Poor Rail Head Conditions

[frobisher]

It just suprised me that it would be enough of a problem that anybody would shut down a line for leaves on the rail. Here in the US, a major class one railroad might have one or two stalls a month in season on ruling grades where the trains are right on their horsepower (13,000 tons and 8800 hp), but other than that its not a common problem and I've never heard of having to clean off the rails or shutting down a line for leaves. We did have to plow seaweed off a coastal line in Texas after a hurricane storm surge. 8-)

 

Part of this is the different operating environment in the UK. We have plenty of railway cuttings with wooded banks to the side (since the end of steam, trees made something of a come back along railway cuttings) so the build up of leaves can be appreciable. The big problem seems to be with multiple units which have to stop and start with greater frequency and encounter unfavourable leave conditions more regularly. I seem to recall there was a big problem in Southern Region with the introduction of the 508's which had a huge susceptibility to leaves compared to the stock that had previously been operated (4SUB's mostly) and it came down to more modern practices with regards brakes. All the slam door stock had brake blocks that operated on the wheel treads so tended to scrape leaf detritus off the wheels so there was no real build up which would facilitate skidding, whereas the 508s had disc brakes and hence nothing that could prevent a leaf build up on the tyres. This period (early 80's) was the first in my recollection when "leaves on the line" became the explanation for delays and it's been with us since to varying degrees.

[Fat Controller]

Part of this is the different operating environment in the UK. We have plenty of railway cuttings with wooded banks to the side (since the end of steam, trees made something of a come back along railway cuttings) so the build up of leaves can be appreciable. The big problem seems to be with multiple units which have to stop and start with greater frequency and encounter unfavourable leave conditions more regularly. I seem to recall there was a big problem in Southern Region with the introduction of the 508's which had a huge susceptibility to leaves compared to the stock that had previously been operated (4SUB's mostly) and it came down to more modern practices with regards brakes. All the slam door stock had brake blocks that operated on the wheel treads so tended to scrape leaf detritus off the wheels so there was no real build up which would facilitate skidding, whereas the 508s had disc brakes and hence nothing that could prevent a leaf build up on the tyres. This period (early 80's) was the first in my recollection when "leaves on the line" became the explanation for delays and it's been with us since to varying degrees.

There's also a bit of a difference in operating a freight railway with trains at fairly long intervals apart, (possibly on tracks that aren't signalled apart from at passing places and junctions) and a reasonably intensively-worked mixed-traffic railway. Once you start to lose the facility to run trains at fairly close headways, because you can't send something into a block section until you know the previous train has cleared it, the timetable very soon falls apart. Once this starts to happen, then pressure on the operators increases such that safety is at risk. A single signaller at a location such as Ashford or London Bridge may be responsible for twenty or more trains at the same time- once more than one or two of these is running out-of-course, then the workload becomes unacceptably high.

[Glorious NSE]

It just suprised me that it would be enough of a problem that anybody would shut down a line for leaves on the rail.

 

Not sure anyone would shut down a line over it, but it is a safety and operating concern that needs watching closely.

 

There's also a bit of a difference in operating a freight railway with trains at fairly long intervals apart, (possibly on tracks that aren't signalled apart from at passing places and junctions) and a reasonably intensively-worked mixed-traffic railway.

 

Mmmm, the line in the RAIB report I quoted earlier is a 4 track main with relatively lightweight EMU trains running at 90mph on as little as 3 minute headways in peak times, i'm not sure anywhere in the US has that exact mix of circumstances even on your busiest commuter lines, but it's not unusual on commuter routes into London.

 

US main line loco's coming in at around 200 tons on 6 axles I suspect also has an impact in terms of the grip available - no disk brakes on US loco's either.

[Hobby]

Going back to the OP, the section they will have had trouble with is around Selly Oak, next time you go down that stretch keep your eyes peeled for the "poor railhead" signs alongside the track, its on a curve, downhill and with plenty of trees just off the railway land and perfectly placed to dump their load over the track... its well known for it even in the old days. The Sandite train has been out and about for several weeks now (as has the "leaf fall timetable"!). There are usually a couple of trains going round the Birmingham area, but it does take them a fair while as they are not that quick!

 

BTW they just reduce the frequency of trains on that line if they need to, not shut it... which usually means that LM and XC diesel services will get routed into New Street via Camphill and leave the Selly Oak line to the locals...

[JZ]

Working 1F23, the 14:30 Cardiff Central - Portsmouth Harbour, on Monday, we encountered 'poor railhead conditions'. First at Bradford-on-Avon. As we left, we managed to reach 5mph by Greenland Mills crossing. Normally about 25-30 and most of this is in a tunnel . Gentle braking was the order of the day for my drivers. Although we did manage to catch up time by Southampton, we lost another 8 minutes by Portsmouth. The Netley line, between St.Denys and Fareham, is notorious for poor railhead conditions.

 

The passenger on the train may not notice slipping, but when you work on trains you do become attuned to them.

[Glorious NSE]

The passenger on the train may not notice slipping, but when you work on trains you do become attuned to them.

 

You might on the Southern region - travel in the motor coach of a 455 this time of year and listen out for the Whzzzzzzzzzzzzz of the spin followed by the POP as the WSP finally kicks in!

 

 

I would guess not helped by the driver travelling in an unpowered vehicle so not having much idea of what's going on behind him!

[Edwin_m]

In braking you can hear the WSP "spitting" repeatedly as it detects slide and dumps pressure from the brake cylinders. This is a lot quicker than the response Glorious mentiones, which is strictly traction control rather than WSP. Acceleration isn't safety critical, and to be cynical wheelspin is damaging NR's rail not the TOC's wheel so the TOC (and ROSCO) aren't so motivated to do something about it. The RAIB report into the Lewes incident reports that the noise of the WSP was what alerted the driver of the other (moving) train that a collision was likely.

[Glorious NSE]

This is a lot quicker than the response Glorious mentiones, which is strictly traction control rather than WSP

 

Ta for the correction.

[big jim]

Locos do but many units, the main problem trains, only have it automatically applied rather than manually controlled. Some units also had one shot emergency sanders but some TOCs have removed them as they weren't used much and didn't justify the cost. Fill in your own response!

 

one shot sanders, your damned if you do, your damned if you don't, its your call as a driver as to whether you hit the button to deploy them, if you don't and you slide through a station etc you get questioned as to why you didn't use them, if you do use them you get questioned as to why you used them and asked why you weren't driving to the conditions!!

 

the only unit i used to drive with them was 158's, the added problem with them being they have disc brakes rather than clamp brakes so when you braked there was nothing "grabbing" the tread of the tyre to clean it meaning the leaf mulch just accumulated on there so you ended up in a slide.

 

it is a very serious problem as others have pointed out, units are worst for sliding, light locos can be as bad but heavy freight isn't as bad when stopping but starting away can be an experience

 

the worst i've ever know it was between shotton high level and hawarden where i was strugging to get any more than 2 mph out of the train, i really thought i was going to stop and slide back, i had the sanders going constantly and luckily it kept biting at just the right time to keep moving, the train i was driving at the time........the rhtt leaf busting cannon with a pair of 37's powering, you knwo its trouble when you are struggling to move the train thats actually clearing the line

 

if someone non railway asks me what experiencing "leaves on the line" is like i can only describe it as being akin to hitting a sheet of black ice in a car

[Gary H]

 

 

US main line loco's coming in at around 200 tons on 6 axles I suspect also has an impact in terms of the grip available - no disk brakes on US loco's either.

Not to mention the fact that theres nearly always more than 2 of em with big sand box's on one train and they maybe pulling dozerns of bogie wagons all with clasp brakes!

I took the picture below near South Brent last weekend. JZ mentions that he had problems with addhesion in a tunnel. This stuff was right the way through Marley tunnels as it gets carried along by lots of wheels. It turns to a carbon like substance that you cant scratch off with your nail! It reminds me of the teflon coating you get in a frying pan. As Big Jim points out, add a little moisture to this stuff and its like driving on ice.

[Edwin_m]

the train i was driving at the time........the rhtt leaf busting cannon with a pair of 37's powering, you knwo its trouble when you are struggling to move the train thats actually clearing the line

 

Nice one Jim. S'pose it shows there was a good reason to run that train!

 

I think the loco-hauled RHTTs now have a loco each end with through jumpers. At least then the rear loco is on the treated track and has a chance of getting some grip. Presume yours was a conventional double header not one of those?

 

Mind you it's not always so. A couple of weeks ago in Leicester I saw a RHTT top'n'tailed by the EWS Executive silver class 67 and its matching DVT!

[The Stationmaster]

Going back to the early 1970s we had an EE Type 3 (Class 37 in later parlance) slip to a stand on a 1 in 38 rising gradient with heavy leaf contamintion - its load was 3 empty 16ton mineral wagons and brakevan. And it took another Type 3 and a lot of hand sanding to get it shifted.

[Fat Controller]

Going back to the early 1970s we had an EE Type 3 (Class 37 in later parlance) slip to a stand on a 1 in 38 rising gradient with heavy leaf contamintion - its load was 3 empty 16ton mineral wagons and brakevan. And it took another Type 3 and a lot of hand sanding to get it shifted.

I remember a '68er' doing that on the Mynydd Mawr at the bend by Furnace School. I also remember at least three loaded coal trains running away on the return journey, due to a combination of insufficent brakes being pinned down and poor railhead conditions. The branch was always difficult- the timing allowance was something in the order of an hour for a distance of about six miles.

I've been on a train that overshot its booked stop (either Chelsfield or Knockholt)at this time of year. It wasn't even modern stock, but a rebuilt 4-CEP. Lynne had an even more alarming experience on the Italian approach to the tunnel at Mont Cenis- her TGV had traction problems and poor railhead conditions, and actually slipped backwards!

[Guest stuartp]

Having once stood in a signalbox and watched a train disappear - it cleared one track circuit several seconds before occupying the next, it is not the most comforting of experiences.

 

In 1992 the up line at Culgaith had a single track circuit covering the whole distance between up home and up section signals (both colour lights), and the overlap of the section signal. It was the 'last wheel clearance' type - occupying the TC put the home signal back to red, and clearing the TC put the section signal back. Even a momentary 'fail to occupy' would therefore throw the section signal back in the driver's face, so when 156s were introduced to the line and started merrily disappearing from TCs all over the place, an instruction was issued to the box that the section signal was not to be cleared for 14x or 15x traction until the train was closely approaching it. I should mention that this particular TC could manage this without any help from leaves or anything else.

 

One day I was sitting in the box doing my twice weekly box visit (a chat and a cuppa). There was a railtour due on the up and the signalman was quite pleased as it meant he could pull all off for a change and see some thrash rather than watching the usual Tupperware trains crawl past. We were enjoying the spectacle as a 47 with 12 on came charging past, then watched in horror as the whole thing, all 54 axles and 500 tons of it, disappeared from the box diagram and went thundering on in a cloud of brake dust and braying horns. The driver was not at all happy, it took some time to convince him that neither of us had touched anything !

[iploffy]

one shot sanders, your damned if you do, your damned if you don't, its your call as a driver as to whether you hit the button to deploy them, if you don't and you slide through a station etc you get questioned as to why you didn't use them, if you do use them you get questioned as to why you used them and asked why you weren't driving to the conditions!!

 

the only unit i used to drive with them was 158's, the added problem with them being they have disc brakes rather than clamp brakes so when you braked there was nothing "grabbing" the tread of the tyre to clean it meaning the leaf mulch just accumulated on there so you ended up in a slide.

 

it is a very serious problem as others have pointed out, units are worst for sliding, light locos can be as bad but heavy freight isn't as bad when stopping but starting away can be an experience

 

the worst i've ever know it was between shotton high level and hawarden where i was strugging to get any more than 2 mph out of the train, i really thought i was going to stop and slide back, i had the sanders going constantly and luckily it kept biting at just the right time to keep moving, the train i was driving at the time........the rhtt leaf busting cannon with a pair of 37's powering, you knwo its trouble when you are struggling to move the train thats actually clearing the line

 

if someone non railway asks me what experiencing "leaves on the line" is like i can only describe it as being akin to hitting a sheet of black ice in a car

 

I remember that section of line well on a 142 out of shotton up the bank walking infront of the unit putting lumps of ballast on the rail to get adhesion what a day that was even running back down the hill to get a run at it

 

Ian

[James]

Go to page 9 items 31 and 32, this is the Signalman and Driver earning their money big time. Quick response by the driver, no panic, a precise emergency call and then a Signalman who put that information and his/her experience to full use keeping everyone safe.

see also items 46 & 47

Did you notice though that the Signalman was actually praised for thinking on his feet and telling the train in front to keep going, I remember this happening and a technical break of the rules actually ensured safety.

 

That's an interesting report and the point about not following the rules exactly is an interesting one; it shows great professionalism on the part of the signaller too.

 

I've been taught that rules are rules but there are times when it's permissable to break them if you are doing so to ensure the safety of others as long as you don't place anyone in greater danger by doing so. A good case of this is an area where red zone is prohibited; however should an incident occur I'd willingly go there if I had to place detonators as I could easily lie down in the cess of six foot, for example, if I had to.

[DavidB]

The passenger on the train may not notice slipping, but when you work on trains you do become attuned to them.

 

I've certainly been noticing the lack of adhesion this week on my morning HST journeys from Didcot to Paddington - but this is during acceleration rather than braking. From my usual seat in the TGS, the rear power cars have been struggling for adhesion all the way from Didcot platform as far as Moreton Cutting - and if the rear power car has been having problems on a railhead that's been cleaned by the nine cars ahead of it, the front one must have been in real difficulties judging by the thumping and banging through the buckeyes. All very bizarre when you consider that the line is basically level, heavily used and perched high on an embankment with virtually no trees around - but it happened consistently with different sets on Monday-Wednesday. Judging from the number of wheelflats on FGW power cars towards the end of the week, they've been having a really tough time with the braking too.

 

David

[Adrian Wintle]

We don't shut lines, but the GO Transit trains (MP40 or F59PH + 10-12 heavy Bombardier coaches running as a push-pull set) can have traction issues in prime leaf season (i.e. now). On a cold, wet morning the train can lose a few minutes due to traction issues on the hills. It could also make braking into stations a little trickier, but I don't believe that it would cause an overrun of more than a coach length in the worst case. Mind you, this is a much heavier consist than a 450 (as in the RAIB report), and is running at about 2/3 of the speed or less. When I was commuting on these things we were the first train on the line each morning, so got the worst of the conditions.

 

That RAIB report is very interesting. The driver and the signaller were on the ball that morning.

 

Adrian

[yellowvanman]

...interesting thread..out today on circuit from EH works to Reading and back via Direct and a quick squirt over the Netley line...pic shows MVP on arrival back in the works for topping up...back out tommorow and Sunday...

[Poor Old Bruce]

It is not always leaves which cause poor railhead conditions. Several years ago an EMU slithered into the buffer stops at (IIRC) Croxley Green. It was the first train of the day and the dew on the rail head had mixed with the rust layer to make a nice slurry. Traction control and WSP equipment are designed to make the most of what adhesion is available. It you aint got any adhesion, you're buggered.

 

Richard

[Oldddudders]

It is not always leaves which cause poor railhead conditions. Several years ago an EMU slithered into the buffer stops at (IIRC) Croxley Green. It was the first train of the day and the dew on the rail head had mixed with the rust layer to make a nice slurry. Traction control and WSP equipment are designed to make the most of what adhesion is available. It you aint got any adhesion, you're buggered.

 

Richard

Not that many years ago, a District Line train rather-more-than-kissed the buffers at Richmond. It transpired that the PW had been fettling a pair of points in the station throat, including renewing the grease. Having scraped out the old grease, they then looked for somewhere to wipe the stick they had used. Easy - just wipe it off on the railhead! There are times when being a driver must be most unpleasant!