- Why are leaves on rail lines an issue now (and never seemingly used to be)?
Really? It’s been a long standing joke.
Basically as I understand it they use an electrical loop to tell where a train is on the tracks to move points and manage junctions. When leaves go mushy they stop this signal being reliable and they have to do more manual checks which takes longer. This is why they fell everything by railways nowPosted 8 months agowwaswasSubscriber
It did use to be an issue for traction for starting/stopping/inclines – wheels would skid and then flat spot or just spin – trains used to have sand boxes next to their wheels the driver could trigger to give traction.
Now as mikewsmith says, with modern signal systems, it also ‘trips’ fail safes when wheel/track circuits become intermittent.Posted 8 months agowwaswasSubscriber
There’s a lot of debate about using railways as green corridors – as noted above during the steam age lines were kept clear due to fire risks. Now people almost want behave as if they’re nature reservces which results in a lot more leaf fall onto the lines and also, during storms, more mature trees falling across tracks or damaging equipment.
So leaves on the line weren’t a historic problem but certainly since the early eighties when I started regularly commuting they have been,Posted 8 months agonjee20Subscriber
The wrong kind of snow came about in the early 90s as a bit of a joke deriving from comments on why the new class 91s (IIRC) were having issues. It’s actually quite valid too – there were instances a few years ago of Desiros catching fire after ingesting fine powdery snow, which doesn’t happen with more dense snow.
Leaf mulch has been an issue for years, less so in steam days because the locos weighed so much more, but certainly ever since. They’ve been using dedicated treatment trains for some years to combat it. They get fairly dirty…
Posted 8 months agoThe DukeSubscriber
Been driving trains for a few years now and leaf fall is defiantly a big problem, the leaves get crushed by the wheels and form a teflon like slippery coating on the rails that can make starting and stopping extremely difficult. Approaching a red signal and not sure your going to stop is pretty terrifying and I’ve failed to climb gradients and had to return to the bottom of the hill for another attempt. Most trains have sanders fitted and wheel slide protection that’s like ABS to stop the wheels locking up when braking, unfortunately the trains I drive don’t have these fitted with the result that too much braking locks the wheels and puts flat spots on them. Leaf fall residue can also stop trains being detected by the track circuits with the potential for a signal to show green with a train ahead. Best way to describe it is like trying to drive your car up a icy hill and stop on the way down.Posted 8 months agoI_did_dabSubscriber
1998 I got stuck on a train to Sutton because of wet leaves. Every time the signal went green the train’s wheel span on the slight incline as it tried to accelerate and it missed the signal and had to wait for the next opportunity. It was a nightmare for a few years before they brought in the track scrubbers. Network rail also cut down a lot of trees in the meantime.
So it’s not a new problem.Posted 8 months agoscc999Subscriber
Got told by a long serving train driver friend that the new Networker trains (SE) had a few issues. They were far lighter than the old slam door units they replaced, the ‘abs ‘ meant stopping distances actually increased massively on slippery surfaces and lastly the sand previously mentioned was now a one shot deal, on the older units they had enough for a lot more applications of sand.
No idea how much of that is true, but he had no reason to lie!Posted 8 months agodove1Subscriber
Good old British Rail used to employ maintenance teams to regularly cut back vegetation and prune trees to stop leaves dropping and building up on the rails. Privatisation and cut backs put paid to that activity, or severely curtailed it so now we get trees growing much closer to and overhanging the tracks and leaves drop on the rails every Autumn.Posted 8 months agoCountZeroMember
A quick look at old photos of railways even as recently as in BR days will tell you that railway cuttings and embankments are now thickly wooded with mature deciduous trees, which they weren’t even in the 60s.
This is very true, I can remember crews cutting back trees and doing regular controlled burning of scrub and bramble, etc., to avoid fires alongside the lines, especially during long dry periods like we’ve had recently. I can also remember fires being caused by steam locos when I was a kid, and the fire brigade being called to put them out. Same with the sound of steam locos pulling away from the station when grip was a bit iffy, you could hear the ‘chuff chuff chuff chuffchuffchuffchuff chuff chuff chuff’ as the wheels spun Another factories likely the size of the driving wheels on modern electric/diesel drive units and old steam locos as well, pretty much the difference between a Moulton and a 29er. The main London-Bristol line runs alongside the bottom of my road, and wasn’t all that far from where I grew up, I could hear trains all the time even if I couldn’t see them, and my second junior school was right next to it, one of my best mates dad was a shunter driver and we used to get footplate rides, so the railway has been ever-present in my life.Posted 8 months agoMing the MercilessSubscriber
Railway man of 26 years here.
1. Modern trains are lighter and cause less wear to the rail head so are not able to grind off the leaf deposits.
2. Leaf mulch turns into an insulator on the railhead for signalling track circuits meaning in worst case scenarios the train dissappears from the signalling system and the protecting signal can give a proceed aspect (as we move to axle counters this is less of a problem). We have to introduce special working if this happens.
3. Lighter trains sitting on the leaf deposits can spin up and slide easier than the heavy trains of old causing flat spots on wheels or burn marks in the rail. Old trains also used brakes that cleaned the wheel surface but again newer trains are disk brakes (as well as regen).
4. Weed killer trains are not as effective as old as we could use the BR equivalent of agent orange in the past.Posted 8 months agothisisnotaspoonSubscriber
The pneumatic rubber tyre on your car is at a pressure of 30psi. So when a car drives over a leaf it turns it to mush and the mush gets washed away.
The pressure under a metal wheel on a metal rail is massive (~20,000lb on a theoretically infinitely small area, the yield strength is ~36,000psi so it will flatten out slightly to that pressure) so it turns it into a very hard, slippery material.Posted 8 months agomuddy@rseguySubscriber
Leaves on lines has been an issue for as long as I can remember. Having witnessed a large steam locomotive spinning its wheels on wet/greasy track I can testify that this isn’t just an issue for modern trains.
The black ice analogy is pretty accurate: its only cold water isn’t it? 🙂Posted 8 months agoBlobOnAStickSubscriber
I’ll just “leave” this here 😱Posted 8 months agomrjmtMember
The more recent provision of condition monitoring on the track circuits that are used to detect the trains (well, actually used to prove the absence of trains) is being used to identify areas of rail head contamination. Where before a train might dissapear due to the insulating properties of contamination, the condition monitoring data is now used to look for trains ‘nearly’ dissapearing and guide the decision on where to send the cleaning train.
I visited the York ROC last week, it’s a real shame that the public can’t see all the hard work that goes on behind the scenes to keep things running during perturbation, and to prevent the perturbation happening in the first place.Posted 8 months agobikebouySubscriber
I’m not sure that we really care about what goes on behind the scenes TBH.
The rail network as a “hole” is run in a sporadic shambolic way as is.
Leaves on the line just adds to our nonchalant attitude towards what you do, and how you do it.
We hear stories of Japanese and Swiss trains running like clockwork, yet they don’t seem to suffer leaves on the line nor flooding nor snow nor strikes like we do here … oh hang on…
In today’s environment, it’s quite odd that you still utilise 18C technology by adding sand to train wheels to aid grip. But I guess all those drawn out meetings and presentations about delivering new solutions to simple problems ends up in an hour of chat, 5hours of drinking tea and eating a third world countries supply of biscuits.Posted 8 months agoBlobOnAStickSubscriber
it’s quite odd that you still utilise 18C technology by adding sand to train wheels to aid grip
The word ‘sand’ here is a misnomer – what is actually applied is something that looks a bit like swarfega and is a potent but environmentally friendly(ish) mixture of citric acid, grit and various other grip and cleaning-enhancing substances. Again, as mrjmt says, the effort that goes into solving these issues is enormous due to the vast sums of money that delays rack up.Posted 8 months ago
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