 The railway's safe operations are taken for granted, especially in the UK, where very few serious accidents or collisions happen. This is due to over two centuries of safety innovations evolving the industry. The UK has complex signalling systems to ensure that two trains aren't allowed on the same piece of track at one time. However, this rule has been broken by either operator error or infrastructure failure. And most of the time, the error doesn't lead to a catastrophic outcome. But a poor wiring installation would cause a free train collision costing 35 lives and over 400 injured. In the modern railway, one thing above all else is paramount and that is safety. This is quite an obvious statement as trains are large metal boxes travelling at speed which are filled with hundreds of people with a collective friction area of the wheels not much larger than a pound coin. The low area of contact between the wheels and track means that they are very efficient, which is great for carrying heavy loads at lower energy costs than road vehicles. Today's disaster is not important just because of the human and infrastructure cost, but it is the cornerstone to modern day health and safety regulations for safety critical work. This video is about the Clapham rail disaster on the 12th of December 1988. Today I'm going to rate the Clapham rail disaster here 5 on my painted to plain difficult disaster scale. This is due to the disaster not having a wider environmental impact, but it is an 8 on my historical legacy scale. Safety critical systems are usually designed to revert to a safe state in the case of any breakdown of operation. This is known as fail safe. An example of this is electromagnets holding control rods out of a reactor core. In the case of loss of power, the rod falls with the help of gravity stopping the chain reaction. On the railway this is no different. If a signal fails it reverts to danger or red. This is usually a given, but in the closing years of the 1980s a simple wiring fault would bypass the fail safe state. But before we get on to the disaster let's have a very brief look into UK railway signalling and I mean a brief look as I could probably make a whole documentary if I was allowed to go into a deep dive. Trains are very efficient as I said earlier which is great for fuel usage but can be the Achilles heel of rail vehicles. You see less friction means less ability to stop and I really mean less ability. If you can see another car slamming the brakes in front of you when you're driving you have a pretty good chance of stopping well before you become a human can of spam. This is because you have a lot of friction between your grippy tyres and a nice skin shredding asphalt. Trains don't have this so you can't rely on line of sight to stop two trains becoming one big squashed one and to allow safe stopping signalling is used. In basic signalling principles the track is broken up into multiple sections where only one train is allowed one section at one time. Each block section is protected by a signal behind it. There are also overlaps which are an extra section of track giving an extra area for safety in case of an accidental entering of an occupied block section. The UK on many of its main lines use four-aspect signalling. This enables trains to be at a safe braking distance from one another and can give the driver advanced information of where the next train ahead is. On lower speed subsidiary lines and on London Underground, excluding automatic ones, three and two aspect signalling is used but for today we're not going to be going there. Four aspect signalling can show you, you guessed it, four indications. The first is proceed or green. This means that at least three signal block sections ahead of you are clear and you can proceed at line speed. The next signal is preliminary caution or double yellow meaning the next signal is at caution and you should probably be thinking about slowing down in preparation for a stop further down the line. Then there is caution which tells you that the next signal is showing danger or stop so be prepared to stop at the next signal. And finally there is danger stop shown by a red. This is pretty simple as it means stop as there's most likely another train ahead of you all the routes you're going to take is not set yet. Right well that was a very brief and quick lesson on UK signalling. If you fancy a more in-depth video check out this charmingly dated BR video on the subject. The next thing to look at is the disaster itself and our story starts off with signal whiskey alpha 25 has been abolished and a new four aspect automatic signal whiskey foxtrot 138 printed in a weekly notice for drivers. Although signalling changes are not a really regular occurrence it is not unheard of and would largely be taken as it was an important but minor change in the grand scheme of things. Likewise for track workers tasked with fitting the new signal it was a regular occurrence for them presenting little in the way of a challenge for someone in that line of work. The new signal would be the cause of the disaster after installation of other wiring during a period of weekend engineering work. The fault would only show itself on a weekday morning rush hour as Clapham Junctions saw short headways between trains. You see during the weekend less trains run meaning it is less likely for them to stack up at signals and traffic would be more free flowing. The location of whiskey foxtrot 138 was the penultimate signal before Clapham Junction in a railway cutting heading towards London. The previous station was Ellsfield. The signal was meant to protect trains that were standing just outside Clapham whilst they awaited a free platform. The final signal before entering the station's platforms was controlled by the Clapham Junction A signal box. Where trains movements were controlled and more importantly where the relays and interlockings for the signals in the area were housed but a fatal wiring error meant that the signal would not display a stop aspect after a train passed it which basically defeated the whole point of it being there. On the early morning of the 12th of December 1988 multiple trains had passed whiskey foxtrot 138 with no issues. Due to the frequency of five minutes between trains all drivers were seeing green signals. Until the beginning of the morning rush hour leading up to 8am as more trains were going to London the pinch point of Clapham Junction's time between trains decreased to two minute intervals. This is business as usual for one of the busiest railway stations in the UK. A large number of drivers throughout the morning had noticed strange but not unusual irregularities with the signal sequence. This was due to the signal in box A changing routes into different platforms causing the signal ahead to go back to red and the signals to the rear to react in sequence. In the rulebook drivers were required to report a signal being more restrictive but due to this being a regular occurrence many ignored this and carried on as usual. This leads us on to the driver of a bazing stoke to London Waterloo Service Mr MacLimans. The 29th train booked to go along past Whiskey Foxtrot 138. As the train made its way past Earlsfield nothing out of the ordinary was noticed until the driver received an unexpected setback when signal Whiskey Foxtrot 138 had changed from green to red as the train was about to pass it. Not being able to stop in time the driver continued to the next signal to report the incident. Driver MacLimans left his cab to walk along to the signal telephone to contact the signaler to find out the issues as per the rulebook. MacLimans had assumed that the signal that had changed back on him Whiskey Foxtrot 138 would stay red at his train occupied the section an assumption that should have been right at a fully working signal. The 30th train the 614am pull to Waterloo driven by a Mr Rolls had been making progress towards London following driver MacLimans train with nothing worth noting on the journey. His train approached and then passed Whiskey Foxtrot 138 at green at roughly 50mph. Driver Rolls fought nothing of it until the next thing he saw the rear of driver MacLimans train by now disaster was inevitable. Driver Rolls applied the emergency brakes bringing the train's speed down to around 35mph as it impacted the rear of the train in front at 0810am. The front of the train had left the tracks and a 3rd train running empty in the opposite direction collided with the pull train. A 4th train following the pull train managed to stop short in the rear. At the time of the impact driver MacLimans was walking back to his train at which it moved forward several feet. He ran back to the signal telephone to inform the signaler who put all the signals under his control to red to stop all train movements. The impact of the front of the pull train on the last carriage of the basing stoke train caused the last carriage to be thrown up above a concrete wall on the side of the cutting around 10 feet high. It came to arrest lying on the embankment above the wall. The first two coaches of the pull train had veered to the right where it had been struck by an empty train. The noise from the collision attracted the attention of nearby residents and workers around the north side of Wandsworth Common. Many called 999 requesting emergency services. Waringly British Rail contacted the emergency services after the first 999 calls at around 8.15am. This was due to the lengthy process of communication from driver to signal box to station supervisor to network control who finally contacted 999. The public had made their first call at around 8.13am. Pupils and teachers from the nearby manual school who were the first on the scene of the disaster helped the walking wounded. Access to the emergency services was limited. This was due to the majority of UK railways being fenced off from the public to prevent trespassers. The railway boundary has access points but these can sometimes be hard to find and require key access. The first three carriages of the pull train had been severely damaged. The first carriage had totally collapsed. The second carriage, the buffet car, had been devastated on its left near side and the last car of driving the Clements basing stoke train was severely derailed and damaged. All of these factors further hindered the first responders. It was estimated that around 1500 people were aboard the pull train creating an overwhelming situation. The trains in use at the time were of a very old design first generation British Rail electric multiple unit and made use of slam manually opened and closed doors which can be opened at any time. Very different from the power control doors of today. Because of this many had already started to escape the wreck trains. The rescue effort would last the rest of the morning into the afternoon. The last casualty was taken to hospital at 1.04pm and the last body was removed at quarter to 4pm. Repair works in the area would take a lot longer as the damaged trains and infrastructure had to be removed before trains could run safely again. And this doesn't include the investigation into how the disaster could happen. With 35 dead, 484 injured the big question looms. How? How can a tried and tested signalling system fail to do the one thing it was designed for and that was protect a train in its respective block? Whiskey Foxtrot 138 was obviously not working as intended. Which as it was a new installation hints that the engineering works were the root cause of the disaster. The replacement of the signal was part of a much wider program called WAS or the Waterloo Area Re-Signalling Scheme. This came about as by the 1970s and 1980s much of the 1930s wiring responsible for the safe operation of the railways had badly deteriorated. The program was undertaken over multiple weekends to improve the reliability of the signalling system. The wiring of the new signal was prepared and laid out over the week to be installed over the weekend. The signal and its wiring was completed on Sunday the 27th of November. It was common for the technicians who laid out the wiring to install it over the weekend, leading to a 7 day week. And for Whiskey Foxtrot 138 this was no different with the book technician working his 13th consecutive 7 day week. During the wiring installation the wires to the relay room in signal box A for the old signal needed to be removed as the new signal was wired to the track circuit block. It was deemed not ideal to fully remove the old wiring and instead it was opted by the technician to leave it in situ albeit disconnected. This is not unheard of as long as precautions such as disconnecting cutting back and taping off to stop the loose wire from coming into contact with any other terminals. The technician decided to keep the old wire still connected on one end and just disconnect and push back to one side the other end with the new wiring holding it out of place. Eventually this loose wire could work itself back to the terminal of the new signal's wiring in the relay room causing the signal to not go to danger when the train occupied the block. No independent inspection by the technician's supervisor was undertaken meaning the shoddy work was not picked up upon. The signal would operate as intended until the weekend of the 11th of December where unrelated work was being undertaken in the relay room on the relay next to the new wiring. The work disturbed the uninsulated wire which had made its way back to contacting the relay causing the failure of signal Whiskey Foxtrot 138. The investigation by Lord Hidden found many contributors to the disaster including poor training, supervision, assessments, all of which were compounded by technical staff not properly understanding the ramifications of signalling failures. One of the largest legacies of the report into the disaster was the amount of hours the technician had worked. It would eventually prompt a change in working hours for people undertaking safety critical work to 12 hour maximum shifts, 12 hours minimum between shifts, a maximum of 72 hours per week and a maximum of 13 days in a row. If you've ever worked on a railway then these rules are hammered into you. The accident changed the culture in British rail and although no one was charged with manslaughter, BR was charged with the Health and Safety at Work Act 1974 and had to fork out a £250,000 fine which doesn't seem like enough even for late 1980s and early 1990s money. This event would be partially responsible for the Corporate Manslaughter and Corporate Homicide Act of 2007. The lessons learned from the accident would help shape the modern UK railway which would never be forgotten. At the time of recording this script I've just finished working on a Tokyo subway attack video so it's been a few weeks of railway stuff for me. I've really enjoyed working on it but more importantly though have you enjoyed the rail based subjects and do you think I should cover more? Let me know in the comments below. Thanks for watching, I hope you enjoyed the video. This is a plain difficult production. All videos on the channel are Creative Commons attribution share alike licensed. Plain difficult videos are produced by me John in a sunny southeastern corner of London UK. Help the channel grow by liking, commenting and subscribing. Check out my Twitter for all sorts of photos and odds and sods as well as hints on future videos. 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