Five days after New York City's worst construction accident in a decade shut down the heart of Manhattan, Times Square remained closed Saturday as construction executives and city officials struggled to overcome unexpected complications in their efforts to make the area safe.

A swath of midtown Manhattan, from Fifth Avenue to Eighth Avenue, remained cordoned off as workers continued to erect an enormous sheath of nylon mesh over the partly collapsed scaffolding on the Conde Nast building, at Broadway and 43rd Street. Once in place, the mesh is intended to keep debris from falling to the street as workers remove the broken and bent scaffolding from the side of the building.At a news conference Saturday, Mayor Rudolph Giuliani confirmed that investigators seeking a cause of the accident were focusing on a section of the scaffolding that was supposed to have been fastened by four large nuts and bolts. "Three of the nuts are missing," he said.