[00:00.00]UNIT12
[00:13.55]The American Dream
[00:15.84]The dream to construct a building
[00:19.89]to house everyone and everything
[00:21.97]connected with world trade
[00:23.94]began in the early 1960's.
[00:27.34]After much deliberation，
[00:29.41]Minoru Yamasaki was commissioned
[00:33.13]over more than a dozen other architects
[00:35.98]to work with the firm of Emery Roth
[00:39.04]and Sons to design this massive edifice.
[00:42.11]His task was evident:
[00:45.05]the building must have
[00:46.92]twelve million square feet of floor space
[00:49.98]on a sixteen acre parcel of land,
[00:52.93]accommodate the new facilities
[00:55.12]for the Hudson tubes and subway connections,
[00:57.97]and be done within the 500 million dollar budget.
[01:02.12]The relatively small site
[01:04.86]combined with the vast space
[01:07.05]needs meant that
[01:08.36]the only way to go was up.
[01:10.44]The development would dwarf its neighbors
[01:14.16]and change the New York landscape
[01:16.13]and skyline at the bottom of Manhattan.
[01:19.52]In order to accommodate
[01:23.13]the nine million square feet of office space,
[01:26.09]Yamasaki made the decision
[01:28.16]that a two?tower development would be best.
[01:31.33]This would serve the dual purpose
[01:34.18]of giving sufficient office area
[01:36.81]on each floor and allowing a manageable structural system
[01:40.74]while taking advantage of the superb views.
[01:43.92]The twin towers would be 110 floors each,
[01:48.73]rising to a height of 1,353 feet (412 meters).
[01:56.06]From the observation decks
[01:59.23]at the tops of the towers
[02:00.76]it would be possible to see 45 miles
[02:03.94]in every direction.
[02:05.69]When asked why he designed two 110-storey buildings
[02:11.49]instead of one 220-storey building,
[02:15.21]he replied, flippantly, “
[02:17.28]I didn?t want to lose the human touch.”
[02:20.35]The first act in the construction process
[02:25.05]was the excavation.
[02:26.48]The 1.2 million cubic yards of earth
[02:30.63]and rock that were removed
[02:32.49]were used to create 23 acres of fill
[02:35.55]in the Hudson River adjacent to the W.T.C. site.
[02:40.37]This landfill project was subsequently developed
[02:45.29]as Battery Park. The excavation,
[02:48.79]besides providing the foundation
[02:50.98]for this enormous construction,
[02:52.95]would house parking garages,
[02:55.14]subway terminals and tubes,
[02:57.54]and shopping concourses.
[02:59.08]Yamasaki believed that
[03:02.91]all buildings must be strong
[03:04.66]in the context of being dominant.
[03:07.17]He felt that each building should
[03:10.24]“be a monument to the virility of our society”.
[03:14.07]The structural system,
[03:17.24]while possessing this strength,
[03:19.31]is also impressively simple.
[03:21.94]The 208-foot front wall
[03:25.34]is essentially a pre-assembled steel web,
[03:28.61]with columns on 39?inch centers,
[03:31.68]providing the wind bracing necessary
[03:34.41]for a building of this height,
[03:35.94]allowing the central core
[03:38.35]to take only the gravity loads.
[03:40.65]This very light,
[03:42.84]economical configuration would result in
[03:46.01]keeping the wind bracing
[03:47.54]in the most efficient place,
[03:49.18]the outside shell of the building.
[03:51.70]In this way, the wind force
[03:54.87]would not be transferred
[03:56.62]through the floor membrane to the core.
[03:58.92]Thirty?three inch deep floors
[04:02.31]made of prefabricated steel trusses
[04:05.49]would act as supports to stiffen the outside walls
[04:09.09]against the buckling forces
[04:10.95]of the wind?load pressures.
[04:13.36]There would be no interior columns
[04:16.76]in the office spaces,
[04:18.29]an amazing feat
[04:19.92]as there would be 40 000 square feet
[04:23.21]of office space on each of the upper floors.
[04:26.17]In total, there would be seven buildings
[04:30.87]in the complex;
[04:36.34]the twin towers standing 110 stories high ,
[04:36.08]four smaller towers,
[04:38.27]and a central plaza.
[04:39.70]Also, there would be seven underground levels
[04:44.18]containing services,
[04:45.38]shopping, parking garages and a subway station.
[04:49.43]When completed, there would be
[04:52.38]ten million square feet of leasable space,
[04:55.88]or an acre of rentable space
[04:58.51]on each floor of each tower.
[05:00.70]The elevator system was intended to be fast,
[05:05.26]efficient,and space saving.
[05:07.67]Express elevators opening onto the forty-first
[05:11.61]and seventy-fourth floors
[05:14.24]would serve the sky lobbies.
[05:16.31]From these floors and from the plaza,
[05:19.70]four banks of elevators would
[05:22.22]carry passengers to each of the three zones.
[05:25.06]Tenders posted, contractors hired,
[05:29.23]and the preliminary materials purchased,
[05:31.85]the groundbreaking ceremony
[05:33.82]was held on August 5, 1966.
[05:38.85]Some offices were ready for occupancy
[05:42.24]in 1970 but the ribbon cutting ceremony
[05:45.96]wasn't held until April 4, 1973.
[05:50.01]Final cost 750 million dollars.
[05:54.82]The institution of the W.T.C.
[05:59.20]would become a symbol of commerce
[06:01.48]and economic superiority to the world.
[06:04.65]International businesses recognized
[06:08.48]that it would be advantageous
[06:10.34]to have offices there.
[06:11.87]Thus, the working population of the W.T.C.
[06:16.14]would incorporate a cross-section of nationalities,
[06:19.64]not just Americans.
[06:21.39]The buildings would be occupied
[06:24.56]by as many as
[06:28.72]fifty thousand people daily during the week.
[06:29.34]Additionally,thousands of tourists
[06:32.18]could be in the center at any given time,
[06:34.81]visiting the restaurant,
[06:36.34]Windows on the World,
[06:38.20]atop One W.T.C.,
[06:40.83]the indoor and outdoor observation decks
[06:44.00]on Two W.T.C., as well as the shops,
[06:47.17]exhibition pavilions,
[06:49.25]and the 250 room hotel.
[06:52.21]A complex of this size
[06:55.16]is not without some problems,
[06:57.35]including fire. Numerous small fires
[07:00.96]and one major one on February 13, 1975
[07:06.03]occurred over the years.
[07:07.67]However, on February 26, 1993,
[07:12.81]a terrorist attack on the W.T.C.
[07:15.77]caused the largest incident ever handled
[07:18.50]by the City of New York's Fire Department.
[07:21.57]The blaze, resulting from
[07:24.52]the ignition of a nitrourea bomb,
[07:27.26]with hydrogen cylinders to add impact,
[07:30.10]and located in the parking garage,
[07:32.83]required the response of 84 engine companies,
[07:36.45]60 truck companies,
[07:38.49]and hundreds of personnel.
[07:41.01]Firefighters maintained a presence
[07:43.31]at the site for 28 days,
[07:46.15]guarding against the possibility
[07:48.67]of further fires caused by the blast.
[07:51.95]Six people died and 1042 were injured.
[07:56.87]The towers survived.
[07:58.83]After this violent incident failed
[08:02.77]in its intended purpose of destroying the W.T.C.,
[08:06.60]who could have envisaged an assault
[08:09.23]as disastrous as the one inflicted on it
[08:12.40]and the United States on September 11, 2001?
[08:16.77]Who could have conceived an attack
[08:19.62]so vicious it would eclipse
[08:21.92]almost every man?made catastrophe?
[08:24.76]Who could have foreseen that
[08:27.17]the American dream would
[08:28.88]blur into a terrible nightmare?
[08:31.40]At 8∶45 a.m. New York local time,
[08:36.32]a hijacked 767 commercial airliner
[08:40.04]with a full load of jet fuel
[08:42.23]for a transcontinentalflight collided with One W.T.C.,
[08:46.60]The north tower,
[08:48.24]with enough impetus to carry it
[08:50.54]through to the opposite side.
[08:52.52]Initially, terrorism was not a consideration
[08:56.67]in the mind of the public.
[08:58.09]This was merely a dreadful accident.