There are 15 carrage trains on the route, they run into Scotland
The 390 is at the limit of what it is able to do for length at 11 cars, the EPS system just stops working on a 390 as does many other control systems due to signal degigation between either end of the unit. This doesn't stop any other units running at 12 or 16 cars long. But they won't be able to use EPS Speeds.
When HS2 comes into being, I would expect (or hope for) a fair few 400m diagrams to run, especially in the peaks.
One thing I am hoping for is that there will be a decision on what will be happening at Manchester, at the inital state of construction, so that building will start on the Manchester HS2 station at the inital stage.
It will be connected into the conventional network between Rugley and Ardwick (Assuming the use of the Mayfeild Insustrial Site as the HS2 station). And the platforms built at Mayfeild would be to the EU Standard, possibly with some additional standard platforms to take some strain off of Piccadilly.
This would allow for minimal level of disruption to the Piccadilly throught, rather than extending the existing platforms at Piccadilly. It would mean that services on the HS2 route, using CC stock would need to cross the slow lines when entering or leaving the station. But it would mean that 400m services would be able to run on Day1 into Manchester, and free up terminal platform space that is desprately needed.
If the linespeed on the slows between Slade Lane and Piccadilly where improved it would mitigate some of the effects of crossing the slows, and would only be for 3 or 4tph, with all of the way from Ardwick to Slade Lane to change sides it would be enough IMO.
It would also provide a good face for HS2 in Manchester, with somthing shiney and new to look at, some Mancunians are known to like shiney things.
I would also intergrate this with a new walkway from the far south side of the inside of the Piccadilly Concourse, down to Platforms 13 - 16 and the new HS Station, with new drop off points on Fairfeild St. I'd also be having pasive or active provision for platforms 17 and 18...
Before I get so far off topic it's rediculous, for anyone who doesn't know my vision of Piccadilly.
3 Additional platforms on the North Side
4 Additional platforms over Fairfeild St or 2 Platforms over Fairfeild St with a reversing siding to the South East in the centre of the slow lines.
The Mayfeild site would be used for the HS2 terminal station in Manchester, with provision for a link over towards Ardwick on a viaduct for services onwards over the Pennines, or looping round onto other routes, if large enough, provision for a link through the HS2 station, roughly paralell with the A57M/A635M Mancunican Way out toward the Chat Moss Alignment, although this link would also be provided at Manchester West Parkway.
So we'd end up with
2 Platforms to the North East of the main shed. 1 & 2
12 Platforms in the current shed. 3 - 14
6 Platforms through to Oxford Road and over Fairfeild Street. 15 - 20
8 Platforms on the Mayfeild Ind. Site for HS2, at appropriate guage. 21 - 28
2 Metrolink platforms in the undercroft.
30 platforms at Piccadilly
I'd also change Oxford Road, until 4 track across Manchester arrives, that I dowbt it ever will, I would have a minor re-alignment and extention of the platforms, if 6 platforms or a good enough turnback was provided at Piccadilly, nothing would terminate at Oxford Road any more, Platform 5 and the space of Platform 6 would be completly superflous, and disconnected from the network. This would allow platforms 1 and 8 to be extended to 8 * 23m length.
Really off topic now, but what the hey....
I would look at using the space of Platforms 5 & 6 for somthing though. Metrolink.
Metrolink viaducts are much cheaper and easyer to construct than Heavy Rail ones. And Oxford road is currently missed off the map. And with how one sides the Metrolink network is becoming, with so much running through Cornbrook, and not that much through Victoria, Oxford Roads former bays would provide a handy place to terminate some metrolink services in the CC. I'll take this further in another thread.