Railways and climate change

The flooded West Coast main line at Carlisle.
The Paris agreement on carbon reduction highlights climate change challenge
Published Mon, 2015-12-14 11:35

A number of events in the past week have helped to highlight the issue of climate change and the impact that the changing climate may have on Britain’s railways in the future.




The flooded West Coast main line at Carlisle. © Network Rail

After two weeks of intense negotiation at the United Nations Conference on Climate Change in Paris, the representatives of almost 200 governments have agreed a package of measures that are supposed to ensure that the world’s reliance on fossil fuels is reduced. The result of this will be to see an increase in the use of renewable power and, presumably, in transport terms, increased electrification of those lines that are currently diesel or steam operated. The end result is that the politicians hope that the rise in global average temperatures will be kept to 1.5-2° above that of the pre-industrial level. Experts suggest that, without more extreme action, the current projections suggest that average temperatures may rise by up to 3° — well above the level where disastrous climate change may result.
It’s too early to say whether or not the Paris agreement will lead to a successful result and — whether one is a subscriber to the notion of man-made climate change or not — it is to be hoped that countries do fulfill their obligations. What is clear, however, is that the railway’s ability to cope with extreme weather conditions is being sorely tested.
Of course, Britain has always suffered from the vagaries of the climate; the winters of 1947 and 1963 brought transport chaos for weeks whilst the floods of 1953 resulted in serious damage along the coast of East Anglia and the Thames estuary (plus the Netherlands) with a significant loss of life. Somehow, however, the past few years seem to have resulted in more catastrophic damage through floods — such as those of early 2014 — and mountainous seas — such as that at Dawlish again two years ago.
As this article is being penned, much of Cumbria is slowly recovering from flooding last weekend which impacted not just on towns and cities like Cockermouth, Keswick and Carlisle but also on transport infrastructure, forcing the West Coast main line, amongst others, to close for several days. The last few days has seen more heavy rain over northern and central Britain, with the result that a number of lines have seen services suspended at various times. These include the Cambrian route from Newtown to Machynlleth, the West Coast main line at Oxenholme, the north Wales coast route from Bangor to Holyhead, between Dumfries and Carlisle on the ex-Glasgow & South Western line, and between North Llanrwst and Blaenau Ffestiniog.
Historically, many railway lines were constructed along river valleys as these offered easier routes to engineer than trying to drive a straight line in an era when railway lines were constructed by hand by navies with picks and shovels. Whilst that undoubtedly reduced the cost of construction at the time, the proximity of railways to the river courses means that lines can be highly vulnerable both to flooding and to erosion should the river break its banks. No doubt flood protection can improve the position but, as the residents of parts of northern England have discovered, even well-engineered flood barriers cannot always cope with torrential rain. Meteorologists suggest that in excess of 13 inches of rail fell in 24 hours over parts of Cumbria over the weekend of 5/6 December; this is a record for rainfall for Britain within that period of time. However, the same meteorologists also say that, with rising average temperatures, such rainfall can become more common. Warm air is able to accommodate greater levels of moisture and, as the rain-bearing clouds rise over the mountains of the Lake District (or North Wales or the Pennines), this moisture will result in greater rain more often. What has been regarded as a once in a lifetime event may become more common and the railways — plus society more generally — will need to gear itself up to cope.
Higher levels of rainfall wit the consequent flooding is but one potential consequence of climate change. There is also the potential threat of rising sea levels as the oceans expand due to becoming warmer and as come of the ice locked in the glaciers of Greenland and Antarctica melt. Much was made at the Paris conference about the low-lying islands in the Pacific — such as Tuvalu — whose very existence is in doubt with rising sea levels. But the estimation is that sea level rise may be a minimum of about one metre; that doesn’t sound massive, but it will have an impact on Britain as well as those threatened Pacific islands. The Thames barrier is already in use more regularly than originally believed year-on-year and a further barrier, upstream of the existing facility, is already under consideration.
The threat to the railways again is quite evident. The damage caused by the storm at Dawlish in early 2014 demonstrates well how destructive the sea can be. The damage has been repaired and the sea wall strengthened; since then, however, rough seas have caused operational problems and the debate about the construction of a diversionary route — probably via Okehampton — continues. Like the river valleys, Britain’s coast provided a cheaper means of constructing lines with the result that many lines — such as the Cambrian from Dovey Junction to Barmouth, the Cumbrian Coast line, the Far North line and many others are close to the sea. Whilst the proximity to the sea does afford the passenger spectacular views, it does make the line vulnerable should sea levels rise and should there by tidal surges. At least one heritage line — the Fairbourne Railway in Wales — is already at risk from rising sea levels as the stretch of coast on which it sits is one that the Welsh administration has identified as being potentially at risk when trying to work out how best to spend money on coastal defences.
There is a third issue and that relates to wind. Gales do cause havoc, bringing down trees and damaging catenary. Indeed, the line between Hereford and Newport was closed on Saturday 12 December as a result of a fallen tree and, with the ground being very wet, any strong wind is likely to result in trees being more easily blown over than usual. With the demise of steam, the pressure to remove vegetation from the lineside was much reduced with the result that many lines started to resemble linear nature reserves. More recently, however, Network Rail has increasingly undertaken a programme of removing many of the more substantial trees from its embankments. This may, no doubt, be opposed by conservationists but, in the light of operational needs, this work is both probably essential and needs to be accelerated.
With the ongoing electrification of lines such as the Great Western main line to Bristol, Cardiff and Swansea and with maintenance work on existing lines, it is to be hoped that the catenary will be engineered in such as way as to be able to withstand higher winds than were perhaps considered 60 years ago when the electrification of the WCML was first proposed.