Stopping a runaway train.

[notadriver]

Thanks people. I know it's all unlikely to happen especially the hijack/rogue driver with a death wish.

I've not been on many fast trains in my life and I'm hoping to try a Pendolino next week from Preston forward facing (last time I did it 5 years ago I was rear facing, and the tilt made me feel quite sick).

Quite scary at 120mph and you're not in control. Being a car driver I'm a bad passenger. LOL

Hello Shakey1961

It's interesting to hear someone with a different view point. I just wondered when you're a car passenger do you prefer to sit at the front so you can keep an eye on the driver and the speed they are doing ? Does the same apply if you are travelling in a bus or coach ?

I ask because I know someone who is quite scared of trains - to the point he won't travel on them because he's unable to have a 'front seat' view like you can get in a road vehicle and sit up front to monitor the driver and keep an eye on their speed. He's actually a driving instructor. Speed kills he says and there is no way he ever wants or needs to go faster than 70 mph on any form of transport so he doesn't(!!)

 

[SPADTrap]

Does he not mean from the train pipe and therefore allowing via the triple valve the reservoir air pressure to be applied to the braking sytem?

I hope so

 

[Jamesb1974]

Does he not mean from the train pipe and therefore allowing via the triple valve the reservoir air pressure to be applied to the braking sytem?

Yes, that is what I meant. Poorly worded by me. I should have said a reduction in brake pipe pressure applies the brakes. I was attempting to keep things simple for the benefit of the OP who said he had no knowledge.

 

[mtbox]

Not on what I drive.

On dmus I sign, (142, + 150 series) the air brake works in a completely different way to the air brakes on freight and loco hauled stock which have the conventional air pipe running the length of the train, triple valves, brake res etc.

On these units, (westcode 3 step brake) air pressure is distributed by the (electrically controlled) brake control unit to the brake cylinders to apply the brakes, brake release is simply by releasing air pressure from the brake cylinder, so they work in a way like a locomotives straight air brake.
These units do not have an air train pipe, they have a main res pipe running through the train which supplies air to everything that needs it, including the brakes. Brake control is by sending electrical signals from the brake handle to the brake control unit, which then distributes air at the selected "step" to the brake cylinders.

 

[Railsigns]

The TPWS arming loops and trigger loops are physically spaced a measured distance apart to provide the required 'set speed' for each installation. These are known as 'over-speed sensors' or OSS, although this is a misnomer because the TPWS track equipment doesn't do any 'sensing', only transmitting.

Indeed, which is why OSS and TSS officially stand for Overspeed System and Train Stop System, respectively.

Those stop signals (and some others) will also have TPWS 'train stop sensors' (TSS) fitted which are basically an arming and trigger loop butted right up to each other, effectively giving a set-speed of zero miles per hour.

An energised TSS arming loop doesn't start the 'trigger delay timer' on board the train - only an OSS arming loop will do that. Hence, 'set speed' isn't relevant at a TSS.

Finally, TPWS isn't intended to stop spads from happening, but is designed to stop trains within a safe margin beyond main aspect running signals (known as the 'overlap') at approach speeds up to 75mph. Beyond 75mph the system still works but variables and parameters can't guarantee that the overlap won't be exceeded.

TPWS can be made effective at any realistic approach speed by adding extra loops (TPWS+) or in conjunction with controls such as Conditional Double Red. TPWS is only designed to stop the train before the first conflict point (ignoring rear-end collisions), which can be hundreds of metres beyond the overlap.

TPWS OSS approaching buffer stops are always set at 10mph. These loops approaching buffer stops are smaller than standard loops, this is to reduce the margin of inaccuracy which would result if the full-size loops (with a greater transmitting area) were used.

The standard set speed at buffer stops was increased to 12.5 mph several years ago, and this may be increased further if the loops cannot be placed in the standard position. The smaller loops are used to overcome a timing issue that can occur if the gap between the arming and trigger loops is shorter than the distance that either loop is detected by the train, which at low speeds can result in the trigger delay timer completing its cycle and starting again, leading to a false intervention.

 

[edwin_m]

Notwithstanding trains carrying inherently dangerous loads, like nuclear or chemical stuff, surely the damage someone could do with a hijacked train would be limited to wherever and whatever the signaller and/or aforementioned equipment lets them?

By the sounds of what's posted above, the hijacker would very quickly become a sitting duck in an immobile train.

Probably so. As I said, I'm not going to go into any details on a public forum.

 

[PaxVobiscum]

... a break in the brake pipe etc would discharge all the air from the system and apply the brakes ....

See how you spell it folks?

On this thread, no problems.

On many others ... Gie's a brake, guys!

Spot the deliberate mistake?

 

[Zoidberg]

See how you spell it folks?

On this thread, no problems.

On many others ... Gie's a brake, guys!

Spot the deliberate mistake?

What deliberate misteak?

 

[Llama]

Indeed, which is why OSS and TSS officially stand for Overspeed System and Train Stop System, respectively.

Not according to RS/522, the driver's manual.

An energised TSS arming loop doesn't start the 'trigger delay timer' on board the train - only an OSS arming loop will do that. Hence, 'set speed' isn't relevant at a TSS.

So how come there are arming loops and trigger loops at a TSS with their own separate frequencies?

TPWS can be made effective at any realistic approach speed by adding extra loops (TPWS+) or in conjunction with controls such as Conditional Double Red. TPWS is only designed to stop the train before the first conflict point (ignoring rear-end collisions), which can be hundreds of metres beyond the overlap.

Yes, if we are going to go deeper into the features, that could be mentioned but still works in the same way, just at different locations.

The standard set speed at buffer stops was increased to 12.5 mph several years ago, and this may be increased further if the loops cannot be placed in the standard position. The smaller loops are used to overcome a timing issue that can occur if the gap between the arming and trigger loops is shorter than the distance that either loop is detected by the train, which at low speeds can result in the trigger delay timer completing its cycle and starting again, leading to a false intervention.

Are you sure about that? Maybe in some locations there are some set above 10mph but not where I drive, we deal with the fall-out from OSS trip incidents often enough. Plus the 10mph is shown with all the other set speeds in the SSIs. By rights a driver traversing an OSS at 11 or 12mph should ring in and report a wrong side TPWS failure (code 16) although we know that drivers are unlikely to do that in practice.

 

[Railsigns]

Not according to RS/522, the driver's manual.

The relevant design standards have always used the descriptions "Train Stop System" and "Overspeed Sensor System". More recently, it has been officially recognised that "sensor" is a misnomer (as you've noted) and the change of designation to "Overspeed System" has been briefed to design staff. The new terminology is reflected in issue 2 of Technical Instruction TI 022.

So how come there are arming loops and trigger loops at a TSS with their own separate frequencies?

OSSs and TSSs both share the same trigger loop frequencies. The arming loop frequencies are different because they each start a different process on board the train. Only an OSS arming loop will start the trigger delay timer.

Are you sure about that? Maybe in some locations there are some set above 10mph but not where I drive, we deal with the fall-out from OSS trip incidents often enough. Plus the 10mph is shown with all the other set speeds in the SSIs. By rights a driver traversing an OSS at 11 or 12mph should ring in and report a wrong side TPWS failure (code 16) although we know that drivers are unlikely to do that in practice.

I'm absolutely sure. The minimum set speed was raised from 10 mph to 12.5 mph several years ago (achieved by increasing the arming/trigger loop separation from 4.5 m to 5.5 m). There may still be some buffer stop fitments around that haven't yet been adjusted but I would expect those to be in a minority.

 

[Llama]

Fair enough, obviously the terminology will differ between technical and operations staff. Driver managers do try to perpetuate the myth that the system knows when drivers have caused a TPWS activation in an attempt to reduce TPWS R&C incidents, this is perhaps abetted by the fact the publications (both from RSSB and TOCs/FOCs) almost universally refer to OSS/TSS as 'sensors'.

 

[SPADTrap]

On dmus I sign, (142, + 150 series) the air brake works in a completely different way to the air brakes on freight and loco hauled stock which have the conventional air pipe running the length of the train, triple valves, brake res etc.

On these units, (westcode 3 step brake) air pressure is distributed by the (electrically controlled) brake control unit to the brake cylinders to apply the brakes, brake release is simply by releasing air pressure from the brake cylinder, so they work in a way like a locomotives straight air brake.
These units do not have an air train pipe, they have a main res pipe running through the train which supplies air to everything that needs it, including the brakes. Brake control is by sending electrical signals from the brake handle to the brake control unit, which then distributes air at the selected "step" to the brake cylinders.

Same the EMUs I sign.

 

[sarahj]

As a conductor i know ways and means of stopping a train that the driver cannot override, but I will never discuss them on a open forum.

 

[jon0844]

As a conductor i know ways and means of stopping a train that the driver cannot override, but I will never discuss them on a open forum.

Tell him/her they're over their hours?

 

[Flamingo]

Tell him/her they're over their hours?

Don't bring them their cup of tea...

 

[clc]

When that high speed train derailed in Spain recently should the systems have spotted that it was going to fast for the bend and applied the brakes?

 

[shakey1961]

Thanks for all your replies guys. It's most comforting to know that it's almost impossible to have a runaway passenger train. I mean, what can happen between Preston and Wigan North Western and back again.

I have no trouble being on a train passenger, positively enjoy it, but I've not been in the best of health through mis-diagnosis by my doctor for 36 years. Now I know what's wrong and I'm cured, I'm trying to build my confidence back. I started back on Merseyrail, though even that was a bit difficult at first, but that's like falling off a log now.

Being the railway fan I am, 5 years ago, before I was cured, I just fancied a trip on the Pendolino, once again Preston to Wigan NW. Had no idea what to expect. Train was packed (it was early September) and the only seats available were rear facing. As it got too fast to look out the window I though I'd just look inside the carriage - and that's when it tilted. Oh dear! Never been one to be dizzy travelling but this wasn't nice and I was stuck.

I'd worked out that if we could time it right we could immediately get the next Pendo back and as luck would have it, as we arrived at Wigan NW the return Pendo was at the platform, so we ran through the subway to the other platform and managed to jump on the last door that was closing, only to once again have the only choice of a rear facing seat LOL!! Typical!

So... I'm willing to give it one more go, but I MUST have forward facing.

If that's ok, then the world is my oyster, well at least south of Wigan NW.

 

[Llama]

When that high speed train derailed in Spain recently should the systems have spotted that it was going to fast for the bend and applied the brakes?

Yes, there should have been a system there which could intervene to reduce train speed within an acceptable margin, but there wasn't.

 

[Hadders]

Thanks for all your replies guys. It's most comforting to know that it's almost impossible to have a runaway passenger train. I mean, what can happen between Preston and Wigan North Western and back again.

I have no trouble being on a train passenger, positively enjoy it, but I've not been in the best of health through mis-diagnosis by my doctor for 36 years. Now I know what's wrong and I'm cured, I'm trying to build my confidence back. I started back on Merseyrail, though even that was a bit difficult at first, but that's like falling off a log now.

Being the railway fan I am, 5 years ago, before I was cured, I just fancied a trip on the Pendolino, once again Preston to Wigan NW. Had no idea what to expect. Train was packed (it was early September) and the only seats available were rear facing. As it got too fast to look out the window I though I'd just look inside the carriage - and that's when it tilted. Oh dear! Never been one to be dizzy travelling but this wasn't nice and I was stuck.

I'd worked out that if we could time it right we could immediately get the next Pendo back and as luck would have it, as we arrived at Wigan NW the return Pendo was at the platform, so we ran through the subway to the other platform and managed to jump on the last door that was closing, only to once again have the only choice of a rear facing seat LOL!! Typical!

So... I'm willing to give it one more go, but I MUST have forward facing.

If that's ok, then the world is my oyster, well at least south of Wigan NW.

Sorry to hear about your difficulties and glad that you're going in the right direction.

I'd get seat reservations via a station, that way they should be able to make sure you get a seat that suits you, ie. forward facing and one by a window.

You might also want to consider going 1st class for the extra space and ambiance. A 1st class carriage certainly won't get wedged like standard sometimes can be. Standard class day return between Wigan and Preston is £7.60, 1st class is £19.80.

 

[SpacePhoenix]

When that high speed train derailed in Spain recently should the systems have spotted that it was going to fast for the bend and applied the brakes?

How would they do that? Possibly two sets of axle counters, a certain distance apart. If the train passes by both sets quicker then a certain time then use something like TPWS to trigger a full emergency stop which can't be over-ridden by the driver with some sort of message to the signalman (who would probably give the driver a serious bollocking)

 

[najaB]

How would they do that? Possibly two sets of axle counters, a certain distance apart. If the train passes by both sets quicker then a certain time then use something like TPWS to trigger a full emergency stop which can't be over-ridden by the driver with some sort of message to the signalman (who would probably give the driver a serious bollocking)

No need to invent a new system - ATP as implemented on the GWML would have done it. ETCS level 2 does it as well.

 

[edwin_m]

The irony of the Spanish derailment was that a train protection system was fitted on the high speed section which would have prevented overspeeding, but the derailment took place on the first tight curve after the end of the high speed line, which was also the end of the train protection system.

 

[Llama]

No need to invent a new system - ATP as implemented on the GWML would have done it. ETCS level 2 does it as well.

A simple TPWS-style installation could have prevented the incident too.

 

[broadgage]

As others have posted, an accidental run away of a passenger train is virtually impossible, even if the driver be suddenly taken ill.
Safety systems exist for exactly the purpose of preventing a train running unhindered to its destruction.

As regards deliberate action, perhaps as a result of terrorists hijacking a train, then IF they knew how to bypass or isolate the various safety systems, then I believe that a serious disaster could follow but is not that likely.
The guard might realise what was happening and apply the brake.
Off duty staff might well be in the rear cab and apply the brake.
Knowledgeable passengers or off duty staff might force open a door, which on some trains at least applies the brakes.
A 999 call might result in the traction current being turned off in time, or even conceivably in the armed forces disabling the train from the air.

From the point of view of the terrorists, a lot could go wrong and they would probably concentrate their resources on more conventional modes of attack that have previously been proved effective.

Even in todays troubled world, rail has an excellent safety record and rail accidents are a long way down my list of things to worry about.
A deliberate attack as distinct from an accident is slightly more worrying, but not much.
Walking or driving to the station is arguably more dangerous.

 

[tsr]

It is also the case that it is a lot quicker to stop a train if you are attacked than landing a plane.

Stopping a train in an emergency can in many cases involve the simple matter of pushing a button or lever. Even if someone is threatening you, it's very quick and, on some stock, some methods are even quite subtle at first. By the time any terrorists could force their way into the cab, remove the driver, diagnose what was done and get the thing moving again, chances are there would be reactions already in place. That's if they hadn't already tripped over the driver's bag or had a t-key shoved up their nostril.

Yes, stopping a train in a controlled manner at a signal or platform takes considerable skill each and every time. But an emergency stop in a randomly selected location involves somewhat less skill, in most cases.

Much scarier is a driver who deliberately wanted the train to run away, or an accidental runaway of an unbraked vehicle. The latter probably causes the highest realistic level of risk. Even with various safety systems being overriden, there are often still ways to stop a train driven out of rational control, forcibly or otherwise, especially if you know where to go to access electronics which are prevalent in much of today's stock. No, I am not going to go into stock-specific details on here. All you need to hope is that there is at least one person competent in using said electronics or switchgear onboard - quite a high chance on many lines, especially higher-speed ones.

 

[RailAleFan]

As it got too fast to look out the window I though I'd just look inside the carriage - and that's when it tilted. Oh dear! Never been one to be dizzy travelling but this wasn't nice and I was stuck.

It may be entirely my imagination, but I'm sure it's a smoother ride in a Pendolino towards the rear of the train.

I often travel at the very front for my short hop to Liverpool and the titling action is very pronounced, but on my London trips, when normally travelling towards the back it seems to be a much smoother ride.

 

[shakey1961]

So... as I was saying about a rogue driver....

How awful for the passengers on the plane

 

[GB]

Yes but gravity (among other things) is on your side on the railway.

 

[Minilad]

Yes but gravity (among other things) is on your side on the railway.

Down the Lickey Bank

 

[GB]

Lol, yes fair point