take long. I could run 49th Street <http://www.trainorders.com/discussion/read.php?11,2940764,2940902#2940902&gt; in the dark in a few days and 75th Street http://zippy.cso.uiuc.edu/~roma/signal/75thStreet.html in a couple of weeks.

About the movable point frogs:
The Short Way DSS is a Number 10, and that relatively flat angle means there is an unguarded length at the center frogs that is too long for safe operation.
The center frogs function like the frogs on a conventional lateral turnout. On a conventional turnout, to prevent the wheel flange from going into the wrong flageway at the point of the frog guard rails are placed on the opposite running rails. As a guard rail cannot be placed opposite the center frog (because that is where the other center frog is), the practice is to use movable point frogs so that there is never a gap at the frog that needs guarding. With the much shorter unguarded length of the No. 6 (?) PE frogs, there is far less risk of a flange going the wrong way.
At Los Angeles Union Passenger Terminal's Terminal Tower almost all the turnouts were (in 1930s) and are No. 8 geometry. The original DSS design used movable point frogs. When we designed the reconstruction of the yard throat, our preference was to use No. 10s for a little more speed but we found that this required too much distance and would shorten the platforms so we stayed with the No. 8s. By that time (1993-95) the industry had adopted a design for rigid cast steel center frogs that Amtrak reported as having good service history so we copied that design, saving about half the number of power switch machines and tons (literally) of moving parts.
Just in case you wondered, a six-axle truck can negotiate a mis-aligned center frog on a No. 10 DSS. One sunny afternoon a signal crew made a hurry-up move to hand throw the No. 10 DSS on the east bank of the Los Angeles River (now retired and replaced by lateral turnouts). The points of the end switches were set for a straight move but the points for the center frog were set to deflect the wheels onto the diverging track. (In signalman's terms, the two center switch machines were "out of correspondence".) A UP 6-axle locomotive, proceeding under hand signals from the signal foreman and with the dispatcher's permission went through the diverging frog and then ran through the points at the far end of the DSS. They applied the brakes as soon as they lurched to the side, but ran through the points on the far end of the DSS and stopped still on the rail. But then they backed up and of course derailed their lead axle on the run through switch points and that is when my phone rang.
At least that answered my curiosity.
We got it picked up before the evening commuter rush but the afternoon trains had to be bustituted.



Edited 1 time(s). Last edit at 04/17/14 10:47 by railstiesballast.

These double slip switches are used everyday at LAUPT by both Amtrak and Metrolink. Trains have accidentally been routed the wrong way before. Like a Southwest Chief departing LA and started heading north! Maybe it wanted to be a Coast Starlight instead! :-)

>Yes, they'd use a matrix diagram?

The signal industry has called a "dog chart" for about 120 years.

Go to: www.rrsignalpix.com/grs_prints.html and click on the left image at the very bottom of the page (it will download as a pdf).

It turns out that this is a sort of a mechanical representation of Boolean algebra, first developed in 1847 by George Boole in England. It's also used in the digital logic circuits of the computers all of us use to post on this forum.

EtoinShrdlu Wrote:
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> >Yes, they'd use a matrix diagram?
>
> The signal industry has called a "dog chart" for
> about 120 years.
>
> Go to: www.rrsignalpix.com/grs_prints.html and
> click on the left image at the very bottom of the
> page (it will download as a pdf).
>
> It turns out that this is a sort of a mechanical
> representation of Boolean algebra, first developed
> in 1847 by George Boole in England. It's also used
> in the digital logic circuits of the computers all
> of us use to post on this forum.



The dog chart is the design drawing for the locking. The manipulation chart I referenced is what is displayed in the interlocking station (generally tower but not necessarily) the operator to use. The operator would not generally have access to or know how to use the dog chart.

TAW

I'm late to this party but thanks to Tom White I found this subject. The puzzle in photo 2 is one of the coolest pieces of track I have ever seen. I do not see any moveable points so am wondering if the trolleys using it had a steering wheel to guide them through! Seeing the dual gauge in the background, does anyone know of a dual gauge double slip switch anywhere? That would be incredible.

Seventyfive Wrote:
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> I'm late to this party but thanks to Tom White I
> found this subject. The puzzle in photo 2 is one
> of the coolest pieces of track I have ever seen.
> I do not see any moveable points so am wondering
> if the trolleys using it had a steering wheel to
> guide them through!

Streetcars often used single point switches. There is a point on one rail and the wheel on the opposite rail just follows the route of the wheel moving across the point. You can see the points on the left rail of the track closest to the photographer and the right rail of the next track.

TAW