After planes hit the World Trade Center towers on the morning of September 11, 2001, Chicago mayor Richard M. Daley jumped into action. He called for a voluntary evacuation of downtown, and soon businesses were sending their employees home from work.  One of those evacuees was a musician from the Pullman neighborhood who began to wonder how long it would it take to evacuate city residents if a disaster did hit downtown Chicago.  WBEZ’s Curious City recently investigated his question, and reporter John Fecile joins Morning Shift to explain what he learned.