A New York City skyscraper that could topple at any moment, a city street that collapses, and the Leaning Tower of Pisa are serious engineering emergencies, and experts use cutting edge technology to reveal if they can be fixed.A New York City skyscraper that could topple at any moment, a city street that collapses, and the Leaning Tower of Pisa are serious engineering emergencies, and experts use cutting edge technology to reveal if they can be fixed.