– City dwellers facing one of the most brutal winters on record have been dealing with something far more dangerous than snow falling from the sky: ice tumbling from skyscrapers.

Streets around New York's new 1 World Trade Center were recently closed when sheets of ice sheared from the face of the 1,776-foot structure — turning them into potentially deadly, 100-mph projectiles.

And sidewalks around high-rises in cities big and small have been cordoned off with yellow caution tape because of falling icicles, a situation that experts warn could get worse as a thaw sets in over much of the country.

"Be very, very aware of your surroundings," said Joey Picca, a meteorologist at the National Weather Service in New York. "If you see ice hanging from a building, find another route. Don't walk under hanging ice."

Some architects say newer, energy-efficient high-rises may be making the problem worse.

"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 of the consulting firm Northern Microclimate in Cambridge, Ontario.

Stangl helps developers opt for shapes, slope angles and even colors — darker colors absorb more melting sun rays — to diminish ice formation. High-tech materials, heaters embedded in glass, also are used in building design.

Such options are not always possible in older cities with balconies and awnings.

Barry Negron said he saw ice hanging perilously off a four-story building near Rockefeller Center and was trying to warn other pedestrians when he was hit in the face with a football-size chunk. Cuts across his nose and cheek, he said, required 80 stitches.

Exactly how many pedestrians are hit by falling ice is not clear, but dozens of serious injuries are reported annually. It's a perennial problem in St. Petersburg, Russia, where dozens reportedly are injured or killed every year.

This week, signs warning pedestrians of falling ice stood outside nearly every skyscraper in Chicago's Loop as temperatures pushed above freezing. Last week near New York's Carnegie Hall, chunks of ice tumbled from a condo tower onto cars and buses.