More complicated than you think

The folks over at Portland Transport recently had their annual Q&A session with TriMet GM Neil McFarlane. A question that came up, as it has before, was about improving MAX speed and efficiency by closing some stops. This led to a follow-up post at Portland Transport (and is making me revisit the series I’d done on the same topic but never finished) and while working on a post for that, I dug out this map of the area around SW 10/11th and Yamhill/Morrison where the Portland Streetcar crosses the eastbound & westbound Red and Blue MAX alignment.

I’m posting it here because it’s a good illustration that shows how there’s a lot more involved in closing/moving a stop than just laying down tactile strip and moving the fare machines. It’s the work involved in changing the track circuits, moving the train-to-wayside-communication (TWC) call loops, reconfiguring signals, etc that would be a barrier as far as expense (and complexity!) is concerned.

Quick explanation since this map introduces something I haven’t mentioned before:

Many readers here will already be familiar with how the operator of a MAX train will press the “Call” button on the console when the transponder under their cab is over a call loop to call their signals and throw power switches in order to proceed. However, by design, that transponder will call some signals without action on the part of the operator. So for example as shown in the map below, signal W6, which is an ABS/pre-empt combination signal for eastbound trains, is not called by the operator doing anything, but is instead called by the train just before SW 13th when the transponder under the lead cab passes over that TWC loop.

This map is outdated – trains do not regularly go through 11th Ave anymore, and each of those tracks have their own signal now instead of all using signal W4, but I still wanted to post it here because it nicely shows the complexity of what otherwise appears to be a fairly simple layout.

Can’t remember if it had been a test question or a Rail Rodeo question that went something like “There is a Yellow Line train in 11th Ave, an eastbound Blue Line at 14th, and a southbound streetcar at Washington. If the Blue Line crosses 13th before the Yellow Line gets their call on, when will the streetcar get their signal?” which reminded me too much of those math problems from high school, where if Mary is on the 9pm train heading due north at 55mph, what time will she pass John’s train which is heading south at 60mph?


9 responses to “More complicated than you think

  1. Where are the other places around the alignment (if any) where the signals are automatically called once the train passes over the call loop?

    Very informative post, by the way!

    • I’m not sure of all of them, since that’s one of several ways that a signal can be called without direct operator involvement and I don’t know in all instances of signals that are “automatic” which are lead cab transponder calls and which are something else. For example, I know that signal 14 on the Steel Bridge westbound is called when the lead cab transponder goes over a call loop just east of the eastern side of the bridge span. However, a lot of the pre-empts on Interstate are called by the trailing cab’s transponder going over loops – there are a couple of pre-empts on Yamhill & Morrison between Library/Galleria and JWF that are trailing cab calls as well. Then there are other signals that are called by entering or exiting a track circuit.
      Thanks! Glad you liked the post.

  2. I guess I’m a rail nerd since I figured this out from observation when i was in high school.

  3. They will never close any MAX stations so that conversation at P-transport is useless.

    • Would be nice if some extra tracks were put in so we could have express service. Only stop at the Central, Airport and TC stations.

      • But the expense involved in that! Really downtown is the biggest bottleneck, which is why a lot of people like the idea of a subway under downtown with limited stops.

        • I find, on the blue line, probably could skip all the lines concurrent with the red line (meaning the westside Blue Line Express stops outside downtown would be Beaverton Central, Willow Creek, Hillsboro Airport, Hillsboro Central and Hatfield) and on the Yellow Line just having to stop so freaking often (Yellow Express trains could probably terminate to the south at Rose Quarter, Lombard TC, Vanport TC and Expo Center), Red Express could probably do BTC, STC, Pioneer Square, Rose Quarter, Hollywood, Gateway, Parkrose and PDX.

          • Interlockings can’t be skipped (e.g. Old Town/Chinatown, Beaverton TC, etc) because you need to select a route through there and there also could be trains making conflicting moves. Galleria can’t be skipped because of the interaction with the streetcar shown here. As far as a skip-stop design goes, the transit mall works pretty well for that given how many blocks apart the stops are spaced. But it’s a lot harder to take the existing layout and do something like that. Out of service trains will get permission to bypass platforms where safe and applicable and if you see one on the Banfield (eastbound for example) it can go clear to 82nd before it has to stop, but there are still platforms where out of service trains will have to stop to get a signal even though they don’t service the platforms.

            • Oh, I don’t doubt there are some signals that you just can’t get a clear on every time, but you could get that clear faster without serving the platform.

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