|Conference Technical Tour|
|June 13, 2013|
Richard Witt, Quadrangle Architects and Daniel Safarik, CTBUH Editor
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See the report on the 2013 London Conference
|LONDON - The Broadgate Tower, developed by British Land and Blackstone as part of their highly successful City office estate, was designed by Skidmore, Owings & Merrill (SOM) and was the first tower building in the City designed specifically for the speculative market.|
|At 161m (529 ft) tall, it provides stunning views of London and elegant, wonderfully light offices over 30 floors. The Broadgate Tower is one of a small number of new buildings that redefine the City skyline, creating a corporate presence and identity. It now anchors the northern cluster of towers that rise near the financial heart of London.
The Broadgate Tower is the location for world-class businesses such as Reed Smith LLP, Itochu, Greenlight, William Blair, Dickson Minto WS, Regus, Gill Jennings & Every LLP, Liquidnet, Hill Dickinson LLP and Itau BBA.
Since launch, The Broadgate Tower has received numerous awards for its innovative architecture and design, including a New City Architecture Award, as well as being named the Best Tall Building in Europe by the Council on Tall Buildings and Urban Habitat.
|Broadgate Tower as seen from below|
|The Broadgate Tower represents the resolution of an architectural and structural challenge, because it was originally designed in the 1990s as a 14-story financial services office building with large trading floors of up to 80,000 square feet. The preparations for that structure involved building a 2.5 meter-deep steel raft over 14 active railway tracks leading into Liverpool Street Station, which could not be taken out of service for any period of time.|
|Delegates take in the view of London from one of the office floors|
|“Over time, towers became more acceptable,” said Kent Jackson, director at SOM’s London office. “The raft was already in, but there was now an opportunity to go tall. We had to retrofit the structural solution that was already in place.”|
Because no columns could be sunk into the railway trench, the majority of the tower’s weight is carried through a network of 2- to 3-m diameter piles with 7-8-m diameter underreams on the west side of the trench, and through massive angled struts that span the width of the trench and channel forces down from the east side of the tower. These struts connect to a steel exoskeleton that gives the building its distinctive appearance. This constraint, combined with the need to maintain view corridors from Richmond Park and Westminster Pier, accounts for the building’s unusual shape, Jackson said.
|The entrace lobby with the escalators to the second floor elevator lobby|
|So little of the site is on solid ground at street level, that there is no room for elevator pits. Tenants take escalators up to the second floor, through a large glass atrium connected to the pedestrian passage between the 35-story west building (the Tower) and the 201 Bishopsgate, the 14-story east building. Bishopsgate now contains more modest trading floors than originally planned in the 1990s, at 40,000 square feet each; the Tower’s floor plates measure about 13,000 square feet. Again, the constraints of the tower’s shape forced another design choice that makes the building distinctive: Broadgate Tower is the world’s first to use destination-controlled, double-decker elevators, Jackson said.|
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