Spurs on the Takayama Main Line?

[ote-m]

I rode the Limited Express Hida a couple days ago, and while looking through videos and pictures, I remembered seeing a strange spur at every passing loop. This imgur album shows what I mean. My friend suggested that it was for ditching trains in an emergency, but I thought it might have been for eventually double-tracking the line. Any ideas?

[Nick_Burman]

I rode the Limited Express Hida a couple days ago, and while looking through videos and pictures, I remembered seeing a strange spur at every passing loop. This imgur album shows what I mean. My friend suggested that it was for ditching trains in an emergency, but I thought it might have been for eventually double-tracking the line. Any ideas?

 

ote-m,

 

Your friend is right, theses sidings are just in case a train decides to ignore signals. Of course the ATS system will try and stop the train first, but if it fails at least the sidings can (hopefully) divert the train off the path of an oncoming one...

 

 

Cheers NB

[kvp]

Some of the turnouts in the gallery are the ride over type, instead of having proper blades. These typically belong to protection turnouts or catch points, which were very common back when unbraked freight cars were in common use. Their compacter form is a derail, which simply removes any runaway cars from the track. These turnouts are better that the cars are not actually derailed and instead diverted away from the track, so when they run out of track, they won't foul the line. In many cases, only the downhill direction has a protection turnout, since runaway trains tend to roll downhill. Generally these turnouts are thrown together with the signals.

[Densha]

'Funny' with these things is that sometimes they divert trains into buildings... :icon_scratch:

[Mudkip Orange]

"Catch points" in British parlance, "Derailer" in US

[kvp]

 

'Funny' with these things is that sometimes they divert trains into buildings...

Either the buildings were not there when the catch points were constructed or the railway just wanted to comply with regulations, without really thinking it over. (a good example can be seen on the enoden, they aimed for a door) On the other hand, a larger building or a brick or concrete wall can actually stop a runaway train, but not in a good way. Generally there should be a buffer stop or a sand trap and some safety space behind every catch point. Derails just remove the cars from the rails, while keeping them aligned with the tracks, so they don't really need a lot of space. Unfortunately, they are rather ineffective against faster trains and have the already mentioned tendency to foul other tracks.

[westfalen]

A train running into a building at relatively slow speed, as it would be when leaving a passing siding, would be a better outcome than a head on collision between two trains at track speed in the middle of the single track section.

[marknewton]

"Catch points" in British parlance, "Derailer" in US

 

If these were on a British railway they'd be referred to as trap points.

 

Cheers,

 

Mark.

[marknewton]

Some of the turnouts in the gallery are the ride over type, instead of having proper blades. These typically belong to protection turnouts or catch points, which were very common back when unbraked freight cars were in common use. Their compacter form is a derail, which simply removes any runaway cars from the track. These turnouts are better that the cars are not actually derailed and instead diverted away from the track, so when they run out of track, they won't foul the line. In many cases, only the downhill direction has a protection turnout, since runaway trains tend to roll downhill. Generally these turnouts are thrown together with the signals.

 

The trap points shown in these photos have nothing to do with "unbraked freight cars" or "runaway trains rolling downhill". They're intended to prevent a train from SPADing the home starter signal at the exit end of a crossing loop and entering the section without authority, against an opposing movement. As Nick and Westfalen have both already stated, their purpose is to prevent a collision. And I can tell you from bitter personal experience that when you run your train past a signal at stop and through a set of trap points you WILL be derailed. And these trap points, like any other turnouts, will ALWAYS be set BEFORE the signal can be cleared.

 

And FWIW, there weren't too many unbraked freight cars in common use on the JGR/JNR. Vacuum brake was in use from about 1880 onwards on the Government lines, until replaced by air brake between 1919 and 1930.

 

Cheers,

 

Mark.

[kvp]

 

They're intended to prevent a train from SPADing the home starter signal at the exit end of a crossing loop and entering the section without authority, against an opposing movement. 

Yes, in modern times, this is one of the main use for them. However the availability of modern ATS systems, like indusi (1934) and integra signum (1933) made the SPAD prevention feature largely useless in most countries that actually use them. They are still used in Europe in modern setups, but nowdays only at yard exits as a way to prevent unbreaked or unmanned runaways. Any freightcar or passenger coach without a spring force storage or manually fixed parking brake will roll away if left on its own for an extended time. On the other hand, unmanned runaways usually happen with trams without a deadman's handle and when catenary power is turned on in a yard, any tram left in drive will start to move. A third use is at the exits of shunting areas, where the end of a train could cut a turnout and foul a mainline without the driver on the other end noticing it.

 

The design of the catch points or derails determine if the vehicle will be derailed before hitting the buffer stop. A derail always derails the wheels, while slide over catch points may or may not derail the wheels (they are also used in the USA and Japan for less used maintenance sidings), and conventional turnouts used as catch points (prussian practice) will usually not derail the train if it's not moving too fast for the turnout. Not derailing the wheels have the added benefit, that if the driver is going slow enough, then it's possible to stop the train before hitting the buffer or the sand/gravel trap and it also allows to divert the train away from the main before actually derailing it.

[marknewton]

Yes, in modern times, this is one of the main use for them. 

 

These days that's the only use for them.

 

However the availability of modern ATS systems, like indusi (1934) and integra signum (1933) made the SPAD prevention feature largely useless in most countries that actually use them.

 

That's irrelevant, as neither system is in use in Japan and incorrect, since SPAD prevention is the last line of defence when everything else fails - the belt and braces approach. Prevention of collisions following SPADS is never a useless feature. 

 

They are still used in Europe in modern setups, but nowdays only at yard exits as a way to prevent unbreaked or unmanned runaways.

 

Agreed, but we weren't discussing European setups, though. The question was specifically about the purpose of these trap points used on this line in Japan. And the answer is preventing a collision after a SPAD.

 

Any freightcar or passenger coach without a spring force storage or manually fixed parking brake will roll away if left on its own for an extended time.

 

Any vehicle without a working park brake will be chocked, chained, spragged or otherwise secured against moving. That's the practice world-wide, and has been for many years. And again, it's irrelevant to the subjetc being discussed.

 

On the other hand, unmanned runaways usually happen with trams without a deadman's handle and when catenary power is turned on in a yard, any tram left in drive will start to move.

 

Now you're just being silly. Under what circumstances do you imagine that would happen?

 

The design of the catch points or derails determine if the vehicle will be derailed before hitting the buffer stop. A derail always derails the wheels, while slide over catch points may or may not derail the wheels (they are also used in the USA and Japan for less used maintenance sidings), and conventional turnouts used as catch points (prussian practice) will usually not derail the train if it's not moving too fast for the turnout.

 

By definition, derails and catchpoints are both designed to derail a train. Speed through conventional turnouts used as trap points is not what will derail you - the sudden end of the track will. Look at the length of overun in all these photos - there's about half a car length. if you're going fast enough to SPAD, you'll run off the end of the track. Trains don't stop anywhere near as quickly as you seem to think they do.

 

Not derailing the wheels have the added benefit, that if the driver is going slow enough, then it's possible to stop the train before hitting the buffer or the sand/gravel trap and it also allows to divert the train away from the main before actually derailing it.

 

I can tell from your comments that you have no actual experience of running a train past a signal at stop. I have. I've had three SPADS over a 39 year career. In one incident I went through catchpoints - my train was derailed. In another I went through trap points - and again my train was derailed. In both cases I wasn't doing much more than walking pace, but I couldn't stop the train in time to avoid a derailment. So please don't presume to tell me what happens during a SPAD, or what the driver can and can't do. I know from first-hand experience.

 

Cheers,

 

Mark.

[Mudkip Orange]

I can tell from your comments that you have no actual experience of running a train past a signal at stop ... please don't presume to tell me what happens during a SPAD, or what the driver can and can't do.

 

OH SNAP

Edited November 29, 2014 by Mudkip Orange

[kvp]

Imho using red text and supercilious language isn't nice on a forum or anywhere. On the other hand, i think i clearly indicated when i talked about japanese or european practice. For a japanese example, on the Hakone Tozan the catch points are mostly installed on the downhill side only, which would suggest the intention to stop runaways, instead of enforcing signals.

 

Also calling a common problem silly is imho not really the correct way. Maybe it's not a problem in japan or other parts of the world, but trams trying to leave the depot without their drivers still happens in Hungary, especially at older depots where there is nothing to stop them. The oldest non museum equipment still in use was made in 1926 and there are also historic trams (even older ones) running every summer on many lines. And guess which new tram didn't get a proper dead man's controller? Yes, the new siemens combinos... (this year one managed to cross a point at 60 km/h in the diverging direction and stop at the buffer without derailing, but the first car got significantly compacted, luckily noone was on board, so nobody got hurt)

 

Third, the fact that someone has personal experience of driving a train past a signal and derailing (twice) does not mean it's always the case. Most of the time when i'm on a train that has a SPAD situation, the usual handling is an emergency stop. This was achived in Hungary by using a speed control system, where a signal can not be normally approached faster than the allowed stopping distance. Doing so would also result in an emergency brake application. In Hungary (not Japan!) dangerous SPAD-s are handled by stopping all trains in the whole signal district. Usually this results in trains stopping a few 100 meters before a head on collision, but no derailed trains. This allows the train which caused the stop to back up behind the signal. Also, this kind of error usually makes it into the evening news a couple of times a year. On the other hand, SPAD-s in the metro system is very common and handled as a normal automatic stop. The result is a train stuck in the tunnel until the line becomes clear before it.

 

Imho stating that all vehicles without active parking brakes are always safeguarded against rolling away everywhere in the world is simply not true. There was a runaway in Canada that leveled a small town, where only a few hand brakes were active and the train rolled away when the air ran out. Also, it's very common in Hungary that coaches in a storage yard go for a walk, when the shunting crew decides that for a few hours, the air brakes would hold, so they don't use the hand brakes. Actually one of my favourite things is to watch trains at Budapest Nyugati station. This ancient terminal is still operated by hand levers and secured by a domino 55, while being one of the busiest commuter stations in Hungary. Since i was a kid, i just like to hang out on the bridge above the station and watch the trains go by. Also, from there i can see into the signal tower too. The most common accidents are cut turnouts, coaches running away during shunting and the most spectacular, when someone throws a switch under a train in the yard and one of the cars get parked on two tracks at the same time. The Nyugati storage yard has a catch point on its exit side (towards the station) and i've seen quite a few shunt movements taking the catch direction. This is usually ok, since they can stop in time, except when someone manages to park a locomotive on the short stub track under the bridge, clearly marked as not a storage area. (it's shorter than a coach, so only shorter locomotives fit and it has a sand trap at the end instead of a buffer stop)

[miyakoji]

Gentlemen, gentlemen...

 

Or as Captain Hastings says, "I say, steady on, old chap" :)

Edited October 28, 2014 by miyakoji