Thinking three-dimensionally

In my blog Bend it, just a little bit (posted 25 Feb 2012) I reported that HS2 Ltd had determined that reducing the design speed of the track where it passes Cubbington village was not the preferred way of avoiding damage to the ancient woodland of South Cubbington Wood.

Now if I may say so, the Cubbington Action Group against HS2 had already said as much in its response to the public consultation on HS2 (here). On page 27 the following appears:

“It seems unlikely that a solution can be found that allows for horizontal realignment of the route to avoid the wood and the pear tree, since this would have repercussions at Stoneleigh and Offchurch and would take the route nearer to either Cubbington or Weston under Wetherley.”

The submission goes on to suggest an alternative approach to protecting the Wood:

“Accordingly, the Cubbington Action Group against HS2 suggests that consideration be given to boring a tunnel through the hillside on which the wood stands, similar to the solution offered to protect Long Itchington and Ufton Woods SSSI. Subject to a survey of the local hydrology, this would protect both South Cubbington Wood and the pear tree.”

The logic of this suggestion can be seen from the cross-section from the latest route map for the Cubbington section issued by HS2 Ltd (here), which is reproduced below.

Track cross-section in Cubbington (source: HS2 Ltd)

The faint green line represents the ground level and the continuous black line is the proposed vertical alignment of the track. South Cubbington Wood lies on the top of the hill, on the right-hand side just before the ground level falls down into the LeamValley. In my view, this situation is crying out for a tunnel and the “dome” in the route alignment could even be flattened out if more headroom is necessary above the tunnel bore.

Now I know that tunnels are expensive, but what price do we place upon our environmental heritage? Also there are savings to be made to offset the cost of tunnelling. For example, the spoil generated by tunnelling will be far less than from the excavation of a cutting and at least one road bridge (including diverting the road) could be saved. To add to the attractiveness of this possible solution, a tunnelling machine will be at work only six kilometres down the line (saving Long Itchington Wood) and a short length of tunnel is all that would be needed.

Unfortunately I have to report that HS2 Ltd appears to have totally ignored this suggestion. The “solution” that HS2 Ltd has come up with is described in paragraphs 3.2.3 on page 22 of Review of possible refinements to the proposed HS2 London to West Midlands Route (here), thus:

“To the south we have sought to minimise the impacts on South Cubbington Wood by reducing the depth of the cutting, removing the access track and incorporating a 1,250m long retaining wall to minimise the width of the railway through the woodland. This would also bring some benefits to Cubbington itself by reducing spoil generation, and local landscape and noise impacts.”

This reduced width cutting is shown in the new route map for the area referred to earlier in this blog, and a portion of this map is reproduced below.

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3 responses to this post.

  1. Posted by William Adam on February 29, 2012 at 8:21 am

    Taking aesthetic tunneling to its logical conclusion. What are thefinancial and environmental affects of doing the present surface track as “cut and cover”,i.e. dig a trench some6 metres deeplay the north-bound track, span the trench, build the south-bound track, span the trench,replace the soil and perhaps plant with native trees. End result only half as much land to purchase, no long term blight, no compensation payments, vast reduction in noise polution and visual pollution.
    Would the cost savings balance the cost of the trench?
    Benefit to HS2 no leaves or snow on the line to disrupt services, no fog, no excuse fo delays?

    Bill Adam

    Reply

    • Unfortunately Bill cut and cover does not solve all of the environmental problems. In the case of ancient woodland it is the disturbance to the soil that causes the destruction. I have read that you can cut all of the trees down in an ancient wood and it will recover, with time, if you replant. If you remove the soil layer you take away the life force that characterises the wood. Some developers maintain that you can “translocate” the soil and recreate the habitat, but the main conservation bodies do not agree; I will be dealing with this subject in a blog soon.
      Also cut and cover does not help protect sites on the surface (e.g. heritage sites and homes) that lie in the path of the track.

      Reply

      • Posted by William Adam on March 2, 2012 at 9:01 pm

        Peter,

        Im not offering the “double-deck” covered trench as a solution to all environental damage but as away of reducing it. The mechnical damage would be limited to a 17 metre wide strip. With the trains in each tunnel being unidiretioinal and not emiting clouds of smoke little vetilation would be needed, just occasional access ways. If a vital asset did manage to be on its narrow path the line could be droped a few metres to normal tunnel depth and leave the asset (your house?) undisturbed

        Bill

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