Traffic density

Discussion in 'Model Rail Operations' started by Triplex, Aug 31, 2005.

  1. Triplex

    Triplex Active Member

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    On the prototype, how many trains can a one- two-, three- or four-track mainline handle per day? Under TT&TO, ABS, or CTC? I know the answers will be variable, but I'd like to have some idea.
  2. MasonJar

    MasonJar It's not rocket surgery

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    In the 1920s, the Grand Trunk line that ran from Depot Harbour to Ottawa (former Ottawa, Arnprior and Parry Sound) ran an average of 1 train every 20 minutes on a single line.

    Andrew
  3. Triplex

    Triplex Active Member

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    I just realized I should make things clearer - I don't just want to know the maximum each type can handle. I also want to know the minimum number that it's worth multi-tracking for.
  4. MasonJar

    MasonJar It's not rocket surgery

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    I think that double-tracking may come about as more of a convenience and a way to reduce risk - e.g. westbound on track 1, eastbound on #2 ONLY. There are very few sections of track that are tripled or quadrupled, and they seem to be at bottlenecks like grades or so on. I don't think you'll find much triple or quad track across the praries, for example, where it is easy to haul trains at speed.

    Sorry I cannot shed any more light on this. Interesting subject though - it should reveal a bit more about the railways' planning process. They are after all in this for the money, and quadruple track costs a lot!

    Andrew
  5. Yard Goat

    Yard Goat New Member

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    I can't recall seeing a formula for traffic density vs. number of main tracks in any of my many railroad-related books. One that might have the answer is "The Railroad: What It Is, What It Does" by John Armstrong, which I don't own and which may be hard to find.

    The easy way to sidestep any guessing is to either model a specific segment of a specific prototype--using the same number of main tracks as it did--or at least emulate the practices of one or more prototypes. If I was freelancing, for instance, a railroad that was set in the Northeast Corridor, I'd consider double, triple or quadruple-tracking. If I was building a model railroad set in the west, I'd probably stick with single-track.
  6. Triplex

    Triplex Active Member

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    Yes, I know triple and quadruple track were never really common and are rare now. That's why I wonder - how many trains does a line need to warrant them?

    Let's say I was freelancing. Then yes, I could make the number of mains appropriate to the locale and era. But then, how many trains would I run in a fast-time day? That's why I want to know this.