Mar 2011

E231 Commuter Train: JR East’s Flagship

Commuter trains, and in particular urban commuter trains, are the workhorse of the Japanese narrow-gauge passenger lines. While there are plenty of suburban and regional passenger trains, the ones that move the most people, over 90,000 passengers per hour at peak time on some lines, are the urban commuters. These are heavy-rail electric multiple-unit trains, typically of 10 to 15 cars in length, running on headways of only a few minutes during rush hour, often sharing their tracks with suburban and regional trains, and in some cases freight. Typical speeds are low, often well under 100 kph (62 mph), with frequent stops, so power and efficient use of power, rather than raw speed, is most important.

Simplicity in Railway Design

It’s a stereotype, and incorrect, to say that the Japanese prefer simplicity in all things. There are plenty of counterexamples. But Buddhist philosophy emphasizes simplicity in life, and some of that mindset has clearly influenced the design of Japanese railways.

Since I started researching for my model railroad, one thing that’s impressed me is the straightforward design of the Japanese railways. Trackwork around stations is usually quite simple, with limited cross-overs and sidings. And mainline track may be one or two tracks in more distant areas, but in urban areas it’s typically a pair of tracks for each line, used in a unidirectional fashion (i.e., each track is always used for trains going in one direction).

That’s not to say dedicated tracks are the rule: there are many single-track lines, even in urban areas, and on single-track lines stations will often have two tracks to allow trains to pass. Also, at secondary stations (particularly on Shinkansen lines) the platform tracks will be separate from the mainline, to allow express trains to pass locals. But in large urban stations, it’s often much simpler, rather than being more complex, which was a surprise to me when I first noticed it. Take a look at the platform assignments described on the Wikipedia pages for Nippori Station or Tōkyō Station, for example.

How I learned to stop worrying and love the BDL168

Well, perhaps that’s a bit strong, but I’m coming to terms with its design flaws and the poor state of the documentation surrounding it and the PM42. I now have the first set of PM42 circuit breakers and BDL168 occupancy detectors (with two sets of RX4 “transponding receivers”) installed, and have done a bit more reading over the weekend. I’ve discovered a few things and come to a few conclusions as a result of that work, and that’s making me feel that I have a handle on this now. But I had to work through a number of issues to get to this point.

February 2011 Status - Occupancy Detection Revisited

Work has progressed slowly this month, partly from distractions, and partly because I’ve been reluctant to finish up the block occupancy detector wiring. I finally realized that the reason for this was that I wasn’t happy with my hybrid approach to occupancy detection and transponding.

To recap, my Subway and Commuter loop tracks were to be divided into blocks, with Digitrax BDL168 occupancy detectors and PM42 circuit breakers (circuit breakers are typically one per track per table, whereas there may be two, three or even four detectable track sections on a single track on one table, and more in a couple of cases). The PM42 provides for four circuit breakers, which is a nice fit for the four tracks, and the BDL168 is divided into four independent quadrants (so each can be wired to a separate circuit breaker), each with four block detectors. I’d originally planned one PM42/BDL168 per scene, meaning that wires would have to cross a table boundary in the Urban and Riverside Station scenes.

And that was a problem, for several reasons. First, running wires between tables violates my “keep all wires except bus wires local” design goal (it makes the layout harder to disassemble), second while the BDL168 can support 16 occupancy detectors, in some places I needed more than four on one track, which broke the association of the PM42 circuit breaker element to a single track, meaning a short would shut down a second line. And finally, I wanted to do Transponding, and the BDL168 only supports 8 transponding sensors (using a pair of RX4 sets), meaning some blocks would be able to report which train was in them, and some would only be able to report that some train was present, but not which. None of these were fatal flaws, but they were eating at me. And I finally realized that I only needed two more sets (seven instead of five) to fix these problems.