Originally posted by twhitehead
I've just been reading about a train crash in spain. Apparently it was going way too fast. I am surprised that we don't yet have computers stopping that sort of thing from being possible. I have used a car GPS that can tell you when you are going over the speed limit. Surely such a thing would be even easier for a train, and it could be configured to enfo ...[text shortened]... e speed limits.
Does anyone know if some trains have this sort of thing, and if not, why not?
Yes there are such devices for trains, this one wasn't fitted with them.
EDIT: correction... It was fitted with them, but that part of the track wasn't.
Sim Harris from Rail News told the BBC he was baffled as to how this could have happened.
"Modern trains have got so many systems on board to stop 'over speed' of this extreme kind," he said.
"The ability of the driver to break the rules in this way is very limited indeed by the on-board systems of the train."
The most modern train safety systems use equipment on the track and within the driver's cab to replace traditional signals and control the speed and movement of the train automatically.
With a system such as the European Train Control System (ETCS), a driver would not be able to break the speed limit.
While parts of Spain's rail network - including a large section of the route the train had travelled from Madrid - do have the ETCS in operation, the curve where Wednesday's derailment took place relies on a less sophisticated safety system known as ASFA.
ASFA - Anuncio de Senales y Frenado Automatico or signal notification and automatic braking - relies on a series of beacons to communicate with the driver's cab - so does not have the constant communication of ETCS.
The system gives audio and visual warnings to the driver if speed limits are surpassed, and will step in and brake the train if there is no response from the cab.
Rail expert Christian Wolmar, author of Blood, Iron and Gold, says that there will have been some sort of warning system in place.
However the derailment occurred at the point where the high speed track transitions to using part of the older railway network. Some experts are asking whether this transition could have been part of the problem.
The accident took place on the A Grandeira curve, which is just after a tunnel and follows around 80km of more or less straight track.
A video posted on El Pais's website shows the curve as the train emerges from the tunnel.
Spanish journalist Miguel Murado told the BBC that there had been concerns about the bend since the line opened two years ago.
"People who travelled in the train felt that it was dangerous that the train had to go from 200km/h to 80km/h in just a matter of seconds," he said.
"They felt that was a very difficult manoeuvre for the driver to execute."
The BBC's transport correspondent Richard Westcott says Spain has led the world in building its high speed network over the past twenty years, and generally has a good safety record.
This is backed up by figures from the European Railway Agency, which put Spain 18th safest out of 27 countries in terms of passenger deaths per kilometre travelled, over the period 2006-2011.