"The agent can within seconds get a message to transit command, and they'll tell them to not come into the station until they figure out what the emergency situation is," Gannon said.
Several subway systems around the world have safety barriers, such as glass panels, intended to prevent passengers from reaching the tracks. Paris' metro operator, RATP, began installing glass panels along platforms at some stations in 2010 after a string of deaths, some by suicide. In Taiwan, the Taipei Rapid Transit Corporation has platform screen doors at some of its 102 subway stations.
"Some stations have glass walls and doors and you don't have access to the platform, but as far as I can tell that would cost a giant fortune," Russianoff, of the Straphangers Campaign, said.
Gannon and train operators agree that safety in the subway starts with alertness on train platforms and common sense.
"Don't go near the end of the platform," Gannon said. "There is no reason to stick your head out and look for the train. Why would you do that?"