Could a train deploy an emergency dragging anchor of some sort, or a dragging wheel on the ballast?

[kermit]

This frightening incident has thrown a spotlight on the whole issue of stopping a train in an emergency.

My thoughts are with the injured driver, the staff and passengers on the trains, and all those affected in so many ways. As bad as it has been, there is an awareness that it could have been even worse.

So, a thought occurs; has there been any research into the possibility of stopping, or slowing, a train in an emergency situation by other means than slowing the steel wheel on the steel rail?

Whatever the cause of this incident turns out to have been, we have heard from drivers and others who have witnessed similarly frightening incidents despite multiple mitigations such as sand, rail head treatment, etc etc. It is reasonable to suppose that something like this will happen again, particularly in our damp climate with deciduous trees.

If you had suggested to me, when I owned a Morris Minor in the 70s, that I would one day drive a car that deployed airbags in the event of a collision, and that this innovation would save many lives and inhibit serious injuries, I would have scoffed.

Could a train deploy an emergency dragging anchor of some sort, or a dragging wheel on the ballast? It might not be good for the track, but is that worth it if a collision is avoided, or the impact reduced?

 

[MotCO]

This frightening incident has thrown a spotlight on the whole issue of stopping a train in an emergency. My thoughts are with the injured driver, the staff and passengers on the trains, and all those affected in so many ways. As bad as it has been, there is an awareness that it could have been even worse. So, a thought occurs; has there been any research into the possibility of stopping, or slowing, a train in an emergency situation by other means than slowing the steel wheel on the steel rail? Whatever the cause of this incident turns out to have been, we have heard from drivers and others who have witnessed similarly frightening incidents despite multiple mitigations such as sand, rail head treatment, etc etc. It is reasonable to suppose that something like this will happen again, particularly in our damp climate with deciduous trees. If you had suggested to me, when I owned a Morris Minor in the 70s, that I would one day drive a car that deployed airbags in the event of a collision, and that this innovation would save many lives and inhibit serious injuries, I would have scoffed. Could a train deploy an emergency dragging anchor of some sort, or a dragging wheel on the ballast? It might not be good for the track, but is that worth it if a collision is avoided, or the impact reduced?

Or electro-magnets to create 'friction' along the rail?

 

[357]

Or electro-magnets to create 'friction' along the rail?

I believe some trams use this system

 

[MarkyT]

This frightening incident has thrown a spotlight on the whole issue of stopping a train in an emergency. My thoughts are with the injured driver, the staff and passengers on the trains, and all those affected in so many ways. As bad as it has been, there is an awareness that it could have been even worse. So, a thought occurs; has there been any research into the possibility of stopping, or slowing, a train in an emergency situation by other means than slowing the steel wheel on the steel rail? Whatever the cause of this incident turns out to have been, we have heard from drivers and others who have witnessed similarly frightening incidents despite multiple mitigations such as sand, rail head treatment, etc etc. It is reasonable to suppose that something like this will happen again, particularly in our damp climate with deciduous trees. If you had suggested to me, when I owned a Morris Minor in the 70s, that I would one day drive a car that deployed airbags in the event of a collision, and that this innovation would save many lives and inhibit serious injuries, I would have scoffed. Could a train deploy an emergency dragging anchor of some sort, or a dragging wheel on the ballast? It might not be good for the track, but is that worth it if a collision is avoided, or the impact reduced?

Due to having to run amongst road traffic and pedestrians, trams often have magnetic track brakes, where electromagnetic attraction forces a skate on each bogie, with a much greater contact area than the tiny wheel contact patch, down onto the rail surface for emergency braking. There are also eddy current brakes used on high speed trains in Germany as an example. These don't make physical contact like the magnetic brakes but induce a current in the rails that reacts with a field generated on the train to produce a braking effect not reliant on friction, but only effective at speed so no good for final stopping.

 

[Annetts key]

This frightening incident has thrown a spotlight on the whole issue of stopping a train in an emergency. My thoughts are with the injured driver, the staff and passengers on the trains, and all those affected in so many ways. As bad as it has been, there is an awareness that it could have been even worse. So, a thought occurs; has there been any research into the possibility of stopping, or slowing, a train in an emergency situation by other means than slowing the steel wheel on the steel rail? Whatever the cause of this incident turns out to have been, we have heard from drivers and others who have witnessed similarly frightening incidents despite multiple mitigations such as sand, rail head treatment, etc etc. It is reasonable to suppose that something like this will happen again, particularly in our damp climate with deciduous trees. If you had suggested to me, when I owned a Morris Minor in the 70s, that I would one day drive a car that deployed airbags in the event of a collision, and that this innovation would save many lives and inhibit serious injuries, I would have scoffed. Could a train deploy an emergency dragging anchor of some sort, or a dragging wheel on the ballast? It might not be good for the track, but is that worth it if a collision is avoided, or the impact reduced?

But keep in mind that whatever system is proposed, it must not endanger the train it is fitted to or other trains, interfere with any of the existing signalling equipment systems (including the many types of track circuits, axle counters, hot axle box detectors, AWS, TPWS, ATP, ETCS/ERTMS, signal data links, signalling remote control systems, points including the electrical motors and their mechanisms) and must not cause too much damage to the track.

Hence it’s a much more complex subject than it looks at first sight. I’m most certainly not saying something can’t be done. But that it’s not easy.

 

[21C101]

This frightening incident has thrown a spotlight on the whole issue of stopping a train in an emergency. My thoughts are with the injured driver, the staff and passengers on the trains, and all those affected in so many ways. As bad as it has been, there is an awareness that it could have been even worse. So, a thought occurs; has there been any research into the possibility of stopping, or slowing, a train in an emergency situation by other means than slowing the steel wheel on the steel rail? Whatever the cause of this incident turns out to have been, we have heard from drivers and others who have witnessed similarly frightening incidents despite multiple mitigations such as sand, rail head treatment, etc etc. It is reasonable to suppose that something like this will happen again, particularly in our damp climate with deciduous trees. If you had suggested to me, when I owned a Morris Minor in the 70s, that I would one day drive a car that deployed airbags in the event of a collision, and that this innovation would save many lives and inhibit serious injuries, I would have scoffed. Could a train deploy an emergency dragging anchor of some sort, or a dragging wheel on the ballast? It might not be good for the track, but is that worth it if a collision is avoided, or the impact reduced?

In the dark days of yore, trains had cast iron clasp brakes. These were incredibly efficient at low speeds and both burned the muck off wheels and roughed up their metal surfaces. It was common for trains like 4-SUBs to run into a station at line speed and stop in the platform length.

Then experts got involved and replaced the cast iron with a composite material that didn't leave brown gunge everywhere, but didn't work so well.

Then more experts got involved who discovered that disc brakes work better at high speed and trains were then built with disc brakes instead. Unfortunately they are not so good at low speeds, don't clean gunk off the wheels and dont scuff the wheels which get polished from running on rails.

Recently the Germans got involved and were asked to procure a train for Thameslink. They looked at the performance requirements and came up with the rather logical solution of putting disc brakes on some of the wheels and clasp brakes on the others. Unfortunately only the Thameslink and City Beam trains have both disc and clasp brakes, just about everything else these days only has disc brakes.

London Underground know a few things about how to run a railway. They never stopped using clasp brakes. Their trains still rush into stations at near enough line speed and stop in the platform length.

Those calling for an anti tree pogrom are rushing to judgement. There are other solutions and even if NR took a chainsaw to every tree on their property, there are plenty of places where leaves from trees on other peoples land trespass on the railway in huge numbers in autumn.

 

[setdown]

This frightening incident has thrown a spotlight on the whole issue of stopping a train in an emergency. My thoughts are with the injured driver, the staff and passengers on the trains, and all those affected in so many ways. As bad as it has been, there is an awareness that it could have been even worse. So, a thought occurs; has there been any research into the possibility of stopping, or slowing, a train in an emergency situation by other means than slowing the steel wheel on the steel rail? Whatever the cause of this incident turns out to have been, we have heard from drivers and others who have witnessed similarly frightening incidents despite multiple mitigations such as sand, rail head treatment, etc etc. It is reasonable to suppose that something like this will happen again, particularly in our damp climate with deciduous trees. If you had suggested to me, when I owned a Morris Minor in the 70s, that I would one day drive a car that deployed airbags in the event of a collision, and that this innovation would save many lives and inhibit serious injuries, I would have scoffed. Could a train deploy an emergency dragging anchor of some sort, or a dragging wheel on the ballast? It might not be good for the track, but is that worth it if a collision is avoided, or the impact reduced?

Some Shinkansen trains have pop-up 'ears' to help increase drag to slow down in an earthquake, would that work at the much slower speeds involved here though?

 

[Grumpy Git]

I believe some trams use this system

I would take an educated guess that this system will be more likely be a linear motor which produces a back EMF (electro-motive force). Effectively a resistance to movement, like when a motor is used as a generator.

 

[zwk500]

This frightening incident has thrown a spotlight on the whole issue of stopping a train in an emergency. My thoughts are with the injured driver, the staff and passengers on the trains, and all those affected in so many ways. As bad as it has been, there is an awareness that it could have been even worse. So, a thought occurs; has there been any research into the possibility of stopping, or slowing, a train in an emergency situation by other means than slowing the steel wheel on the steel rail? Whatever the cause of this incident turns out to have been, we have heard from drivers and others who have witnessed similarly frightening incidents despite multiple mitigations such as sand, rail head treatment, etc etc. It is reasonable to suppose that something like this will happen again, particularly in our damp climate with deciduous trees. If you had suggested to me, when I owned a Morris Minor in the 70s, that I would one day drive a car that deployed airbags in the event of a collision, and that this innovation would save many lives and inhibit serious injuries, I would have scoffed. Could a train deploy an emergency dragging anchor of some sort, or a dragging wheel on the ballast? It might not be good for the track, but is that worth it if a collision is avoided, or the impact reduced?

The risk with dropping something into the track is that you can cause a much worse incident by a rapid derailment as the track spreads underneath. Or you could throw obstructions into the path of trains on adjacent lines. Imagine dropping an anchor at 125mph on the ECML or WCML, the damage you do could easily cause a further crash.
Personally I think the magnetic systems are much more likely to be a viable answers - any issues with interference etc will need to be dealt with, but if you linked their deployment to a REC 'ALL STOP' Message then it might manage the risks down to an acceptable level.

Some Shinkansen trains have pop-up 'ears' to help increase drag to slow down in an earthquake, would that work at the much slower speeds involved here though?

I doubt it.

I can't understand how he's still alive considering the state of the very part of the cab in which he would be sitting. It looks completely demolished.

Didn't the cab have to be cut away, so the picture doesn't show what damage was part of the collision and what was caused by the fire service afterwards?

 

[Annetts key]

In the dark days of yore…

So how does what you say tie in with the InterCity 125 HST? By HST I mean a ‘class 43’ power car on each end with a rake of seven, or eight MK3 coaches in between. Or indeed the (so called ‘Castle class’) 2+4 or 2+3 sets.

How many of these have suffered long slides?

 

[WesternBiker]

In the dark days of yore, trains had cast iron clasp brakes. These were incredibly efficient at low speeds and both burned the muck off wheels and roughed up their metal surfaces. It was common for trains like 4-SUBs to run into a station at line speed and stop in the platform length.

That thought occurred to me - I remember that being part of the explanation about leaf fall problems when it first hit the news, in particular about the clasp brakes cleaning the wheel surface. I think I'm correct in thinking that the first TGVs had them in addition to disc brakes?

 

[21C101]

So how does what you say tie in with the InterCity 125 HST? By HST I mean a ‘class 43’ power car on each end with a rake of seven, or eight MK3 coaches in between. Or indeed the (so called ‘Castle class’) 2+4 or 2+3 sets.

How many of these have suffered long slides?

They are high speed trains. It was the disc brakes that enable them to go on lines signalled otherwise for 100 mph at 125mph.

As I said disc brakes are far superior at *high* speed. Disc brakes work at low speed but clasp brakes work better and mitigate the adhesion issues in autumn conditions. HSTs are also "heavy" units, it is more lightweight units that tend to have more wheelslide issues.

Thats why the German engineers, clever chaps that they are, put both types on the Thameslink Class 700s which are required to both go at 100mph and behave like Metro trains in the core.

It is unfortunate that the introduction of disc brakes largely coincided with a drastic reduction in vegetation clearance. Personally I think modifying train types prone to wheelslide to have both disc and clasp brakes, as the class 700s do, is more proportionate and will be more effective than a chainsaw massacre of trees (and will avoid acute political protests from some quarters).

I would take an educated guess that this system will be more likely be a linear motor which produces a back EMF (electro-motive force). Effectively a resistance to movement, like when a motor is used as a generator.

Regular use of electromagnetic brakes was one reason that the London Tram network was phased out quickly after the war, it is very wearing on the track.

I suspect it would cause all sorts of signalling electromagnetic immunity issues and at high speed could risk destablilising the train/track

Suspect using the motor as a brake on electric/diesel electric trains would be a better bet for rapid deceleration from high speed. I believe the Southern Railway/Region electric "booster" locos could do this.

 

[Annetts key]

HSTs are also "heavy" units, it is more lightweight units that tend to have more wheelslide issues.

Thank you.

So the real problem is due to a combination of:

• Modern trains being lightweight multiple units,
• Fitted with only disc brakes,
• Poor lineside vegetation management,
• Not enough rail head treatment being carried out.

 

[RPI]

I'm not sure if it's been mentioned, GWR (not sure about SWR) 158s are fitted with wheel scrubbers to clean the muck off the wheels, the job that is done by brake blocks on trains with clasp brakes. (I've ended up skim reading some of this thread as when I come back there are loads more posts!)

 

[21C101]

Thank you.

So the real problem is due to a combination of:

• Modern trains being lightweight multiple units,
• Fitted with only disc brakes,
• Poor lineside vegetation management,
• Not enough rail head treatment being carried out.

Rarely is there a single cause.

 

[hwl]

Thats why the German engineers, clever chaps that they are, put both types on the Thameslink Class 700s which are required to both go at 100mph and behave like Metro trains in the core.

It is unfortunate that the introduction of disc brakes largely coincided with a drastic reduction in vegetation clearance. Personally I think modifying train types prone to wheelslide to have both disc and clasp brakes, as the class 700s do, is more proportionate and will be more effective than a chainsaw massacre of trees.

The reason that 700s have clasp brakes on the motored axles is that there isn't space with inside framed bogies for disc brakes and the transverse traction motor unless you have an unusual motor design patented by Bombardier and used on Aventra and Talent3 platforms.

Siemens elected to use inside frame bogies and tread brakes.

Hitachi's solution for the 385s (and 9car 80x to an extent) was to retain outside frame bogies for the motor bogies and inside frame for the non motor bogies with disc brakes.

 

[21C101]

The reason that 700s have clasp brakes on the motored axles is that there isn't space with inside framed bogies for disc brakes and the transverse traction motor unless you have an unusual motor design patented by Bombardier and used on Aventra and Talent3 platforms.

Hitachi's solution for the 385s (and 9car 80x to an extent) was to retain outside frame bogies for the motor bogies and inside frame for the non motor bogies.

Its not the only reason. It killed two birds with one stone. Clever chaps those Germans.

 

[zuriblue]

This frightening incident has thrown a spotlight on the whole issue of stopping a train in an emergency. My thoughts are with the injured driver, the staff and passengers on the trains, and all those affected in so many ways. As bad as it has been, there is an awareness that it could have been even worse. So, a thought occurs; has there been any research into the possibility of stopping, or slowing, a train in an emergency situation by other means than slowing the steel wheel on the steel rail? Whatever the cause of this incident turns out to have been, we have heard from drivers and others who have witnessed similarly frightening incidents despite multiple mitigations such as sand, rail head treatment, etc etc. It is reasonable to suppose that something like this will happen again, particularly in our damp climate with deciduous trees. If you had suggested to me, when I owned a Morris Minor in the 70s, that I would one day drive a car that deployed airbags in the event of a collision, and that this innovation would save many lives and inhibit serious injuries, I would have scoffed. Could a train deploy an emergency dragging anchor of some sort, or a dragging wheel on the ballast? It might not be good for the track, but is that worth it if a collision is avoided, or the impact reduced?

In Europe anything going above 160 Km/h must have bogie mounted magnetic brakes. I'm surprised you don't see them in the UK.

 

[Domh245]

Its not the only reason

It is the main reason though, braking adhesion benefits were secondary. Siemens were quite happy to build disk brake only units for the UK for many years with the Desiro classic fleet, but it was only they needed to shave significant weight off that they started putting clasps brakes on.

 

[kermit]

Some Shinkansen trains have pop-up 'ears' to help increase drag to slow down in an earthquake, would that work at the much slower speeds involved here though?
View attachment 105132

I have a reputation for being inappropriately flippant, but .......c'mon.......

 

[21C101]

It is the main reason though, braking adhesion benefits were secondary. Siemens were quite happy to build disk brake only units for the UK for many years with the Desiro classic fleet, but it was only they needed to shave significant weight off that they started putting clasps brakes on.

Don't forget the 700s have higher performance requirements to maintain service intervals in the core which for the full service requires ATO which behaves more akin to a tube train rushing into a station than a defensively driven train.

 

[LOL The Irony]

would that work at the much slower speeds involved here though?

Neko Shinkansen wouldn't be much help in this situation, as you've probably surmised. 158s are known for their bad performance during the early days, and there were a few 156/158 hybrid units during one leaf fall season before modifications were made to their braking systems.

I'm not sure if it's been mentioned, GWR (not sure about SWR) 158s are fitted with wheel scrubbers to clean the muck off the wheels, the job that is done by brake blocks on trains with clasp brakes.

I don't know why more disc brake trains aren't fitted with scrubbers when they would lessen or prevent such incidents as happened now.

 

[irish_rail]

Bare in mind, 150s have the tread brakes, yet they have been involved in plenty of station overruns in the far south west this past few years, I can think of several. I think the benefits of tread brakes (in my experience) is slightly overstated.

 

[21C101]

Bare in mind, 150s have the tread brakes, yet they have been involved in plenty of station overruns in the far south west this past few years, I can think of several. I think the benefits of tread brakes (in my experience) is slightly overstated.

Ironically some of the benefits of them were lost when they changed from cast iron to composite. As I understand it only the cast Iron brake blocks scuffed up the surface of the wheel stopping being polished from running.

 

[172007]

If leaf scrubbers really worked as being suggested then by the way they scrub the wheels once the wheels have picked up crud from the rail head then logically disc braked trains wheelw would be absolutely covered. This simply does not happen, I am not aware of any depot where the wheels are cleaned daily due to this. Yes, disc braked trains can pick up debris and not make a track circuit but this is very unusual.

 

[millemille]

Dual (or Double) Variable Rate Sanders (DVRS) have been proved, through RSSB research project T1107, to allow seasonally agnostic driving (sic) with brake step 2 stopping performance being achieved no matter what the railhead conditions.

I can provide a more detailed explanation if there is interest...

 

[21C101]

If leaf scrubbers really worked as being suggested then by the way they scrub the wheels once the wheels have picked up crud from the rail head then logically disc braked trains wheelw would be absolutely covered. This simply does not happen, I am not aware of any depot where the wheels are cleaned daily due to this. Yes, disc braked trains can pick up debris and not make a track circuit but this is very unusual.

From memory, the crud is crushed into a very thin invisible film. A bit like greasing both the road and your car tyres.....

 

[Grumpy Git]

This new approach is currently being developed, lets hope they can source enough CO2!

https://www.railengineer.co.uk/cleaning-the-rail-head/

Rail Engineer has often written about the problems of low adhesion caused by, inter alia, leaf debris rolled into the railhead. As a reminder, dry leaf debris can cause wrong-side track circuit failures and, when wet, can lead to very low wheel-rail friction levels.


A coefficient of friction of approximately 0.2 will allow trains to brake normally, but wet leaf debris firmly rolled into the rail can deliver an exceptionally low coefficient of friction in the order of 0.01. To put this in context, the coefficient of friction in a well-lubricated car engine is circa 0.05.


Every Autumn, Network Rail runs Rail Head Treatment Trains (RHTT) to clean leaf debris from the rails. These trains blast the leaf debris, which by now has been firmly rolled onto the rail head by passing trains, with water jets at between 1,000 and 1,500 bar and then deposit sandite – sand with some ground metallic material suspended in a sticky paste. These trains carry a very large quantity of water and sandite, are very effective, but also use capacity on the network.

 

[Cliveblackpool]

It is......and there are also some trials to have similar equipment fitted to service trains......

Good idea!
Glanced at a document on subject 351 pages! https://www.raildeliverygroup.com/m...2018-01-managing-low-adhesion-ed6-0/file.html
A simple solution could be a jet of air on rail to blow the leaves away, before they get pulverised on the rail head and wheels?

 

[tiptoptaff]

From memory, the crud is crushed into a very thin invisible film. A bit like greasing both the road and your car tyres.....

It's most akin to driving over black ice. In most cases, the contamination presents itself as a black line on the railhead. Quite unnerving when you notice it