Petronas Twin Towers ... Some facts and figures

Did a brief Wikipedia study of the Twin Towers this morning, what did I find out about my 2 favourite features of the building (The Skybridge and Lifts)?...

Skybridge
The towers feature a skybridge (constructed by Kukdong Engineering & Construction) between the two towers on 41st and 42nd floors, which is the highest 2-story bridge in the world.
The bridge is 170m above the ground and 58 m long. The same floor is also known as the podium, since visitors desiring to go to higher levels have to change elevators here.
The skybridge is open to all visitors, but free passes (limited to 1,700 people per day) must be obtained on a first-come, first-served basis. The Skyway is closed on Mondays.
Visitors are allowed to go only on the 41st floor as the 42nd floor is used only by the tenants of the building.
The skybridge also acts as a safety device, so that in the event of a fire or other emergency in one tower, tenants can evacuate by crossing the skyway to the other tower. However, the total evacuation triggered by a bomb hoax on September 12, 2001 (the day after the September 11 attacks destroyed the Twin Towers of the World Trade Center in New York City) showed that the bridge would not be useful if both towers need to be emptied simultaneously, and the capacity of the staircases was insufficient for such an event.
Plans thus call for the elevators to be used if both towers need to be evacuated, and a successful drill following the revised plan was conducted in 2005.

Elevator system
The main bank of elevators is located in the center of each tower. All main elevators are double-decker with the lower deck of the elevator taking passengers to odd numbered floors and upper deck to even numbered floors.
In order to access an even numbered floor from ground level, passengers are required to use an escalator to access the upper deck of the elevator.From the ground floor there are three groupings of elevator.
The "short haul" group of 6 elevators take passengers to floors between level 2/3 and level 16/17.
The "mid haul" group of 6 elevators take passengers to floors between level 18/19 and level 37/38. There is also a set of shuttle elevators that take passengers directly to levels 41/42.
In order to get to levels above 41/42, passengers are required to take the shuttle elevators and then change elevators to the upper floors. These connecting elevators are placed directly above the elevators serving levels 2 to 38. The pattern now repeats with the upper levels, one set serving levels 43/44 to 57/58 and one set serving levels 59/60 to levels 73/74.
Apart from this main bank of elevators, there are a series of "connecting" elevators to take people between the elevator groupings. Unlike the main elevators, these are not of the double-decker type. Two elevators are provided to take people from levels 37/38 to levels 41/42 (levels 39 and 40 are not accessible as office space).
This avoids the need for someone situated at the lower half of the building to go down to the ground floor in order to gain access to the upper half of the building.
The elevators contain a number of safety features. It is possible to evacuate people from an elevator stuck between floors by manually driving one of the adjacent elevators next to it and opening a panel in the wall. It is then possible for people in the stuck elevator to walk between elevator cars.
During an evacuation of the buildings the shuttle elevator is allowed to be used. This is because there are only doors at levels G/1 and levels 41/42 therefore should there be a fire in the lower half of the building, this enclosed shaft would remain unaffected.



Other facts and figures
Combined, the towers have 1,000,000m2 of floor space
The towers have 32.000 windows
The building costs were US $ 1,2 billion
The towers were designed to symbolise strength and grace using geometric principles typified in Islamic architecture
Without pinnacle the buildings are 'only' 378m/1,240f tall
The towers are part of the 100-acre KLCC Development. Other components of the development include the Suria KLCC, a six-story, 93,000 square feet shopping centre(with 270 specialty shops, cinema's and a food arcade), Menara Maxis, Menara Esso, the 20-hectare KLCC Park
The whole complex was built on a former horse-racing track
The main occupant of the buildings is Petronas, the national oil-company
Though completed in 1998, the buildings were officially opened on August 28th, 1999
Each tower contains 80,000 m3 of concrete in strengths up to Grade 80, almost 11,000 tonnes of reinforcement,and 7,500 tonnes of structural steel beams and trusses.
And, an interesting movie fact ...

Entrapment
The 1999 movie Entrapment starring Catherine Zeta-Jones and Sean Connery, features the Tower's complex security systems being infiltrated in order to steal from a high-security bank in the tower at midnight on New Year's Day.
A prime stunt sequence takes place when the pair are stranded atop the connecting bridge and are confronted by a Kuala Lumpur police helicopter. In one scene, the skyline of Kuala Lumpur (prominently featuring the Petronas Towers) was super-imposed with an urban river filmed in the city of Melaka, some 80 kilometers away.
The scene created an illusion whereby the Petronas Towers were surrounded by shanty towns, thus prompting disapproval from Kuala Lumpur residents. Ironically there are indeed shanty towns within a couple of miles of the building, simply not the ones shown in the film. The film was never banned in Malaysia although FINAS viewed the film as degrading to the Malaysian community.

How does it compare with other mega-tall-structures?
The Petronas Twin Towers were the tallest buildings in the world until Taipei 101, as measured to the top of their structural components (spires, but not antennas), took over the record. Spires are considered integral parts of the architectural design of buildings, to which changes would substantially change the appearance and design of the building, whereas antennas may be added or removed without such consequences. The Petronas Twin Towers remain the tallest twin buildings in the world.

The Sears Tower and the World Trade Center towers were each constructed with 110 occupied floors – 22 more than the Petronas Twin Towers’ 88 floors. The Sears Tower and the World Trade Center’s roofs and highest occupied floors substantially exceed the height of the roof and highest floors of the Petronas Twin Towers. The Sears Tower’s tallest antenna is about 250 feet (76 meter) taller than the Petronas Twin Towers’ spires. However, in accordance to CTBUH regulations and guidelines, the antennas of the Sears Tower were not counted as part of its architectural features. Hence, surpassing the roof of the Sears Tower by 10m.

The designers and builders
These towers, which were designed by Cesar Pelli, an Argentine-American architect, were completed in 1998 and became the tallest buildings in the world on the date of completion. The 88-floor towers are constructed largely of reinforced concrete, with a steel and glass facade designed to resemble motifs found in Islamic art, a reflection of Malaysia's Muslim religion.
Because of the depth of the bedrock, the buildings were built on the world's deepest foundations. The 120-meter foundations were built by Bachy Soletanche, and required massive amounts of concrete.
In an unusual move, a different construction company was hired for each of the towers, and they were made to compete against each other. Eventually the builders of Tower 2, Samsung Constructions (the Construction Division of Samsung Corporation), Kukdong Engineering & Construction (both of South Korea), won the race, despite starting a month behind Tower 1, built by Hazama Corporation, and Tower 1 (Hazama Corporation) ran into problems when they discovered the structure was 25 millimeters off from vertical. The shopping mall beneath both towers was constructed by Birmingham, Alabama based Bill Harbert International.
Due to a lack of steel and carbon fibre bombshells the huge cost of importing steel, the towers were constructed on a cheaper radical design of super high strength reinforced concrete. High-strength concrete is a material familiar to Asian contractors and twice as effective as steel in sway reduction; however, it makes the building twice as heavy on its foundation than a comparable steel building. Supported by 23-by-23 meter concrete cores and an outer ring of widely-spaced super columns, the towers use a sophisticated structural system that accommodates its slender profile and provides from 1300 to 2000 square metres of column-free office space per floor.
Petronas, Malaysia's national oil company, set out to build the world's tallest building. Although other buildings such as the Sears Tower have higher occupied floors, a higher antenna, and a higher roof, the Petronas Twin Towers' spires are classified as architectural details and rise to 452 m (1483 feet), giving it the greatest structural height until Taipei 101. Taking advantage of the rules governing building measurements (counting spires but not antennas) has generated controversy over the towers' claim to the title. However, the tradition of including the spire on top of a building and not including the antenna dates back to the rivalry between the Chrysler Building and the Empire State Building.