Atlanta has had experience dealing with acts of terror at major events (the 1996 Olympic Park bombing). The city has also had more practice than most in providing security for big events. But the bombings at the Boston Marathon have again focused the attention of law enforcement and security people here. MARTA is a key part of all the major events in Atlanta. With the Peachtree Road Race and other warm-weather celebrations on the way, WABE’s Denis O’Hayer spoke with MARTA Police Sergeant Aston Greene, who command’s the system’s emergency preparedness unit.