Recent train wrecks and people getting killed by trains have been in the news, becoming a major headache for America's railways. The wrecks and rollovers might be mitigated if a way were found to make the railroad tracks "feel" the trespassers or blocking objects. The idea would work like this:
1) Person or object is stuck on the tracks or trespassing.
2) Sensors/ detectors lining the tracks, or cameras, detect the person or object.
3) Sensors/detectors send signals or alerts to the engineer/ motorman/ train driver about the trespasser. Signals/alerts are also sent to the cops and/or trespasser himself/herself.
4) Train slows down. Trespasser gets off tracks. If blocking object is stubbornly stuck, the train comes to a halt.
5) No crash occurs, but service is likely delayed if blocking object needs to be removed.
Research into this subject would help save lives.