A shift in the course of the jet stream in the upper atmosphere of the northern hemisphere this winter has caused temperatures to plummet to extreme lows in North America and sent severe low pressure systems hurtling across the north Atlantic towards the British Isles at two to three day intervals for nearly two months, resulting in record-breaking rainfall and winds approaching hurricane force.
In North America railways battled to keep lines open despite frozen equipment and deep snow, while Britain's rail network has faced flooded tracks in numerous locations, landslides, embankment failures, and washed away tracks. High winds have brought down overhead electrification equipment and trees, and forced operators to reduce train speeds. At one point in early February all three main lines linking London and Bristol with southwest England were severed.
The worst damage is at Dawlish between Exeter and Plymouth where the sea wall was breached on two occasions causing around £5m worth of damage. This means one of Britain's main lines will be closed for more than two months, prompting politicians to consider constructing a new inland railway.
This is the second winter in succession where lines in southwest England have been badly affected by flooding and landslides resulting in line closures lasting several days. With such extreme weather events predicted to become more frequent as the planet's climate changes, railways need to have a much better understanding of the condition of their infrastructure and its vulnerability to bad weather.
Modern measuring systems can play a vital role in helping railways to improve their asset knowledge to assess its susceptibility to weather damage. As most of the world's railways are more than a century old, structures were not built to withstand prolonged heavy rain and will in any event have been weakened over the decades. Railways need to examine the stability of embankments and cuttings, the efficiency of drainage systems, and the effectiveness of flood and wind defences.
Railways also need to look strategically at their infrastructure. For example, should lines be raised up or protected better to prevent them from flooding? The Berlin – Hannover high-speed line was closed for nearly five months last year following damage to a 4km section caused by the River Elbe bursting its banks. It cost €150m to repair damage to the slab track and formation plus another €80m in lost revenue, and this was on a relatively new railway. Could this costly event have been avoided by better planning and design?
The effects of the track washout at Dawlish have been exacerbated because signalling cables were also damaged. Most of the Exeter – Plymouth main line is controlled from Exeter, which meant only a limited train service could be maintained beyond Dawlish. Radio-based signalling would be one solution in vulnerable locations or the capability to control trains from another location.
There is also an urgent need to consider what provision exists for diverting trains onto other lines and, where diversionary routes exist, whether they have sufficient capacity to cope with additional traffic. There used to be an alternative route from Exeter to Plymouth, but the central section was closed in the 1960s leaving south Devon, Plymouth and Cornwall, which have a combined population of around 1 million, extremely vulnerable as current events show.
Consideration must be given to the economics of making railways more resilient to extreme weather. Should more money be spent on protecting railways from floods and high winds to lessen the risk of damage which is costly to repair and results in loss of revenue?
It is ironic that rail transport, which prides itself on being one of the most environmentally-friendly modes of transport, has proven so vulnerable to extreme weather caused by climate change, which many blame on global warming and increased CO2 emissions.
It is not good enough for lines to be out of service for weeks or months at a time, and failure to address this will result in rail transport being marginalised. The cost of acting now to strengthen our infrastructure will be insignificant compared with the cost of repairing vulnerable railways year after year.