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in a crowded london underground station
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a small routine fire suddenly erupts
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into a deadly inferno and kills 31
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people dozens more are injured
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a team of forensic experts searches for
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clues to the cause of the blaze and
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finds that the fire seemed to defied the
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very laws of physics
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to unravel the cause of the mysterious
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fire
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investigators would need to recreate a
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historic train station inside a modern
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computer
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[Music]
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[Applause]
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[Music]
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[Applause]
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the sprawling london underground is the
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largest and oldest subway rail system in
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the world
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but on the evening of november 18 1987
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commuters are unaware that disaster
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lurks beneath them
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at 7 30 p.m a passenger at the historic
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king's cross station sees a flicker of
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flame underneath a heavily varnished
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50-year-old wooden escalator
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the london fire brigade is dispatched
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it seems to be a routine call an
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everyday call to a fine and escalator
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something we were receiving probably
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20 or 30 times a month
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so it was no big deal
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fire captain roger kendall one of the
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first to reach the scene waits above
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ground for his supervisor to report
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we will wait for message to come back to
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say either we're all going home or we
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may need a bit of equipment
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trains continue to come and go despite
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the minor commotion
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musician ron lipsius arrives at the
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station on one of those trains
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we've noticed these two
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men
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i don't think they were in uniform but
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they were blocking physically blocking
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entrance to the wooden escalators
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on our left which are the ones that
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directly go to piccadilly train
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so we thought oh that's strange and
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it was actually a tiny bit hazy
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in there too we noticed that too
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a little bit smoky firemen see a small
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fire burning about halfway up one of the
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escalators bringing passengers from the
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tracks up to the ticket hall
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a very experienced fire officer looked
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down the escalator
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and
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assess the fire
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as being it's about the size of a
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cardboard box
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but firefighter colin townsey spots
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something he believes is dangerous
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he calls firefighters above ground
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asking for more equipment and saying
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people are in danger
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he through his experience had seen
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something going on above the fire around
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the fire whatever he could see he knew
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that something bad was about to happen
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on the train platform below
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passengers are now being urged to get
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out
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the quickest escape route is up another
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bank of escalators near the fire these
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two lead directly to the ticket hall
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as soon as we got near the top
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we noticed it was really dark
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and smoky
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at that time there was this policeman
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with a
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flashlight and saying hurry up don't
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don't just stand there
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but the warning comes too late
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as soon as i went through that turnstile
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some kind of explosion
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happened
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when i was halfway up that escalator a
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sheet of flame erupted and shot across
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the top of the whole of the top of the
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exit from that escalator so i was just
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moving up towards a wall of fire
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searing flames rip up the escalator and
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into the ticket hall incinerating
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everything in their path they were like
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these living things in
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up in the corner by the ceiling and they
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were huge and it was awesome and i just
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took one look at that thing and i just
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i felt like an ant i mean it felt like
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this thing is like a monster there was
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just a complete rush of thick black
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smoke from the subways
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right all the subways leading out onto
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the main roads around the station and it
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was right at that moment we realised
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that the flashover would occur
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flashover is a virtually instantaneous
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spread of fire everything flammable
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ignites simultaneously
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so from two minutes it had gone
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apparently the size of a cardboard box
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to a major disaster
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firefighters tried desperately to get
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inside the station but are driven back
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by the intense heat and smoke
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firefighters were collapsing left right
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and center
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the heat down there
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had made some of them urinate themselves
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with fear
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and when they came out to the top they
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weren't capable of moving again a lot of
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them were collapsing in the heaps
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ron lipsia stumbles into the chaos
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outside
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and for the first time realizes he is
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badly burned
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i looked at my hands and there was this
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skin just
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hanging down like
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like when a snake sheds its skin
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firefighters battled the blaze for an
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hour
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when it is finally out
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31 people are dead and more than 70
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others are injured
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among the dead
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is firefighter colin townsley
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colin was found with two two members of
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public that he'd obviously pulled along
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the tunnel trying to get him out to
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safety
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two people that he'd obviously tried
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desperately to get out of that inferno
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and it cost him his life
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the king's cross station is shut down
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the london underground is crippled
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thousands of commuters are stranded
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through the smoky haze of the ruins a
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mystery emerges why did a fire the size
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of a cardboard box explode into a deadly
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inferno in a matter of seconds
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in the hours following the deadly king's
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cross fire
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investigators from england's health and
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safety executive sifted through the
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charred station looking for clues
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but finding them in the ruined ticket
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halls and tunnels
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wasn't easy
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there is nothing quite like seeing a
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fire scene
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firsthand to give you a full
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appreciation of the the devastation that
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has taken place and also to give you a
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feel for how the fire might have
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developed
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they needed to answer two critical
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questions what sparked the fire and how
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could it appear so suddenly and erupt
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into a fatal blaze that claimed 31 lives
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nearly a million people relied on the
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underground each day
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they needed to know if the system was
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safe
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this is the stuff of nightmares being
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trapped by fire underground
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i mean it really is
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something that tugged at the
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heartstrings of ordinary londoners it
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was on the front pages of every
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newspaper obviously for several days
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and there was enormous demand to find
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out why it had happened
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investigators started where the flames
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were first spotted the escalator this
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was the lowest point of the fire
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indicating the fire had started there
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and burned upward
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no accelerants or other indications of
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arson were found
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underneath the escalator investigators
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found accumulated grease litter and
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debris
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ideal fuel for starting a fire
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they also found evidence of many
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previous small fires started by
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smoldering matches and cigarettes
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the actual source of ignition
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is
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assumed to be
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a dropped match which had not been
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extinguished
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and if that had come in contact with the
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grease on the running track of the
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escalator
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the grease would have ignited very very
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easily
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investigators speculated that someone on
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the escalator lit a cigarette and
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carelessly tossed away a burning match
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but could one match cause
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such a deadly fire
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they tried dropping matches from heights
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they found that a match would be able to
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in certain circumstances to light the
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grease
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on the escalator
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but in the tests the fire was slow
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burning and didn't explode up the
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escalator
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there was all sorts of theories as to
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how this could have happened so fast and
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amongst those theories everyone was
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desperately searching for the truth
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meanwhile journalists uncovered dozens
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of previous escalator fires in the
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london underground
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to some extent
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the
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underground had been extremely lucky for
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50 years they had a lot of these wooden
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escalators
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they all suffered from
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similar problems
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there'd been a series of escalator fires
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it was
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reasonably predictable that there was
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going to be a serious one
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after a fire two years earlier at
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another station
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investigators said the system's aging
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wooden escalators were a disaster
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waiting to happen
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but why did this fire turn into a deadly
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inferno
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there was a lot of thoughts about the
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the trains actually fanning the flames
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because it was extremely clear whenever
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a train came into that station that the
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smoke that was bellowing out of the
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subways where i would increase
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but measurements of air flow in the
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escalator area showed this would not
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affect a small fire on the steps
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other theories blamed the varnish on the
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wooden escalator and multiple layers of
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paint on the ceiling there are examples
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of fires in
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old buildings in in the uk
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which have been painted regularly every
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three or four years and these buildings
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are 100 years old and if the paint
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becomes involved it becomes an inferno
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very very quickly because paint
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delaminates blisters and burns rapidly
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when they did some tests when the hse
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did some tests on the ceiling page
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something that was not damaged
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they couldn't make the flame spread fast
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enough along it and that's when they
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started to question what else could be
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the main fuel and that's when they came
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to talk to us to see if we could do
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anything to help
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what do you think of these results
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now turned to a team of forensic
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mathematicians at the investigative firm
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of cfx
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their goal was to create a computer
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simulation of the deadly fire using
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computation fluid dynamics or cfd
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this was the first time it would be
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applied to the behavior of fire
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but they believed it would work because
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heat and air flow like fluids
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hot air causes the the fluid to expand
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and it makes it lighter and then it
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tends to rise relative to the other
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ambient fluid around and so then you see
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smoke rising smoke plumes
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and that's the kind of thing that we can
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simulate with the software because it
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really is just simple fluid mechanics
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but could it solve the mystery of the
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king's crossfire
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[Music]
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to recreate the deadly king's crossfire
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in a virtual world the station was
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measured and mapped onto a computer grid
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then factors such as the fire's point of
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origin air flow and types of wood and
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paint were added to the simulation
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but the result showed
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something unusual
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according to the computer model the
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king's cross fire had literally defied
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the laws of physics
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the hot air around the fire
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did not rise
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instead it clung to the steps
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we saw that the hottest air seemed to be
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lying down in the escalator trench which
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was unexpected to me anyway and the
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other people from hse who came to look
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at those early simulations
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i think the initial reaction was it was
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possible that i've got gravity upside
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down which you can do in the computer so
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maybe i'd made things go the wrong way
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was it a human error could we have input
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the data incorrectly
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could there be a bug in the program
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the investigators entered all the data
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again the results were the same we did
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all the checking and did more runs and
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and still found that the hottest air was
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lying down in the trench eventually
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spiraling up over the ceiling but
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initially lying down in the trench
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it was a startling but significant clue
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the hot air and gases should have risen
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up to the ceiling
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but the escalator stairway appeared to
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channel them into the ticket hall
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and that made us start to think about
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maybe the wood of the escalator could be
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the main fuel if the flames are lying
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down in the trench they're preheating
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the wood ahead of the main flame front
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and therefore
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once it gets going it could move very
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very rapidly
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they called what they saw
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the trench effect
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but it was merely a theory using
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untested computer simulations and it was
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inconsistent with typical fire behavior
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if you have a fire burning in the open
00:14:02
on a flat surface
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the fire feeds itself
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with air by drawing it in from the
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outside it's created by the dynamics of
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the flame itself the buoyant gases rise
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creating slight pressure differences
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which draw air into low at a low level
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but on an incline that airflow is
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restricted on the uphill side
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to examine this
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a rough model one tenth the size of the
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escalator shaft was placed flat on the
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ground
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the result was a slow vertical burn
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but at a 30 degree angle the angle of
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the king's cross escalator the flames
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leaned into the shaft at an angle and
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raced upwards in the confined trench the
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fire could only draw air from below
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creating a draft
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because the air can't come round the
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fire it has to come effectively through
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the fire
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investigators then ran a bigger test on
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a one-third size model of the complete
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king's cross station
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if the trench effect worked this time
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it would prove their theory was right
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in the match of three or four seconds
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the flames went from the upright to
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being lying uh along the escalated
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trench and from then on it was just as
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we predicted
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which is very gratifying
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it was clear
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that the previously unknown phenomenon
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called the trench effect
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was real
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people suddenly saw
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a fire
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and said
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now we understand you've got an
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explanation of what it is it's now all
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obvious it fits together the jigsaw fits
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together
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perfectly
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the investigative team now had
00:15:50
compelling evidence that would reveal
00:15:52
the deadly sequence of events
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[Music]
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for months a government inquiry into the
00:16:01
disaster at the king's cross station
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fire had struggled to find out how a
00:16:06
small fire had exploded so quickly and
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killed 31 people
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[Music]
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now a team of forensic experts said new
00:16:17
computer technology provided the answers
00:16:21
the computer graphics helped us to
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understand what had taken place and also
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to present the results to people
00:16:28
who were maybe not as familiar with the
00:16:30
technology that we were using so we
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could explain the results to them very
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simply
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sometime around 7 15 p.m
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a smoker at king's cross carelessly
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dropped a match on the wooden escalator
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the match fell between the steps and the
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side of the escalator into the gear bed
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below
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it was lined with years of grease and
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debris
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a slow burning fire began
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at 7 30 p.m
00:16:57
the flames became visible and
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underground staff called the fire
00:17:01
brigade
00:17:02
at 7 40 p.m
00:17:04
two firemen saw the low-lying flames and
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at first assumed it could be easily
00:17:09
extinguished
00:17:10
the fireman who was walking down
00:17:12
escalator number six and looked across
00:17:15
to escalator number four approximately
00:17:18
one minute before flashover and
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described the fire as being relatively
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small
00:17:23
but then the fire spread across the
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steps the bottom of the trench
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it could only draw oxygen from one
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direction from below
00:17:33
this was the trench effect
00:17:36
and once you had established a fire
00:17:38
across the
00:17:40
width of the escalator it meant that the
00:17:43
flames were deflected into the trench
00:17:45
and began to flow up the
00:17:48
treads the risers and exposing the
00:17:51
balustrades to very high levels of heat
00:17:54
flux
00:17:55
then it just switches and flips
00:17:57
over to stick to the floor
00:18:00
of the escalated trench
00:18:02
from there
00:18:04
it pre-heats the wood the hot gases are
00:18:07
going up the escalator trench ahead of
00:18:09
the flame
00:18:11
they're heating the wood
00:18:12
quite considerably gets quite hot even
00:18:14
though there's no flame there it's
00:18:16
sucking up the air from below like a
00:18:18
chimney wood which is what it needs to
00:18:19
do
00:18:20
and that would tend to flatten the
00:18:21
flames down in the early stages as well
00:18:23
which would start this effect off of the
00:18:26
trench effect
00:18:28
the escalator trench acted as a chimney
00:18:31
made not of brick but of highly
00:18:33
flammable wood
00:18:35
at 7 45
00:18:36
a torrent of superheated gas rushed up
00:18:39
the escalator priming everything in its
00:18:42
path to burn
00:18:43
it was called a flush over the sudden
00:18:45
movement of the fire up up the escalator
00:18:48
was called the flashover as it burst
00:18:50
into the booking hall at the top
00:18:52
the hot gases and flames exploded into
00:18:55
the ticket hall
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feeding off years of thick paint on the
00:18:59
walls and three tons of varnished wood
00:19:02
on the escalator below
00:19:04
the cavernous room
00:19:05
was a death trap
00:19:07
those people would have died extremely
00:19:09
quickly and if there's anything if
00:19:11
there's any comfort there it is the
00:19:13
comfort that they didn't suffer for very
00:19:14
very long at all they were taken
00:19:16
extremely quickly
00:19:18
the government's board of inquiry
00:19:20
accepted the new science of the trench
00:19:22
effect
00:19:23
and found
00:19:24
it had caused the disaster
00:19:27
there was a general sense
00:19:29
amongst people that
00:19:31
really
00:19:33
the underground should
00:19:36
and could have prevented this
00:19:39
i mean there were resignations of course
00:19:41
but um
00:19:43
i think
00:19:44
there was a sense that the underground
00:19:46
hadn't really been on top of the problem
00:19:49
of fire
00:19:50
underground
00:19:52
to ensure such a tragedy would never
00:19:54
happen again
00:19:56
all wooden escalators were eventually
00:19:58
removed from the system
00:20:00
flammable grease and debris
00:20:03
are regularly removed from beneath
00:20:05
escalators
00:20:06
and the underground staff is now
00:20:08
required to be trained in fire
00:20:10
evacuation procedures
00:20:16
those directly affected by the fire
00:20:19
can take some comfort that science
00:20:21
explained the mystery that changed their
00:20:25
lives
00:20:26
it ruined the life that
00:20:29
i was having
00:20:31
my life was going certain ways
00:20:34
perfectly happy with it
00:20:37
and it totally ruined that life but i
00:20:41
i got onto a different life
00:20:43
i don't use the underground i've used
00:20:45
the underground since
00:20:47
that night at king's cross
00:20:49
i'm not saying it's not safe because i
00:20:51
believe it's far safer now than it ever
00:20:53
was but for me personally i'm happy to
00:20:55
avoid it
00:20:57
those who solved the mystery of the
00:20:59
king's crossfire no
00:21:02
their intensive efforts will help save
00:21:04
lives
00:21:06
there's also plaque in the booking hall
00:21:08
to the memory of the people that died
00:21:09
then you know i often just stop there
00:21:11
and stand and read it and just spend a
00:21:13
quiet moment in reflection
00:21:15
because there was a human tragedy there
00:21:17
which sometimes can easily be forgotten
00:21:20
so i feel strange going back there
00:21:24
and a little shiver
00:21:26
i enjoyed seeing the computer model be
00:21:29
used in a way that was good so people
00:21:32
could
00:21:33
understand what had happened and
00:21:34
therefore try and prevent it happening
00:21:36
again
00:21:36
it's opened a whole new line of study on
00:21:40
flame spread that
00:21:42
perhaps we've taken much longer to
00:21:45
achieve
00:21:47
if we hadn't had the experience of kings
00:21:50
cross
00:21:52
[Music]
00:22:03
god
00:22:22
[Music]
00:22:29
you
