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Great Western Main Line to join the national high-speed rail network

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July 2012 marks the date on which the decision was made that the Great Western Main line linking London with Bristol and Cardiff should become part of the nation’s high-speed rail network.

Electrification of the route will provide for future operation at 225 km/h between Airport Junction (Heathrow) and Bristol Parkway. This will be achieved by higher tensioning of the overhead 25kV power supply, and the use of ECTS in place of conventional signalling.

Greengauge 21 had called for a progressive improvement in line speeds so that, with a new hub station at Heathrow, the South West and South Wales can join in the benefits of HS2 and the new connection to HS1: the benefits of a national high-speed rail network are becoming more evident with this exciting development.

The Great Western Main Line is perhaps the one rail alignment in Britain where the prospect of upgrade as opposed to new build looks an exciting prospect, capable of delivering journey time, capacity and performance capability enhancements together. The foresight of Victorian engineer Isambard Kingdom Brunel has to be acknowledged, once again. Future steps could include four tracking of the Didcot – Wotton Bassett section, separating out high-speed services from enhanced local services and freight, with speeds of 250km/h or 300km/h to be considered.

In its work for the Great Western Partnership (GWP) of March 2012, Greengauge 21’s report also called for those bidding the replacement Great Western franchise to deliver the DfT’s outline service timetable for the new IEP train fleet, for which the procurement process, including what has been claimed to be the largest ever private finance deal for rolling stock, has just been completed.  The IEP service plan sees a big speed up in longer distance services to/from Paddington and a doubling of service frequency to four trains/hour for London – Bristol.

Interestingly, franchise bidders have to supply a benefit cost appraisal of their proposals as part of their bid. This is a new departure, reflecting the fact that DfT is not specifying the timetable bidders should use, simply asking them, for instance, to ensure that the benefits of IEP are fully realised. As in all cost-benefit appraisals, the question is what incremental difference does the investment offer, in this case, the franchise proposal – against an assumed ‘do minimum’. The DfT specification requires bidders to incorporate the full DfT-specified IEP timetable in the Do Minimum in their appraisal submissions.

Greengauge 21’s work for the GWP provided the evidence on the value of better journey times for the economies served by the Great Western corridor. It also pointed to the need for a new direct connection to Heathrow – the Western Rail Access – which is to be developed by Network Rail in CP5 and implemented in CP6, as set out in the HLOS/SOFA also published in July.

The Great Western Partnership places an emphasis on the economic value of rail investment at corridor level, complementing the work of local groups who seek enhancements to local rail services – several of which feature as options in the GW franchise ITT. Also included was the creation of much enhanced service over the Salisbury – Westbury – Swindon corridor, as requested in the Greengauge 21 report. While this is only an option, the ITT scores its delivery with a 100% weighting, since third party funding has already been committed for this particular development.

With the commitment to electrify the Great Western Main Line to Swansea and not just Cardiff, the scope to introduce much enhanced ‘regional metro’ style services between Swansea, Cardiff, Newport, Bristol and Bath also becomes a possibility, as also featured in the Greengauge 21 report for the GWP. There is a burgeoning commuter market across the Severn Estuary, where the road alternative comes with a hefty crossing toll, giving rail a strong competitive advantage.