HS2 Ltd has pledged that the infrastructure for the new railway will be designed to manage the effects of extreme weather such as the high temperatures that caused chaos on the rail network this month.
The firm building the high speed link said it would seek to avoid both the issue of rails buckling at high temperatures and power lines sagging as they expand – an issue that brought some lines to a standstill on Thursday.
A HS2 Ltd spokesperson told Transport Network: ‘We are building a railway which will be able to operate well into the next century. Using the latest technology, we are designing HS2 to not only meet the needs of future passengers, but to tackle environmental risks such as extreme weather conditions.
‘This includes ensuring our overhead catenary system fully compensates for extreme weather within the temperature range of -20°C to +60°C.
‘In addition, by using slab track and applying the latest thinking in track design, we will make the risk of buckling in high temperatures negligible. We are also looking at increasing the stress free temperature of the rails from the current UK practice to compensate for future increases in temperature.’
Much of Britain’s railway is built using sleepers on a ballast trackbed, which makes rails more susceptible to buckling but significantly cheaper than slab track – at least in the short term.
In explaining why its track is often prone to buckling Network Rail said this week that it uses a process called stressing rails to protect against buckling, which allows it ‘to set the range of temperatures the track can comfortably cope with’.
It said that stressing rails to cope with higher summer temperatures would mean making them less able to cope with low temperatures during the winter.
It said: ‘Our rails have a stress free temperature of 27C, the average summer rail temperature in the UK.’
However, HS2 Ltd said the stress free temperature (SFT) for tracks has been the same in the UK for many years, adding that a higher SFT means that the rails go into compression at a higher temperature, thereby reducing the risks.
The firm also said its designs take into account latest guidance on climate change predictions on the increase in river levels and rainfall intensities to ensure that flood risk impacts over the lifetime of the scheme are appropriately mitigated.
It added that a key design principle is to ensure there is no increase in flood risk to third parties. Its hierarchy of mitigation seeks to avoid impacts where possible, minimise impacts through design, and where this is not feasible include appropriate mitigation such as the use of replacement flood plain storage and new flood defences.
The spokesperson said: ‘Our design approach to operational flood resilience is aligned with the National Planning Policy Framework, industry research and best practice.’
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