After 140 years, this old technology still keeps trains safe 

I know it's obvious, but I should say it anyway: the public can't get close to these signals. Do NOT go onto tracks without permission. Access and overflight requires a lot of co-operation and paperwork, and I'm extremely grateful to all the Network Rail team who helped with this video!

“As small as a microwave […] as large as a washing machine”: I love the idea that this guy only ever uses the relative sizes of kitchen appliances as a unit of measure.

The Epitome of "If it ain't broke, Don't fix it" There's actually a lot of old technology that thrives that runs minor and crucial systems around the world. Brilliant pieces of engineering that you can only marvel at. From there are inventions that are merely advancements of one person's design. It's one of the best things about the human brain to Tinker.

140 years, the ABSOLUTE definition of, "if it ain't broken, don't fix it"

This system was originally designed to keep Glasgow residents out of Edinburgh, but it was far more effective for rocks and trains

The crew behind Anderson's piano probably had no idea that their system would last longer than the era of steam locomotion, let alone into the 21st century

Very impressed by Alastair's knowledge of the systems involved and eloquence when explaining the various aspects of each. It's nice to hear an expert talk about a subject they're passionate about and it's one of the main reasons I enjoy Tom's videos so much. Cheers @Tom!

The fact that Tom consistently, week on week provides an extremely interesting video about a subject I would have never thought about before is magnificent. Thank you Tom for all that you do!

I honestly could hear this guy talk about trains and rail for days.

It's actually a bit funny to imagine someone from the rail service ordering new wire for Anderson's Piano starting with the line, "I need 100 metres of your weakest wire"

I'm a train operator in the US. I can completely understand how this system would still be the best. Sometimes it's an old solution or principle that is the most reliable in terms of energy requirements or practicality. Also, I can definitely vouch for the dangers of larger objects. It takes a lot to derail a train but sometimes, all it takes is a cow or a deer. I've seen it both ways.

The timing! Wow!

Alistair could announce an impending apocalypse and I'd still feel calm

Petition for all physical hazards to be measured by the Scottish Standard "Microwave to Washing Machine" Scale.

I've travelled on this line many times and I had no idea there was anything like this going on behind the scenes. I've a new found respect for Scotland's railway men and women.

I love train watching in Scotland . Old school semaphores , Manned interlocking towers , friendly employees and spectacular scenery . Well done !

I wonder why they haven't written a manual on the maintenance of this system? Sure, a lot of it is probably fiddling with it (in an engineer way) until things work properly, but there should be no barrier to writing out what the general methods are, and the "DO NOT DO THIS UNLESS YOU WISH DEATH" warnings.

Anderson's Piano would have made a great subject for the Technical Difficulties. That is all; carry on.

There is a similar tripwire system used at the eastern end of Southend Airport to protect against an aircraft running off the end of the runway and onto the railway. If it's tripped, the approach signals on both roads are dropped back to red and it requires a physical re-set afterwards. (Presumably Instruction No.1 of the local procedure reads something like "Check for bits of burning aircraft on the railway".)

Love trains, all the best from Finland to the dear Scots!

0:47 It took me a minute to realize "as small as a microwave" didn't mean "between 1mm and 1m". Although, I guess that technically still fits.

6:18 The train’s musical accompaniment to “Hey, couldn’t they just…” is excellent.

1:58 - "There's no user manual." - Er... then shouldn't someone *_make_* one? I mean, user manuals don't just materialise out of the ether, someone needs to write them.

Railroader for eight years here. I worked in Montana for a while and we had these for a section of our track which was adjacent to a rock face. I have personally only seen this system set off once before which was for a fairly large rock that got through, but wasn't on the actual track. There's also a permanent slow order through that zone which was 30 mph. If it works, no need to fix it. The fact is that many of the technologies used on trains and track is decades old, some of it over a century old now.

I work for a Software company that creates a lot of technology for ensuring the Rail Network in the UK is safe (such as gauging). I have absolutely no idea how I'd approach this issue, and honestly, I think wire on a stick is still the best approach. Well played, Scotland.

"something as small as a microwave could cause problems to a train" for a moment there i was mesmerized about how a wavelength could cause problems to a train

On the North American rail network, the lines carry an electric current. When a rockslide, snowslide, or other avalanche breaks the circuit, it triggers a red signal on the track and alerts the control center (which is often thousands of miles away).

Thanks for having subtitles👍

I just think that this proves that trains and train related devices are already near-perfect. I mean whenever someone tries to reinvent transportation, it just ends up coming back to trains one way or another. What I'm saying is that trains are perfect and awesome machines.

I don't know if Tom realizes how much his videos make people like me want to visit the UK. Those Scottish landscapes look absolutely gorgeous.

As a kid, I always imagined that cars could just be converted into rail vehicles by getting rid of the tires and these guys actually realized kid me's imagination

Very well done. It’s a real treat being able to view parts of Scotland’s railway system. American railways are built on the foundation of what was created in your land so long ago. Love the semaphore signals! I’ve visited Glasgow and Edinburg, but I would love to see the whole country; especially all that lies to the north of G & E. What a lovely country!

"small rocks can be an issue for trains" "huh never thought you'd be able to stop a train with a pebble" "rocks as small as a microwave oven can be problematic, washing machines sized obstacles could cause derailment" oh

Tom loves trains, and landslide warning videos.

As a happy passenger who's been lucky enough to travel by train through the Highlands, I'm grateful for this technology! And I highly recommend this trip to everyone, it's spectacular! 🚂❤️

No matter how much I learn about the English language and the world, all Scottish people sounding like the TF2 Demoman will never stop being amazing to me

I work in an underground mine in canada, and we use the same type of "tensioned rope with a flag at each end" system to monitor the beltways that run underground. It works, and it makes it easy to find a problem. You just drive until you find a flag up.

Wow, mad props and respect to the people who work to deal with this. There's a lot of teamwork and cooperation involved in just making this work.

I think this is a good example of how undervalued experience and knowledge have become in the modern world.

My uncle Fred is smiling down on me as i watch this lovely video; i guarantee he knew of the piano despite working in the USA govt regarding rail infrastructure & technology. ❤️❤️❤️❤️

"Something as small as a microwave can cause a train problem, something as big as a washing machine could lead to derailment..." I guess they have problems with domestic appliances tumbling down mountains in Scotland!

I like the size comparison to microwaves and washing machines, rather sensible. And the timing of the Sprinter at the end there was impeccable! Also was quite surprised Geoff didn't make an appearance here :P Interesting bit of kit too, think I've heard of it before but never really looked into it.

Ah Tom Scott doing the work that the discovery network once did and perhaps should still be doing. Great work as always Tom.

When I saw the thumbnail, I thought you were talking about semaphores. :) I was confused because there are regular lighted signals on certain railway lines these days, not just semaphores. The mechanical rock fall detection system makes more sense (and makes a lot of sense for needing to use semaphores :) ).

There are so many critical systems built today that aren't built to last 10 or 20 years, much less 100+ years. I hope the lessons and work of engineers and construction workers from back then survive our modern 'build it as fast and cheap as possible' mindset and thrive with a new generation. That said, the mindset and detail-oriented designs of past decades, applied to the technology we have today, could result in systems that are as robust and resilient, while also cheaper to maintain. We just need to back off a little bit from the "always choose the lowest bidder" option.

Tom really has impeccable timing for things, like if every person has magic in their own way, that must be Tom's magic.

0:40 gotta love those "debry flows" xD

I feel like I just listened to the most knowledgeable person on earth and I could listen to them all day

Tom your timing is always on point! I would not be surprised if that was planned :D

I find it amazing how many big institutions rely on "tribal knoledge" passed down previous employees to newer ones. The inability to store and access legacy information on processes and equipment is a major problem that needs to be addressed of we are to operate in a world of very long life systems.

I have the perfect solution. Buy a few pieces of gold and randomly scatter them near any large mountains that are causing you problems. Report to the news/newspaper that you found gold near said mountains. Within a few months the mountains will be gone.

6:26 That's the most perfectly timed perfect harmony I've ever heard.

During Christmas 2016 I got stuck for an extra overnight at Kyle of Lochalsh (that's on the northwest mainland looking over to Skye) due to a landslip disrupting the tracks. The wires broke, word got out and my train was cancelled. Spent it in a cabin looking out to a ruined castle during a storm, with a log fire going and history books to read by the window. The system works. PS There was a battle at the Pass of Brander / Cruachan area in 1308 where Robert Bruce and James Douglas ambushed the Macdougalls by climbing over Ben Cruachan. The more you know!

Exactly the same problem exists for conveyor systems - pull wire switch monitors exist to tell operators exactly which switch is tripped on 20 km conveyor systems with a switch every 100m. On conveyor systems they still need local resets because they are a safety of life system but simply knowing which of the 400 switches (they are on both sides) has tripped is a massive time saving. The radio transponders use lithium batteries that are changed every five years.

4:44 If a tree falls on a railway and there's no one to hear it.... it does make a sound. We now finally have proof.

In Germany we use the same system still today. It's called "BALA": BoschüngsALarmAnlage". Word by word translated something like "embankment alarm system". We use it not only for rocks but also as detector for levee slides after massive rainfalls. The only electric thing in the BALA ist a simple box in the office of the signal dispatcher which screams loud as hell, when the steelwires on the hills lose their tension.

I love how the guy went "We don't need them to be stronger; we need them to break." Sometimes, improving on something has a negative effect on the current needs huh?

I love the environmental side of this. You're trying to upgrade a system, and you're not allowed to use (much) power. Having that reminder that not everything needs to have a million sensors and a self-learning algorithm is kinda nice.

Not related to the system but that’s the most pure and natural Scottish accent I’ve ever heard and it’s so interesting and soothing to hear,

This is like looking at the Future of British Railways.

"There's not a user manual or a downloadable book on how to maintain Anderson's Piano. We need to pass that down through generations of technicians and engineers." Have those technicians and engineers considered making a user manual or downloadable book to make that process easier? :P

This concept is widely used in the US, except it's generally based on on an electrical current passed through the wires, and any break is detected and alerts the Dispatch directly. It is mechanically much simpler, just wires stretched on insulators, but this is unique in that it does the job with no power required. If it were me, I would put a small telematics box at each signal that sends an alert anytime it is tripped. If the cell network is available, they can last 5 years on a lithium battery because they don't actually use power until they are tripped. If you only had satellite available, a solar panel and battery pack could keep it going the majority of the year at least, and you add this to the mechanical signal so even in the dead of winter if the solar system dies the train still gets a warning. But having the remote alert would allow track workers to respond as soon as it happens, rather than only after a train reports it. On the other hand, maybe there is a train through there every half hour, and adding a remote alert would not gain anything!

Thankful for all these great minds and people who essentially keep the world running smooth. Thanks for another great video & effort Tom!

Wow that's amazing, I have hopped almost every mainline in America. I would love to hop through there it looks gorgeous. I love old analog tech, especially in the train sector.

Love Victorian era railway engineering, the ingenuity applied to problem solving without electrical and electronic systems is amazing. Having said that, as an old hand Signalman it came as a bit of a shock to see non absolute semaphore signals with red arms

Sometimes an old solution is still a good solution, or at least "good enough for now." I'm willing to bet whatever technology eventually solves for this problem doesn't last 140+ years like this has.

Wow that was crazy timing in the end

I consider this one of the best short descriptions of a technical device on RU-vid. Thanks to a cleverly setup of introduction, questions and moderation, it is the thoroughly thought-through text spoken in on and off of the railway engineer that does one make interested in railway design way beyond the pure coveredge of the 'Anderson's Piano'. So, thank you for it from Austria. /wp

For those wondering why the double-semaphore has one painted red and white. A signal is painted red on one side, or yellow if it's a distant signal (iirc), and white on the other. Train drivers facing the red or yellow side must obey the signal's position, but facing the white side the position is ignored.

"A RU-vidr in Network Rail PPE looking at railside engineering" usually means Geoff Marshall, these days. Good to see Tom getting some of the action.

1:55 says it all. The Scots love their heritage. They choose not to formalise things to preserve the idea of 'knowledge passed on through generations'. Similar stories are told at distilleries.

The timing at the end honestly put a smile on my face.

0:37 is an incredible, incredible shot.

I love this mix of the old and new technology he's talking about, the balance of what works and what's innovative and potentially more capable, with an eye to geography, weather, and what's possible. That's the right mindset.

It's a bit incredible that they've tried to stop rocks from falling on the rail for 140 years and there are still rocks falling. Makes you think about how even a mountain can be a living system.

Love to see old tech that's still kicking, it's so pleasing! Thanks for the captions again too!

“As small as a microwave” that’s a big fricking rock

In a similar vein, the 1800s telegraph city-wide fire alarm system still used to this day in Boston USA because it just works.

That was great timing at the end…

That was very well and clearly explained. Good interview!

"there's no book or manual…" no one ever wants to be the one to write the documentation

Permissive signals, where after they're at danger you're allowed to proceed anyway just slowly and within sighting distance, are very common worldwide. France and the Netherlands are full of them. Britain is actually quite unusual in not using them anywhere.

I could listen to this guy talk all day.

The timing of the train at the end is so satisfyingly perfect.

Ironically the issue of not having power in remote areas also plagues the power grid. If you're trying to set up a SCADA system in the middle of nowhere to measure current flow it's going to cost $10,000 just for the transformer that gives you access to 120V/240V power for your computer systems. That's the best case scenario for an issue that by definition is under an existing power line.

Crazy what even so old engineering could accomplish so reliably

Your timing is always impeccable

Another fascinating video. Alastair's descriptions and explanation of the systems was excellent.

Fascinating as always. When I saw that last train coming by I thought "Wow, Tom really did a great job of setting up and timing that final shot!" Little did I know . . .

I like this video, it has a good point. The fork is thousands of years old and chopsticks, older. Sometimes you don't need to update

That ending was perfect.

A very nice video, thank you. It's about the same over here, for slide/fall detection. Very much more integrated with the signal system and dispatcher, but a fence is a fence at the guts of the system! I worked with the railroad for 39 years and I will say that "If it ain't broke, don't fix it" is a viable option in considering system changes or upgrades. Every system/option has its trades.

Having passively active systems that don't require power is just great. I whish more solutions with less or "other" power would be used. Electricity and computers have become the common standard, but aren't necessarily the best option. Thanks for this intriguing video. :)

That timing was incredible

This is fast becoming one of my favourite channels. Always such interesting and fascinating videos

That was cool to see. Thanks.

That was great timing with the Class 66 at the station and later the ScotRail Class 156. I'm always pleasantly surprised when Tom uploads a railway video.

Given the amount of avalanche and rockslide detection systems here in North America I’m surprised none have fitted the needs in Scotland. Also, the continuing past a “danger” signal exists here in Canada; there are two in fact: “restricting signal” and “stop and proceed signal”. Essentially, you continue at a speed below 15mph at which you are able to stop at half the view range distance (ex. You can only see 500 meters ahead so you must go at a speed in which you can stop in 250 meters). These are usually in automated CTC (central traffic control) portions of track that operate by the axels of trains completing a faint electrical circuit in the rails to trip signals and usually give this indication if there is a grounding of current or a cracked rail.

this is simple and effective for it's designated function. there's nothing wrong with maintaining such system.

That timing in the end was great!