Tuesday, March 25, 2008

Earthquake Hazard Battery Park City Underscores Official Plannings Disregard for Safety

Foolishly Placed Buildings on Landfill WITHOUT Foundations to Bedrock May Imperil Vital Transportation Links.


As for the subsoil conditions in NYC itself, the well-known Manhattan bedrock rises to the surface in the northern part of the island, extending also to the north. The bedrock falls deeper as we go to the south and east, forming still a reachable foundation for buildings in Midtown, but generally not as far south as in Downtown. Because bedrock forms a solid base for a building, it, despite also transmitting seismic shockwaves effectively, will be a better choice than soft soil. The ample soft soil in New York would be the cause for the city's major harm in case of an earthquake. Not only does it amplify the seismic waves and direct them to the surface, but parts of the city land are also prone to so-called liquefaction, an abrupt loss of soil cohesion. The sand particles lose their friction resistance under the earthquake vibration and get mixed up with water beneath the ground surface, naturally losing any support it gives to a structure. A particularly clear example of its effect was the accident in Brooklyn, where building a sewer in reclaimed land with a vibratory pile driver collapsed four houses within two blocks with the loss of a life. The agitated soil had given way even from that distance and led to the collapse. Much of the waterfront is filled-in and reclaimed from the rivers with soil that is prone to liquefaction, especially below water level. The most notable of these landfills is the Battery Park City in Downtown Manhattan, which would face severe problems in a major earthquake -- as would do many other vital services, like several major hospitals or the Long Island airports on fills, with JFK also near Rockaway.

An earthquake could make BPC buildings tilt, possibly towards the Brooklyn-Battery Tunnel portal approach, requiring their subsequent demolition as a hazard to transport.

Perhaps this is also applicable to the irresponsibly placed Chase Manhattan buildings immediately along the south side of the Holland Tunnel in New Jersey? I would not be too surprised given the extreme disregard to transport amongst 'new urbanist' planning.

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