including why some subway cameras were not operating as they should have. reporter: the new york city s 472 subway stations, there are approximately 10,000 surveillance cameras. every station has at least one, but listen to what new york city s transit boss sam waynes said. there were a couple of cameras with internet hook-up linkage problems yesterday. reporter: cameras involved in the shooting and the escape, faulty computer systems disrupted the feed from the cameras. we talked to the former executive director of the chicago transportation committee. unable to get from the general line to the general control. today, distinguished professor at city college in new york says diligently keeping the technology well maintained is essential. but you also want to make sure that if something isn t working, you have a team of people that you can get at quickly to be able to repair these. reporter: the locations of the subway system cameras are not any secret, although