From NY Times …there have been a million or so visitors to the memorial since it opened last September, and there have been no suicide attempts. Nonetheless, the police said a plan had been put in place. “We have to think of these possibilities,” Police Commissioner Raymond W. Kelly said in an interview with Esquire magazine. “People might commit suicide. We’re concerned about the possibility of somebody jumping in.” ………. “Our big worry several years ago, in the original design, was terrorism, and now we add suicide to the equation,” said Glenn P. Corbett, an associate professor of fire science at John Jay College, who is advising the Skyscraper Safety Campaign in its criticism of the memorial as inadequately safe and secure. “I think it’s going to happen — a suicide. I think it is an unbelievably emotional site.”

www.nytimes.com/2012/02/16/nyregion/at-9-11-memorial-police-raise-suicide-fears.html