po8crg
Member
- Joined
- 6 Feb 2014
- Messages
- 559
You make two significant assumptions here.
One - that they'll definitely be double deck trains - the gauge being designed for it doesn't mean they have to use DD trains.
Two - single door per carriage. Presumably you think this because the original Eurostar sets have only one door (per side) per carriage? But the latest Eurostar sets have doors at both ends, so why wouldn't HS2 captive stock?
One - No, I don't mean they will definitely be that size, but that the infrastructure would have to be designed to be capable of coping with that capacity. I think I mentioned that initially, the trains will be single-deck.
Two - no, I was basing that on the TGV Duplex, which are the only high-speed DD trains. Given the (large) size of a DD vestibule/stairs area, I'd expect any future DD train to have only one door per carriage to maximise seating space.
Turn-around times for DD trains are going to be large, partly because there are lots of people exiting through each door, and partly because even the wide platforms are going to get clogged up with passengers when a thousand or so emerge from a single train.
However, I clearly didn't get my point across. So let me try again:
Long-term, there could well be 18-20 trains per hour, all of them 400m DD captive. But that might not be until the first-generation HS2 trains get replaced, probably in the 2050s (by which time, HS2 will have been extended to Newcastle, Glasgow, Edinburgh and Liverpool).
It would be sensible to build Euston to be able to cope with HS2 running at full capacity, even if it takes a long time to complete - better that than having to rebuild Euston again when HS2 is extended to Scotland.
But Euston HS2 won't be running at full capacity for a long, long time after construction. At the completion of Phase 2, it will have no more than 9tph captive, and 3-4 tph of 400m classic-compatible. And some of those captives may be 200m SD to start with. That means that the rebuild doesn't have to be complete even for Phase 2 - as long as there are some captive platforms, and there's an interconnect into the WCML platforms from HS2 track, then trains can be managed until the works are completed.
SD trains probably do have two doors per carriage, as the doors don't need stairs to the upper deck; that means their turnaround times are dramatically better than DD trains, so their platform occupancy is much lower. If a platform could serve 4tph, then four captive platforms would be enough for Euston for a few years until the full rebuild is complete.