Is enough being done?

The next issue of Rail Review ( RAIL’s quarterly business journal - Q2 2016, available in July) digs deeper into the evidence for climate change on the railway, speaking to Network Rail experts who are already being challenged by the impact of higher rainfall and increased flooding in the west of England.

The report concludes that “the cost will be staggering”, and finds that some aspects are already measurable, with Network Rail paying increasing compensation to train operators for the effects of weather-related disruption. Over the past eight years the average annual cost was more than £ 50 million. From now on it is expected to rise to £ 80m.

In the past few months the collapsed sea wall at Dover, the cutting at Harbury, and landslips at Wrecclesham and on the Settle-Carlisle Line are all cited as examples that can be linked to climate change.

“It is essential that we take a long view,” says Rob Nicholls, Professor of Coastal Engineering at the University of Southampton.

“Over the next ten to 20 years the risks to the railway will grow a little bit. But it is not going to be a dramatic change - it will be very gradual and therefore it will not always be easy to identify. The trouble is, the longterm view is often lost in the immediate need to react to day-to-day situations.”

At Dawlish, a 2014 study found that by the end of this century the annual number

The long-term view is often lost in the immediate need to react to day-to-day situations. Rob Nicholls, Professor of Coastal Engineering at the University of Southampton

of days with line restrictions will rise from today’s ten to between 84 and 120.

A 2010 study had similarly concluded that the sea level rise could cause rail services through Dawlish to be disrupted on average for 35% of the winter by 2060.

“At a high level within Network Rail I think there is good awareness of the issues,” says William Powrie, Professor of Geotechnical Engineering at the University of Southampton, and one of the world’s leading experts on how climate change affects infrastructure.

However, Powrie tells Rail Review: “Getting that message out to the routes to implement it seems to be a challenge. Making the resources available is also a challenge.

“Trying to educate the public is still a challenge - getting people to understand that it is not an exact science. We are inevitably talking about levels of probability.”

Network Rail defends its regional approach. Each route has developed its own agenda, rather than treating the country as a whole. On the Western route, that work is led by Director of Route Asset Management Mike Gallop.

“On Western we are a special case. In response to the catastrophic events in 2014 the Government effectively gave us £ 31m to spend on a series of targeted interventions.”

These include a 16-day closure of the line between Didcot and Banbury next month. This is an £18m project to lift the railway 1.5 metres above the flood plain of the River Thames at Hinksey, near Oxford. Two large culverts will be built to drain what Gallop describes as a 400 metre-long puddle.

Downstream at Maidenhead, he has already moved signalling equipment clear of occasional flooding. In 2014 high ground water levels severed the Great Western Main Line for several days. Signal cabinets have now been lifted on stilts to stand four metres higher than before.

“What we are doing is buying resilience,” says Gallop. “We are not buying prevention.”

Particularly at risk are the clay cuttings and embankments on which much of southern England’s railway was constructed.

“They are having to handle patterns of weather which are much wetter than they have had to deal with in the past,” says Powrie.

“To do anything about it is incredibly expensive. If you leave trees on the embankments you get a cycle of shrinkage and swelling. If you take the trees away, you get a gradual rise in pore water pressure. If the water pressure is too high, you get a potentially major slip.

“The downside of trees is that they blow down in front of trains. They cause leaves on the line. But the upside is that the roots of the trees are effective in taking moisture out of the slopes, and that will help with stability.

“The question really is whether you try to make the embankments resilient enough to stand a 1-in-50-year event, or a 1-in-100-year event.”

A 2014 review of transport resilience by the Department for Transport noted that most railway earthworks were hand-built by the Victorians, and were poorly engineered by today’s standards. It identified the 18,200km of embankments and cuttings as a particular risk. Some 105 earthworks failed in the winter of 2013-2014, some of which led to lengthy line closures.

The 2014 review concluded: “It would be both very difficult and prohibitively expensive to ensure total physical resilience, so it is equally about ensuring processes and procedures to restore services and routes to normal as quickly as possible after extreme weather events have abated.”

Powrie concludes: “You can only go so far to make the railway climate change-proof. You have to accept that in an increasing number of circumstances there will be restricted speed running and sometimes a suspended service. That is just an economic fact of life.”