Quantum of Desiro
If the HS2 railway were built into London’s Euston station, there would be a reduction in the number of platforms available for use by trains using the existing tracks, HS2 chief engineer Professor Andrew McNaughton told the High Speed Rail Bill Committee on 15 February 2015.
[Andrew McNaughton, 15 Feb 2015]
[…] But, [in 2026 the Euston classic platforms] are now being used for […] new services, which don’t take so long to turn around. A train from Glasgow spends 40 minutes being cleaned, victualled, watered, before it disappears off north again. So, it uses a platform for a very long time. A commuter train from Milton Keynes comes in, decants everybody, puts more people on, disappears off in five or six minutes. So, the mix of train services does affect the number of platforms you need, as well.
But as can be seen from Prof McNaughton’s slide #13 (below), HS2’s proposed re-mix of the West Coast route does not feature dedicated Fast line commuter trains terminating at Milton Keynes. All the Fast line services would run on to Northamptonshire or beyond (in some cases, well beyond).
According to the Department for Transport, most of the Fast line trains would be operated by Class 350 (or similar) units. These have a lower top speed than the Pendolino or IEP designs. So it seems likely that journey times on West Coast would tend to increase, rather than decrease.
At present, most peak London Midland Euston trains are short-length, which suggests a continuing insufficiency of rolling stock. The number of Class 350 (actual or ersatz) required to operate the Professor’s re-mix is unclear, but seems likely to be considerably in excess of what currently exists.