EAST JAPAN Railway has started planning its next generation of commuter trainsets for Tokyo suburban services to follow the Series 209 ’half-life’ EMUs introduced five years ago. An experimental prototype will be developed over the next two years, with series production starting around 2003.

The Series 209 launched on the Yamanote line has been adopted for other routes, and the fleet will reach 850 cars when the Keihin-Tohoku line is re-equipped this year. With 315 Series 217 cars and other derivatives, the total ’half-life’ fleet is now over 1300 cars; this will rise to 2500 by the time the design is superseded in 2003. At that point Series 209 will account for 30% of the Tokyo suburban fleet.

For its next generation EMU, JR East is looking for a ’lean’ design which eliminates waste, minimises weight and maintenance, and maximises the recyclability of components after a 13-year service life. For example, modular skeletal body sections based on bus technology are under consideration. The units must also be ’flexible’, enabling easy changes to the interior layout and styling to adapt a standard car body to a variety of roles. Compared to the Series 209, the new design could cut energy consumption by 20% and maintenance costs by a further 30%.

The company is studying the possibility of a multi-section wide-bodied concept similar to Danish State Railways’ København S-bane trainsets. This would have 24 sections 8m long and 3m wide, against Series 209’s 11 conventional coaches 20m long and 2·8m wide. The wider bodies would increase capacity by around 5 passengers/car. o