The Anonymous Widower

The Longest Underwater Electrification In The UK Since The Channel Tunnel

It may only be a tunnel seven kilometres long and a lot shorter than the Channel Tunnel, but the Severn Tunnel has two tracks, which both have to be electrified, so that the Great Western Railway can run electric trains to and from South Wales.

But the Severn Tunnel was built between 1873 and 1886 and it posed various problems during its construction with water ingress and since with operation because of its length, profile and the pumping of constant water. There is a section in Wikipedia, which is called General, which gives more details.

The Severn Tunnel is probably one of those places, sane engineers wouldn’t want to electrify a railway.

So I was interested to read this article in Rail Engineer, which is entitled Preparing For Severn Tunnel Electrification. The article gives this overview of the project.

The electrification project now moves on to probably one of its biggest challenges: the electrification of the 7.012km long Severn Tunnel. The tunnel will be closed to trains between 12 September and 21 October for the work. It is referred to as the “Severn Tunnel Autumn Disruption” or STAD for short and, just to make it a bit more interesting, included in the STAD are the Patchway Tunnels –1.139km Old (Down); 0.057Km Short (Down); 1.609Km New (Up).

Some facts about the tunnel and the work already done.

  • More than 76.4 million bricks were used in the construction.
  • Between 10 and 20 million gallons of water have had to be extracted every day to prevent flooding.
  • There is also a ventilation shaft through which 80,000 cubic feet of fresh air can be forced into the tunnel each minute by means of an eight- metre diameter fan at the top.
  • The contractors first had to scarify 2,500 square metres of tunnel lining to remove more than 35 tonnes of soot.

It is not a small job. But at least the tunnel was in better condition than expected.

The article gives a deep insight into how the Severn Tunnel electrification is a collaboration between several major contractors, who are installing a Swiss system from Furrer + Frey called Rigid Overhead Conductor Rail System in the roof of the tunnel. The ROCS system uses a rigid aluminium rail supported on appropriately designed fittings fixed to the roof of the tunnel. There is more on the ROCS system in this article in Rail Technology Magazine.

To makes things more difficult, the engineers have only got thirty-nine days to do the work.

And if it all goes wrong, there are two sets of politicians who will get very angry!


June 3, 2016 - Posted by | Transport/Travel | , , ,

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