That would work just as well for other track configurations. Scr4 got it right - the 3 track system has special wheels that ensure each carriage goes where it should, making mechanical switches unnecessary
Jeez, and I thought TvTropes was a time warp. Train videos are even worse.
In the UK the track gauge is 4 feet 8 [sup]1[/sup]/[sub]2[/sub] inches. The rail itself is 2.75 inches wide, and the gap between two running lines is six feet wide. Taking the outside edge of the rails as the outside width of the running lines, that makes the running lines 5 foot 1 wide in total, as opposed to the six foot gap between the tracks.
OK, a few more inches than I first thought - clearance would be tight, but not impossible - but in any case, the sort of usage I was imagining would have been more about gradation of placement, if anyone had need for it. (sounds like not)
There’s no need for active switching if each track of the four-rail section is used in only one direction; just shape the bifurcation point of each rail to direct the wheels of an ascending car one way while accepting the wheels of a descending car entering from the opposite angle.
The cable problem could be overcome by using pulleys to move the lower car’s cable out of the upper car’s way, but I’ll accept that offsetting the travel paths was mechanically more efficient.
The arrangement described by the OP would never be used for several reasons:
-
There is no advantage to it.
-
Trains are run on a “block” system. A block is occupied or not. Only one train can occupy a given block. With adjacent tracks having the possibility of a train on it, how do you define a block?
-
It would be impossible to keep all the tracks in gauge. The distance between the two rails on the same track is crucial. The distance between adjacent tracks, not so much. The multiplied errors across many tracks would be a nightmare.
-
If you look, the distance between the rails of adjacent tracks is greater than the gauge of the rails. This is needed for clearance.
-
I don’t know that it would be possible to construct turnouts to make such an arrangement possible.
There are some bridges where two tracks sort of merge into one to cross the bridge (or tunnel) but these are rare, if still extant at all. It saves maintenance because you don’t need a switch mechanism at each end, but again presents the above block control problem. In that configuration however, each track has it’s own individual set of rails.
And usually the segment through the bridge/tunnel is its own block, just to be clear.
Oh, and to clarify on #4, railroad rails are 4’ 8 1/2" apart, inside to inside. That would leave 2’ 4 1/4" inches for each train’s overhang. A boxcar is about 9 1/2’, so you can see that there would be not nearly enough clearance. There has to be room for the cars to sway, and there needs to be additional space so passing trains do not create a vacuum. If you are riding on a dual track line and a train passes you going the other way, you can feel that vacuum pulling the car towards the other train. The narrower the gap, the more pronounced the effect. In addition, when trains go around curves, the center of the car is farther to the inside of the curve, and the ends are closer to the outside of the curve, so additional spacing is required between tracks in curved sections. Some places, they vary the spacing, allowing more at curved sections than at straight ones, but there would have to be a good reason for them to do this, in most cases, they set an ample spacing and keep it constant over the route, on both straight and curved sections.
I am sure if you look more closely, this is not the case. If it is, I would love to see some pics.
And on reflection, I have never noticed this on an actual railroad, although I am sure there is an example somewhere. It happens on model railroads because space is often an issue, particularly on smaller layouts.
In modeling, we sacrifice realism sometimes to squeeze more stuff in. So we may use closer track spacing than on the “prototype” (model railroad speak for the real thing), especially in yards, and we sometimes use the trick of increasing the spacing on curved track.
Where the real fun comes in is in designing things like yard “throats” as seen here. One way to make a throat is just to have a bunch of switches branching off to one side of what is called the “ladder track” but that wastes space. Notice in the link, each track branches and branches again, saving valuable real estate. It gets interesting when the railroad is using an irregular area to build their yard due to real estate or geography. That is when the guys that do this stuff earn their money, squeezing the most usable yard trackage out of a given parcel.
And I guess this was way TMI, and somewhat off topic, but I like to share my RR knowledge. 
It is still a yard, as far as railroad operations are concerned. Just because it is in a passenger station, does not mean that it cannot have all the features, throat, parallel tracks that can be used to store and sort trains, do engine runarounds, etc., although making up consists is often done at an auxiliary yard a short distance away, in small stations yard type switching can be done right in the train station. That happened more in the old days when railroads had branch lines to every podunk station, though even not much then. Shuffling cars around costs money. So the 5:15 to bumfuck will probably not change the consist for the return trip. They would just have run the locomotive to the head of the train and maybe turn it on a turntable or a “Y” (wye) track in the days of steam.
For example, here in our own Union Station in Los Angeles, there are what are called “escape tracks” so a locomotive can disconnect from one of end of the train and go back out to connect to the other. You can see that here. See the little Y shaped tracks between the platform tracks? And as luck would have it, when the linked image was taken a locomotive was in the spot where that would happen. So that is definitely a yard function. A passenger station is just a yard with platforms next to it, from an operational point of view, no different than if there was a loading ramp in a freight yard.
And escape tracks are hardly ever used anymore. Most of the trains at Union Station are Metrolink diesel commuters and Amtrak local services that run in pushme-pullyou configurations, so there is no need, and the Amtrak long distance trains like the Coast Starlight are made up in a yard a short distance away adjacent to the LA river, where cleaning and maintenance are performed as well. They used to turn the whole train, so the first class sleepers would be farthest away from the engine noise, fumes and horn, but I think they have dispensed with that nicety for cost reasons. Now they just run the loco pair to the other end and call it a day.
On reflection, I think it’s probably a little more than the few inches I estimated initially, but it’s still quite close - less than a foot for sure. You can get a feel for it from the map link I posted in post #8. I’ll get a photo from the window on the way home tonight - from the window of a train, or the station platform, there’s not much discernible difference between the track gauge and the spacing where that beige boarded area is set out.
A miss is as good as a mile.
I see a very normal track arrangement there.
I will be very interested in that in person photo. I would guess that you are seeing an optical illusion. As I look at your link, what I see is that, yes on casual inspection, the rails on adjacent tracks look like they could have he same distance, but they are not. You must consider the width of the rail, angle of the photo, etc. The spacings are not anywhere near equal in the image and you must also realize that, as I said before, a miss is as good as a mile, and there is virtually NO rolling stock that can run on the clearance in your scheme. You will never see this for all the reasons that I have posted upthread, not the least of which is that it is useless, and unmaintainable. Railroads are immensely practical creatures, they don’t waste a move. Take a long distance train sometime and pay attention to what you see outside the window. The whole right of way is a storage yard.
Don’t confuse UK railway practice with US or European continental practice, The width between the tracks in the UK is smaller than elsewhere, because the ‘loading gauge’ is smaller; that is to say, the width of the trains are smaller. Stan Shmenge mentions a width of 9.5 feet for a boxcar; that would be too wide for Britain’s railways, where the loading gauge is generally 9 foot. This leaves a clearance between trains of two feet one inch - an allowance that is necessary to allow for the movement of carriages; this allowance is increased on curves, for obvious reasons).
Note that we are building new lines, like HS1 and the proposed HS2, to the wider European loading gauge, since there are many through trains via the modern Channel Tunnel. There were a few wider lines built in the Victorian era, such as the long-closed Great Central Railway, that was originally intended to link up with a Victorian Channel Tunnel which was not built.
I guessed you might say that, so I took a photo of tracks passing through a station from above (from a footbridge).
Here’s the original image:
http://sdrv.ms/ZNKRzJ
Here’s a section that I rotated so it was straight, then cropped:
http://sdrv.ms/10RQgHd
(right click it and ‘view original’ - something dumb happened to the metadata and it’s appearing on its side)
I drew arrows on the image - the red one from the platform edge to the centre of the first rail, the green one from rail centre to rail centre (i.e. measuring gauge), the blue one from the centre of the outer rail to the centre of the outer rail of the opposing track.
(Ignore the two innermost rails - they’re the live rails for electrified trains)
Then I copied and pasted the arrows over the top of a black rectangle - as you can see, the distance between tracks is not very much greater than the gauge, and the clearance between track and platform is less than half the gauge, therefore, it would be possible (forget the live rails and pretend we’re talking diesel trains) to have the two tracks spaced at exactly the same distance as the gauge and there would still be room for two trains to pass.
In any case, note that the question isn’t even whether it would be practical or safe to do this on through lines - it’s whether anyone has done anything like this, for any reason - maybe even sacrificing clearance, if some other goal took precedence.
The outside width of the running lines is 5’1’', as I’ve posted above. The maximum width of a UK train within UK loading gauge restrictions is 9 feet; the overhang is therefore 1 foot 11.5 inches. The running lines are a mandatory six feet apart; you can’t get any closer under UK law (and note, once again, this distance is significantly smaller than the mandatory distance in Europe and the US on standard track gauge lines).
If you put the running lines 4’8.5’’ apart, so that trains could run in the gap as well, then the overhang of 1 foot 11.5 inches on the two tracks would leave a gap of 9.5 inches. This is not a safe distance, but in the UK it is not actually an impossible distance- trains could just squeeze past at slow speed.
Nowhere on the public railway is there anywhere where this situation exists because it is prohibited by law, but it might possibly exist or have existed inside locomotive carriage or wagon construction factories where space is at a premium. I doubt it, but it is not in theory impossible.
Note that I have seriously simplified the details of loading gauge and track clearances in the UK; if you really want to know it all you can study the Network Rail specifications online
http://www.networkrail.co.uk/aspx/11153.aspx