Tuesday 11 June 2024

Ashing at Caen Hill

Whilst walking down the Caen Hill flight this afternoon, I chatted to several members of CaRT staff who, as usual, were both helpful and friendly as well as being well informed.

In the process I learnt that this year the team were experimenting with ashing three of the locks in the flight in an effort to mitigate the effects of water losses through leaky gates. I was fortunate to be able to witness this action with one of the locks.

The photos show the before and after situations - it is clear that the losses through the centre mitre were all but eliminated. Even more astonishing (although many years ago I had seen this once before) was the speed at which this happened. It was almost instantaneous - well, at least within just a small number of seconds. The cessation quickly worked its way down the mitre as the ash (from Avon Valley Steam Line) was being poured.

Monday 10 June 2024

Canal Vegetation - Then and Now

This is not a cruising blog but just an item of interest - hopefully some anyway!

In a number of places recently we have wondered about the historical approach to canalside vegetation. This has also been prompted by what seems to be a significant rise in landslips, often  associated with tree falls. The Shroppie is, of course, especially prone to this, When built, soil mechanics had not yet been devised and the design of cuttings and embankments, the slopes especially, was a matter of 'try and see'. The steeper the bank the cheaper to construct since there is less material to move. However, push it too far and the bank readily become unstable.

Having started to think about, I happened to encounter a CaRT manager with responsibility for vegetation management contracts and we had a very interesting, albeit too brief, chat. (It seems that for the first time CaRT are developing a medium term plan for regular inspection and maintenance with a view to reducing costs - planned is usually cheaper than emergency reactive. It seems that some of the thoughts that had been forming in my mind aligned with the emerging understanding within CaRT. This chap has been building a picture of how things were in the past as well as now.

I had been theorising that it is only very recently (perhaps a small number of decades) that the immediate surroundings of canals have been allowed to develop vegetation. In urban areas this often creates a much pleasanter environment for users of water and towpath and is thus by many  to be 'a good thing'. More contentious is the treatment of the towpath itself, especially the verge with the water itself where a lot of moorable space has been lost.

A few days ago, browsing through some recent and not so recent photos that we have taken, one example stood out as encapsulating the contrast, taken on the New Main Line in Birmingham (strictly Smethwick) where the former pumping engine stands that once raised water from the Birmingham to the Wolverhampton levels.

The first dates from the mid 1980's - not sure as mass processed film lacked dates in those days! The second is from 2021. 

As can be seen, even just four decades ago, the cuttings and embankments were kept almost entirely free of vegetation and it is easy to see why the modern approach is considered more attractive. However, the vegetation-free approach must have had its own costs and would surely have been viewed as necessary in the light of experience with land slips, or not. Perhaps there needs to be a more balanced debate that takes into account the choice between saving costs in the short term with larger ones later, together with the environmental impacts. What is clear is that we appear to have drifted into the present policy without gaining wide acceptance of the implications. However, it is good that CaRT are now addressing the matter! 

As an aside, note how the older picture has the chimney missing - we think that this was re-built during the more recent restoration of the pumping station.