Risk factors for a train collision:
(1) trains going in opposite directions using the same set of tracks
(2) high level of train traffic
(3) poor visibility
(4) breakdown or stoppage of one train (as for bridge failure)
(5) absence of, or failure of, automated safety features
(6) absence of, or failure of, manual warning systems (such as rail torpedo)
(7) one train traveling at high speed, especially when one engineer is trying to hurry or to make up time
(8) an engineer impaired due to health or intoxication
(9) an engineer who is inexperienced or poorly trained
(10) brake failure (runaway train)