Amtrak Washington train crash: Deaths as carriages fall on US motorway

[kraznyi_oktjabr]

Originally Posted by Platapus

My cheap Garman alerts me when the posted speed limit changes and alarms when I exceed that speed limit by about 2-3 mph. Is there any reason why such a device could not be used on a train?

Those systems work by determining where you are and then check what the map says about speed limit. In railways that works fine until next interlocking where there are different speed limits for main and secondary routes. That means in almost every interlocking you encounter, you have a problem.

For example lets say that main route has speed limit of 80 mph but when switches are turned into siding there is speed limit of 20 mph over switches (exceed that and you may derail). If your safety system relies on GPS and map then you must enforce lowest speed limit possible in that section of track. At first glance it may not look too bad but you must take into account braking distances and length of siding. Delays caused by unnecessarily low speed limit add up quickly.

Originally Posted by Platapus

With practically everything on trains being controlled by computers, is there no way to program a governor to kick in when the speed of the train is almost three times the speed limit?

That is standard functionality of automatic train protection (ATP) systems provided that sufficient information about applicable speed limits is available (see above). Installation of ATP system into locomotive is relatively easy (emphasis on relatively) and is generally not restricted by technological level of locomotive. Ofcourse in modern locomotive you can integrate stuff directly into controls which avoids clutter (and hence human factors troubles) in locomotive cab design.

Here in Finland computerized ATP system has been installed into pre-WWII (museum) steam locomotives but fortunately it wasn't my headache to make it work!