Great Western Coffee Shop

All across the Great Western territory => Across the West => Topic started by: TaplowGreen on December 05, 2013, 21:04:33



Title: ......are there any conditions.......
Post by: TaplowGreen on December 05, 2013, 21:04:33
...........which are conducive to a reliable railway?

If it's hot or cold we get "poor rail conditions", ditto Autumn due to the failure to cope with the natural phenomenon of leaves falling off trees, if it snows, forget it and stay at home, and today it was apparently the wrong kind of wind. ............for years now at the weekends and later in the evenings the service is frequently decimated by engineering works, as will be the case over Christmas (again).

To say nothing of frequent signal failures.

......would I maybe be OK say on a mild April day, midweek, between 8 am and 5pm?

Sometimes seems we have a fair weather, 7 am to 7 pm, weekday railway? (with massive overcrowding thrown in)  :(


Title: Re: ......are there any conditions.......
Post by: trainer on December 05, 2013, 22:43:53
Possibly the same conditions as reliable road transport?  No collisions closing motorways, no ice/spray/fog/heat melting surfaces, no road works lasting months, no fireworks nearby, no pedestrians crossing stupidly etc etc...

Let's face it - travelling is always going to have some potential for uncertainty, no matter how you do it.


Title: Re: ......are there any conditions.......
Post by: Fourbee on December 06, 2013, 11:15:53
Possibly the same conditions as reliable road transport?

I did hear that yesterday there was an accident in the road tunnel to Heathrow Terminals 1, (2), 3 and people were reported to be abandoning cars. There was also gridlock reported on the surrounding roads.

Presumably the underground/heathrow express/heathrow connect would have been the only way in/out at the time. Not sure if there is any direct pedestrian access?


Title: Re: ......are there any conditions.......
Post by: IndustryInsider on December 06, 2013, 11:36:25
Presumably the underground/heathrow express/heathrow connect would have been the only way in/out at the time.

Or possibly a plane...  ;)


Title: Re: ......are there any conditions.......
Post by: Fourbee on December 06, 2013, 11:49:04
Presumably the underground/heathrow express/heathrow connect would have been the only way in/out at the time.

Or possibly a plane...  ;)

 ;D Hadn't thought of that one!


Title: Re: ......are there any conditions.......
Post by: Network SouthEast on December 06, 2013, 11:54:49
It amazes me how many folks suffer from weather related amnesia.

We've always had problems in this country with inclement weather and transport. It seems we have one good year for weather, and then suddenly the next year when usual conditions resume people have forgotten what reality is like.

Then come the inevitable comparisons with railways in Europe, which are without merit. For example, in the Netherlands, Arriva and NS had suspended rail services after 14:00 yesterday and there were blanket speed restrictions in parts of France and Germany.


Title: Re: ......are there any conditions.......
Post by: thetrout on December 06, 2013, 21:45:42
I'm not sure I agree with most of this at all. Yes Signal Failures are incredibly irritating and a few could perhaps be avoided. But things do break down such is life. Computers Crash, Cables degrade with changing weather and sometimes human error and poor judgement causes "unforeseen consequences". We are only human and it happens.

I am very much minded of the Southall Rail Crash and the role that the OHLE (Overhead Line Equipment) played in the accident. Great technology implementation for electric trains. But I don't think anyone could see the potential for such an outcome with the Supporting Stanchions. Thankfully the UK has a very reasonable safety record when you look at the amount of fatal road accidents that happen in just a day alone... :( :-X Trains also travel much faster than Cars/Lorries/Buses etc

I must say though that as FGW are now paying significantly higher track access charges. Then as FGW I would seriously be taking Network Rail to the cleaners considering the recent signalling issues. However I must also stress that with the fail systems in place, I would rather a significant delay and be safe, than risk proceeding but there being a dangerous risk of something going terribly wrong.

Finally, some of the public and the media especially seem to take very dim views on Planned Engineering Works, Emergency Engineering Works and Delays as of the result of Track Side Equipment failing on the railways. So roads are never closed for roadworks, Accidents never happen on the highways, Road Bridges are never closed due to high winds, Roads are never closed to hold a street market on the 3rd Sunday every month. Lorries never break down on Junctions. Traffic Signals never break down in the rush hour. The list is endless.

I would rather be stuck on a train, than in a traffic jam on the motorway any day of the week. At least you can get up and use the toilet, get a cup of coffee etc. Also, who compensates you for a 3 hour traffic jam vs. a 1 hour train delay?!?! ;-) Don't see any reductions in Vehicle Tax I'm sure...

Whilst I may be being overally harsh here. I certainly think your OP was made in frustration which is completely understandable. But as trainer says. Delays to travel no matter what method (even walking) you use are all very possible to delays and you just need to take it on the chin sadly. I don't like saying that. But I get stressed out over more than enough things as it is. I don't need to be contributing to that level any further whatsoever!

I hear an announcement that the train is going to be delayed by an hour and watch most people sigh or get annoyed. But why the need? Yes you can scream and shout at the staff, but is that going to get the train moving any quicker? Fact is, not alot can be done. I personally on hearing these announcements will go and order at the Travelling Chef if I can, or get my laptop out if it's a short journey and occupy my time that way. No point stressing over what is out of my control. The only time I would approach staff with a concern is if the delay was likely to mean I was going to miss last connection of the day. On occasions when this has happened, I've got the staff at the station to endorse my ticket before I've even gotten on the delayed train and then can deal with it as I conclude my journey.


Title: Re: ......are there any conditions.......
Post by: johoare on December 06, 2013, 21:51:53
I totally agree with you thetrout with an exception.. If it's one of those many trains where there is just enough room to breath (as long as you stand in the right position).. Then I don't think being on a delayed train is better than being stuck in a traffic jam etc


Title: Re: ......are there any conditions.......
Post by: ellendune on December 06, 2013, 22:02:16
I have just come back from Glasgow. The wind yesterday morning was so bad pedestrians were being injured because they could not stand.  Network Rail shut the rail system in Scotland because debris was being blown onto the lines. 

I am told that planes manged to land at Glasgow airport, but they could not put the steps in place as it was not safe to be out in the wind and there was a fear that passengers disembarking would be blown off the steps!

Roads are cannot be easily closed (except at specific sites) so people go out regardless of the conditions and two or them were killed (not just in Scotland). Others were injured. And so the emergency services had to go out and risk their lives as well.

The police closed the forth road bridge, but somehow a cyclist got past and was filed on the bridge.  How utterly stupid.

Perhaps we should have a mechanism to close all roads when conditions are too dangerous.


Title: Re: ......are there any conditions.......
Post by: Lee on December 06, 2013, 22:16:10
I have to ask - How does one get filed on a bridge?


Title: Re: ......are there any conditions.......
Post by: Electric train on December 07, 2013, 08:35:37
I really do believe that the Highways Agency should publish performance figures the same as Network Rail.  With the proposed changes to the Road Fund Licence (Tax Disk) it would be easy to give road users a refund if their journey was delayed due to a problem on a Highway Agency asset including where such a failure rippled out to local road users................... But that isn't about to happen any time soon is it the Government would end up paying us more than they get in.

There are lot of people employed in the Railway industry who work very hard to keep the wheels moving, sometimes they are thwarted by equipment failures and there is a very robust investigation process that looks for common mode failures, some of the failures are due to upgrade and renewals works disturb something that has not been disturbed for 30 or 50 years it ceases to be reliable.  Often the failures are through external events which are outside the railways influence to control


Title: Re: ......are there any conditions.......
Post by: broadgage on December 07, 2013, 09:58:48
Not much can be done about truly extreme or exceptional weather conditions badly affecting road, rail, air and other transport.

However UK railways seem to be increasingly affected by only moderately adverse weather, such as may be expected if not every year then at least every few years.

Modern trains seem increasingly vulnerable to hot weather or leaves on the line.
Modern signalling systems control huge areas with the result that a single fault can close hundreds of route miles, or major termini.

Electrification though a good idea in theory seems to result in major delays whenever it is windy.
Ice on the third rail network has always been a problem, but newer trains seem more vulnerable than say an EPB.

And of course with the general move towards shorter trains with high density seating or more standing, then when breakdowns occur conditions are far worse.
To be stuck for a few hours on an old train sitting down, with heating/air conditioning, lighting, working toilets, and openable doors and windows, and perhaps even a buffet or restaurant is merely irritating.

To be stuck standing on a new shorter crush loaded train in the dark in freezing cold or sweltering heat, without refreshments or toilets is a potential emergency not merely an irritation.


Title: Re: ......are there any conditions.......
Post by: bobm on December 07, 2013, 12:26:16
Modern signalling systems control huge areas with the result that a single fault can close hundreds of route miles, or major termini.

Similar problem with air traffic control....  http://www.bbc.co.uk/news/uk-25278163 (http://www.bbc.co.uk/news/uk-25278163)

Quote
Flights are being delayed across the UK and Ireland because of an air traffic control centre fault.

Affected airports include Heathrow, Stansted, Cardiff, Dublin, and Glasgow.

The National Air Traffic Control Service (Nats) said its Swanwick centre, in Hampshire, was having "difficulty switching from night time to daytime operation".


Title: Re: ......are there any conditions.......
Post by: thetrout on December 07, 2013, 18:48:37
I totally agree with you thetrout with an exception.. If it's one of those many trains where there is just enough room to breath (as long as you stand in the right position).. Then I don't think being on a delayed train is better than being stuck in a traffic jam etc

That I hadn't considered, and I quite agree with you on that Jo :) That is more of an emergency in my opinion rather than a mild inconvenience to travel plans. As we've seen before, that's when people start opening doors using the emergency escape systems! >:( Thus potentially making the problem much, much worse!

To be stuck for a few hours on an old train sitting down, with heating/air conditioning, lighting, working toilets, and openable doors and windows, and perhaps even a buffet or restaurant is merely irritating.

To be stuck standing on a new shorter crush loaded train in the dark in freezing cold or sweltering heat, without refreshments or toilets is a potential emergency not merely an irritation.

I also agree with broadgage' comments here completely which draw into your suggestions Jo.

During the January Slough Signal Failures my train was held at Chippenham for 50 minutes and then a further hour just outside Slough. Arrived into Paddington 1 hour 50 minutes late! Yes it was annoying and got tiresome when trains were running past us in the opposite direction. But with my logical thinking head on... If they didn't let the trains from Paddington side out, there would have been no room for my train to get in! Conditions onboard were good and announcements kept us well informed. I just wish the buffet didn't close just after Reading and IMHO that was the worst part of the whole experience.


Title: Re: ......are there any conditions.......
Post by: TaplowGreen on December 07, 2013, 21:43:08
Thankyou Broadgage for hitting the nail squarely on the head. The point is that it takes exceptionally bad weather for roads, airports etc to close down, regardless of the type of vehicles operating (indeed many of these are designed to cope with extreme weather), and yet it seems that in our relatively benign climate,  modern rail systems/trains are increasingly vulnerable to entirely predictable weather  compared to other parts of the world, who seem to cope, and the same goes for overcrowding.

I appreciate that many who post on here are employed by and/or in love with the railways, however a little objectivity is always a good thing - simply implying that because there are occasionally problems on other means of transport should make it acceptable for us to tolerate a fourth class rail service at first class prices is a pretty poor argument, but it seems to be the default position.



Title: Re: ......are there any conditions.......
Post by: ellendune on December 07, 2013, 22:04:12
The leaves on the line - I would agree would count as moderate weather - and railways must find a way to cope.

However the gales in Scotland and Northern England this week and the previous gales in Southern England at the end of October were extreme and we should expect that our railways will be affected by them.


Title: Re: ......are there any conditions.......
Post by: Chris from Nailsea on December 07, 2013, 22:10:46
The leaves on the line - I would agree would count as moderate weather - and railways must find a way to cope.

Playing devil's advocate, then, ellendune: What would you suggest as that simple solution to Network Rail's annually recurring problem?  ;)


Title: Re: ......are there any conditions.......
Post by: ellendune on December 07, 2013, 22:56:13
The leaves on the line - I would agree would count as moderate weather - and railways must find a way to cope.

Playing devil's advocate, then, ellendune: What would you suggest as that simple solution to Network Rail's annually recurring problem?  ;)

Oh I quite agree that it is not easy incredibly difficult to solve, but it is not possible to write it off as exceptional weather in the same way as the winds of recent days. The leaves do not affect roads or air travel so people will not understand.


Title: Re: ......are there any conditions.......
Post by: broadgage on December 08, 2013, 08:40:26
The leaves on the line - I would agree would count as moderate weather - and railways must find a way to cope.

Playing devil's advocate, then, ellendune: What would you suggest as that simple solution to Network Rail's annually recurring problem?  ;)

1) Cut down trees on railway property, especially those with problematic leaves. Many rail routes now resemble linear forests if compared to pictures taken 20 or 30 years ago. This will also reduce delays due to fallen trees.

2) Consider fitting new trains with tread brakes that when applied scrape leaf residue from the wheels. (the replacement of tread brakes with disc brakes is one of the reasons that new trains are worse than old in leaf fall weather)

3) Install leaf traps at particularly bad locations. These consist of short lengths of chain link fencing installed at an angle to the track. The prevailing wind and the air movement from trains blows leaves against these fences were they become trapped rather than blowing onto the rails.
The leaves can then be collected, or burnt on site, or allowed to decompose naturally.

4) Ask overseas railways how they cope ! Leaves on the line do cause delays overseas, but not it seems on the scale that we suffer.


Title: Re: ......are there any conditions.......
Post by: Network SouthEast on December 08, 2013, 19:27:54
1) Cut down trees on railway property, especially those with problematic leaves. Many rail routes now resemble linear forests if compared to pictures taken 20 or 30 years ago. This will also reduce delays due to fallen trees.
How can you do this when many trees aren't on railway land? Network Rail are good at cutting down trees and removing foliage on their own land, but what can they do when the tree is in someone's back garden? What can they do when a tree has a preservation order on it? What if they remove a tree from an area with a venerable embankment and then it leads to landslides?

Quote
2) Consider fitting new trains with tread brakes that when applied scrape leaf residue from the wheels. (the replacement of tread brakes with disc brakes is one of the reasons that new trains are worse than old in leaf fall weather)
Fitment of tread brakes would prevent trains running fast. Tread brakes have terrible braking performance at higher speeds, that's why we see brake discs fitted to pretty much anything that moves quickly (i.e. Mk3s, 158s, Turbos etc).


Title: Re: ......are there any conditions.......
Post by: ellendune on December 08, 2013, 19:50:35
1) Cut down trees on railway property, especially those with problematic leaves. Many rail routes now resemble linear forests if compared to pictures taken 20 or 30 years ago. This will also reduce delays due to fallen trees.
How can you do this when many trees aren't on railway land? Network Rail are good at cutting down trees and removing foliage on their own land, but what can they do when the tree is in someone's back garden? What can they do when a tree has a preservation order on it? What if they remove a tree from an area with a venerable embankment and then it leads to landslides?

Recent research suggests that the link between trees and embankment stability is not as simple as we had thought. We had assumed that the tree roots would bind the soil together.  However it now seems that in dry summers the presence of trees in clay soil embankments leads to further drying of the clay, which causes cracking. When the soil rehydrates these cracks remain as a weakness in the embankment structure. 

Quote
2) Consider fitting new trains with tread brakes that when applied scrape leaf residue from the wheels. (the replacement of tread brakes with disc brakes is one of the reasons that new trains are worse than old in leaf fall weather)
Fitment of tread brakes would prevent trains running fast. Tread brakes have terrible braking performance at higher speeds, that's why we see brake discs fitted to pretty much anything that moves quickly (i.e. Mk3s, 158s, Turbos etc).

Would it be helpful to fit, in addition to the disk brakes, a sort of wheel rim scraper (something that looks like an old fashioned rim brake) which could clear the leaf slime off the wheel rim?


Title: Re: ......are there any conditions.......
Post by: broadgage on December 09, 2013, 09:06:40
There are a lot of mature trees on railway property that were but saplings 20 or 30 years ago. Many could be cut down, or drasticly cut back.

Not much can be done about trees on other peoples property, but they could make a start on the railway owned ones. (and possibly offer to remove unwanted trees on private property)

Tread brakes do indeed have inferior stopping capacity as compared to modern disc brakes. It has been suggested that a basic tread brake be added to disc brake wheels, as suggested in the previous post. Since most of the stopping power would come from the disc brakes, the blocks on the tread brakes should be long lasting.


Title: Re: ......are there any conditions.......
Post by: ChrisB on December 09, 2013, 10:45:32
NR used to do a lot of trackside vegetation & tre clearance, but with funds short, it's a 'wait until they fall' policy now


Title: Re: ......are there any conditions.......
Post by: IndustryInsider on December 09, 2013, 11:23:23
There are a lot of mature trees on railway property that were but saplings 20 or 30 years ago. Many could be cut down, or drasticly cut back.

NR used to do a lot of trackside vegetation & tre clearance, but with funds short, it's a 'wait until they fall' policy now

There are indeed many locations where vegetation could be significantly cut back.  Even a 'main line' like the Cotswold Line has several locations where leaves have been allowed to grow right up to where the train profile is located, and as soon as a shower weighs the leaves down they smack the side of the train as it passes in the summer.  That's also a safety risk for passengers who might lean out of the window of a HST at the wrong time and get a face full of leaves at 90mph - I know they shouldn't, but people still do!


Title: Re: ......are there any conditions.......
Post by: ChrisB on December 09, 2013, 11:38:59
Worse still, is that NR have apparently cut back on using sandite....


Title: Re: ......are there any conditions.......
Post by: Henry on December 09, 2013, 14:37:43

 I have also heard that now the 'leaf fall season is now over' no further sandite trains.

 If my part of Devon is anything to go by, there's still some way to go yet.
 After last week's series of events at Totnes, I've given up using the train for a few months.


Title: Re: ......are there any conditions.......
Post by: ChrisB on December 09, 2013, 14:40:18
Over? - it obviously isn't!

NR need to accept that leaf-fall doesn't just finish when they want it to.....doh!


Title: Re: ......are there any conditions.......
Post by: stuving on December 09, 2013, 19:23:15
From the RAIB  (http://www.raib.gov.uk/publications/current_investigations_register/131120_chester.cfm)

Quote
Buffer stop collision at Chester station

At 12:10 hrs on Wednesday 20 November 2013 a passenger train collided with the buffer stop at the end of platform 1 at Chester station and became derailed. The train involved was the 10:10 hrs Virgin Trains service from London Euston to Chester. Two passengers on the train were slightly injured in the collision.

As the train approached Chester station the driver applied the brakes to reduce the speed for the 20 mph speed limit into the platforms. The weather at the time had been dry but a rain shower was just starting and the adhesion between the wheels and rails was reduced. The train^s wheel slide protection system detected that the wheels were sliding on the rails, regulated the application of the brakes, and the train was able to achieve a rate of deceleration sufficient to bring its speed down to within the speed limit as it approached the station.

As the train approached the platform the driver lightly applied the brakes again but the wheels immediately started to slide. Despite the immediate automatic activation of the wheel slide protection system, the train^s deceleration was insufficient to bring it down to a safe speed as it moved along the platform. Consequently, the emergency brakes were applied by train protection and warning system and the driver pressed the emergency stop button very shortly afterwards. The combination of emergency braking and the detection of wheel slide triggered the automatic sanding system on the leading vehicle to drop sand onto the rail head.

The presence of the sand improved adhesion for the wheels that ran over it and the speed was reduced before the train collided with the buffer stop at the end of the platform.

The buffer stop was of an old design with only minimal capacity to absorb energy. The train destroyed it before overriding its remains to mount the platform where it came to rest. The front bogie was lifted off the track as the front of the leading vehicle rode up onto the platform.
 

(http://www.raib.gov.uk/cms_resources/Chester%20image.jpg)
Image of derailed train at Chester station

Platform 1 was closed to traffic until the following day for recovery of the train and repair of the track and buffer stop.

The RAIB^s investigation will seek to identify the sequence of events. It will include consideration of the braking system on this train, in particular the wheel slide protection system and the sanding equipment. It will also consider adhesion conditions in the area at the time (using information from other trains that experienced low adhesion conditions that day), the condition of the rails on the approach to the platform and the efficacy of any actions taken to treat the rail head.

The RAIB will also take into consideration the findings from other similar events that the RAIB has investigated; most notably the investigation into a series of low adhesion events in the autumn of 2005 (RAIB report 25/2006, parts 1 to 3).

The RAIB^s investigation is independent of any investigation by the Office of Rail Regulation.

The RAIB will publish its findings, including any recommendations to improve safety, at the conclusion of its investigation. This report will be available on the RAIB website.

You can subscribe to automated emails notifying you when the RAIB publishes its report and bulletins.

I though this was relevant here - it is braking rather than traction effects of low adhesion, but closely related.

If you want to see how much work and head-scratching has gone into the topic, follow the link to their previous report 25/2006 part 3 (http://www.raib.gov.uk/publications/investigation_reports/reports_2007/report252006.cfm). This observes (inter alia) that the many new trains introduced in 2004-2005 recorded more "failure to brake" incidents than the older ones, but does not really find out why. They seem to be suggesting that this new report will review what has happened since 2006, though that review may be quite limited if it is just what is relevant to this accident.

If you still want more information there are several RSSB reports - search through the catalogue (http://www.rssb.co.uk/SiteCollectionDocuments/pdf/reports/Research/Quarterly%20Publications/Research%20Catalogue.pdf) for "adhesion working group" and you should be kept busy for hours.


Title: Re: ......are there any conditions.......
Post by: BerkshireBugsy on December 09, 2013, 21:19:49
I've just picked up on this thread and found it very interesting reading.

This week I am working in the Edmonton area of north London again. The last times I've had to do this gig I've travelled by train from Thatcham . The journey time could vary as much as an hour even if there were no major delays because the end point of the journey is at a station served by very few services (angel road) to be honest when I did this a few weeks ago the signalling issues were starting to wear on me a bit.

So this morning I was driving to the station and on the spur of the moment I decided to drive to site. At 515 this morning I had a good run through and because I arrived on site early I left early and was home by 535 - about 2.5 hours earlier than if I had done the journey by train.

Of course , as others have posted, the roads are subject to delays but  my feeling is if that happens I can choose to take an alternative route whereas if I was on a mass transit system (such as a train,tube dlr etc) that option wouldn't be available to me

If I was working in Central London then this is not an option I would consider although on occasions I have driven to hatton cross and take the tube in.

Ironically I feel more alert having driven although I can't explain why. I (personally) find train travel more tiring in the darker months.

I am conscious that taking today as an example my driving could be considered as environmentally selfish but it gave me back between 3-4 hours of my life. Like others though I can't stand sitting in jams- such a waste of time.



Title: Re: ......are there any conditions.......
Post by: stebbo on December 09, 2013, 21:36:33
Older locomotives and carriages - note not modern multiple units - had tread brakes as rightly pointed out in an earlier post so the driving wheels were cleaned off. Also, steam engines and older diesels with steam boilers had the ability to spray steam onto the tracks under the driving wheels.

Tube trains carry some de-icing equipment to clean the live and return rails. Shouldn't modern BR stock have something similar? (OK I hear the argument that the problem doesn't occur regularly - I'd buy that for snow clearance but not leaf fall/frost).

And, of course, better tree surgery would help given we no longer have steam locomotives to help burn off the canopy. It was not so long ago that the lineside vegetation used to bang against the side of trains along the Cotswold Line.


Title: Re: ......are there any conditions.......
Post by: Network SouthEast on December 10, 2013, 07:24:04
There are normal passenger trains in service that can de-ice third rail. A member of public might have trouble spotting an Electrostar that has a de-icing tank, for example, because the tank is below sole-bar level.


Title: Re: ......are there any conditions.......
Post by: stuving on December 10, 2013, 09:22:43
Older locomotives and carriages - note not modern multiple units - had tread brakes as rightly pointed out in an earlier post so the driving wheels were cleaned off. Also, steam engines and older diesels with steam boilers had the ability to spray steam onto the tracks under the driving wheels.

There is - of course - a Railway Group Standard: "Low Adhesion between the Wheel and the Rail ^ Managing the Risk" (GE/RT8040, Issue Two, February 2009).

Its important requirement is contained in a single paragraph:

Quote
2.1 Joint requirements for infrastructure managers and railway
undertakings
2.1.1 General requirements

2.1.1.1 Infrastructure managers and railway undertakings shall jointly implement measures to reduce the risks generated by low adhesion between the wheel and the rail that cannot be eliminated by local treatment at specific sites.

It then goes on to the requirement for site specific [sic] action plans, to define that local treatment. It mentions train-mounted equipment (sanding), but not other more general measures such as rail treatment trains (Sandite and jetting).

However, there is a guidance note that gives lists of potential measures:  "Guidance on Low Adhesion between the Wheel and the Rail ^ Managing the Risk" (GE/GN8540, Issue One, February 2009).

The main list is as follows:
Quote
GN22 Example of possible measures include:
a) Vegetation clearance
b) Water jetting (including frequency)
c) Sandite application (including frequency)
d) Traction Gel application
e) Hand sanding
f) SPAD prediction equipment fitted at level crossings
g) Driver briefing
h) Take signalled route out of use
i) Special box instructions restricting certain moves
j) Selected trains to perform running brake tests
k) Train strengthening
l) Use of tread braked stock instead of disc braked stock
m) Fitting scrubbing devices to the wheels of rolling stock to eliminate or reduce
contamination of the wheels
n) Fitting devices to the wheels of rolling stock to enhance the performance of the
braking system
o) Fitting sanders to trains
p) Turning off flange lubricators
q) Monitoring and inspection of low adhesion sites.
and a little later:
Quote
GN25 In developing the plans, consideration should be given to any train borne equipment fitted
to improve braking performance under conditions of low adhesion, including:
a) Optimised wheel slide protection (WSP) equipment
b) Scrubber brakes
c) Track brakes
d) Sanding equipment including:
i) Emergency sanding device
ii) Automatic sanding device
iii) Dual function sanders (braking and traction)
iv) Variable rate sanders.
GN26 Plans should also consider the benefits, where provided, of systems to detect wheel slide
and alert the driver or systems that provide remote monitoring to alert drivers of low
adhesion.

... and, if you know of a way to improve adhesion with a kitchen sink ...

The fact that something is in the list does not mean it works, or even that all parties think it does. Tread brakes are thought to help by a lot of drivers, but attempts to measure the effect show it is at best marginal. The RAIB, in report 25/2006 part 3, looked at the evidence, and said this:

Quote
194 Disc brakes are provided on modern rolling stock whereas the stock they replaced was
equipped with tread brakes. Some drivers have suggested that tread brakes are better than
disc brakes at stopping trains in low adhesion conditions because they act directly on the
wheel, having the effect of cleaning the wheels and improving adhesion accordingly. This
may, in part, be attributable to the fact that tread-braked units achieve deceleration rates of
0.7m/s2, whereas modern disc braked rolling stock can achieve deceleration rates of 1.0m/
s2 or greater. Thus the risk of exceeding available adhesion will be greater, although WSP
should intervene to ensure that braking rate is matched to available adhesion. It may also
be the case that drivers of modern trains are more aware of wheelslide as the display on the
driver^s desk will indicate if WSP activity is taking place.

195 The AWG low adhesion manual addresses the issue of tread braking and disc braking.
Quoting work carried out by British Rail Research in which the relative performance of the
two brake types was examined, the AWG Manual makes the following assertions (RAIB
comments in brackets):
  • Tread braked stock generally has lower operating speeds and lower braking rates
    than disc braked stock. This can help to create the impression that the brake itself is
    contributing to better performance.
  • When rail conditions are able to support full braking demand, disc brakes are superior
    to tread brakes (this is borne out by drivers of modern rolling stock who agree that in dry
    conditions disc braking is more effective).
  • When rail conditions are poor (i.e. in drizzle) a good WSP with disc brakes will stop the
    train in a comparable distance to a tread braked train (this runs counter to the evidence
    from drivers who have indicated that modern rolling stock was not as effective at
    stopping under drizzly conditions in autumn 2005 as the tread braked stock that it had
    replaced).
  • When rail conditions are severe a good WSP system will stop the train in a comparable
    distance to a tread braked train (however, the incident at Lewes on 30 November 2005
    described in the Part 2 report suggests that WSP alone is not sufficient when drizzle falls
    onto a contaminated rail) but will avoid damage to the wheels in so doing, whereas the
    tread-braked train is likely to suffer wheel damage.

196 Although there may be no evidence to prove that tread braking yields benefits in stopping
performance under low adhesion conditions, one advantage of the cleaning effect on
wheel treads is to improve electrical contact between the wheel and the rail. For this
reason, auxiliary tread brakes (sometimes known as scrubber blocks) were fitted to some
disc braked vehicles to aid track circuit operation by cleaning and roughening the wheel
treads. There is insufficient evidence to judge whether vehicles equipped with auxiliary
tread brakes are less likely to be involved in adhesion-related station overruns because the
number of units so equipped is small.


I don't know if WSP (wheelslide prevention) could be applied to tread brakes, but I get the impression it could not. In any case, no-one is going to go back to tread brakes only, so it would have to be additional wheel-tread conditioning equipment. And that would need scientific evidence that it would be effective - which appears to be lacking.


Title: Re: ......are there any conditions.......
Post by: IndustryInsider on December 10, 2013, 10:14:43
From the RAIB  (http://www.raib.gov.uk/publications/current_investigations_register/131120_chester.cfm)

Quote
Buffer stop collision at Chester station

...
The buffer stop was of an old design with only minimal capacity to absorb energy. The train destroyed it before overriding its remains to mount the platform where it came to rest. The front bogie was lifted off the track as the front of the leading vehicle rode up onto the platform.
 

I though this was relevant here - it is braking rather than traction effects of low adhesion, but closely related.

Thanks for posting the link.  If anyone is in any doubt as to why modern standards insist all new terminal platforms, such as the rebuilt 4,5 and 6 at Reading, have better quality buffers and roughly a carriage length of safety overlap, there is the proof!


Title: Re: ......are there any conditions.......
Post by: Chris from Nailsea on November 25, 2014, 10:53:25
The Rail Accident Investigation Branch (RAIB) has released its report (http://www.raib.gov.uk/cms_resources.cfm?file=/141124_R262014_Chester.pdf) into a buffer stop collision at Chester station on 20 November 2013.

RAIB has made three recommendations and identified two learning points.

Quote
Summary:

At 12:12 hrs on Wednesday 20 November 2013 the 10:10 hrs passenger train from London Euston to Chester collided with the buffer stop at the end of the platform as it arrived at Chester station. The impact destroyed the buffer stop and caused the leading vehicle of the train to start to override the platform, demolishing a glass screen and damaging the platform. It was fortunate that there was no-one in this area at the time.

Several passengers fell over as the train stopped, but did not report injuries. One passenger was taken to hospital as a precaution and was released later the same day. The front of the train was damaged by the impact and the leading bogie was derailed.

Platform 1 at Chester station was closed until 04:15 hrs on 22 November for recovery of the train and repair of the buffer stop.

The accident was caused by the train sliding on wet rails that were also contaminated with leaf residue and traces of lubricating oil. The train was not equipped with automatic sanding equipment, which could have applied sand to the rails to improve adhesion. The train was fitted with emergency sanding equipment but the driver did not activate this until the train was too close to the buffers to be able to stop before striking them.

The train involved was a class 221 unit operated by Virgin Trains. The RAIB analysed records of low rail adhesion incidents on Network Rail infrastructure during Autumn 2013 and found several other cases of class 221 trains, and the similar class 220, encountering low adhesion when attempting to stop. In some cases the driver had to use the emergency sanding equipment. The RAIB analysis found that, per attempted stop, class 220 and 221 trains were the most likely type of train to be involved in a low adhesion incident. Almost all other types of train are fitted with automatic sanding equipment, or equivalent.

The RAIB has identified two key learning points and made three recommendations. The operators of class 220 and 221 trains are recommended to fit equipment to their trains to automatically apply sand when wheel slide is detected during heavy braking (Virgin Trains has recently informed the RAIB of its intention to fit such equipment to its fleet of class 221 trains). A recommendation is made to Virgin Trains to amend its operating instructions to drivers and a recommendation is made to RSSB to update the standard which governs the fitment of train sanding equipment.

The first learning point concerns the analysis of data from train data recorders to provide information on the location of low adhesion conditions on the network. The second learning point is that infrastructure managers need to be aware of changes in traffic patterns which necessitate the reassessment of the adequacy of buffer stops in terminal platforms.


Title: Re: ......are there any conditions.......
Post by: stuving on November 25, 2014, 12:57:52
There's quite a lot about how WSP systems work in this report, which is relevant to the discussion earlier about the merits of tread brakes. This is the relevant bit:
Quote
64 The second function of the WSP is provided to maximise the retardation of the train in the prevailing friction conditions. Research has shown that a degree of sliding contact between wheel and rail is beneficial in that it ^conditions^ the wheel and improves the friction between wheel and rail. The WSP on the class 221 was designed to attempt to keep the speed of the wheels 17% below the speed of the vehicle during braking in wheel slide conditions.

So when the wheel wants to slide, the WSP (rather like a car's ABS) brakes it in a succession of tiny slides alternating with freely speeding up again. That's meant to "wipe" the wheel and rail on each other, as well as preventing any localised flatting. I guess there is a minor point left: whether the there is a delay for this to have effect that tread brakes or scrubbers would avoid.

There was also this assessment of the available braking:
Quote
81 The fact that the WSP indicator lit up as soon as the brake was applied in the lowest setting indicates that the friction available between the wheels and rails was too low to support even the initial brake application (ie indicating a coefficient of friction less than 0.019).

The OTDR showed a deceleration of less than 0.1g - even with all this clever WSP stuff in action. Not much, to stop a train.



This page is printed from the "Coffee Shop" forum at http://gwr.passenger.chat which is provided by a customer of Great Western Railway. Views expressed are those of the individual posters concerned. Visit www.gwr.com for the official Great Western Railway website. Please contact the administrators of this site if you feel that content provided contravenes our posting rules ( see http://railcustomer.info/1761 ). The forum is hosted by Well House Consultants - http://www.wellho.net