MikT

Being unfortunate enough to commute on the choo choo and listening to their varying excuses for cancellations and delays, the latest one that has cropped up is the "poor rail adhesion".

Does anyone know if this is the latest phrase for "leaves on the track" or does it mean something else?

Thanks
Paul

trackman

Yes it is. I work on rail maintenance (hence the obvious username) and at this time of year the leaves are obviously falling.

They land on some areas of the track, get compacted down by trains and form a very greasy film on the rail-head. It's the railway equivalent of black ice.

Nigel H

It's a real problem; it's very slippy and difficult to get rid of. Network Rail spend millions of ponds a year managing the problem, cutting down trees spreading Sandite (wall paper paste and sand) on rails over night to combat

Modern trains can cope with it better than old trains. Some operators produce special timetables where journey times are extended due to the poor adhesion (e.g. Metropolitan Line)

An insider

CrisPDuk

The problem is more prevalent than it used to be for one reason alone, these days because Network Rail get no end of grief from enviromentalists (more concerned with ickle bunnies than commuters) when they cut back the trees, they don't cut them back as far as they used too.

Of course in the 'good old days' if they didn't cut them back, sparks from the exhaust of a steam train soon cured the problem

_RIP_

Why dont they put some sort of scraper in front of the wheels? Or am I missing something here?

NotoriousREV

Think of the noise and the drag and the damage to the rail itself.

urban

iTrader: (1)

Because of the joints in the tracks I'd imagine.

_RIP_

Hmm. But trains are noisy anyway and the rails look pretty tough to me.

_RIP_

Yes that's more like it. Forgot about the joints.

trackman

Network Rail have introduced a machine that effectively jetwashes the rail-head as it goes along. I think It's being trialled in low adhesion areas at the moment.

David Lock

I've often wondered that. Something like a wire or bristle brush that is spring loaded and forced down onto the rails. This would ride over any joints. Of course it would wear quickly but easy and cheap to replace regularly I would have thought..........

CooperS

I saw a program the other day about a guy who's invented a 5000 degree celcius laser that burns them off from a specially adapted train, just trying to perfect it before selling it, it was awesome

NotoriousREV

Yes, but that doesn't mean adding a the sound of a scraping blade travelling at 125mph (or 12.5mph for most of the country) is acceptable.

The track are tough, but how many trains pass a particular stretch of track a day? The increased wear would probably cause more problems than scraping the leaves off as they shut entire sections of track for rail replacement.

Dracoro

Fire risk anyone?

Brendan Hughes

Finally an answer why the same seasonal characteristics we've had for the last 100 years are only affecting us in the last 10-20. Thankyou.

ALi-B

iTrader: (1)

The last greasy rail excuse I heard blamed that the problem only came more apparent when they started using modern braking systems. Older trains and rolling stock had brake shoes that use the wheels as the braking surface. Thus cleaning the wheels that made contact with the track. Personally, I think that is mostly rubbish.

Do newer trains have ABS? And would this make the problem worse? As friction/heat caused by locked wheels would in effect clean the track, if they did use ABS then maybe this wouldn't remove the crap off the track?

MikT

WOW - the wonders of NSR!

Thanks for all the replies - particularly to those in the know.

Paul

CooperS

Hehe

Honestly, looked quality, you could touch the track immediately after the laser had been past, you could see the mashed on leaves disappearing.

Jay m A

iTrader: (2)

Ah ha! that was the thing that went past the other day. Made a right misty racket!

PPPPPPSSSSSSSSsssssssssshhhhhhhhhhhhh

Nigel H

Ali

The 'excuse' about the new systems is correct. The old brake systems conditioned the wheel by removing all the crud thus keeping things nice and clean. Dead leaves are extremely sticky and slippy, removal is difficult.

Trains have had ABS (and 'Traction Control') for many years now, well before it was fitted to cars.

Chelspeed

Steel wheels on steel rails. And then everyone acts all surprised when there are braking and traction problems?

Can you imagine driving a car with steel tyres? Even less grip than with Michelins.....

Surely there must be better solutions with the materials available today? Maglev is one solution but still a bit futuristic. Steel wheels for guidance, long life etc but something a bit less tribologically challenged for traction and braking perhaps?

MikT

I don't think anyone in this thread is surprised by the steel wheels on steel rails issue. The question was to do with what the lack of adhesion related to!

Paul

Leslie

Wet leaves are not ever so good on the road either. especially to bikers!

Les

ALi-B

iTrader: (1)

I agree the wheels would have been kept clean, but it doesn't really address the problem with the greasy track. Which is why I suspected that story isn't completely true.

Would I still be right in saying locked wheels would have more effect at stopping a train on greasy tracks through heat/friction burning and wearing through the greasy layer on the track as opposed to ABS allowing the wheels to rotate?

CrisPDuk

You're obviously not an engineer, or you would know that steel on steel is an excellent recipe for good traction, it's when you introduce a lubricant that the fun starts

Older trains used a pair of brake blocks clamping the wheel tread, which wore out the wheels as well as the brakes, moder locomotives have each axle individually driven by an electric traction motor, simplified, braking is effected by turning the motor into a generator thereby creating a drag load on the axle, slowing down the train, with no touching parts there is no wear. None powered stock, i.e: coaches and wagons, have had disc brakes since the early seventies.

Incidentally, when electrification was first introduced from London to Manchester & Liverpool, the first generation electric locomotives (before regenerative braking) needed their brake shoes changing once per WEEK

vindaloo

Aren't there two problems?

How to keep the line clean and how to keep the trains' wheels clean.

Q1 Line: Does the entire line have to be clean? Surely there are obvious areas where it's better to have enhanced friction such as approaching signals and gradients.

Q2 Train wheels: Fit something to clean them at certain stations (as the wheel passes), preferably as the train slows and enters the station.

I don't see that every train or carraige in service has to scrape, spray or laser the tracks. Surely once or twice a day would do.

J.

alcazar

iTrader: (2)

As regards the reason why it's only recently become a problem, it's due to the growth of trees near the tracks.

The old steam locos effectively cleared the vegetation on a regular basis by firing it. Then diesels/electrics took over at the end of the 60's, and trees began to grow again.

British Rail, yes the much maligned, and now, much mourned, once did a good job of clearing vegetation, mostly before it got to be a problem.

Now, money talks.........no-one wants the job. It no longer gets done. You only have to look at weed growth in station areas etc......something British Rail would NEVER allow. It absolutely KILLS the ballast.

If you look at some of the railway publications, there is a series carrying photos showing trains at the same location, "then and now", (then being 50's 60's mostly). The most noticable thing, in almost every case, (apart from the stock and loco, of course) is the lack of vegetation then, and the massive increase now.

Alcazar

trackman

Well this is what I drive and it uses the older brake block mechanism. You just have to be careful with your braking thats all. You get plenty of warning of double yellow, single yellow and red signals. You just have to brake accordingly.

When you sign a particular route, you are made aware of all the low adhesion areas and you drive with extra caution. I don't know if there will ever be a full cure for poor traction but until then I'll drive safely .

(Hope this works)

http://i22.photobucket.com/albums/b3...emplemeads.jpg

trackman

Damn it! Knew it wouldn't work.