Why November is the most dangerous month for trains 

hmm, that also explains why they don't spread jam on the tracks..

- "Darling, what's the noise up here?" - "Oh don't worry honey, I'm just jumping on a sheet of metal with ice skates on!"

Expectation for test: a Model train set with little leaves - Reality: some guy with skates

I feel like the lesson learnt here is that train announcers shouldn't say there's delay because of "leaves on the line", they should say something like that the "lines are dangerously slick". It's a bit newspeak-y sure, but it gets to the real problem better than "leaves on the line" because how many people know anything about the chemistry of crushed leaves on steel?

As a train driver, I can definitely confirm that leaves on the line is a very real thing. The slipperiest condition for a train is lots of leaves and just a very slight drizzle. Snow and ice, on the other hand, doesn't really cause slippery conditions at all. At least nothing like what you see on the roads. The problem with wintery weather has more to do with stuff like switches getting packed with snow, doors not closing, signs lamps getting covered with snow and many other things.

Fun fact: Steam trains didn't suffer the "leaves on the line" problem, since they were so good at setting it on fire, foliage was kept to a minimum around the tracks/embankments, therefore, no leaves!

"So I ran those tests a few million times each..." 4:35 Almost didnt hear it lol!

Leaves on the line Falling so slow Like tiny fragile trains driving themselves home. Little conductor boy riding to Rome Brave conductor boy Driving to Rome

Pedants' Sidebar: Even in North America, Jam and Jelly are not synonyms; jelly is either thickened juices or at least strained; whereas jam is actual fruit flesh, puréed and gelled, optionally with intact pieces.

I can only imagine what his wife must have thought as he ran through the house fetching these materials. A sheet of metal. Ice skates. Leaves. Spray bottle. Pectin. Wife: What are you doing.... Steve: Science!

Hi Steve, speaking as a tram driver, I can SO relate to this because these days I live by it. Just a small correction point - when it rains steadily and the whole track is wet, that's my jam (pun intended), the friction is high and I can stop better than on a dry rail. But besides the leaves, the friction is also low when it's just drizzling, or the fog is settling down and the track is kind of wet but not really. We slide throughout the year, November is just extra sliding :D

As well as increased stopping distance, another problem that can occur when breaking on slippery tracks is wheel flats. If a train wheel slides against a rail, it will grind the metal of the wheel (because out of the 2, wheels are made of softer metal). This grinding will create a flat section on the circumference of the wheel causing it to not run smoothly, which in turn can create extra vibrations which could damage even more of the train.

People laugh until they step on leaves during rain. Totally absolutely no reason why I'm mentioning this.

When you think it's a physics problem but turns out to be more of a chemistry question.

And the reason why modern trains have more problems than they did back in the steam and early diesel and electric days, at least in the UK, is a combination of there being less mass on each shaft on modern trains, and older trains used to have special steam jets and/or sand dispensers to improve traction and clean the rails that modern trains tend not to have. instead they rely on 'smarter' (read, "less harsh on the tracks") anti-slip brake systems, more cautious timetables, and the crushed souls of commuters

4:33 "so I ran those tests a few million times each" lmao

4:00 dude you can't leave your phone lying around like that, imagine stepping on it with the skates on

As a driver myself, I know that leaves are a real problem. Although still bad, things are much better than 20 years ago thanks to intense treatment of the rails and on board train technology. The "Leaf Season" is still the most stressful time of year for a driver, as even the most experienced can get caught out. I also learnt alot from this video, as I knew nothing about pectin and the science of that.

5 blades on your razor and you're still stubbled

Back on in the 1960's, I worked for W.A.Gov. Railways on the Mullewa - Meekathara line (Now closed). Our problems were with plagues of grasshoppers (locusts) that would bring trains to a standstill as all traction was lost. Sand on the rail helps a little. So as the climate changes don't be surprised at announcements that trains are delayed because of locusts or some other bug.

Steve, you should have also mentioned the interaction of leaf mulch with the signalling system. Insulation between the wheel rail interface causes trains to 'disappear' in track circuit areas!

I live in australia and ive never ever heard of a train delayed for leaves. Yes, we have trees here too

:Buys fancy pectin powder to simulate jam-like conditions: :Ignores jam:

The 2021 Salisbury rail crash is the perfect example of why leaves cause delays, a train with full emergency breaks demanded both by driver and TPWS still couldn't stop.

I read the title "leaves on the vine" at first and got Uncle Iroh feels

The most amazing thing in this video is the remarkable ability of the human body to dynamically balance itself in real time. Watching even the best robots in the world trying to do the same thing really brings home how difficult it is.

A few million times, I feel like I smell a slight fib

Beautiful example of incremental perspective buildup. That's a mouthful. Familiar. Familiar plus. Familiar plus plus and so on... Leading up to the final ultimate simple test of measuring different levels of friction between the metal tray and the sheet metal.

Jam =! Jelly Jam has fruit pieces Jelly has only juice Marmalade is usually citrus and contains the peel

As a motorcycle rider I can feel these conductors' pain. Leaves are so slippery!

Can you explain the railway condition of "couldn't find a driver"?

Once I was traveling on the west-coast mainline and there was a delay due to sheep on the line.

as a former hockey player, seeing skates being used like that causes me to cringe every time. growing up we were told never to walk with your skates on metal or wood since it would ruin them. i know it is a bit irrational since i saw you mention that you modified the blade in another comment but it is hard to shake off something that has been grilled into you. great video though

My best slide was in autumn 2000 when I decided to test the brakes at British Tissues Crossing on the Maesteg branch in a 158 at 50mph. The wheel slide prevention (sort of equivalent to ABS) immediately kicked in so I applied full brakes and let it do its thing. 2½ miles later, approaching Tondu, I was still doing 25mph. I did manage to stop at the platform, thankfully ;)

I’m a conductor in New York and leaves are the worst

I've never heard of leaves on the line being a problem in the Netherlands. I think it's because the train lines (at least near my part) are raised almost everywhere and the trees near the tracks have been removed.

“The chemistry of lubrication” mmm yeah Steve.

Jam and Jelly are two different things. Jam is better, but we have both in America, though most prefer(or may not know better) jelly. Jelly is just juice mixed with sugar and pectins, where jam is made with the fruit pulp rather than just the juice. Jams spread and taste better in my opinion.

In the US jam and jelly are two different things. Jams tend to have pieces of fruit in them and they are have a lower viscosity than jelly. Jelly on the other hand is a lot like jello. It's viscous and sugary,and tends not to have fruit. I personally find jelly to be nasty.

I noticed you seemed to be using green leaves not the dead, crumbly brown ones that land on the tracks in fall. I can't say exactly why, but I really do think that would make a big difference. I suspect the fall leaves may have more pectin and I am reasonably certain they break down, release pectin and stick to the tracks much more readily. Source: I spend a lot of time cleaning up stacks of leaves that arrive inside my front door on the soles of my family member's shoes. They stick together quite firmly and are slimy when wet. That doesn't happen with leaves in the summer. This is true even when we spend entire days pruning trees and walking on leaves.

That has to be one of the worst experimental designs I've ever seen, so hats off to you for getting any data from it.

Thank you for not walking with wobbly ankles in skates

Leaves on the vine Falling so slow

1:12 That locomotive cannot go through any turn, unless the middle wheels can slide sideways. 😂

Thank you for running millions of trials to make sure we got the most scientific results possible!

Man, I get the chills everytime I see the skates touch the metal. Idk why, it just seems so wrong.

This may be a stupid question, but why not just put brushes on the front of all the trains, just in front of the wheels?

Ice skates have a concave blade surface, along with sharp edges, which cuts into the metal sheet. You must dull the skates first

Oh, so this is why leaves are so damn slippery after a rain?

8:33 "To give this video some semblance of scientific rigour" This part with the cinder blocks would have been enough on it's own, but not even nearly as entertaining. You know what you are doing, please carry on! We love you, Steve!

Every skater in the audience just cringed so hard watching you damage those runners

It's a big oof from me, an train driver in Germany. I can totally relate to that!! When you're experienced in driving trains, then you drive respectively with your gut feeling.. and this feeling definitely changes during autumn. It happens automatically because the feeling you get, braking on the slippery tracks is immensely different... Yes, we have an antiskid system, but that elongates the stopping distance even further (primarily to reduce damage resulting of blocking wheels). The real tool to deal with this kind of problem, is to apply sand right in front of the wheels to increase friction. It works wonders to shorten the stopping distance in these conditions.. for a measure, I'm adding 50% to the stopping distance, to safely stop the train at any given moment. That's roughly accurate and based by experience only, but never the less, therefore I can stop a train within a few centimeters in precision, at any given moment...

Whilst I understand it's difficult, this is also something that happens **every** year. It's not like it's unexpected to have leaves in autumn, you'd think they'd be able to deal with it better by now.

I worked for a north American rail lubrication company and we teamed up with a company in the UK. They use a product with sand inside which helps to grind off the pectin and "leaves on the line".

6:06 OMG CAN YOU NOT?!?!?! that made my whole body squirm watching you run your finger up and down that razor REEEEEEEEEEEEE

This is cool! I wondered about this as a kid when I would fish off a train bridge in the late fall. I haven’t thought of it for decades.

5:03 exactly 😄 🤣

They didn't use to have this issue in the days of steam, for two reasons: 1. They cut down vegetation next to the line, so that it didn't catch fire. 2. They used sand (often steam blasted) to put sand on the track to improve adhesion. The only mostly steam railway, (The Romney, Hythe and Dimchurch) doesn't have issues like this.

I love your video but that test is ridiculous xD Don't risk your life for an unreliable demonstration, we care about you ! Or at least make a clickbait thumbnail out of it ! The test at 8:40 is way more scientific, without being perfect of course and you could have talked about static friction and dynamic friction, you mesured the latter and it's the one we don't want for our train (wheels turning = static friction, wheels stopping and slipping = dynamic friction, which is always lower). You could have explain that your measure need to be done at a steady speed with no acceleration, overall spend a bit more time on that experiment.

I don't know why but this is one of my favorite videos of yours.

Now can you make a video where you come up with a solution to fix this issue so that you don't see puzzled faces anymore.

Actually a train not stopping on time is not the real problem as you might think. They tend not to stop that fast anyway. It's that slipping creates flat spots on the wheels, which in turn ruin the rails. That is quite costly and time consuming to repair as you might imagine.

Well you just taught everyone how to derail a train.😁 Lay down some pectins/pectie (what ever the plural is) before a sharp curve or train station.

That's actually great! Thanks for explaining it, makes it a lot less annoying knowing that it's a good reason for delays

I wouldn’t mind Steve mould lubricating my track.

I'm watching this on November 29th. Phew. I made it through alive.

Did you take into account the fact that the skate blades have effectively two knife edges per blade when figuring out the relative pressure?

I remember being on a train to uni once, about 20 years ago, and at some point we were between stations and had come to a stop. For the next ten minutes or so you could hear the train making a lot of noise, then calming down, and we were moving forwards only very slightly, far below walking pace. At one point when the train was vibrating quite heavily, at a near standstill, there was an announcement: "Ladies and gentlemen, we are currently travelling at 60mph towards London... this is known as leaves on the line". It was quite enlightening and eventually we managed to get through it, but I was definitely late that day!

I'm surprised you didn't Mount to ice skate blades to a weight and then pull it with a rope attached to a scale so you could measure the amount of force it took to break the friction. Wouldn't that serve the same purpose?

Leaves in the lines Falling so slow Like fragile tiny shells Drifting in the foam

wow steve are you cosplaying as tom scott

My car (RWD and manual) once lost traction on wet leaves and a slight bump as I entered a sharp corner. Luckily I was quick to respond and natural intuition kicked in. I saved myself, the car, my passenger and oncoming traffic with split seconds left. If I hesitated, it would have most likely been a major incident. My childish days of reckless driving had saved my life by teaching me how to regain control of a vehicle.

This would be more convincing if not for the fact that trains still run on time in Japan, a country with an abundance of leaves. Perhaps because they spend more time, effort and money on railway maintenence than Southeastern? (And less on sponsored videos to explain away their failures.)

Train guard here, quite exciting being sat in the cab, Speedo drops to zero as the wheels have locked up and you're literally sliding along the rails at 40mph. WEEEE!

1:52 Hmm, for some reason I am reminded of a Mythbusters episode where they ended up concluding that in order for one of their small scale models to be accurate they would have needed to use a doll made of enriched uranium. I wonder why?

If you ride a bike with slick tyres, you'll agree wet leaves are an absolute nightmare.

Man ever since I saw your collab video with Destin I'm in love with your videos they're awesome 🤩🤩 your dedication and curiosity blows my mind Everytime

Only seconds into the video but, slippage. Slippage is the reason leaves interfere with rail operations. I've conducted trains that when you hit a patch of leaves the "wheels" start slipping.. Which is problematic when you're trying to accelerate or stop\slow down. How do I know? I work at a railroad and was once a train conductor.. but I wanted to watch this to see if there's more to it.. also grass on overgrown train tracks have the same effect. And grass is always wet so it's usually a problem more consistently

I love it when ppl say that I'm dedicated lol

Concord, Jam, Jelly and so on are names for seeds-in, sugar cooked or sugar-added and so on. They're different, we use it the same as you do in the USA.

“Leaves on the track” is just British people being hysteric, as always. Nowhere else are people afraid of a train passing through leaves. Yes, it increases braking distance, but there are already safety margins enough to take that.

A similar situation happens to cars, motorcycles, bicycles and pedestrians when people rake or blow their leaves into the street. They get wet, they become slick, accidents happen and yet those homeowners don't care.

Though nothing lasts forever, pectin decomposition is slowed dramatically by the cold November rain.

Ice skates are typically hollow ground giving them sharp edges which would certainly cut right through the gel giving you a shorter stopping distance.

So that's why autumn leaves in a puddle go all squishy and gelatinous

Okay, so 2:33 finally proves that the goddamn red pipe IS a real physical object that Steve does NOT edit into all of his videos.

Good demonstration! I am glad you did not get hurt

The leaves on the line polymer formation is very similar to “seasoning” an iron skillet, pouring some oil on the pan and heating it at very high heat to bind the oil to the cast iron

I feel so lucky that I have found this channel. Thank you for these interesting videos.

I'm a train driver, in a metro system. The worst and slippiest conditions are transitions between wet and dry, a light drizzle, leaves, and dew formation. Driving up steep sections of track leads to a lot of careful application of throttle to avoid loosing traction. Worst case the train decides that it needs to emergency brake and now you gotta get moving from a standstill. Pouring rain isn't so bad, because once the tracks and wheels are covered in water, the slippery effect largely goes away. The guys in the maintenance depots have their work cut out for them replacing flat-spotted wheels, and replacing rail-brakes. The latter being electromagnets that clamp onto the the rail when you turn a switch, which helps both braking and removing the slippery whatever for the wheels behind it to get better traction.

Another safety aspect of leaves os the effect on track circuits. To detect occupancy, sections of track are energised by either a DC or an AC current and a train passing over that section will short out the signal and indicate the section is occupied. If contamination on the track prevents good electrical contact to the wheels you end up with a very dangerous situation of a track section being occupied but the signalling system doesn't know about it.

I recall in high school history, when we were studying the pyramids . One theory regarding their construction was ; sled driven wagons lubricated by water that rode on ramps built around the pyramids ,which enabled the hulling of blocks to such high altitudes .

I mean all I thought of was that wet leaves are slippery. That’s why we don’t walk on them. But then he gave the most scientific explanation for a basic primary school experiment I’ve ever seen.

Leaf jelly jams trains in autumn rains. Thanks to Steve I now believe!

Here in Switzerland we have a very good train / railway system and we never have problemes because of leafes haha

Imagine running these tests a few million times each. Super-Steve.

There are also issues relating to signaling that will lead to further delays on top of defensive driving from the train drivers. If a rail becomes covered enough or the wheels on the train become contaminated enough, you also have a risk emerge of the trains failing to correctly show up on the track circuits as the build up insulates the train (Not an issue on axel counter areas). This presents the potential of creating a situation in which two trains could end up in one section or other issues relating to incorrect track activation. In response there is often double blocking introduced, or working by telephone between signal boxes to decrease the potential of accidents.

In the US, we call it Jam if it's just normal fruit preserve Jam. Jelly is clarified and usually much more gelatinous. Grape Jelly is probably the most common but it's usually just something kids eat on Peanut butter and Jelly sandwiches. I usually only eat Jelly at a restaurant or hotel breakfast where they have those little plastic tubs of the stuff. At home, it's jam all the way.

In some countries they use metal wire brushes to clean the rails, especially on narrow gauge railways where there are steeper slopes and less horse power.

As a freight train driver in based in the French Alps, I would say that the main problem is wheel spin when trying to build up speed, or even maintain speed on the slightest slope. Sand helps but not that much. Never had any issues whith braking though ; probably because by the time the engine & first trucks have passed, the brakes on the next few hundreds of meters of trucks get the job done.