Down in the valley, part 2

(… continued from Down in the valley, part 1, posted on 12 Feb 2014).

I ended the first part of this three-part blog with the recognition that the HS2 trackbed would be a brutal intrusion into the Leam valley, and a promise that I would examine HS2 Ltd’s mitigation proposals for the valley in this second part. These proposals rely, for the most part, on two large spoil tips – sorry, that should be “environmental mitigation earthworks” – one on the southern side of the valley and one on the northern side. These two earthworks would be joined by a viaduct spanning the river, with a length of 110 metres.

The southern earthwork is depicted in drawing CT-06-090, which is in Volume 2 Map Book CFA17 of the Environmental Statement (ES), from which the section below has been taken.

Proposed Leam valley earthworks - south (Source: HS2 Ltd)

Proposed Leam valley earthworks – south (Source: HS2 Ltd)

This depiction is only a plan view, and so contains limited information – as I said in my blog Moving the earth (posted 31 Jan 2014) the ES does not appear to contain any details of the profiles of environmental mitigation earthworks. However, we can tell that the dimensions of the proposed southern earthwork are substantial, since the footprint would be a uniform 250 metres across over most of its length. We also have very limited data regarding the proposed height of the trackbed, something that I will look at further in the next blog that I am planning to post. ES Volume 2 Report CFA17 renders a little assistance in this respect. Paragraph 2.2.8 in that report identifies that, in the most southerly section of the earthwork the trackbed would, strictly speaking, be in a cutting for about 50 metres, but it would be “less than 0.5m deep”; this section can be seen on the above map, immediately to the right of where footpath W129y crosses the track. The next 600 metres of trackbed northwards would all be less than 2 metres above grade; it is only for the most northerly section of the earthwork that the trackbed height would rise progressively to bridge the Leam. Report CFA17 doesn’t say how high the viaduct is, but previous indications were that it would be about 11 metres above the riverbed. The above map appears to show this rise in height on an embankment, but it is not clear whether this embankment is hidden within the screening earthworks.

At the risk of making too many assumptions, it might just be possible to take a few measurements from drawing CT-06-090 and try to get some impression of the geometry of the proposed earthwork. For example, the outer slope of the earthwork has a footprint of about 85 metres from crest to the outer edge of the earthwork. If that slope is intended to be contoured at 1:8,, making it suitable for arable farming, then the height of the crest of the earthwork would be just less than 11 metres above grade. So for the section where the trackbed would be around 2 metres, the screening height would be 8 or 9 metres. If we apply the same logic to the inner slope, and assume that it would be at 1:2.5, we get a roughly similar answer (assuming that the slope is 25 metres across).

If my fag-packet calculation is reasonably representative, then the train will be screened fairly well; that is for an observer at ground level. Just how effective it will be for someone standing on the ridges either side of the valley is far less certain. The screening will however be improved further, presumably, by the pockets of “woodland habitat creation” and the “sustainable placement” – which I think is ES speak for a hedge – that is proposed along both sides of the trackway in sections where there is no new woodland planting proposed.

The northern earthwork is depicted in drawing CT-06-091, which is also in Volume 2 Map Book CFA17.

Proposed Leam valley earthworks - north (Source: HS2 Ltd)

Proposed Leam valley earthworks – north (Source: HS2 Ltd)

It is clear that, in plan at least, this northern earthwork would be smaller; it averages only about 150 metres across. However, the trackbed height, according to the latest information that I have, is around 7 metres, or more, for most of the length of the embankment, which is considerably higher than for the southern earthwork. My guess is that the reason for the more compact footprint of this northern earthwork, despite the higher trackbed, is that HS2 Ltd does not plan for the outer slopes to be suitable for arable farming, as evidenced by drawing CT-06-091 showing most of the outward slopes as “landscape mitigation planting”. If I apply the same fag-packet calculation as I did for the southern earthwork, but assuming a 1:2.5 outward slope for the northern earthwork, I get, to my great surprise, a consistent answer that the crest of the earthwork is about 8 metres above the trackbed.

If my interpretation of the plan depictions of the earthworks is correct – and that’s probably a big “if” – then it would appear that HS2 Ltd is proposing to hide the train from view, at least from an observer down in the valley, and that has to be a good thing. My problem is that I shouldn’t have to resort to measuring distances on the plans and making assumptions to work out what is proposed, the ES should tell me all that I need to know to judge the worth of the mitigation proposals. Also, the ES should give me the assurance that I need that the proposal is appropriate and effective mitigation; in particular, I need to be sure that dumping all of that surplus excavated material in the valley is really necessary and that other mitigation options, with less visual impact, are not feasible or as effective.

Surely in all of the 50,000 or so pages of the ES it would have been possible to find the space to provide the explanations that I am seeking.

(To be concluded …)

Acknowledgement: The Ordinance Survey mapping upon which the HS2 Ltd route design is overlaid has been reproduced in accordance with the principles of fair dealing as set out in the Copyright, Designs and Patents Act 1988.  On this basis, this mapping is:

Reproduced by permission of Ordnance Survey on behalf of HMSO.

© Crown Copyright. All rights reserved.

Advertisements

3 responses to this post.

  1. Posted by chriseaglen on February 16, 2014 at 10:50 pm

    Peter the two images did not emerge in the article.

    The impact of such high embankment sides will be to create the better gusting arrangement with vortex to remove the pantograph from the overhead wire. A most unreliable railway is in the making.

    Dont believe the depictions will emerge in practice as value engineering by the contractors rules more supreme than HS2 intentions unexplained in full.
    Thank you

    Reply

  2. Posted by simon on February 17, 2014 at 1:54 pm

    Dear Peter,

    Am truly impressed at how much you have written in the last few years and the incredible depth you have gone into for each topic you have posted. I am looking for other bloggers or journalists who have similar view points to yourself on this topic, would you be able to direct me to blogs and newspapers that you yourself have read for inspiration and information. I believe that you are a busy person so only if you have time and want to.

    Best wishes
    Simon

    Reply

    • Hi Simon and welcome to the site. If you persist in massaging my ego you will be welcome back anytime. No one is more surprised than me that I am still managing to find inspiration to blog about HS2, but then the attitude of HS2 Ltd to the local communities affected by HS2 and our environment has proved to be a very effective spur to make me bash away at the keyboard.
      I get my inspiration from a vast array of sources. Without doubt, my chief source is the publications of HS2 Ltd and the DfT. The Environmental Statement, for example, has enough in it to keep me going for months. In addition, I get sent a lot of links to articles and blogs and print out those that might inspire a blog and put them to one side for leafing through when I am looking for a new topic.
      If you want to consult a contrary view to the Government propaganda, then the most authoritative voices from the anti HS2 campaign are HS2 Action Alliance (http://www.hs2actionalliance.org) and Stop HS2 (http://stophs2.org). Many of the action groups campaigning against HS2 also have their own websites; I particularly like the South Heath, Bucks site (http://south-heath.co.uk) and the associated satirical blogs at HS2 Buzz (http://south-heath.co.uk/newspeak).
      For well-researched blogs on HS2 and other transport matters you can’t do better than Beleben (http://beleben.wordpress.com).
      For my money the best anti-HS2 journalist is Andrew Gilligan of the Sunday Telegraph (e.g. see http://www.telegraph.co.uk/news/uknews/road-and-rail-transport/10551060/HS2-Government-ministers-sat-on-critical-report-by-Department-for-Transport.html).

      Reply

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: