So as expected, the Port Authority announced today that construction at the World Trade Center site is behind schedule and over-budget, apparently because the original plans were unrealistic. There’s also 19 different government agencies and numerous other organizations involved in the site, with no central governing agency. Anyway, I am not going to try to duplicate the news reports here, or try to comment on it all. What I do have for y’all is a photo I took with my cameraphone last night of the Freedom Tower. After the jump, you can compare it a photo I took from the same location on April 2. So … slow progress.
I got an email on my flickr account awhile back from someone whose company apparently sold some of equipment being used to Freedom Tower (aka One World Trade Center). He said that it was a “self-climbing system,” meaning that it would take awhile to set up but once the “Power Tower” was set up the the stories would rise rapidly. I really didn’t understand what he meant even after he tried to explain it, but then by chance I saw an episode of the Discovery Channel’s “Extreme Engineering” that focused on the “Turning Torso” skyscraper in Sweden. This I think helped me understand, although I could still be wrong. But basically, in traditional construction everything is lowered onto what is currently the top story by crane. The workers build that story and then the process is repeated. With a “self-climbing system” there is a “power tower” in the center of the building on hydraulics. Once a level is completed the hydraulics raise the “power tower” up a story and the workers build around that. (The Discovery Channel segment said the hydraulics was a feat of engineering, akin to boosting an entire gas station off the ground one story).
Anyway, this is still not a very good description, but hopefully I have given you an idea. If there is an engineer here or someone who could explain it better, please post in the comments.
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