Simplicity in Railway Design

Riverside Sep 2010

It’s impossible to think about modeling Japanese railways right now without also thinking about the situation in Japan following the earthquake and tsunami. This is a site about model trains, which are supposed to be an escape from the real world, so I won’t dwell on it, except to say that my thoughts and hopes are with the people there, who have to deal with a world that’s all too real right now.


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.

Some of that is simply driven by volume, as there are enough peak trains in urban centers to dedicate tracks to many lines, and dedicate platforms to a single track. Some lines do share tracks, and many “lines” in urban areas split into multiple lines away from the city, going to different endpoints. But there’s a simplicity to the urban stations: where the Chūō line enters Tokyo station, its two tracks are parallel to the tracks of the Yamanote line, and those parallel the tracks of the Keihin-Tōhoku Line, and each of those three lines has a pair of platform tracks, one per line per direction. It’s quite different from large stations elsewhere, where any approach track can be routed to any platform, and the same train never seems to end up on the same platform twice in a row.

Recently I ran across a blog entry written by a prototype railroad signal engineer describing a presentation that had been made by staff of a Dutch railway operator describing Japanese practice, and it had some insight into why Japanese railways are structured this way. The blog entry is worth reading, but I’ll summarize the basic concept: there’s a combination of a minimalist approach to track work for reliability (“if it isn’t there, it can’t break”) and closely-spaced signals designed to get trains into and out of station platforms quickly, minimizing dwell time at the platform. This keeps trains moving when they can move, and allows them to stop just short of a platform, or just away from it, if the line is congested, leaving them ready to move immediately when conditions improve. It also reduces potential conflict by guaranteeing that an arriving train will (almost) always have access to an available platform without any need to coordinate two or more schedules.

As a measure of the simplicity, they compared Tōkyō Station to Utrecht Central Station in the Netherlands. Tōkyō handles three times the traffic in trains per hour, with one tenth (28 vs 280) the number of track switches. Although the blog author said the two were similar in size, by my reading Tōkyō has twice as many platforms as Utrecht (28 vs 14, if you count all the different lines), so there’s clearly a trade-off of size for simplicity being made.

Part of this simplicity comes from a focus on uni-directional running. Paired tracks typically aren’t signaled to allow running the “wrong” direction, a major change from western railroading practice. Bi-directional signaling allows trains to be routed around maintenance activities, or stalled trains. It can significantly reduce delays when things go wrong. But it comes at a cost, affecting signal spacing and possible locations, and when it is used it may help traffic in one location, at the cost of creating problems elsewhere with backed-up trains.

Japanese planners take a different approach, and arguably a sensible one: if one line is out of service due to accident, often parallel lines will be too. Their thinking appears to be that it’s preferable to clear the accident quickly, and get things moving again in both directions. Given how many trains use major lines (often on headways of a few minutes at peak times), any delays at all have major knock-on consequences. They even keep boxcars full of equipment for wreck cleanup and track repair, called “rescue cars” at strategic locations, ready to be taken to a wreck site promptly when needed.

That’s not to say there aren’t cross-over tracks. You’ll see them where there are train-storage sidings or maintenance equipment sidings (which are often adjacent to stations), but they’re usually just sufficient to get in or out of whatever sidings there are, not usually a full “any to any” set of crossovers (there are exceptions; there are always exceptions when generalizing about something as large as a nation, or even a city: Ōmiya Station, for example, shares platforms between several lines and has fairly complex trackwork). But for the most part, tracks in and adjacent to urban stations have surprisingly few track switches and a simple relation of line to platform.

I’ve actually made my stations more complicated than they should be. The Riverside station has a crossover in the middle (just visible on the right in the photo above), allowing trains to be moved between the two lines. This isn’t required for normal operation, and exists only because I needed a crossover somewhere, so I put it near the access to the storage tracks. And my Urban station has two sets of platform tracks for the commuter line, and while that’s not completely unprototypical (Shin-Urayasu station is an example), it’s less than commonplace.

I’m not going to change these, as my original reasons for both are still valid: I need a crossover somewhere on each of the three loops, and this was one of the few places with straight track, and it’s handy to have it near the staging access. And the platform sidings at the Urban station allow me to operate two trains per line (local and rapid, for example), to add to my operational complexity. But should I eventually expand this into a larger around-the-room layout (someday, when I have a larger basement), I’ll keep these concepts in mind for future stations, and pay closer attention to specific prototype station layouts.

Other website changes:
- I added an index for these Musings, as a year plus of them had gotten hard to search through linearly in the Archives (and my titles aren’t always obvious as to the content). Note: index replaced with the navigation bar on the left in the new Sumida Crossing.
- I’ve added a bit to the “Phase 2k” Construction page, but not much (and no new photos).

== Comments from old system:
Tuesday, March 15, 2011 - 01:45 PM
A nice article, thank you!

A couple points worth noting. When the 11-car Yamanote line trains gave up on the 6-door cars, one of the replacements was made with door placement to match the door placement on the 10-car Keihin Tohoku trains. The reason is that with the advent of platform barriers, if one or the other had to be routed onto the other line for an emergency, the barriers would still line up with the doors. So, sometimes re-routing does occur, apparently, but I'm guessing only in extreme circumstances, or in case of construction.

The second is that the local/express platform set up for commuter lines, while uncommon with JR, is quite common with, e.g. Keio or Keisei. So you're not straying too far from the prototype as you think :)