1 World Trade Center (1970–2001)

The original One World Trade Center (also known as the North Tower, Tower 1, Building One, or 1 WTC) was one of the Twin Towers of the original World Trade Center complex in New York City. It was topped out in 1970, and completed in 1972. It stood at a height of , and was the tallest building in the world until 1973, when surpassed by the Sears Tower in Chicago. On the 106th and 107th floors of this building were a complex of dining, meeting, and entertainment venues known as Windows on the World.

It was distinguishable from its twin, the original 2 World Trade Center, also known as the South Tower, by the telecommunications antenna on its roof. Including the antenna, the building stood at a total height of . The North Tower was 6 feet taller than the South Tower because floor 43 was 2 feet taller and floor 67 was 4 feet taller than the standard ceiling of 12 feet. These two floors were used by the Port Authority. Other things that made the North Tower distinguishable from its twin was a canopy connected to the North Tower's west facade on street level as well as two pedestrian walkways that extended from the west and south promenades of Three and Six World Trade Center to the North Tower's north and south facades on plaza level, all of which the South Tower lacked. The building's address was 1 World Trade Center, and the WTC complex had its own ZIP code (10048) due to its large size.

The original World Trade Center was destroyed in the terrorist attacks of September 11, 2001. Struck by American Airlines Flight 11 at 8:46 a.m., the North Tower was the first of the Twin Towers to be hit by a hijacked aircraft, and the second to collapse, at 10:28 a.m. The North Tower stood for 102 minutes after the aircraft impact. Of the 2,996 people killed in the attacks, around 1,700 were in the North Tower or on the ground.

The North Tower was succeeded by the present-day One World Trade Center tower, which was opened in November 2014 as the lead building of the redeveloped World Trade Center site. At the National September 11 Memorial & Museum, the northern pool marks the spot where the North Tower once stood.

History

Development

thumb|left|upright|1 World Trade Center under construction, May 1970

In 1961, the Port Authority of New York and New Jersey agreed to build the World Trade Center on the site of the Hudson Terminal in Lower Manhattan, New York City. On , 1962, the Port Authority announced the selection of Minoru Yamasaki as lead architect and Emery Roth & Sons as associate architects. but to meet the Port Authority's requirement for of office space, the buildings would each have to be 110 stories tall. Yamasaki's design for the World Trade Center, unveiled to the public on , 1964, called for a square plan approximately in dimension on each side. Demolition work began on , 1966, and groundbreaking for the construction of the World Trade Center took place on , 1966. In January 1967, the Port Authority awarded $74 million in contracts to various steel suppliers. Construction work began on the North Tower in . The topping out ceremony for 1 WTC (the North Tower) took place on , 1970. and a ribbon cutting ceremony took place on , 1973.

On the 106th and 107th floors of this building were a complex of dining, meeting, and entertainment venues known as Windows on the World.

Operation

On February 12, 1975, a three-alarm fire broke out on the North Tower's 11th floor, spreading to the 9th and 14th floors. At that time, the World Trade Center had no fire sprinkler systems. A disgruntled custodian was discovered to have deliberately started the fire and was criminally charged. Following the fire, in 1981, the Port Authority announced a $45 million plan to install sprinklers throughout the World Trade Center.

The first terrorist attack on the World Trade Center occurred on February 26, 1993, at 12:17 p.m. A Ryder truck filled with of explosives (planted by Ramzi Yousef) detonated in the North Tower's underground garage. According to a presiding judge, the conspirators' chief aim at the time of the attack was to destabilize the North Tower and send it crashing into the South Tower, toppling both skyscrapers. Six people were killed and 1,042 others were injured in the attacks. Following the bombing, floors that were blown out needed to be repaired to restore structural support.

In February 2001, the Port Authority leased the entire World Trade Center complex to Vornado Realty Trust. However, Vornado insisted on last minute changes to the deal, and the next-highest bidder, Silverstein Properties, signed a lease for the complex on , 2001.

Destruction

left|thumb|The remains (from bottom to top) of One, [[6 World Trade Center (1974–2001)|Six, and Seven World Trade Center on September 17, 2001]]

At 8:46 a.m. (EDT) on September 11, 2001, five hijackers affiliated with al-Qaeda crashed American Airlines Flight 11 into the northern facade of the North Tower between the 93rd and 99th floors. Seventeen minutes later, at 9:03 a.m. (EDT), a second group of five terrorists crashed the hijacked United Airlines Flight 175 into the southern facade of the South Tower, striking between the 77th and 85th floors.

By 9:59 a.m. (EDT), the South Tower collapsed after burning for approximately 56 minutes. After burning for 102 minutes, the North Tower collapsed due to structural failure at 10:28 a.m. (EDT). When the North Tower collapsed, debris fell on the nearby 7 World Trade Center, damaging it and starting fires. The fires burned for hours, compromising the building's structural integrity. Seven World Trade Center collapsed at 5:21 p.m. (EDT).

Together with a simultaneous attack on the Pentagon in Arlington, Virginia, and a passenger revolt that resulted in a plane crash in Shanksville, Pennsylvania, the attacks resulted in the deaths of 2,996 people (2,507 civilians, 343 firefighters, 72 law enforcement officers, 55 military personnel, and the 19 hijackers). More than 90% of the workers and visitors who died in the towers had been at or above the points of impact. In the North Tower, 1,355 people at or above the point of impact were trapped, and died of smoke inhalation, fell, jumped from the tower to escape the smoke and flames, or were killed when the building eventually collapsed. One stairwell in the South Tower, Stairwell A, somehow avoided complete destruction, unlike the rest of the building. When Flight 11 hit, all three staircases in the North Tower's impact zone were destroyed, making it impossible for anyone above the 91st floor to escape. 107 people below the point of impact also died. During the World Trade Center's construction, the structural engineers ended up following draft versions of New York City's 1968 building codes, which incorporated "advanced techniques" in building design. The Twin Towers used a tube-frame design, which required 40 percent less structural steel than conventional building designs. The structures were inspired by the architectural ethic of Le Corbusier and was the seminal expression of Yamasaki's gothic modernist tendencies. Yamasaki was also inspired by Islamic architecture, elements of which he incorporated in the buildings' design, having previously designed Saudi Arabia's Dhahran International Airport with the Saudi Binladin Group.

When completed, the North Tower stood tall. It featured a telecommunications antenna or mast that was built on the roof in 1979 (upgraded in 1999 to accommodate DTV broadcasts). With this addition, the highest point of the North Tower reached . Each tower stood over high, and occupied about of the total of the site's land.

Facade

The Twin Towers' facades were made of high-strength, load-bearing perimeter steel columns which acted as Vierendeel trusses. Although the columns themselves were lightweight, they were spaced closely together, forming a strong, rigid wall structure. There were 59 perimeter columns, narrowly spaced, on each side of the building. In all, the perimeter walls measured long on each side, and the corners were beveled. The perimeter structure was constructed of prefabricated modular pieces connected by spandrel plates. From the 7th floor to the ground level, and down to the foundation, the columns were spaced apart to accommodate doorways. All columns were placed on bedrock 65–85 feet (20–26 m) below the surface.

Structural features

The building's core housed the elevator and utility shafts, restrooms, three stairwells, and other support spaces. The core of each tower was a rectangular area 87 by 135 feet (27 by 41 m), and contained 47 steel columns running from the bedrock to the top of the tower. The North Tower's structural core was oriented with the long axis east to west. All elevators were located in the core. Each building had three stairwells, also in the core, except on the mechanical floors. The large, column-free space between the perimeter and core was bridged by prefabricated floor trusses, which connected to the perimeter columns.

Hat trusses (or "outrigger truss") located from the 107th floor to the top of the North and South towers were designed to support a tall communication antenna on top of each building. Only the North Tower actually had an antenna fitted, which was added in 1978. The framed-tube design using steel core and perimeter columns protected with sprayed-on fire resistant material created a relatively lightweight structure that would sway more in response to the wind. In designing the World Trade Center, Leslie Robertson considered the scenario of the impact of a jet airliner crashing into the building. The National Institute of Standards and Technology (NIST) found a three-page white paper that mentioned another aircraft impact analysis, involving impact of a jet at , was indeed considered, but NIST could not locate the documentary evidence of the aircraft impact analysis.

Sprayed-fire resistant materials (SFRMs), gypsum wallboard, and vermiculite were used to provide fireproofing to the interiors. More fireproofing was added after a fire in February 1975, but after the 1993 bombing, inspections found fireproofing to be deficient. The 1968 New York City building codes did not require sprinklers for high-rise buildings, except for underground spaces, but the entire complex was retrofitted by 2001.

Tenants at the time of the attacks

The tenant list below was compiled from the original list provided by CoStar Group (a provider of electronic commercial real estate information), quoted by CNN, and was sourced from UnBlinking.com. Cantor Fitzgerald's corporate headquarters were located in 1 World Trade Center.

Note: Floor numbers in  red  were part of American Airlines Flight 11's impact area on September 11, 2001, with floors trapped by its impact numbered in  dark gray .

{| class="wikitable"

! Fl# !! Companies

! style="background:#444; color:white;"| 110/R

| Local radio and TV stations: Channel 2 (WCBS), Channel 4 (WNBC), Channel 5 (WNYW), Channel 7 (WABC), Channel 9 (WWOR), Channel 11 (WPIX), Channel 13 (WNET), Channel 31 (WPXN), Channel 47 (WNJU), WKCR-FM, WPAT-FM, WNYC-FM, WKTU-FM, CNBC, Genuity, CNN

|- style="background:#999;"

! style="background:#444; color:white;"| 109

| Mechanical floor

|- style="background:#999;"

! style="background:#444; color:white;"| 108

| Mechanical floor

! style="background:#444; color:white;"| 107

| Windows on the World, Greatest Bar on Earth, Wild Blue

! style="background:#444; color:white;"| 106

| Windows on the World, Windows on the World Wine School, Windows on the World Conference and Banquet rooms

! style="background:#444; color:white;"| 105

| Cantor Fitzgerald, eSpeed, Genuity

! style="background:#444; color:white;"| 104

| Cantor Fitzgerald, eSpeed, Channel 4 (WNBC), UmeVoice

! style="background:#444; color:white;"| 103

| Cantor Fitzgerald, eSpeed

! style="background:#444; color:white;"| 102

| Cantor Fitzgerald, Alliance Consulting Group, The Nishi-Nippon Bank Limited, PaineWebber, Kidder Peabody & Co.

! style="background:#444; color:white;"| 101

| Cantor Fitzgerald, eSpeed, Boomer Esiason Foundation, Chances for Children (charity), Kidder Peabody & Co.

! style="background:#444; color:white;"| 100

| Marsh & McLennan Companies

! style="background:red;"| 99

| Marsh & McLennan Companies

! style="background:red;"| 98

| Marsh & McLennan Companies

! style="background:red;"| 97

| Marsh & McLennan Companies

! style="background:red;"| 96

| Marsh & McLennan Companies, Sumitomo Mitsui Banking Corporation

|-jillack parachutes, john Lodder

! style="background:red;"| 95

| Marsh & McLennan Companies

! style="background:red;"| 94

| Marsh & McLennan Companies, Marsh Private Client Services, Guy Carpenter

! style="background:red;"| 93

| Marsh & McLennan Companies, Fred Alger Management, Castle Convertible Fund Inc.

! style="background:#444; color:white;"| 92

| Carr Futures, Lower Manhattan Cultural Council, LMCC Art Program, LMCC Open Studios

! 91

| American Bureau of Shipping, Cedel Bank International, Meyers Pollok Robbins, New Japan Securities International, Lower Manhattan Cultural Council, LMCC Art Program, LMCC Open Studios, Shiga Bank

! 90

| American TCC International Group, Chugoku Bank, Dun & Bradstreet, Clearstream International, Pass Consulting Corporation

! 89

| Barcley Dwyer, Bayview Services LLC, CIIC Group (US), Cosmos Services America, Frank W. Lin & Co., Daehan International, Drinker Biddle & Reath, MetLife, Mutual International Forwarding, Strategic Communications Group, Wai Gao Qiao USA, Wall Street Planning Association, Banco LatinoAmericano de Exportaciones Sud America, Italian Wine & Food Institute, Majestic Star Yacht Chartering, Tokyo Securities Company

! 88

| Viking Sea Freight, WTC Construction Manager

! 87

| May Davis Group, Bank of Kinki, Thor Technologies

! 86

| Julien J. Studley, Asiatic Chemical, Society of Satellite Professionals International

! 85

| SMW Trading Corporation, Thermo Electron, Chicago Investment Group, Hyakugo Bank, Ohrenstein & Brown

! 84

|Bright China Capital, David Peterson Law Offices, LG Securities America (Later merged separately to NH Investment & Securities and KB securities), San-In Godo International Bank, Temenos USA Wholesalers, Unicom Capital Advisors, Blue Star Line North America, Daehan International

! 83

| Axcelera, General Telecommunications, eMeritus Communications, Lava Trading LLC, Global Crossings Holdings, Ameson Education and Culture Exchange Foundation, Taipei Bank, Toho Bank, Wako Securities America

! 82

| New York Metropolitan Transportation Council, DMJM Harris

! 81

| Bank of America, Blue Star Line North America, Network Plus, New Continental Enterprises

! 80

| Agricor Commodities Corporation, Intrust Investment Realty, Noga Commodities Overseas, Noga Hotels New York, Shizuoka Bank, RLI Insurance Company, Bank of Yokohama, Zenshinren Bank, TheBeast.com Sixty-nine people reported to work that morning, including 67 employees of Carr Futures, a tenant on the 92nd floor. The impact itself spared every single person on Floor 92 and did no damage to the floor directly. However, the force of the crash collapsed walls and inflicted nonstructural damage such as smashed windows, broken ceiling tiles and severed electrical wires, as well as causing knee-deep flooding throughout various rooms on the 92nd floor after the water pipes burst. Multiple calls were recorded from people trapped on the floor, the workers reporting that although the stairs on the 92nd floor had not been destroyed, they were walled off by fallen debris from Flight 11's impact zone immediately above. In addition to the stairs being rendered impassable, the centralized impact into the North Tower's core also interrupted elevator service in the skyscraper from its 50th floor and higher, severing all escape routes for anyone above the 91st floor.

Initially, conditions on the 92nd floor were likely not dissimilar to what they were on the 91st, from which everyone survived and escaped. The situation changed very quickly when flammable aviation fuel spilled down into the 92nd floor, igniting fires that rapidly began consuming its east side; within 12 minutes of the impact, the first known fatalities from the floor occurred over a three-minute period when eight workers were forced to jump from the northern end of the tower's east side to escape a rapidly advancing wall of flames.

Those who remained made their way to an unoccupied area on the west side of the floor that was initially free of smoke and fire. However, images show that the blaze on the tower's north face eventually spread westward to their safe haven in that section of the floor, making conditions there unsurvivable.

The last phone call from the North Tower came from Thomas McGinnis, a trader on the 92nd floor, when he got through to his wife Iliana at 10:18. McGinnis and a number of others had been confined to a conference room the entire time after the door jammed shut from the building buckling as the plane hit, separating them from everyone else on the floor. Most of the floor was engulfed in flames by the time McGinnis called, with extremely limited space for the group to avoid being burned.

Despite his wife's attempts to reassure him, McGinnis did not believe they would survive. The South Tower had already collapsed, and McGinnis revealed to her that he could see people jumping from the floors above. The line went dead at 10:26, two minutes before the tower collapsed. Home Lines once occupied Suite 3969 from 1974 until 1988. Telerate Systems, Inc., which was subsumed by Dow Jones, occupied the 104th floor.

References

Citations

Sources

External links

List of World Trade Center tenants via CNN (Archive)
World Trade Center Tenant Relocation Summary via TenantWise.com
World Trade Center Tragedy: Information for Families, Friends and Colleagues – Marsh and McLennan Companies

(North Tower)