West Street near the World Trade Center in lower Manhattan was shut down Wednesday because of falling ice from the rebuilt skyscraper, authorities said.
The six-lane thoroughfare was closed for about 2 miles southbound from Canal Street to the Battery Park underpass, and about a mile northbound from Battery Park to Murray Street.
The Battery Park underpass was also closed.
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City officials warned of major traffic delays throughout lower Manhattan.
Streets around the trade center have been closed a number of other times this winter for the same problem.
Some architects say newer, energy-efficient high-rises may actually be contributing to ice buildup.
"They keep more heat inside, which means the outside is getting colder and that allows more snow and ice to form," said engineer Roman Stangl, founder of the consulting firm Northern Microclimate in Cambridge, Ontario.
Anthony Hayes, spokesman for the Port Authority of New York & New Jersey, which owns the trade center site, said crews have been removing the accumulation of ice that formed on the 1 World Trade Center and on an external construction hoist that stretches from the ground to the 90th floor.