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Equilateral switches in Japan

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Equilateral switches in Japan

Unread postby DSKYNS » Sun Jan 22, 2017 9:53 am

How do you do?

I am a rail lover writing from Japan.

I have a long-standing question about railway switches.

In Japan, wye (equilateral) switches are commonly used in stations with passing loops on single-track sections (for example, https://upload.wikimedia.org/wikipedia/ ... _eki_1.jpg), but I have rarely seen such designs in British or other Western railway stations.

During the expansion of railway networks in the late 19th century, Japanese engineers mainly followed British practices: left-hand traffic, elevated platforms, and station track layouts. It appears that wye switches were introduced independently by the government railway management (the Imperial Railway Bureau) after railway nationalization in 1907. One of the possible reasons is to prevent derailing.

I would appreciate any information on the use of wye switches in British railway system/history.
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Re: Equilateral switches in Japan

Unread postby JRB » Sun Jan 22, 2017 6:42 pm

Symmetrical points. Not our custom indeed. Why indeed?
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Re: Equilateral switches in Japan

Unread postby Frank » Sun Jan 22, 2017 7:29 pm

Hello DSKYNS,

the origin of the wye switch (or sometimes also called Y-Switch) goes to the former Austria-Hungary Monarchy.
Because this type of switch need less space then other switches for a resonable speed in such cases as a loop.
Also it is a cheap one.
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Re: Equilateral switches in Japan

Unread postby DSKYNS » Mon Jan 23, 2017 5:27 pm

Hello JRB,

I used to have an impression that Y switches are as common in the UK as in Japan
because various Y switches are in the PECO catalogue, but I was wrong.

Thanks Frank,

Following your information I read a bit about the Semmering pattern.
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Re: Equilateral switches in Japan

Unread postby scarpa » Tue Jan 24, 2017 8:28 am

They do exist in the UK handpoints in particular and I have seen power operated Y switches.
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Re: Equilateral switches in Japan

Unread postby John Webb » Tue Jan 24, 2017 10:11 am

'Y' points are probably more common in model railways than in the British prototype, hence their presence in Peco and other catalogues. They are compact, and as most railway modellers are trying to work in a limited space, they often tend to deviate from the prototype's practice to squeeze in the maximum of track that they can!
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Re: Equilateral switches in Japan

Unread postby Mike Hodgson » Tue Jan 24, 2017 2:28 pm

This does not strike me as a signalling question but more of a PW matter.

The railway does not course buy its points from Peco. They are not produced as a limited range of radii, they are made to suit the situation on the ground. Set track is a modelling compromise necessary to enable products to be available commercially off the shelf. It is true that we generally use points with one straight (or at least straighter) leg, with that route generally being the more important. This allows us to run faster on the main, albeit at the expense of more severe restriction over the crossover or less important/less frequently used route, as hinted at by Frank. There are certainly cases where a wye is preferable, but in many low-speed cases it probably makes little difference which type is used.
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Re: Equilateral switches in Japan

Unread postby Bob Davies » Tue Jan 24, 2017 2:39 pm

The only uses of 'Y' points in the UK that I can think of are entry/exit to sidings placed between running lines (usually for terminating trains to run into/out of) - London Underground have quite a lot of these but you do also find them on Network Rail - and in marshalling yards on hump lines so that the resistance for wagons running in any direction was largely the same.

I am not a permanent way engineer but my suggestion is that a 'Y' point imposes a speed restriction and rail wear whichever way you are travelling, whereas a 'normal' (in British terms) point has no speed restriction and has no resulting side wear in the straight-ahead direction, albeit at the cost of a greater speed restriction in the diverging direction. However, if 90% of trains keep straight on and only 10% get diverted, that is probably a price worth paying.

I accept however that this logic does not really apply on loops on single lines but I would suggest (and wait to be shot down) that, if no other factors come into play (big IF), then the most common layout in the UK is to have the 'straight on' direction for trains entering a loop and the 'diverging' direction for trains leaving the loop, which goes back to the relative speeds of arriving and departing trains in steam days. I do however have a vague recollection that in the early days of self-operating hydro-kinetic points on single lines back in the 1980's, some loops did get re-laid with 'Y' points but that might be a false memory.
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Re: Equilateral switches in Japan

Unread postby DSKYNS » Tue Jan 24, 2017 3:11 pm

So, the widespread use of Y switches is “endemic” at least to Japan’s national railway network (I mean the conventional 3'6" network, not Shinkansen). I have prepared a graphic illustrating the changes in station layout in Japan: http://s345.photobucket.com/user/Daisuk ... n.jpg.html?
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Re: Equilateral switches in Japan

Unread postby Nicko » Tue Jan 24, 2017 5:47 pm

I believe there is a set North of rugby ration that have equal speeds in excess of 100 mph for each direction
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Re: Equilateral switches in Japan

Unread postby Mike Hodgson » Tue Jan 24, 2017 7:56 pm

Bob Davies wrote:The only uses of 'Y' points in the UK that I can think of are entry/exit to sidings placed between running lines (usually for terminating trains to run into/out of)
.

Even these may sometimes be "wide to gauge" traps -ie the blades do not move as a pair in the usual manner, but rather one only blade moves together with the platform point as a crossover when required to enter/leave the centre siding) where a derailment to the left would foul one platform and to the right would foul the other. If
both platforms are set for the normal straight route, the wye point is pigeon toed and any runaway should be dropped into the dirt but remain (hopefully) central and clear of the running lines.
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Re: Equilateral switches in Japan

Unread postby StevieG » Tue Jan 24, 2017 11:46 pm

Nicko wrote:I believe there is a set North of rugby ration that have equal speeds in excess of 100 mph for each direction
Correct. At Trent Valley Jn., in the Down Fast IIRC, being the Cov./ Birm. and Trent Valley (Nuneaton etc.) split : 125mph both ways IIRC: ('J' switches in PWay-speak, I think).

Ditto (or very similar) at Colton Jn., south of York (Up Fast IIRC), being the split for Doncaster / Leeds.

However, without discussion of the signalling associated with such junctions, I support Mike Hodgson's comment that this is not a signalling topic.
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