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50C temperatures and buckling tracks: how the UK rail industry copes during a heatwave.

Posted on Aug 16, 2018

Extreme temperatures can cause tracks to warp

June and July 2018 was something of a scorcher for the UK. The island nation that’s joked as being obsessional about the weather is arguably treated to unsettled showery summers more than the temperature values that eclipsed much of the rest of Europe for weeks at a time. With highs of around 38C in southern, eastern and central England, and 33C north of The Border in Scotland (the longest hot spell in 42 years) lorries normally used to grit icy roads during the colder months were deployed to some roads to spread chippings and prevent melted tar from sticking to car wheels.

That was part of the story on the roads but what impact did the conditions have on the UK rail network? It was widely reported that passengers on the London Underground had to endure stifling temperatures that exceeded 33C, but despite the obvious discomfort the infrastructure below ground appeared to remain otherwise impervious to the heat. But what about above ground where track temperatures topped 50C – what did that do to the infrastructure?

To gain a better understanding of the situation, SmartRail World contacted the organisation that oversees and manages much of the UK’s network, Network Rail, to see if the sweat-inducing temperatures posed any problems and what it did to help mitigate them.

Network Rail depolyed extreme weather action teams during the heatwaveFocusing on the hundreds of thousands of miles of track on which the UK’s train run, Network Rail said that the extreme heat the UK was in the grip of was more than capable of buckling it and causing knock-on travel disruption. The forces that come as a consequence of focused heat from the sun effectively push and pull the rail tracks out of shape, which the huge number of sleepers and ballast are there to prevent. Track installers also bear this in mind when they lay new sections of rail, leaving gaps that allow the metal to expand and contract (as metal does when it cools) without it warping. In order to create a rail suited to the UK’s conditions, Network Rail fits pre-stressed metal that performs best with the parameters of the UK climate. That magic number, it turns out, is 27C – the stress-free temperature that means the metal on the tracks is the same as when it left the factory. Using this specifically-engineered metal means that it has enough latitude to withstand track temperatures variances of between -15C and 50C – both of which have been experienced in some parts of the UK in 2018.

When track temperatures are as high as that, Network Rail said they deploy extreme weather action teams, otherwise known as EWATs, which monitor trackside temperatures and vulnerable locations – such as bends where track is susceptible to more pressure from the moving train. It will also introduce temporary speed restrictions if required during the hottest part of the day to keep trains running, albeit more slowly than normal. Preventative action also sees something altogether more simple, but no less effective: painting the tracks white – action Network Rail says prevents expansion by keeping tracks up to 10C cooler.

The Office of Rail and Road (ORR), the government department that monitors the UK’s rail and road networks, told us it recognised the challenges faced by Network Rail in very hot weather and the impact this can have on operators. “We aren’t planning any changes of policy as a result of this hot spell, however, as in any disruption, we expect the train operators to do all that they can to keep passengers informed of any changes to timetables that may result. Where on the day disruption occurs, passengers need to be sure of the options that are available to them and reminded of the need to claim compensation if disruption means that they arrive later than planned at their destination.”

Keeping cool under pressure

White tracks have proved a success [Credit - Greater Anglia]As for those operators that the ORR speaks of, we heard back from Great Western Railway (GWR), Greater Anglia and Merseyrail on what they did during the out-of-character weather. GWR said that while they were at the mercy of Network Rail to impose speed restrictions should they be necessary, none had been enacted to the best of their knowledge – “certainly not impacting service”, said the operator. In order to prevent unnecessary crossing of points or tracks that could stress the tracks when abnormally hot, GWR imposed a key route strategy that relieved pressure on relief lines to the main lines.

Greater Anglia said they directly benefited from Network Rail policy to paint sections of track white, and the South East operator highlighted an example of their use on a set of its points at Colchester North station. Merseyail, meanwhile, said they experienced one incident of buckling on a line to Kirby, which caused some disruption, but softened the blow by apologising to passengers and ensuring they were keeping cool with complementary water and ice lollies – a strategy also employed by GWR and Greater Anglia that they said was appreciated by its customers.

Not to forget the companies brought in to help complete the work taking place on the UK network, we also heard from two major contractors that are involved with the industry on a daily basis to see what tactics they employed in abnormally hot conditions. Arup told us about the consortium-led research project it helped put together for the Rail Safety and Standards Board that explored the changing weather conditions, Tomorrow’s Railway and Climate Change Adaption. In the report, Arup says climate change will have a “significant and damaging impact” on the railway network and reviewed the possible effects of changing weather patterns on Britain’s railway. “A major disruption to the rail network caused by adverse weather conditions doesn’t just affect the rail network; it is likely to have wider impacts on the economy. When you take into account the impact on local businesses and communities, the case for building a resilient network becomes much more compelling,” said an Arup spokesperson.

Focusing on employee welfare, the contractor Murphy, said that delivering infrastructure was vital but not at the expense of its workforce. “We have taken a range of steps this summer to do that – from developing and trialling a heat stress risk assessment process, adopting a buddy system and making sure there are more refreshments, sunscreen and shade available for our teams.”

You may also be interested in this:

Read: 5 Minutes With… David Shipman, signalling innovations manager at Network Rail.

Read: Behind the liveries: Who owns what on the UK rail network? (Part Two).

Read: MTA announce that “every day is Earth Day” as they launch latest public transit report.

Watch: An insight into China's high-speed rail production line.

Topics: TransportSecurity

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