A truck transporting a toxic substance turns over on a highway near your house. A terrorist’s radioactive ”dirty bomb” goes off blocks from your downtown apartment building. A line of tornadoes is bearing down on your church. How will you be warned right away and told what to do? Chances are you won’t. The nation’s emergency alert system is broken. And despite frequent warnings from federal officials that terrorists could strike again — possibly with chemical, biological or radiological weapons of mass destruction — little has been done since the attacks of Sept. 11, 2001, to fix it. As a result, many Americans risk not knowing about a potentially dangerous situation until it’s too late to do anything about it. ”If you get warned, it’s as much luck as anything else,” says Kenneth Allen, executive director of the Partnership for Public Warning, an organization of government emergency managers and industry executives. The partnership is raising concerns about the lack of a unified, coherent warning system. Full Story