Double vs single slip

Discussion in 'FAQs' started by billk, Nov 21, 2001.

  1. billk

    billk Active Member

    Someody tell me if I'm right on this. You have two parallel tracks and a slip switch between them that allows you to either stay on the track you're on or go onto the other one.

    With a single slip you can only change tracks if you are coming from one direction, with a double you can do it coming from either direction.

    If you 'roll your own', using 4 turnouts and a crossing, you have a double switch, right?
  2. Gary Pfeil

    Gary Pfeil Active Member

    Hi Bill, The situation you refer to is a double crossover, not a double slip. A double slip is like a crossing where when approaching from any of the four tracks, you can switch to either of the two diverging routes on the other side of the turnout. I'm guessing here, but a single slip would then be like the double slip, but not all four routes will allow switching over to both diverging routes. Are you considering hand laying a double crossover? Awesome! Good luck.

  3. billk

    billk Active Member

    Thanks Gary - you just (I think) confirmed what I thought.

    Another question, though. Isn't a double crossover and a double slip the same thing, functionally, in that they both allow you to do the same thing?

    And no, I don't intend to handlay either a double crossover, a double slip, or a single slip, at least not in this life time.

  4. roryglasgow

    roryglasgow Active Member

  5. billk

    billk Active Member

    Rory - What part of railroad did you miss here? Actually, I think that would be a good example if you were to make the the two intersecting highways parallel.
  6. Gary Pfeil

    Gary Pfeil Active Member

    Bill and Rory, The picture Bill posted is a double slip. As I stated, and now you can see (a picture is worth a thousand words) a double slip is basically a crossing which allows a train to choose a diverging route. I believe a single slip would just have one set of points rather than two. A double crossover is something else entirely. The double crossover is used between two parallel tracks. The double slip is often used in the throats of yards, to allow access to as many body tracks as possible is as short a distance as possible. Rory, I'm not sure what I see in your link, it really does look like a highway interchange. If it is railroad tracks, then that is quite a highspeed flexible arraingement. What railroad is it now and which were they earlier?

    One other thing: a double crossover is used only where space is at a real premium. Two individual crossovers would be prefered as it involves less frogs(no diamond crossing).

  7. billk

    billk Active Member

    Got it - so here's a double crossover:
  8. Gary Pfeil

    Gary Pfeil Active Member

    That's it.
  9. shamus

    shamus Registered Member

    Good on you guys, that crossover with live frogs will need some special wiring to make it work, i.e. Double pole double throw switches, unless you have the electronic module for it. It's like using four points facing each other, with a crossover in the middle.

  10. roryglasgow

    roryglasgow Active Member

    I get it now... No, the "thing" in that photo I posted is Valley Junction. It is the intersection between what used to be Missouri Pacific (east-west) and Southern Pacific (north-south) railroads. It's now all Union Pacific. Valley Junction is located a few miles west of Hearne, TX, and is visible from Hwy 79.


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