World Trade Center surveyors using advanced Leica plumb system

06/09/2010

Leica Geosystems equipment, which has been integral to the construction of many of the world's tallest buildings, is now being used on perhaps the most iconic building project in the world today – the redevelopment of the World Trade Center site in New York.

The Leica Geosystems’ Core Wall Survey Control System was initially developed for the Burj Khalifa skyscraper in Dubai, United Arab Emirates – the tallest man-made structure ever built – and is now being used on One World Trade Center.

The 1,776-foot tall tower is being built in the footprint of the former North Tower, destroyed in the terrorist attacks of September 11, 2001.

The Core Wall Survey Control System will use a network of on-site GPS observations, remote reference stations and precision inclinometers to monitor the tilting of the building as it is being constructed. Tilting is inevitable in high-rise buildings, due to environmental and construction factors and a surveyor needs to know exactly how much a building is moving from its design position to determine the precise position at the instrument setup.

One World Trade Center project manager, Gerard Lamarre, said, “Without the GPS you have to imagine that today they would be sitting at the bottom of this building trying to square up a line, while that building moves."

"The traditional method would be to transfer the locations from the ground on all four sides and box it—try and do a best fit. That would take at least three to five hours, but with the GPS, every hour you have a good position.”