So having had a chance to read through the 2 reports here are my thoughts:
There are still 4 options on the table. Given the costs involved I suspect a staged solution is going to have to be the one implemented so the Peebles (Route D) and Coldstream (Route B) routes are going to fall at that hurdle.
The time penalty for Glasgow is also likely to scupper the ECML route, leaving WCML as the hot favourite to be chosen.
To make the Benefit Cost Ratio work and fit in with overall policy for rail the new route will need to provide additional capacity, particularly on those areas most constrained by freight movements. This means the priorities for investment will be bypassing Lanarkshire, Haymarket East Junction, Beattock, Shap and Golborne - Wigan - Euxton Junction.
The first stage to be built in CP6 is likely to be the Glasgow - Edinburgh section which can be taken forward by the Scottish Government and provide wider benefits in Scotland beyond the cross border element. The HS2 report identifies Lockerbie - Beattock - Abington as one of the priorities for the WCML route because of both the freight constraints over Beattock summit and the speed constraints through the Crawford Curve. I would expect this to be taken forward by Transport Scotland as well. Abington - Thankerton is identified in the HS2 report as a lower priority, due to its existing high speeds, but I wonder how the cost of 2 new grade separated high speed junctions here (£0.5-£1bn each?) compares with 20km or so of plain high speed line (about the same price I reckon). So for me the logical thing for the Scottish Government to pursue is a high speed line from just north of Lockerbie directly to the outskirts of Glasgow and Edinburgh.
Another unnecessary junction looks to be Golborne. As the WCML capacity shortage is identified as far north as Euxton Junction it seems logical that HS2 Phase 2b could be extended northwards bypassing Wigan and joining the WCML as close to Preston as possible. If not possible in Phase 2B perhaps this could become Phase 2C with a separate parliamentary process but with construction alongside Phase 2B for 2033. By dropping Golborne junction 2 grade separated junctions can be saved and the work can be aligned with Network Rail plans to improve Euxton Junction and extend 4-6 tracking south of Preston.
The Lune Gorge is a big obstacle for any scheme and I suspect the most difficult issue to resolve on the whole section north of Wigan. What I hadn't really appreciated until reading this report is that the worst freight bottleneck at Shap can be bypassed by starting immediately north of the Lune Gorge and something along the lines of a new Tebay - Southwaite bypass line would provide the speed and capacity benefits required without tackling the most difficult terrain and avoiding encroachment on the recent Lake District and Yorkshire Dales national park extensions.
In terms of where the 400m services should split / join I think the obvious choice is Carlisle.
- Given the slow speeds through Carlisle the journey time penalty for stopping and splitting services there is relatively low.
- There is also a high level of difficulty bypassing Carlisle, with the flood plain and Hadrian's Wall World Heritage site making alternative routes difficult and expensive.
- There are good benefits to Cumbria and Dumfries and Galloway from having a connection to High Speed Rail at Carlisle that help spread the benefits to more local areas (and constituencies).
- Less mileage operated by 2 x 200m long trainsets reduces capacity loss and has lower operating costs with fewer drivers and guards to pay.
So for me the priorities (in order) should be:
- 400m long platform island at Carlisle for Splitting / Joining with some linespeed improvements.
- Edinburgh - Glasgow - Lockerbie High Speed Triangle
- Golborne / Wigan - Euxton Junction route change / Phase 2C.
- Tebay - Southwaite High Speed Bypass.
- Preston - South of Lancaster High Speed extra tracks.
I reckon together that delivers something in the region of 30-35 minutes time saving made up of:
- Glasgow - Edinburgh - Carstairs 10 mins
- Carstairs - Abington - 2 mins
- Abington - Lockerbie 6 mins
- Tebay - Southwaite 9 mins
- Wigan - Euxton 3 mins
- Preston - Lancaster 3 mins
So it won't quite deliver a 3 hour journey time but it will get very close, and deliver the majority of the additional capacity benefits.
To get down to the 3 hour journey time I'd look next to a Gretna - Lockerbie section that would provide an additional 8 minute time saving and get journeys down below the 3 hour mark.
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Do the BCRs for the C and D options take account of the 10 minute time saving for cross border passengers which is attributable to the Central Belt infrastructure?
As I understand it D1 won't take into account any cross border benefit as it doesn't deliver any cross border infrastructure. C1-3 and D2 should do so.
However they don't necessarily properly capture the benefits as the assumptions are either that no more High Speed Infrastructure is built beyond HS2 Phase 2 (so the journey time reduction is from 3.40 to 3.30) or that a full line is built from Wigan to Carstairs (so the reduction is from 2.40 to 2.30).
My assumption would be that as part of a staged investment where say C1 provided a reduction from 3.10 to 3.00 it would generate a higher BCR.
Worth remembering that all the BCRs in the Transport Scotland report were done by AECOM before any of the work by HS2 Ltd was even underway.