>>998901They're designed to last no more than 20 years. It's about keeping reliability up and simply being bleeding edge. Last I heard (from Guillaume Pepy's mouth in a transcript apparently), the typical Shinkansen reliability hardware wise is 1 in 10 million km (that was about 8 years ago).
There is also a marginal energy saving element. E.g. the N700S which will begin to replace the N700A upgrade (as opposed to those which started life as N700A) and completely kill off the 700 has a 7% increase in energy efficiency. In Japan, that probably means a lot more and compared to previous models, it's bigger. The 700's energy saving over the 0 was 34%.
In terms of cost, we'll never know the true cost but Shinkansen trains are relatively cheap compared to high speed trains elsewhere. Hell, they're just over half the price of the chinese bodied commuter trains in Australia on a per carriage basis.
Elsewhere you should look is commuter trains. The energy savings across those are substantial and JR East more or less claims that it's more energy efficient to manufacture than keep old trains running, particularly emphasised post 3/11.
Also, didn't even realise the 819 was already in service as test. There's some JR Kyushu material out where which says the modern trains use half as much power as the resistor ones if I remember correctly.
