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1 // The Height Libeskind's initial master plan stipulated that the skyscraper reach a height of 1,776 feet. That historically symbolic number makes for an extremely tall building—and an unprofitable one, since no tenant would want to be up that high. (It's just too scary.) The solution? Cheat. Reach the prescribed height by stretching out a 450-foot extension. Of course, a giant bundle of antennas standing more than 1,300 feet off the ground presents its own challenges. Namely, it can't sway more than half a degree, because that would compromise the constant energy levels needed for clear digital TV transmissions. To help keep the spire stable, the architects placed a ring a quarter of the way up the central steel mast. A system of Kevlar cables attached to the ring will anchor the antennas in place. Meanwhile, a shield made of glass-reinforced resin composite panels will protect the spire from the elements.
2 // The Base The initial design, unveiled in late 2003, would have been far too vulnerable to threats like truck bombs. So SOM made two sweeping changes. First it squared up the base, formerly a parallelogram, to move the part of the building closest to the West Side Highway away from the road. It also added a 205-foot cube of protection: An interior layer of concrete provides brute resistance; glass prisms on the outside of the bunker make it look cool. Between the two layers, a quirky-looking grilled screen keeps birds from entering the mechanical systems. Right past the entrance will be a 62-foot-wide wall and blast barrier decorated with art.
3 // The Trains Libeskind positioned the tower over the tracks leading out of the Port Authority commuter train terminus, which raised concerns that rumble from the trains could possibly cause structural disturbance (and shake the chairs of tenants above), and the electromagnetic field generated by the high voltage could harm occupants. The tracks and platforms also interfered with some of the tower's supporting columns. To minimize train rumblings and EMF exposure, SOM encased the building's steel supports in concrete. It isolated vibration by designing the joints between the concrete walls and steel columns to be flexible—connecting them like shoulder sockets, not like right-angled bookshelves. To keep the support beams out of the train tracks' way, SOM ran the columns diagonally away from the train paths and in one case split a load-bearing column over a single track.
<p>TWorld Trade Center went down seven and a half years ago, and since then New Yorkers have talked nonstop about what to put back up. The replacement—first called the <a hdom Tower</a> now named <a hWorld Trade Center</a> been slow in coming, in part because of the challenges involved in constructing a 1,776-foot-tall building that's impregnable to attack and yet can still function as a hub for a city of 8.3 million. The project, designed by <a hmore, Owings & Merrill</a> principal architect <a hd Childs</a>lowing an early concept by planner <a hel Libeskind</a> scheduled to be finished in 2013. Here's what SOM had to consider when it tackled the peculiar requirements of building 1WTC.</p>
trconstraint:</st>d a skyscraper that both screams "freedom" and stymies Al Qaeda.</emrsolution:</st>ntenna, a new shape, and blast-wall art.</emg
rl used:</st>00 tons</emrce space:</st>million square feet</emrected cost:</st> billion</em—>Hagberg (<a hagberg@mac.com</a> an architecture writer and author of the forthcoming book</emk Nostalgia.</p>
lated Design Under Constraint: <a hLimits Boost Creativity</a>hd a Streamlined Electric Car</a>h an SLR Into a Pocket Cam</a>h Antenna in the Cell Phone</a>h a Better Plastic Bottle</a>hgn Tiny Album Covers</a>
