00:01 an ordinary government building nine
00:03 floors of glass and steel reinforced
00:05 concrete built to code built to last
00:08 then one morning a crude bomb causes
00:11 destruction on an unimaginable scale in
00:14 seven seconds the building disintegrates
00:17 168 people will die as a result of the
00:20 explosion 00:21 now with cutting-edge computer
00:23 technology we reveal exactly what went
00:26 wrong 00:30 disasters don't just happen there a
00:32 chain of critical events unravel the
00:35 fateful moments in those final seconds
00:38 from disaster
00:39 [Music]
00:47 the United States Midwest campus April
00:56 18 1995
01:00 4:30 in the morning a truck pulls out of
01:03 a motel in Kansas shriya's later it
01:07 drives off the road and parks beside a
01:09 lake the driver is on a mission against
01:14 the American government he pills 13 208
01:19 liter barrels with a deadly combination
01:21 of chemicals the next day April 19 he
01:26 drives the Ryder rental truck and it's
01:28 lethal cargo south on route 77 there we
01:35 are takes him closer to his target even
01:41 the date he has chosen deliberately
01:44 exactly two years before in Waco Texas
01:46 federal agents storm a militia compound
01:50 at least 75 people died during the siege
01:55 the man visits Waco to show his support
01:57 the armed resistors inside
02:00 he blames the US government for their
02:03 deaths and flowers revenge his name is
02:10 Timothy McVeigh
02:14 [Music]
02:16 Oklahoma it's the start of a bright and
02:19 sunny day early morning traffic heads
02:22 for the bustling capital of this
02:24 Midwestern state 7 o'clock 02:28 Timothy McVeigh the Ryder truck and its 02:31 deadly cargo joined the flow of vehicles 02:32 going south along Highway 77 02:35 [Music] 02:38 ahead out of the plains Rises Oklahoma 02:42 City a regional center in the American 02:46 heartland 02:46 where numerous government agencies are 02:48 located in one particular building the 02:55 nine story Alfred P murrah Federal 02:57 Building houses 16 federal agencies 03:00 including Housing and Urban Development 03:02 a military recruiting office and the 03:04 Secret Service built 18 years earlier 03:10 the Mara was a modern purpose-built 03:12 office clock with a glass atrium and a 03:15 wide pedestrian Plaza at its front off 03:17 Robinson Avenue 03:22 and at its rear the glass-fronted facade 03:24 towers above pit streets the first floor 03:28 of the Mara is a daycare center 03:31 employees in the Mara and other downtown 03:33 offices leave their children here while 03:36 at work one of them is 35 year old 03:39 Dolores what's new this morning she 03:42 heads in early to drop off a 20 month 03:44 old grandson PJ PJ is for life he just 03:49 pulled off his coat no jacket he's happy 03:53 ready to go play 03:55 PJ joins 20 other thug lism preschoolers 03:58 in the daycare center some are as young 04:01 as six months the eldest is five years 04:04 old I was able to see him during the 04:07 course of the day he was accessible to 04:09 me from my job Delores a telephone 04:13 engineer often services the phones in 04:16 the Mara but this morning she heads 04:18 across town to a meeting 04:20 [Music] 04:22 8:15 McBay is 35 minutes away from 04:27 Oklahoma City heading straight for the 04:29 center of town and the Opera P murrah 04:31 Federal Building on the second floor 59 04:39 year-old Florence Rogers is in charge of 04:41 the Federal Employees Credit Union she's 04:45 looking for to seeing colleagues as it's 04:47 her first day back from vacation I was 04:50 anxious to get to work because I had 04:54 scheduled a meeting with some of my 04:57 upper management people I was very 05:00 excited to show my cruise pictures ain't 05:03 just to get my day started and to take 05:06 care of business 8:53 Timothy McVeigh is 05:13 in Russia traffic that fills the 05:15 downtown streets for months earlier he 05:18 checked out the Mara and selected it as 05:20 his target 05:22 [Music] 05:24 his plan is to park the truck filled 05:26 with explosives right beside it 05:32 age 55 the Social Security office is on 05:38 the ground floor of the Mara inside 20 05:43 year old Dana Bradley her children 05:44 mother and sister joined the waiting 05:46 line 05:47 [Music] 05:50 they're standing near the rear entrance 05:52 of the building just our fifth Street 05:55 then I'm streamlining for us while 05:59 investors to stead by the door and fill 06:01 out the papers for a Social Security 06:03 card for myself driving along Fifth 06:08 Street McVeigh's truck is filmed by a 06:10 security camera 06:11 [Music] 06:14 he pulls over inside the cab he's 06:17 drilled a hole and fed up food fuse wire 06:19 through to the bomb barrels in the back 06:22 he lights the fuse 06:25 he now has only five minutes the parka 06:28 truck and make his getaway before the 06:29 bomb explodes 06:31 [Music] 06:33 nine o'clock the Ryder truck is forced 06:36 to stop at a red light 06:37 91 meters shy at the target 06:41 there are just two minutes left to burn 06:44 on the fuse McBay crosses hobby Avenue 06:48 and drives to the rear of the Murrah 06:49 Building 06:50 Dana Bradley's still waiting in line 06:52 spots the truck from the ground floor 06:54 window I am turning around and I see a 06:58 fan a movie truck in front of the Social 07:02 Security office 901 on the second floor 07:13 Florence's meeting is underway there 07:16 were eight and I was the ninth person in 07:19 that little crew 07:22 [Music] 07:24 on the first floor TJ and the other 20 07:27 children enjoy breakfast and on the 07:32 ground floor 07:33 Dana is still watching the truck the 07:38 driver gets out pushes back 07:42 hey walks past our window 07:45 901 and thirty seconds McVeigh walks 07:48 away there are now three hundred and 07:50 sixty-one people inside the Murrah 07:52 Building the fuse has just 43 seconds 07:55 before it explodes the bomb Timothy 07:59 McVeigh marks a Ryder truck packed with 08:01 explosives outside the murrah Federal 08:03 Building in Oklahoma City 08:08 now using advanced computer technology 08:11 we'll discover what really happens when 08:14 the bomb explodes 08:18 902 the fuse has just 30 seconds to burn 08:23 361 people are in the Mara building 08:34 [Music] 08:45 Dana Bradley is on the ground floor in 08:47 direct line of the blast all I seen was 08:50 a violet light and everything was black 08:56 on the second floor 08:58 Clarence Rogers is in a meeting with a 09:00 chief of staff there was a rash of air 09:03 like a tornado everything literally was 09:07 blowing up before my eyes I knew that 09:10 was it yeah I prayed I said God please 09:14 save me I have to take care of 09:19 dolorous Watson's grandson is in the 09:21 daycare center on the first floor 09:23 directly above the exploding truck the 09:27 entire front of the Hetal building was 09:29 nothing but glass the children that were 09:32 in the Wendell's would just order the 09:34 blaze 09:36 [Music] 09:42 it takes seven seconds for the 09:45 nine-story building to collapse in ruins 09:49 the blast devastates 324 buildings over 09:53 ten city blocks window chatter and cars 09:56 erupt in flames 09:58 people hear it as far as 89 kilometers 10:02 away the shockwave registers 6 on the 10:05 Richter scale equivalent to a major 10:07 earthquake if you are anywhere Deonte on 10:11 you probably heard it and closed it from 10:15 across the city 11 fire engines race 10:17 downtown 10:18 [Applause] 10:30 firefighter Chris fields is one of the 10:32 first on the scene 10:34 you see these hordes of people run 10:36 toward just and having no idea what we 10:39 were but step into district Fire Chief 10:44 Mike Shannon arrives four minutes after 10:46 he hears the explosion looks like we 10:50 were in a war zone we've been stretched 10:53 they were just overwhelming 10:55 he takes charge of the rescue squads 10:57 about to enter the dangerously unstable 10:59 ruins but produces the type of carnage 11:04 that isn't seen in earthquakes or 11:07 tornados more than 5,000 square meters 11:17 of offices are reduced to 650 square 11:20 meters of rubble 11:23 the frantic search for survivors begins 11:26 [Music] 11:31 on the remains of the second-floor 11:33 credit union chief plans Rogers stares 11:36 into a gaping hole 11:40 I started wondering about the staffing 11:44 ring with me they were gone and a swish 11:51 Florence is helped down to the 11:53 pedestrian Plaza just below her 11:54 second-floor window it took a few 11:57 minutes after I was even out of there 11:59 that realized that they hadn't run away 12:03 they hadn't left my office they had 12:07 literally been taken away by all the 12:11 floors on top of them but why does 12:16 Florence survive when all eight of our 12:18 colleagues vanish under the rubble the 12:21 answer will provide a crucial lead to 12:22 investigators trying to unravel the 12:24 disaster 12:25 [Music] 12:28 Florence goes into shock news cameras 12:31 catch a wandering nearby wrapped in a 12:33 blanket 12:36 [Music] 12:40 9:08 seven blocks away 12:44 Delores Watson hears the explosion but 12:48 20 month old grandson PJ is in the 12:50 daycare center on the first floor only 12:56 there no longer is a first floor she 13:01 joins the flood of anxious parents 13:03 rushing to the scene 13:05 in my mind I was thinking is this real I 13:09 know it was real I'm looking at it but a 13:13 big part of me was wanting to say this 13:15 is not really happy 13:20 [Music] 13:21 rescuers claw through the tons of 13:23 mangled steel and rubble desperately 13:25 searching for any sign of life in the 13:27 debris even seasoned fireman mike shanin 13:31 is shocked by the scene and devastation 13:34 they try not to be emotional a frantic 13:38 logical but your mind keeps going back 13:43 to what you're expecting to find 13:50 rescuers begin to find people alive one 13:54 is a baby boy he's rushed to hospital in 13:59 critical condition 14:00 it's PJ and I saw his little face and he 14:04 was wrapped all in these guards and he 14:07 was sedated and he was laying there but 14:10 I mean there was his arms there was his 14:11 legs and there was my baby 14:13 you know they told me that his chance of 14:17 survival were very slim and that the 14:21 next 24 hours will be crucial 14:24 [Music] 14:34 10 20 78 minutes after the explosion 14:38 while PJ remains in intensive care and 14:41 the rescuers are struggling to pull out 14:43 people alive 97 kilometers to the north 14:46 of Oklahoma City State Highway patrolman 14:49 Charlie hanger pulls over a suspicious 14:51 battered old car alongside yellow 14:56 Mercury Marquis I had realized that 15:00 there was not a tag displayed on the 15:02 rear bumper and stopped it I saw a tall 15:07 young white male we met more us between 15:11 the two cars asking for a driver's 15:15 license 15:15 pepper Alois he was recruiting a license 15:18 I saw what appeared to be a weapon under 15:20 the jacket he says my weapon is loaded 15:26 at that point I thought he was trying to 15:29 intimidate me and I noted him a little 15:32 bit with the barrel of my weapon and I 15:33 said so it's mine I've removed the 15:37 weapon threw it on the shoulder of the 15:39 roadway 15:40 [Music] 15:44 he was then handcuffed and placed in my 15:47 human officer hangar checks the man's ID 15:52 was a Michigan driver's license I looked 15:54 at the picture it appeared to be the 15:56 same individual I had stopped and it did 15:59 list Timothy James McVey has the name 16:04 the arrests McVeigh for the missing 16:06 license plate and the loaded gun 1028 86 16:12 minutes after the explosion 16:14 back at the Mara building rescuers have 16:17 come across something other than a 16:18 victim in the rubble they said they 16:21 thought they found another explosive 16:23 device there's panic and the rescue 16:28 operation comes to an abrupt halt while 16:30 the bomb squad investigated 16:32 [Music] 16:35 54 minutes later they sound the 16:38 all-clear it's a false alarm but 16:40 rescuers have lost precious time now 16:43 they're back amongst the carnage as 16:45 vital minutes tick by 16:50 two o'clock in the afternoon 16:54 Dana Bradley has been trapped in the 16:56 rubble for five hours as these images 16:59 show there was a blood going through the 17:02 concrete that was laying over someone 17:07 else's blood all she can remember is 17:11 standing on the ground floor with her 17:12 mother and children watching the Ryder 17:14 truck park 17:21 Dana has been found hours earlier that 17:24 can't be moved her leg is trapped under 17:27 a massive concrete floor if there are 17:32 safer the rescuers have only one option 17:35 they said the only way we're gonna be 17:38 able to get you out of here it's a good 17:40 shot dr. Andy Sullivan senior orthopedic 17:47 surgeon rushes to the scene I just kind 17:50 of said a prayer got to do with me and 17:52 some kind of combat crawled into the 17:54 area had to go under some rebar or 17:56 reinforcement steel my plan was to use 18:01 just sharp instruments and separate the 18:03 leg from the thigh through the knee I 18:06 was awake and aware of them claiming my 18:09 leg off she was awake she was screaming 18:15 they said the Sun was so bad it broke 18:18 the heart to hear me scream like that 18:24 I don't remember she says she doesn't 18:27 remember any of this I hope that's true 18:39 it takes 11 hours to recover all the 18:42 survivors 18:43 [Music] 18:46 168 people have died as a result of the 18:49 explosion including 19 children all 18:52 under the age of 5 18:56 the photo of a baby being carried from 18:58 the rubble comes to symbolize the 19:00 tragedy it's taken only seconds after 19:03 she's handed to fireman Chris fields 19:07 now your standard looking down at her 19:09 and just thinking you know that know 19:11 this is somebody baby she had an open 19:14 wound to her skull and I pretty well 19:16 knew at that time that she had already 19:17 passed 19:21 the explosion and collapse of the 19:24 building takes everyone by surprise 19:27 Oklahoma City had never suffered such a 19:30 catastrophic disaster until this moment 19:36 but it takes just seven seconds for the 19:39 nine story building to collapse 19:45 using the investigators data he can 19:47 piece together the deadly chain of 19:49 events to find out what really caused 19:51 this terrible tragedy 19:53 [Music] 19:56 state-of-the-art computer graphics will 19:59 take you to where no camera can go into 20:01 the heart of the disaster zone it's 20:08 obvious from the scale of devastation 20:10 that this is not an accident 20:12 but the result of a bomb explosion what 20:16 kind of bomb could cause such 20:18 devastation investigators start by 20:22 looking for any evidence that be like a 20:25 giant crater in the road in front of 20:27 Amarra building indicates the center of 20:29 the explosion dr. Paul maraca is a 20:35 military blast expert and co-author of 20:37 the official report into the Oklahoma 20:39 bombing what we did is use the crater 20:43 size to estimate the size of the 20:45 explosion was a question of working 20:49 backwards we now have the crater so how 20:52 big was the explosive have been the bomb 20:55 crater is nine meters wide and two and a 20:58 half meters deep we estimated that it 21:01 was approximately 4,000 pounds of TNT 21:04 that's equal to four major battlefield 21:06 bombs used by the US military 21:14 eyewitness accounts place the Ryder 21:16 truck at the heart of the crater it's 21:21 clear to investigators the bomb must 21:23 have been inside to demonstrate what 21:27 happens a truck is filled with just half 21:29 the amount of explosives that detonated 21:31 outside the mara building that morning 21:42 the bomb that explodes in Oklahoma City 21:45 destroys virtually everything close to 21:47 the blast including the vehicle that 21:49 carried it 21:52 but within an hour of the explosion 21:54 investigators buy their first vital 21:56 piece of evidence over 91 metres away 22:00 they discover a truck axle that doesn't 22:03 seem to belong to any other vehicle 22:05 could this be all that is left of the 22:07 vehicle that carried the bomb on the 22:14 twisted metal they discover the clearly 22:16 marked vehicle identification number 22:21 FBI agents trace the number to a 1993 22:24 Ford truck owned by rider rental the 22:30 rider branch in Junction City Kansas 22:31 rented it two days earlier to a man 22:34 named Robert clean within eight hours of 22:39 the bombing an FBI artist draws an ID 22:41 etiquette picture of cleaned based on 22:43 descriptions given by staff of the 22:45 rental company 22:45 [Music] 22:50 the FBI launches one of the biggest 22:52 manhunts in American history by evening 22:56 the next day they make the crucial 22:58 breakthrough a motel owner recognizes 23:00 the identical picture as a man who 23:02 recently stayed there driving a Ryder 23:05 truck 23:06 [Music] 23:10 he checks in using ID in the name of 23:12 Timothy James McVey but where is he now 23:19 FBI agents discovered that state trooper 23:22 hangar ran a computer check on a man 23:24 with that name less than two hours after 23:26 the bombing amazingly they discovered up 23:30 McVeigh is still in jail for traffic and 23:33 firearms offenses 23:34 [Music] 23:36 the FBI arrests McVeigh as a suspect in 23:39 the attacks something that you never 23:42 envision being involved all came out of 23:46 a routine traffic stop 23:48 four months later McVeigh is charged 23:51 with mass murder in Oklahoma he would 23:54 probably the last thing that I would 23:55 think of that an American we actually 23:58 commit a terrorist act against American 24:01 people the FBI discovered that the bomb 24:04 is home made from materials easily 24:06 bought over the counter 24:11 McVeigh eventually admits that he made 24:13 it by filling barrels with ammonium 24:15 nitrate and liquid nitromethane better 24:20 known as fertilizer pellets and rocket 24:22 fuel used in drag car racing the deadly 24:26 mixture of more than 3,000 kilograms 24:28 cost less than five thousand dollars but 24:34 the question remains how could such a 24:36 simple homemade bomber cause such 24:38 destruction to a steel reinforced 24:40 concrete building 24:48 a bomb explodes outside the Murrah 24:51 Building in Oklahoma City in just seven 24:54 seconds it collapses killing 161 people 24:58 it's not just a great human tragedy but 25:01 a devastating blow to national security 25:05 the FBI tracked down and arrest Timothy 25:08 McVeigh the man responsible now the 25:11 investigation shifts focus 25:13 how can a crude homemade bomb caused 25:15 such devastation is there a fatal flaw 25:18 in the Mara's design that could put 25:19 similar office buildings at risk the 25:30 architecture of the acclaimed Mara 25:31 building is in fact extremely well 25:33 designed Oklahoma is in the middle of 25:36 the Midwestern tornado belt the Mara is 25:40 built from steel reinforced concrete 25:41 used in military bunkers able to 25:44 withstand winds of up to 160 kilometres 25:46 per hour 25:49 so why did buffets simply homemade bomb 25:52 caused it to collapse so catastrophic 25:54 Lee investigators track the last moments 25:59 of McVeigh's journey second-by-second 26:04 at 901 just 73 seconds before the 26:09 buildings collapse he parks the truck 26:11 packed with explosives he deliberately 26:16 chooses a place where his bomb will 26:18 inflict maximum damage the rear of the 26:23 building beside one of the four columns 26:26 that support the floors above the bomb 26:30 explodes 26:37 in just seven seconds the Mara is 26:40 reduced to rubble what happens during 26:44 those seven seconds now becomes the 26:46 focus of the enquiry 26:49 the ruins of the building hold the vital 26:51 clues that will provide answers 26:55 dr. John Auster ass is a renowned 26:58 structural engineer who analyzes how 27:00 buildings collapse part of my expertise 27:04 is being able to rebuilding I can form 27:08 sort of a three-dimensional mental image 27:10 of what's going on it would tell me how 27:12 the building had responded we see the 27:14 patterns of how how beams and columns 27:16 broke apart but dr. Ostrow asked the 27:20 broken floors and twisted columns are 27:22 key pointers in working out exactly how 27:24 the building reacts following the bomb 27:26 blast this film of a military test shows 27:32 what happens during an explosion the 27:36 first stage is the bombs lightning fast 27:38 blast waves as the bombs energy is 27:43 released it compresses 27:44 air particles in its path to create a 27:46 shockwave this compressed air travels 27:51 faster than the speed of sound sweeping 27:54 away everything in its path the blast 27:58 wave goes through the building in a 28:00 blink of an eye so we can break it down 28:02 into what happens millisecond by 28:04 millisecond a millisecond is one 28:09 thousandth of a second about the time it 28:11 takes for a person to blink twice or a 28:13 bullet fired from the gun to travel one 28:16 meter 28:18 so to understand how the catastrophe 28:20 unfolds 28:21 we'll use unique computer simulations to 28:24 slow down the chain of events 28:27 millisecond by millisecond we'll see how 28:29 the blast wave cuts through the building 28:31 to answer the tragic question of why so 28:34 many died seven seconds before collapse 28:39 the bomb explodes in the first 28:43 millisecond one thousandth of a second 28:45 the shock wave covers four point seven 28:47 five meters traveling at five kilometers 28:50 per second and hits the closest part of 28:53 the building the column McVeigh parked 28:56 next to engineers call this column g20 29:02 the blast wave hits g20 with immense 29:05 power 29:07 dr. mulatto is an explosives expert 29:10 [Music] 29:12 researching his report into the bombing 29:14 he conducts scale model blast tests on 29:17 concrete columns with the same 29:18 dimensions and properties as g20 29:22 as the air blast expands violently it 29:26 exerts this enormous pressure on 29:29 anything in its path 29:32 dr. Malacca calculates that the 29:34 shockwave hits the fella with a force of 29:37 more than 350 kilograms per square 29:39 centimeter destroying it to put that in 29:46 perspective a hundred mile an hour 29:49 hurricane wind is much less than one 29:52 pound per square inch so these blast 29:55 pressures were enormous 29:57 dr. Malacca and his colleagues feed 29:59 their test data into the 100 30:01 million-dollar supercomputer of the US 30:03 Army Corps of Engineers 30:06 this helps them visualize a blast wave 30:09 as it penetrates a building like a melon 30:15 they discover that one millisecond after 30:18 destroying g-20 the blast wave hits the 30:21 glass covered rear of the building the 30:25 facade of the building provided almost 30:28 no resistance to the airplane military 30:33 high-speed film shows what it's like 30:35 when a blast wave hits a wall of glass 30:41 the windows are turned into a hailstorm 30:43 of deadly shards after shattering its 30:53 windows the blast wave penetrates the 30:55 Mara's entrance lock I knew that was 31:01 just it I prayed the void of the atrium 31:09 acts like a funnel channeling the deadly 31:11 blast wave up into the building it slams 31:14 into the underside of the first floor at 31:16 more than 16,000 kilometres per hour 31:20 tragically directly above is the 31:23 children's daycare center where baby PJ 31:27 and 20 other children are playing 15 31:32 children aged from 6 months to 5 years 31:35 are killed 31:38 [Music] 31:45 after eight milliseconds the blast wave 31:48 reaches the second floor where florence 31:50 rogers is holding a meeting before my 32:04 eyes the blast wave continues to surge 32:08 up through the building it reaches the 32:10 eighth floor in just 31 milliseconds the 32:13 time it takes for a vehicle airbag to 32:15 inflate after a crash but as it travels 32:18 upwards it is rapidly losing its 32:20 destructive energy the yellow highlight 32:26 shows how the damage decreases as the 32:28 blast wave Rises through the building 32:30 and shows that floors four and above 32:32 remain intact the blast wave is over but 32:38 it's what happens next that causes the 32:40 greatest destruction in less than seven 32:44 seconds all nine stories collapse those 32:47 who survived the initial blast are now 32:49 crushed under tons of falling concrete 32:57 investigators must now find out what 32:59 causes this second wave of destruction a 33:05 massive homemade bomb is torn through 33:08 the mara Federal Building in Oklahoma 33:09 City 161 people lose their lives even 33:13 though many survived the initial blast 33:17 [Music] 33:20 the blast was powerful enough to damage 33:23 only the lower floors of the nine story 33:25 building 33:32 investigators now struggle to understand 33:35 why the upper floors collapsed as well 33:39 in an effort to solve the mystery they 33:42 revisit the first moments of the 33:43 explosion as the blast wave spreads it 33:47 destroys the closest frontal column 33:49 known as g20 in less than four 33:51 milliseconds above the remaining three 33:55 columns is a massive girder known as a 33:58 transfer beam that runs the length of 34:00 the building this transfer beam carries 34:04 the weight of the six floors above these 34:06 walls in turn are held up by nine 34:08 columns these nine columns pass the 34:11 building's weight down to the transfer 34:13 beam which then distributes it evenly 34:15 across the four pillars below at first 34:20 some experts believe that after 34:21 destroying g20 the blast then damages 34:24 two more pillars under the transfer fee 34:30 with the fillers blown away the beam 34:32 loses its support and pause making all 34:34 the upper floors with it 34:41 but the position of the transfer beam in 34:44 the rubble doesn't support this theory 34:46 it hasn't fallen straight down as it 34:48 would if the columns had collapsed 34:50 beneath it 34:52 instead the transfer beam is discovered 34:54 lying inside the building suggesting 34:57 it's been pulled inwards it was in the 34:59 debris pile behind the columns so there 35:02 was supported on this column and it was 35:05 found in the debris pile behind the 35:07 column but dr. Auster asand his 35:09 colleagues the location of the collapsed 35:11 transfer beam provides the vital clue 35:13 they can now piece together what happens 35:16 in those crucial seven seconds after the 35:18 explosion 35:24 the blast destroys g20 but does not 35:27 destroy the other three columns and the 35:29 transfer people with the buildings still 35:32 intact the blast wave then rips through 35:34 the atrium at the Mara it smashes into 35:36 the floors above at more than 16,000 35:39 kilometers below there are 8 storeys of 35:43 concrete four slabs in the Mara 35:45 connected to nine supporting columns but 35:50 the second floor is also connected to 35:52 the transfer beam that holds up the 35:53 columns this proves a critical Creta as 35:58 the blast wave powers through the 36:00 building dr. Eve Hinman a blast expert 36:07 worked with dr. Ostrow ass on the 36:09 investigation I think of the floor slabs 36:13 often as the sale like a sail on a 36:16 sailboat because they had so much 36:18 surface area that the blasts can act on 36:21 the blast forces up the floor slabs on 36:24 the lower four storeys blast pressure 36:27 comes in lists the floor slab up four 36:31 sizes come up and shear off the columns 36:33 and then gravity takes over and down 36:35 they come 36:42 within milliseconds we got collapse of 36:47 floor slabs on the second through fifth 36:50 floor about 100 milliseconds after the 36:53 explosion the time it takes for the 36:55 human brain to recognize an image the 36:57 third and fourth floors collapse onto 37:00 the second which is still attached to 37:02 the transfer beam 37:04 this added weight means the second floor 37:06 also gives way but crucially its 37:09 connection to the transfer beam remains 37:10 intact the beam is ripped off the 37:14 columns by the falling floor and dragged 37:16 into the building 37:20 my theory is that when the floor slabs 37:24 came down they pulled the transfer 37:27 girder in transfer girder rolled over as 37:31 that third floor slab collapsed and fell 37:34 into the debris it is it is pulling on 37:36 the top edge of the transfer beam and 37:38 there's nothing to resist that force one 37:42 hundred milliseconds after the blast the 37:46 transfer beam is pulled down and around 37:48 by the falling floor 37:51 200 milliseconds after the blast the 37:54 falling transfer beam sets off what 37:56 engineers call progressive collapse 37:59 professor collapses collapse that that 38:03 spreads beyond the initial zone of 38:06 damage one second after the blast 38:09 progressive collapse begins to destroy 38:12 the Mara building you knock over one 38:16 domino that falls in the knocks over the 38:19 next and so on can can you get this 38:20 progressive chain reaction the transfer 38:23 beam is the critical element or domino 38:26 in the market it supports the columns 38:30 that in turn support the seven storeys 38:32 above with the transfer beam gone the 38:38 upper floors are fatally weakened and 38:40 the building begins to collapse 38:46 gravity takes another 5 seconds or so 38:49 thought to bring the building down it's 38:51 all over in seven seconds this is the 38:54 time it takes the night story for to 38:56 drop the 31 meters to the ground more 39:00 than 5,000 square meters of steel 39:02 reinforced concrete collapses into a 39:04 two-story hide pile of rubble 39:10 really isn't the air blessed that's 39:12 hurting people it is the building that 39:16 is hurting 39:24 among those killed by the collapsing 39:27 building a Florence Rogers eight 39:29 employees who are wither on the second 39:31 floor 39:32 [Music] 39:38 as the floor slabs collapse only she 39:41 survives because she's sitting directly 39:43 over a supporting beam on the opposite 39:45 wall from the explosion that remains 39:46 undamaged 39:50 I didn't realize what a small little 39:52 portion of my floor didn't break away 39:57 someone said there was only about 18 39:59 inches left it that didn't break away 40:04 Engineers now know why mat Bay's crude 40:07 bomb causes such devastation but was it 40:10 inevitable today there's an awful 40:14 realization that an extra $100,000 spent 40:18 on the construction of the building 40:19 could have prevented its collapse April 40:27 19 1995 is a date Oklahoma City will 40:30 never forget the day 168 people are 40:35 killed when a massive truck bomb 40:36 explodes outside the murrah Federal 40:38 Building but could the building's 40:42 devastating collapse have been prevented 40:46 a new seismic study has assessed how the 40:50 Mara building would have responded if it 40:52 had been built to Californian earthquake 40:54 resistant standards something not 40:56 required in Oklahoma its conclusions are 41:01 startling it reveals that only one 41:04 exterior column and the lower floors 41:06 would have been damaged as their 41:09 computer simulation shows the building 41:12 would remained intact to meet the 41:16 earthquake resistant code the whole 41:18 building would have been strengthened 41:19 with much more reinforced steel this 41:23 added steel would have tied the building 41:26 together and stopped the fatal failure 41:28 of the transfer beam the catastrophic 41:31 progressive collapse would never have 41:33 happened 41:34 [Music] 41:36 it would have cost less than 1% of the 41:39 building's original construction budget 41:40 around $100,000 the study suggests four 41:45 out of five of those killed may then 41:47 have survived 41:48 [Applause] 41:49 [Music] 41:51 but in 1977 when the Mara was built 41:54 no one ever imagined that it would be 41:57 the target of a terrorist attack those 42:02 who lived through that terrible day in 42:04 1995 still bear the scars Vijay is one 42:12 of only six children from the daycare 42:14 center who survived 42:16 [Music] 42:21 his grandmother Delores Watson mounted a 42:24 tense vigil beside baby PJs incubator 42:28 for nine years he's lived with a 42:31 tracheotomy tube down his throat to help 42:33 him breathe it was only removed in 2003 42:37 I made the statement once that when the 42:41 trach was out that PJ and I would be 42:43 able to move from April 19 to April 20th 42:46 but each day when this child looks in 42:49 the mirror the scars are still there as 42:52 the second-floor office fell to the 42:54 ground 42:55 florence rogers lost 18 of her 33 42:57 colleagues of the credit union 43:03 nothing has ever been this thing or ever 43:08 will be the same it literally changes 43:10 your life forever she recruited new 43:13 staff and reestablished the company then 43:17 every time 43:21 [Music] 43:24 the falling floors killed Dana Bradley's 43:27 mother her son and three-year-old 43:31 daughter Dana survived the emergency 43:34 amputation of her leg months of 43:37 treatment followed but Dana has achieved 43:38 a miraculous recovery it was WOW it was 43:46 like wow I'm walking beautiful 43:49 I was strutting down the hallway I loved 43:53 it 43:53 the more I wanted to walk in the more I 43:56 carried about living the remains of the 44:03 Mara were destroyed five weeks after the 44:05 attack 44:13 five years later the site opens as a 44:16 national memorial to remember the 168 44:19 lives lost that day 44:23 the site commemorates the exact moment 44:26 in time that hurts so many 44:30 the road the truck parked on is gone 44:32 replaced by a lake there's one chair for 44:38 every life lost 44:42 man woman and child across the street 44:49 from the site of the Mara 44:51 a new federal building opened in 2003 44:56 state-of-the-art its design incorporates 44:58 key lessons learnt from April 19 there's 45:03 no point for the building to stand after 45:05 the event and if everyone inside is is 45:09 killed the lobby the entrance that 45:15 funneled so much of the explosion into 45:17 the Mara is now protected by two 45:18 centimeter steel blast shields the glass 45:24 is new-generation blast proof material 45:26 designed not to shatter but the most 45:31 affected measure to prevent a repeat of 45:33 the tragedy is also the cheapest 45:36 ramp roof parts around the building's 45:39 perimeter so no one can park close to it 45:44 this simple step would have stopped 45:46 McVeigh driving his truck up to the Mara 45:48 and limited the destruction that 45:50 followed Timothy McVeigh is found guilty 45:56 of mass murder and executed by lethal 45:59 injection on June 11 2001 74 months 46:03 after his bomb kills 168 people but the 46:09 stark reality remains there's little 46:12 that can be done to stop a determined 46:13 terrorist who decides to target innocent 46:16 civilians most office buildings around 46:20 the world are just as vulnerable as the 46:23 Mara if a bomb went off outside them 46:27 they would react just as catastrophic 46:29 Lee as the Mara in those fatal seven 46:32 seconds at 902 on April 19 1995 46:40 [Music]
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