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In Australia when it's flat, there were still collisions. Trains are very very heavy. The collision report recommendations had been to keep a long distance betw

by Joakal 9y ago

In Australia when it's flat, there were still collisions. Trains are very very heavy. The collision report recommendations had been to keep a long distance between trains. For trains ahead, the coming train would slow down and would come to a stop, if it's probably one train length ahead. I'm not sure how long the distance is though. 40 seconds is really really hard to estimate with very very heavy trains and no weight sensors. Even AI/ML cannot predict this (re: no weight sensors).

CountSessine 9y ago
Why would a computer need weight sensors? It knows exactly how hard the electric motor worked when it was accelerating the train and exactly how quickly the train accelerated. It should be able to come up with an entirely usable estimate of the train's weight.
- ant6n 9y ago
  Just as an aside, modern transit trains have weight sensors anyway which adjusts the pressure in the air suspension to make sure the train is exactly level with the platforms.
adrianN 9y ago
If there were collisions the signalling was crap. Train intervals below one minute are definitely possible. For example the new Thameslink line in London will have (or already has?) intervals well below one minute. Trains know their position very precisely, with errors less than 20cm, and their braking characteristics and error margins are well known, especially in tunnels where there are now wet leaves or snow on the tracks. Automatic train operation makes trains stop at precisely the same spot each time (for example to match train doors to gates), to the point where increased track wear becomes a concern.
exadeci 9y ago
On peak hour in Paris there is a metro every 2min and on the 7 years I lived there I don't recall any collision. And according to this Wikipedia list: https://fr.wikipedia.org/wiki/Liste_des_accidents_de_métro https://fr.wikipedia.org/wiki/Liste_des_accidents_de_métro The last collision in Paris metro was in 1981

by Joakal 9y ago

CountSessine 9y ago

Why would a computer need weight sensors? It knows exactly how hard the electric motor worked when it was accelerating the train and exactly how quickly the train accelerated. It should be able to come up with an entirely usable estimate of the train's weight.

ant6n 9y ago
Just as an aside, modern transit trains have weight sensors anyway which adjusts the pressure in the air suspension to make sure the train is exactly level with the platforms.

adrianN 9y ago

If there were collisions the signalling was crap. Train intervals below one minute are definitely possible. For example the new Thameslink line in London will have (or already has?) intervals well below one minute. Trains know their position very precisely, with errors less than 20cm, and their braking characteristics and error margins are well known, especially in tunnels where there are now wet leaves or snow on the tracks. Automatic train operation makes trains stop at precisely the same spot each time (for example to match train doors to gates), to the point where increased track wear becomes a concern.

exadeci 9y ago

On peak hour in Paris there is a metro every 2min and on the 7 years I lived there I don't recall any collision. And according to this Wikipedia list: https://fr.wikipedia.org/wiki/Liste_des_accidents_de_métro https://fr.wikipedia.org/wiki/Liste_des_accidents_de_métro The last collision in Paris metro was in 1981