I read elsewhere that HOOP will be expected to do about half of the total work, with the rest by traditional methods. It is a fantastic bit of Four Sprung Duck Technique, which I look forward to seeing in action in due course. It's the first all-in-one that I know of, even though bits will operate independently quite often.
As with all these projects, the preparation takes as long and costs as much as the actual job. Bridges all along the route are being dealt with one way or the other. The only bit I have seen with my own eyes has been the replacement of this bridge:
with this new one:
at Stapleton Road station, between Bristol Parkway and Bristol Temple Meads. The new one is taller, has filled-in sides and steep coping on top. It is also modular - there is an aspiration to relay two additional tracks that were removed in the 1980s, and it will be a simple matter to extend the bridge.
Swindon to Kemble is coming along to plan, it seems. A number of preliminary works have been carried out, and a couple of miles of track and sleepers have appeared in parts where the alignment allows. There is to be a total shutdown from 9 August to 2 September, with bustitutions and diversions. The line was slewed after being singled, and in part is aligned down the centre. That needs putting back where it was, hence the need for the long possession. There will be another probable shutdown over Easter next year, after which the whole shoot-bang works will be done. Ribbons will be cut, speeches made, the odd cork will fly, and it will make a fine diversionary route whilst the Severn Tunnel is sorted out.
On that last item, I am happy to accept the assurance that powering the tunnel will not be a big issue. Beam electrification was once seen as trickier than cable, because of the way electricity behaves in a beam. On Thameslink, a new type of reduced depth conductor beam was developed by Balfour Beatty. It is 80mm in depth, compared to 110mm for traditional beam. It is a lightweight aluminium tube, arranged in a sinusoidal wave to spread wear on pantograph bushes, and it carries the untensioned power cable within it. It is harder wearing and longer lasting than cable, and doesn't behave like a solid beam There's a report in
Rail Engineer.
