The Wrong Type Of Rain?

[Eric]

Can someone explain to me just what this wrong type of rain does so that all train services end up being 30 minutes + late?

While on the late running 16:03 Brimingham -- Edinburgh (it was terminated early and thus didn't call at Motherwell & Glasgow Central) I was talking to the train manager who was explaining that today was the wrong type of rain as this results in significant loss of friction between the train wheels and rails.

Is there anything that could be done to improve this so that we don't have 80% of the network running late due to this cause.

 

[87031]

Might have something to do with leaves as well as rain or just the fact that Voyagers are junk

 

[Eric]

Might have something to do with leaves as well as rain or just the fact that Voyagers are junk

The XC TM said it was the wrong type of rain, but didn't explain really what the wrong type is.

I can't begin to tell you how relieved I was on seeing a HST pull into New Street station today.

I don't think I could have made it if a Voyager had turned up.

 

[route:oxford]

Is there anything that could be done to improve this so that we don't have 80% of the network running late due to this cause.

I doubt if 80% of the network was running late because of wet weather in the North.

It was dry, albeit quiet windy in the south today.

 

[Eric]

I doubt if 80% of the network was running late because of wet weather in the North.It was dry, albeit quiet windy in the south today.

The 80% figure is no way an exact one, but it certainly did feel that high when passing Sheffield, Wakefield today (looking at the departure boards through the window) on a train that was 90/100 minutes late.

 

[daikilo]

The 80% figure is no way an exact one, but it certainly did feel that high when passing Sheffield, Wakefield today (looking at the departure boards through the window) on a train that was 90/100 minutes late.

Eric, I doubt the real issue was wrong rain. Rain leads to wet rail but this is part of the planning allowance. Other factors such as leaf-fall may have been an issue as maybe a combination of rain with e.g. wind at exposed locations, but I doubt in your case.

Can't find any signs that more than a few % of services were late on arrival on evening of 2/11.

 

[Peter Mugridge]

The XC TM said it was the wrong type of rain, but didn't explain really what the wrong type is.

I am tempted to suggest it was the wrong type of train, being a Voyager...:roll:

 

[O L Leigh]

Wet rails can make for an interesting trip.

The problem with metal wheels running on a metal track is that the contact patch is tiny. Consequently, almost anything that gets in between the two can cause a loss of grip. I'm not sure what this TM thought constituted the "wrong type of rain" except that it clearly must have robbed the train of grip causing problems with both acceleration and braking.

There's not an awful lot you can do in the situation. When accelerating you can try notching up to apply power more gradually in an attempt not to break grip or you could drop sand (though I'm given to believe Voyagers only have "one shot" sanders). When braking you'd just need to be a bit more cautious and brake earlier in case you don't have sufficient grip for normal braking.

O L Leigh

 

[DavidBusDriver]

Just to add further:

More problems can be experienced with wheelslip/slide when a light fall of rain occurs just after a prolonged dry spell, with the effect of the water lifting various ingrained contaminants from the railhead and therefore further reducing rail adhesion - whereas a very heavy rainfall often has the benefit of clearing such deposits from the railhead by the force of the rain, or of course the artificial method of the RHTT water cannon trains!

Never had much low adhesion driving yet but I am sure it will start happening soon... needless to say though it can cause delays as O L Leigh has said, the wheel/rail interface is a tiny area and very easy to interfere with!

 

[WatcherZero]

Just to add further:

More problems can be experienced with wheelslip/slide when a light fall of rain occurs just after a prolonged dry spell, with the effect of the water lifting various ingrained contaminants from the railhead and therefore further reducing rail adhesion - whereas a very heavy rainfall often has the benefit of clearing such deposits from the railhead by the force of the rain, or of course the artificial method of the RHTT water cannon trains!

Never had much low adhesion driving yet but I am sure it will start happening soon... needless to say though it can cause delays as O L Leigh has said, the wheel/rail interface is a tiny area and very easy to interfere with!

Same thing happens on the roads, particularly in spots where there had been an accident/spill previously and it had dried. Thats what I thought a candidate in this case anyway.

 

[yorkie]

I see you left BHM at 1730. Depending on your destination, the 'real' 1730 may have been better as this 'overtook' between Sheffield and York, although I too would have opted for the HST despite going via the slow (and delay-prone) Leeds route!

You called at Sheffield around 1900. Of the 12 trains scheduled to leave between 1900 and 1930 only 3 departed 10 or more mins late (2 Northern trains to Leeds and one to Donny). So around 80% of trains departing on time!

 

[O L Leigh]

I'm not sure when we last had a prolonged dry spell, though.

O L Leigh

 

[The Planner]

Eric, I doubt the real issue was wrong rain. Rain leads to wet rail but this is part of the planning allowance.

No it isnt, we dont factor in anything weather related, it would be impossible. Timetables are thinned out/changed for leaf fall such as on the Birmingham Cross City, but day to day nothing is added.

 

[wibble]

The 1603 was delayed because of 'heavily contaminated railheads' in the Lawrence Hill area near Bristol. Sand was used but without much effect.

 

[Oliver]

I'm not sure when we last had a prolonged dry spell, though.

O L Leigh

From June to September 2010 we had almost no rain in East Devon.

 

[Chapeltom]

I certainly remember a 3 month spell in Derbyshire earlier this year with about 4/5 days of real heavy rain and that was it! We have had a massively dry year.

 

[mumrar]

Got a control email this morning and the problem has been awful adhesion caused by the light rain bringing greasy muck out on the railhead surface. Once trains started to slow being cautious and finding acceleration very difficult, this has the effect of making the signal headways hopelessly reduced because of the slower speeds. So congestion kicks in, trains are having to stop and start more due to restrictive signalling, which is the two things they are finding most difficult in these conditions. At around 20:30 there were 9 services running over 30min late, some up to 80 in fact.

Whilst the problem may have not sounded very sensible, I don't think passengers require and/or would understand an exaplanation as complex as above. If NR had an effective vegetation management system, then a lot of the railhead contamination would be reduced, as it's the naturally occurring stuff which is most common, particularly this time of year. As it is, we get this instead.

For those who drive cars, you must surely notice how treacherous it is when it starts to just spit gently after a dry spell, as opposed to heavy rain. Any diesel spills or oil etc become very dangerous with the light covering of water, and it is less of a problem in the heavier rain. Now imagine that with metal on metal contact surfaces instead of rubber and tarmac, and up the vehicle weight a lot too.

 

[Eric]

Got a control email this morning and the problem has been awful adhesion caused by the light rain bringing greasy muck out on the railhead surface. Once trains started to slow being cautious and finding acceleration very difficult, this has the effect of making the signal headways hopelessly reduced because of the slower speeds. So congestion kicks in, trains are having to stop and start more due to restrictive signalling, which is the two things they are finding most difficult in these conditions. At around 20:30 there were 9 services running over 30min late, some up to 80 in fact.
Whilst the problem may have not sounded very sensible, I don't think passengers require and/or would understand an exaplanation as complex as above. If NR had an effective vegetation management system, then a lot of the railhead contamination would be reduced, as it's the naturally occurring stuff which is most common, particularly this time of year. As it is, we get this instead.

For those who drive cars, you must surely notice how treacherous it is when it starts to just spit gently after a dry spell, as opposed to heavy rain. Any diesel spills or oil etc become very dangerous with the light covering of water, and it is less of a problem in the heavier rain. Now imagine that with metal on metal contact surfaces instead of rubber and tarmac, and up the vehicle weight a lot too.

Cheers for the information mate.

That would explain why the 158 coming out of Leeds last night was having trouble gaining momentum (either that or the engine was cracked).

 

[mumrar]

Cheers for the information mate.

That would explain why the 158 coming out of Leeds last night was having trouble gaining momentum (either that or the engine was cracked).

158s are pretty awful in the wet, when I had one under Central Trains for a Rugeley I was working, we had similar drizzly conditions, and it took us 28 minutes to get to Hednesford, because as soon as wheelslip is detected, the power is shut off. Re-apply, wheels spin, power off. We didn't get above 20mph the whole way.

 

[moonrakerz]

158s are pretty awful in the wet, because as soon as wheelslip is detected, the power is shut off. Re-apply, wheels spin, power off.

That might explain my local trains all being "to pot" on Saturday last. I was at Warminster waiting for Bittern to come through and all the service trains (all 158s) were running late.
While we were waiting a "de-icing" unit D98974 arrived from the Salisbury direction, crossed over, and headed back in that direction, leaving what appeared to be sand on the rails.
Have seen the high pressure track washing train before, but not this thing.

Bittern eventually arrived about 40 mins late following the Brighton to Gt Malvern service which was a good half an hour late itself.

 

[driver9000]

While we were waiting a "de-icing" unit D98974 arrived from the Salisbury direction, crossed over, and headed back in that direction, leaving what appeared to be sand on the rails.

That will have been a Sandite train, a kind of coarse wallpaper paste like substance that helps trains grip the rail in times of low adhesion.

It has been a nasty week or so in the North West for low adhesion including locations that don't normally suffer from it experiencing adhesion problems. A combination of high winds and rain bringing leaves down and making the rails very greasy. Network Rails booked water jetting trains have been running overnight and the p/way staff have been kept busy applying sand to the rails by hand using a hand held applicator during the day.

 

[90019]

158s are pretty awful in the wet, when I had one under Central Trains for a Rugeley I was working, we had similar drizzly conditions, and it took us 28 minutes to get to Hednesford, because as soon as wheelslip is detected, the power is shut off. Re-apply, wheels spin, power off.

That would explain the 158 I was on recently that seemed to be doing that.
I'd wondered if there was something wrong with it as it took 6 or 7 attempts to get it started in Waverley.

 

[Eric]

158s are pretty awful in the wet, when I had one under Central Trains for a Rugeley I was working, we had similar drizzly conditions, and it took us 28 minutes to get to Hednesford, because as soon as wheelslip is detected, the power is shut off. Re-apply, wheels spin, power off. We didn't get above 20mph the whole way.

That sounds a lot like the journey we had yesterday.

The engine revving up repeatedly as the driver looked to gain speed.
--- old post above --- --- new post below ---
The 158 I was on this morning made heavy work of trying to get up the incline to get out of Bradford and at one point came to a complete stop as we reached Mill Lane signal box.

 

[O L Leigh]

More problems can be experienced with wheelslip/slide when a light fall of rain occurs just after a prolonged dry spell, with the effect of the water lifting various ingrained contaminants from the railhead and therefore further reducing rail adhesion - whereas a very heavy rainfall often has the benefit of clearing such deposits from the railhead by the force of the rain, or of course the artificial method of the RHTT water cannon trains!

I've been thinking about this today as the weather has made things very *ahem* "interesting".

This idea of water lifting contaminants out of the railhead was something I was also told when I was being trained. While this holds true for an asphalt road surface I just can't believe that it also applies to the railhead.

Both the railhead and the train wheels are made from a hard steel and become highly polished with use. While they will not always be perfectly smooth and without any blemishes, I just can't see where contaminants can lurk undetected until such time as a drop of rain causes them to float off and cause problems. Sure if you already have contaminants on the railhead adding water to them doesn't help because suddenly you've got something wet on top of something slippery and it just greases the rail up further, but the contaminants were already there and would be causing problems anyway.

I think the more likely explanation is due to the difference in water droplet size and how this affects the behaviour of water. As a biker I have ridden in all sorts of rain and seen how it behaves differently when it strikes a handy surface (in this case, the outside of my visor).

The worst type of rain is a very fine rain, almost like a mist. The droplet size is very small with very little mass, too small for the weight of the drop alone to overcome the force of it's own surface tension. Therefore it appears to stick and, on a crash helmet visor, quickly builds up into an foggy layer. Even travelling at motorway speeds and turning my head so the visor is more into the air flow fails to clear it because it is not possible for even a strong wind blast to clear the drops away. Where you get a more "normal" rain with larger droplet size the force of the surface tension is more easily overcome because the droplet has sufficient size and mass.

The same would apply to the railhead. A very fine, light rain would cause a build-up of water on the railhead that would not clear of it's own accord because of the size of the water droplets, where larger droplets would bead and run off. Therefore in light rain you would actually end up with MORE water sitting on the railhead than would be the case in medium to heavy rain, making the rail proportionately more slippery.

I'm not a scientist, but this explanation makes much more sense to me.

O L Leigh

 

[142094]

Cheers for the information mate.

That would explain why the 158 coming out of Leeds last night was having trouble gaining momentum (either that or the engine was cracked).

Between Cottingley and Morley today was pretty bad, could tell the 144 couldn't cope.

 

[John Webb]

When working in St Albans South box, particularly on Sundays when the train service is less frequent, it is clear that a fine drizzle causes more problems for drivers accelerating out of St Albans City Station than a heavy down-pour. The difference is clearly audible in terms of the motor noise as the anti-wheel slip system cuts in and out.

 

[wessex]

I was doing my practical handling on a 319 emu on the TL route, and could not get over 40 mph at times. It was a good learning experience of the worst railhead conditions to expect.

 

[chuffchuff]

Thank you O L Leigh, saved me a lot of writing
Even a dewy night will make the first couple of trains out of Dover late, due to
wheelslip. You have to be careful braking as well, with the wheel slide going
'ape' on the front bogie, you're left there wondering if the rest of the train isn't
going to do the same

 

[MrC]

I just can't see where contaminants can lurk undetected until such time as a drop of rain causes them to float off and cause problems.

I suppose it is possible - after all the wheels don't have a contact patch across the whole top surface of the rail. You tend to end up with a narrow polished 'stripe' with the remainder being untouched and I suppose it's possible that's where contaminants can build up and then be redistributed across over the contact patch under light rainfall conditions.

Mind you that doesn't explain the complete loss of grip you get if you follow a NR MPV doing high pressure jetting........:roll:

 

[Flywaver]

I really want to vent some steam on this subject..........
I am totally disgusted with the way NR are (not) treating vegatation. Trees are hanging over lines. Not just leaves but a storm is bad enough to damage rolling stock....
There have been a few serious incidents over the last few days related to leaves. I've hardly seen RHTT's about over Anglia. Have DRS lost the contract?
Units are being built lighter but no intention of fitting block brakes as extra back up to disc brakes to clean the grime off. Signalman are asking Drivers where they are as they are not showing up on Track Circuits. Sand tends to get blocked in pipes.. the list goes on..... As far as im concerned the timetable goes out the window. A to B safely that is all that matters!