The ITSS with no link to the WCML north of Crewe, Fig.A.8 in that document, has the same service pattern on the WCML north of Crewe as the ITSS for Phase 2a only, Fig.A.6, i.e 2tph Euston to Liverpool, 1tph Euston to Lancaster (portion worked with one of the Liverpools) and 1tph Euston to Glasgow, all 200m. Presumably the classic Euston to Edinburgh and Birmingham New Street to Edinburgh services, via the WCML all the way, are assumed to be retained as well.
Maybe the timetable would not work satisfactorily if an Edinburgh portion were added to the HS2 Glasgow train? Carstairs to Edinburgh takes longer than Carstairs to Glasgow, and splitting/joining adds a few minutes to journey time. Crewe to Wigan via the WCML takes about 13 minutes longer than via the Golborne link, so perhaps the turnaround time at Edinburgh would be too short, necessitating the purchase of additional costly Classic Compatible trainsets?
Of course, these are only
Indicative Train Service Specifications.
The rationale for considering the business case for the 2b Western Leg without no Golborne link is given in section A.39 of the Business Case Update document (p117):
Design option without a link to the WCML north of Crewe
A.39 As highlighted in the Strategic Case, the Union Connectivity Review, undertaken by Sir Peter Hendy, identified that there could be opportunities to further improve capacity and journey times to Scotland with an alternative HS2 connection to the WCML from that assumed in this business case, and recommended that the Government should review alternative options. The Government is considering its response to UCR recommendations, that it review options for alternative northerly connections between HS2 and the West Coast Main Line.
It is the Government’s intention to deliver the right infrastructure for long term benefits to the rail network, to the North and to Scotland. To this end a modelling sensitivity has been taken on a design option for the Proposed Scheme with no link to the WCML north of Crewe. This results in the removal of all HS2 services between London and Edinburgh and between Birmingham and Scotland, as well as reducing the number of HS2 services between London and Glasgow from 2tph to 1tph, shown in Annex 2. This scenario is shown to have a BCR of 0.7 with Level 2 WEIs [Wider Economic Impacts].
The comparable BCR of the reference Western Leg scheme, including the Golborne link, is 0.9, calculated on the same basis. So omitting the Golborne link makes the poor Value for Money of the Western Leg even worse!