Why are they coupling the E5 and E6 together?

[Sascha]

Why are they coupling the E5 and E6 together between Tokyo Station and Morioka. Why can't they drive by themselves?

[kvp]

This way they require only one scheduling slot and station track and occupy only a single block on the line. This increases the capacity of the line as there is no need to keep at least one block of distance between the two sets following each other. On the other hand, the coupled sets require longer platforms and some time to couple/uncouple. The same strategy is used by many commuter lines around the world to provide higher line capacity by maxing out platform lengths on one leg of the trip then splitting the trains for the lower traffic legs. The E5 and E6 are essentially the same type, but one is built for the legacy loading gauge of the mini shinkansen line it runs on after the split. Its pair is built to maximise the loading capacity of the standard shinkansen lines it runs on.

 

ps: On many old films, you can see single car trams running bumper to bumper on the streets. Then someone had the idea to connect them together into longer sets, so they move together with a single driver and don't hold up each other. This was the basic idea of using multiple units to increase capacity.

[Sacto1985]

Occasionally, you will see E6 trainsets run by themselves between Tokyo and Morioka before going onto the Akita Shinkansen line, but those are usually "extra" trains running during busy periods.

[Sascha]

As always my thanks to y'all. :)

[Sacto1985]

This coupling was why they developed the E6 Series trainset for the Akita Shinkansen service. That way, the coupled E5/E6 trainset combination can run at the full 320 km/h speed between Omiya and Morioka Stations; with the older E3/E5 trainset combination, the top speed was limited by the 275 km/h top speed of the E3 trainset.

 

If I remember correctly, due to the shorter distance traveled on real Shinkansen full-speed track (only between Omiya and Fukushima) , the Yamagata Shinkansen trains don't need the full speed of the E6 trainsets, so they will keep with the newer-production E3 trainsets for the foreseeable future.