4 ms·

Axle counters are "positive only" systems e.g. if the numbers don't match or the counter resets, it will report an error and the next train needs a special safe

by rmoriz 10y ago

Axle counters are "positive only" systems e.g. if the numbers don't match or the counter resets, it will report an error and the next train needs a special safety order to enter the track section. So if you manage to combine a 256 axle train, it will just slow down everything on its way and cause chaos, but no accidents. In the old times there was a manned caboose car at the end which job was to ensure the completeness of the train (and that switches are cleared). Here's an example of such an SBB car decommissioned some centuries ago http://www.bahnbilder.de/bilder/gueterwagen-266906.jpg http://www.bahnbilder.de/bilder/gueterwagen-266906.jpg Video (1986) https://www.youtube.com/watch?v=ev4szZ4iNTY https://www.youtube.com/watch?v=ev4szZ4iNTY

tvmalsv 10y ago
Ya, I remember those. My friends and I would always wave to the cabooseman (I doubt that's the right word, but I really like it) as it went by, and he would usually wave back at us.
- Symbiote 10y ago
  In Britain, he'd be called a guard or brake-man, and rode in the brake van. The US probably has a different term.
  - waqf 10y ago
    Ironic since "van" means the front, as in vanguard.
    - morsch 10y ago
      I realize you weren't being serious, but this van is an abbreviation of caravan, which ultimately has its origins in Persian: In 16th cent. carouan, < Persian kārwān, in same sense. Found in medieval Latin carvana (Hoveden), caravanna, caravenna (Matt. Paris), and French carvane, from Crusading times, but apparently not in English before 16th cent. The form caravan was perhaps caravane from French.[1] [1] http://www.oed.com/view/Entry/27717#eid10166797 http://www.oed.com/view/Entry/27717#eid10166797
  - PLenz 10y ago
    In the U.S. that would the train's rear conductor or a brakeman, basically the conductor's assistants. In the days before vacuum brakes the rear conductor would have the job of reading lantern messages from the front conductor (in the locomotive) and then dispatching brakeman to walking along the train car roofs and individually setting the brakes on each car.
    - jacquesm 10y ago
      That sounds like a pretty dangerous job.
      - slededit 10y ago
        The railroad industry has a very sordid history of killing its employees. All the way from track construction to actual operation. Even in this 1955 fire training video you can see they care more about the locomotive than the safety of the crew: https://www.youtube.com/watch?v=hkUQ3rTfU4s https://www.youtube.com/watch?v=hkUQ3rTfU4s tldw: crew were expected to enter the confined area of the engine room in the middle of a fire and turn at least two valves (that have complex interactions with each other) filling the same confined area with CO2.
jacquesm 10y ago
That makes good sense. Still, given that the warning was issued quite explicitly it would seem that the designers of the operations guide definitely thought it was possible to have a train that long. Otherwise, why bother with the warning?
- rmoriz 10y ago
  Because you have to cover all possibilities, even if they are highly unlikely. It's sad most people mistake this for weakness of a system.
  - jacquesm 10y ago
    > It's sad most people mistake this for weakness of a system. I don't think that conclusion is warranted.
    - rmoriz 10y ago
      Well, maybe. I've seen a lot of "Hyperloop" fans who don't know basics about transportation systems (planning, technology, financing). So maybe I'm overly aggressive here. Sorry.
      - jacquesm 10y ago
        I've re-written a bunch of fuel quantity calculation software for a small airline, the degree of planning and verification that went into that totally blew my mind, it completely changed my way of thinking about writing any piece of software and even now I have to catch myself not to 'overthink' the solution to some problem. As soon as there are lives on the line the amount of thinking about undefined situations skyrockets. Even so, given that the system fails 'positive' (as in: it can't register 'no train' when there is a train, it can only register 'train' when there is none) I'm quite impressed with the foresight to even think about that exact possibility occurring. Another field where you see this kind of planning is in medical electronics and software systems.
throwanem 10y ago
> decommissioned some centuries ago Decades, perhaps? (A decade is ten years; a century is one hundred.)

by rmoriz 10y ago

tvmalsv 10y ago

Ya, I remember those. My friends and I would always wave to the cabooseman (I doubt that's the right word, but I really like it) as it went by, and he would usually wave back at us.

Symbiote 10y ago
In Britain, he'd be called a guard or brake-man, and rode in the brake van. The US probably has a different term.
- waqf 10y ago
  Ironic since "van" means the front, as in vanguard.
  - morsch 10y ago
    I realize you weren't being serious, but this van is an abbreviation of caravan, which ultimately has its origins in Persian: In 16th cent. carouan, < Persian kārwān, in same sense. Found in medieval Latin carvana (Hoveden), caravanna, caravenna (Matt. Paris), and French carvane, from Crusading times, but apparently not in English before 16th cent. The form caravan was perhaps caravane from French.[1] [1] http://www.oed.com/view/Entry/27717#eid10166797 http://www.oed.com/view/Entry/27717#eid10166797
- PLenz 10y ago
  In the U.S. that would the train's rear conductor or a brakeman, basically the conductor's assistants. In the days before vacuum brakes the rear conductor would have the job of reading lantern messages from the front conductor (in the locomotive) and then dispatching brakeman to walking along the train car roofs and individually setting the brakes on each car.
  - jacquesm 10y ago
    That sounds like a pretty dangerous job.
    - slededit 10y ago
      The railroad industry has a very sordid history of killing its employees. All the way from track construction to actual operation. Even in this 1955 fire training video you can see they care more about the locomotive than the safety of the crew: https://www.youtube.com/watch?v=hkUQ3rTfU4s https://www.youtube.com/watch?v=hkUQ3rTfU4s tldw: crew were expected to enter the confined area of the engine room in the middle of a fire and turn at least two valves (that have complex interactions with each other) filling the same confined area with CO2.

jacquesm 10y ago

That makes good sense. Still, given that the warning was issued quite explicitly it would seem that the designers of the operations guide definitely thought it was possible to have a train that long. Otherwise, why bother with the warning?

rmoriz 10y ago
Because you have to cover all possibilities, even if they are highly unlikely. It's sad most people mistake this for weakness of a system.
- jacquesm 10y ago
  > It's sad most people mistake this for weakness of a system. I don't think that conclusion is warranted.
  - rmoriz 10y ago
    Well, maybe. I've seen a lot of "Hyperloop" fans who don't know basics about transportation systems (planning, technology, financing). So maybe I'm overly aggressive here. Sorry.
    - jacquesm 10y ago
      I've re-written a bunch of fuel quantity calculation software for a small airline, the degree of planning and verification that went into that totally blew my mind, it completely changed my way of thinking about writing any piece of software and even now I have to catch myself not to 'overthink' the solution to some problem. As soon as there are lives on the line the amount of thinking about undefined situations skyrockets. Even so, given that the system fails 'positive' (as in: it can't register 'no train' when there is a train, it can only register 'train' when there is none) I'm quite impressed with the foresight to even think about that exact possibility occurring. Another field where you see this kind of planning is in medical electronics and software systems.

throwanem 10y ago

> decommissioned some centuries ago Decades, perhaps? (A decade is ten years; a century is one hundred.)