 This video is proudly sponsored by NordVPN. More about that later on. A match. Something so mundane and ordinary. You probably have a box in your house. But from a young age we are taught of the dangers of matches and the fire they can create. This is understandable as a small wooden item like this can cause immense fires in endangering life and limb. But something so run of the mill would create havoc in the world's oldest underground railway and burn a tragic event into the collective consciousness of the tube travelling public in London. One evening in November 1987 will shock the world and kill 31. During its investigation it would ultimately lead to a new discovery in the way fires reach enclosed spaces called the trench effect. In the aftermath of the disaster fire regulations across the country would change and the look of the underground would be altered for good. Today we're looking at the King's Cross fire of 1987 and as such I'm going to rate this event here seven on the plainly difficult disaster scale and here eight on my historical legacy scale. It is the 18th of November 1987 and a traveller lights a cigarette from the match as they travel on the escalators at King's Cross station. Smoking on the underground has been illegal since 1985 but many openly flaunt the law and make use of the cover of the escalators of King's Cross tube station to light a cigarette before going out into the evening air. The match still lit falls down on the wooden escalator stairs and eventually works its way into the machine mechanism. This seemingly innocuous act would start a raging fire but let's pause there and have a look at the escalator set up at King's Cross. The tube station entrance of King's Cross has two sets of escalators from the ticket hall one serving the Piccadilly line and another serving the Victoria line. The former led out to a concourse from there passengers could go down further on another set of escalators to the northern line platforms. Needless to say this area of the station is busy as it is an interchange between lines that serve the north south and west of London. To deal with the high traffic flow three M series escalators were installed to transport passengers along the 30 degree incline over a rise of 17.2 meters. The M series were a familiar sight around London underground with a total of a hundred and eight installed across the network. They were capable of speeds between 30 and 35 meters per minute and consisted of wooden decking, side panels, cleated steps and risers. The steps were metal backed plywood with maple wood cleats at each side of the step is a metal fire cleat which is designed to cover the gap between the step and the skirting board. These were meant to stop cigarette butts and matches from entering the escalator mechanism but they needed regular adjustment as unsurprisingly with around 250,000 daily users of King's Cross station damage was a regular occurrence. Through the machine's working life some of the cleats became missing leading to around a quarter not installed on the escalators. The three escalators for the ticket hall to the Piccadilly line were installed in 1939 and were meant to be maintained every six months to remove grease, paper debris and other flammable materials. Proposals for a smoke detection system were made during the 1950s but interestingly these were not realised meaning wooden escalator plus no smoke detection means higher risk of fire. The escalators had two machine rooms an upper and a lower. The former housed the electric motors, worm reduction gears, chain drives to the drive shafts for each of the escalators, the electrical control gear, circuit breakers connecting motors to main supply and the water fog controls. The latter housed the return wheel and the sump pump. From inspection there are three sets of steps below the escalators two narrow and one larger central set. The middle largest set of steps had the supporting walls for escalator five and have periodic gaps through which the only and very restricted view can be seen of the underneath of escalators four and six. There are two pairs of wheels for each step on the escalator each running on a track. One pair of these wheels the chain wheels run outside and the other called the trailer wheels run on the inside of the track. There is a large gap of around 15 centimetres between the two sets of wheels giving enough space for a large build up of grease and other debris which due to the space once again is very difficult to remove. Such a build up is pretty much the perfect supply of fuel for a fire. To add to the cherry on a disastrous cake in order to fully clean the equipment it would need to be completely dismantled putting out of use a busy thoroughfare. Instead cleaning maintenance was undertaken on the running tracks by hand only and all without removing the steps and ever since installation no full deep clean was ever undertaken. Between 1956 and 1988 London Underground had experienced around 400 fires on escalators and this leads us to 1987 and a tragic day in November. It's time to talk about this video's sponsor NordVPN. As you may know I like my privacy hence why I'm a disembodied voice on the YouTubes and because of this I'm an avid user of VPNs. 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Get a two-year plan plus one additional month free with a huge discount. Borderships like this really help the channel to stay financially independent especially with some more darker content I cover. At around 1930 on the 18th of November 1987 a member of the public noticed a small fire on the Piccadilly line to ticket hall set of escalators. Around the same time another passenger operated the emergency stop button and shouted at others to get off the escalator. A British transport policeman checked the fire and saw flames coming from a gap between the sides of the stairs of the escalator over the length of one step. Whilst this happened a staff member in the booking hall and BTP control were informed. A few minutes later at 1934 the London Fire Brigade was also informed. Just two minutes later the BTP ordered an evacuation via the Victoria line escalators. For now smoking escalator four was taped off but members of the public continued to step over and continue on the unmoving escalator steps. BTP officers reported the fire as mainly on one side and stretching about halfway across the width of the escalator over one or two steps. The fire was burning cleanly with flames about handrail height. By now smoke was permeating its way into the ticket office and could be seen from the outside. The fire now established around halfway up escalator four was spreading albeit slowly. The order to evacuate the station was given but deep below on the Piccadilly and northern line platforms trains continued to stop letting off passengers. By 1943 the flames were spreading and around four feet high were becoming a very big concern for underground staff. Just one minute later the flames were now five to six feet high four to five yards long with extra flames shooting up from both sides of the escalator. In 1945 a flash over was witnessed by passengers in the ticket hall as a jet of flames shot up the escalator shaft enveloping it with intense heat and thick black smoke. The flames struck the ticket hall ceiling as the jet hit the ceiling the ceiling turned into a layer of flame rapidly spreading outward. During the flash over 30 were killed instantly another would die of burns a week later. Victoria line trains were told to enter the station slowly to pick up passengers stranded on the platforms. By 1959 the first ambulance was on the scene and would be followed by in total 14 more and over 155 fighters all of whom would be treating the injured and ferrying them to hospitals all around London. In total 100 people were taken to hospital with 19 severely injured. It would take another two hours to contain the fire and by 146 in the morning the King's Cross fire was finally over but it had left in its wake severe death damage and destruction. The ticket hall and platforms for the Metropolitan line were unaffected and reopened the next morning. Victoria line escalators were only slightly damaged and resumed operation the following Tuesday. The ticket hall for the three deep lines of Piccadilly, Northern and Victoria was reopened over four weeks later. The escalators down to the Piccadilly line were completely destroyed necessitating passengers to exit the station via the Victoria line and mid-city platforms but with so many escalators like the ones at King's Cross in use across London underground the cause of the fire had to be investigated and prevented for the future. The investigation was initiated by the police soon after the fire and the scene was preserved and with the help of the London Fire Brigade found that arson was not the cause. This was due to no evidence of accelerants difficulty to get into the machine room large build-up of grease and debris and remains of matches and cigarettes. Now matches and cigarettes you might think might actually hint towards arson but they would tip the investigation towards the actual cause. You see smoking was banned on London underground in 1985 way earlier than almost every other part of society in the UK and as such people tended to flaunt this rule this meant that smoking on the tube was often seen even two years after the ban. It was a common sight for people to light up the cigarettes before leaving the station leaving a potential ignition source. Investigators also found with the evidence of discarded matches large amount of lubricating grease, fibrous material and paper all of which had made its way under the tracks of the escalator. To try and find out for certain investigators used an unburnt portion of the escalator for an in-situ experiment. Three attempts to initiate the fire were made by dropping smoldering cigarettes through the gap at the side of the escalator but all failed. However the first lighted match dropped initiated a fire under the tracks. Within minutes the flames spread by the time the fire was visible to the passenger side of the escalator the spread was almost uncontrollable. After nine minutes the fire was put out and the cause was now understood but what made the fire flash over in such a dramatic way? This would involve a computer simulation and scale model. In December 1987 the AERE Harwell Laboratory was commissioned to carry out modelling of the flows and temperature distributions in the Piccadilly line escalator shaft leading up to the flash over. The computer simulator discovered something shall we say unexpected. It was thought that the flash over might have been linked with the type of paint on the ceiling but strangely modelling found that once ignited the fire stayed low. It travelled along the 30 degree angle running parallel to the escalator trench which concentrated the jet of flame up towards the ticket hall. The health and safety executive sceptical of the computer results made a scale model of the escalators and ticket hall and lo and behold in the next experiment the fire followed the exact same characteristics of the computer simulation. The now newly discovered phenomenon was called the trench effect and was the ultimate reason for the extreme flash over. The public inquiry also put blame on London underground limited with the station staff not reporting the fire quick enough which allowed over 10 minutes of smouldering to develop into a full blown fire. The Desmond Fennel report was released to the public in 1988 and multiple recommendations were made which involved the removal of any hazardous materials, CCTV fitted within stations, installation of fire alarms and sensors and giving personal radios to staff. The report also recommended improvements to some of the busiest stations on the network with better passenger flow. Eventually the three escalators for the Piccadilly line were completely replaced being commissioned on the 27th of February 1989 but it wouldn't be until 2014 that the last wooden escalator would be decommissioned on the network at Greenford. A big thank you to NordVPN for the sponsorship. For a holiday season deal, go to www.nordvpn.com slash Plainly Difficult to get a two year plan plus one additional month three with a huge discount. Their support really does help out the channel. You have been watching a plainly difficult production. All videos on the channel are Creative Commons attribution share alike licensed. Plainly Difficult videos are produced by me, John, in the currently wet and windy south-eastern corner of London, UK. Help the channel grow by liking, commenting and subscribing. Check out my Twitter for all sorts of odds and sods as well as hints on future videos. I've got Patreon and YouTube membership as well if you fancy supporting the channel financially. 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