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.

When the Japan National Railway (JNR) was broken up into the several JR Group companies in 1987, they were operating an aging fleet of urban commuter trains dating from the 1960’s. Perhaps chief among these were the 103 series, with 3,447 cars built from 1963 to 1984. The design was old: heavy steel bodies that needed to be frequently repainted, and inefficient series-wound DC traction motors with a resistor control mechanism. JNR had experimented with modernizing their urban commuter trains, with the 201 series of 1979 and several successors experimenting with lightweight stainless steel bodies and new control systems including regenerative braking, but still using DC motors. However, budget pressures prevented them from moving to replace the older fleet with any of the new designs, although the 201 was ultimately produced in some volume and went on to serve for many years (some are still in service).

When JR East was formed, with ownership of the busy Kantō region containing Tōkyō, one of their goals was to improve efficiency by reducing labor costs. New trains, particularly commuter trains, that required less maintenance were an important part of that (and gaining other efficiencies, such as lower operating costs, was also important). They continued and built on JNRs work, with a goal of developing a train that had half the maintenance and operating costs (and half the lifespan, but given how hard they were used 15 - 20 years was seen as acceptable).

The 209 series of 1993 was a major step forward, and 1,046 cars would ultimately be built. This train introduced the use of a Variable Voltage, Variable Frequency (VVVF) inverter, and power control via both the Gate Turn-Off (GTO) thyristor, and later the Insulated-Gate Bipolar Transistor (IGBT), technologies needed to enable the use of efficient AC motors on a DC powered train. In Japanese EMU trains, not all cars are equipped with motors. Older trains typically had six motor cars in a ten-car train, but the 209 series reduced this to four without giving up on acceleration.

The E231 was introduced in 2000 after an initial prototype test, and refined these technologies. The class remains in production, and to date 2,736 cars have been built. Several specialized derivatives of the train have been created: the E531 AC/DC model, the E233, and the Sagami Railway’s Sōtetsu 10000 series and the Tōkyū Corporation’s 5000 series trains. Like many urban commuter trains, the train can also serve in a suburban commuter role with minor modifications (typically more seating and the addition of toilet facilities). A narrow-bodied E231-800 series was also built for use on services running into the tunnels of the Tōkyō Metro Tōzai Line.

The E231 also introduced the use of a data-bus for control and information displays within the train, rather than separate wires, simultaneously lightening and simplifying the train, and enabling more sophisticated braking and motor control. This provided for smoother rides for passengers, but also improved efficiency in terms of power use.

The E231 then, is a mature design following over two decades of experimentation and refinement, and is now approaching the scale of the old 103 series, and in a much shorter time. It is likely to be a staple of the Tōkyō scene for another 15 to 20 years. Although JR East is already working on technologies for what they call the Advanced Commuter train (or “AC train”), including a prototype, the E331 series, and this or a derivative will likely supplant the E231 for new production in a few years, the E231 will remain in service for many years, even with “half the life” of previous generations.

The E231 is the train that captured my interest in Japanese passenger railroading, and my current roster numbers ten of them (including variants) from Kato and Micro Ace, far more than I can operate at a time. And I expect I’ll acquire a few more as time goes on (I really want an E231-800, but nobody makes one). Despite the nearly subway-like simplicity of design and paint scheme, particularly when compared to some of Japan’s more colorful Limited Express trains, I find the look appealing. And from an Engineering standpoint it is an “elegant” design, in the sense that it does exactly what it needs to do, and does it well, with a minimum of waste or unnecessary elaboration.

For more about the E231, see my JR East Urban Trains page and the (still incomplete) E231 page, and for some more history on propulsion systems, see the Electric Propulsion page.

Other website changes:
- Began writing an overview page describing the layout as a whole.
- Added photos to the Station, Construction and Electronics photo albums.
- Created a new page about my Urban Station and updated my page about Kato’s Overhead Transit Station.
- Added some material to the “Phase 2k” Construction page, including information about the lighting for my Subway station. Also made some related updated to my LED Strip Lighting page.
- Updated the list of occupancy detectors assignments on my Power Wiring Standards page to reflect recent work.
- Updated the Suppliers page to reflect the closure of HW Japan (not due to the earthquake; apparently their sole English-speaking employee left).
== Comments from old system:
Saturday, March 26, 2011 - 01:32 AM
quinntopia
Interesting overview of the evolution of Japanese commuter trains. Its funny how little we get to appreciate some of the engineering issues that these companies face - or some of the thinking behind the design of a new type of locomotive or train. I always find it fascinating. Thanks for the right up.

Tags: E231, E233, JNR, JR East, Subway Train