Building infrastructure fit for a changing climate

Our weather and climate is changing. In 2015 the UK had the hottest July ever on record, and the mildest winter since 1910. We were also affected by 9 storms in a 4 month period which caused widespread disruption to businesses, our infrastructure, communities, individuals and our economy.

Network Rail is not immune to the effects of these extreme weather events. Flooding, landslips, heatwaves and cold snaps all impact on our ability to run our business and service our customers.

In Infrastructure Programmes the rail infrastructure we build today needs to be fit for the climate of the future to be able to operate a sustainable business that is safe, high performing and provides an efficient and reliable service to our customers.

But how do you build infrastructure today that will cope with an ever changing climate? Thameslink Programme aimed to tackle this difficult question through a number of climate change interventions.

Climate change – a global threat

It is well documented that man-made carbon emissions has led to increasing global temperatures and climate change. Since pre-industrial time our carbon emissions have increased by 40% and global temperatures have risen by 1°C. As a country we are already feeling the effects of climate change through extreme weather events such as wide spread flooding and heat waves, which has had significant impacts on our economy, businesses, infrastructure, communities and individuals.

Climate change is one of the top ten global risks for 2016 (World Economic Forum). To tackle this risk global leaders agreed at COP21 in December 2015 (United Nations Climate Change Conference) to limit the rise of temperatures to well below 2°C, with efforts to hold it to 1.5°C. For the first time in history this agreement has highlighted the global importance of reducing global temperatures to tackle climate change.

The role of Infrastructure Projects in mitigating the effects of climate change on the railway

The railway network has been significantly affected by severe weather conditions including wind, snow, rainfall, lightning, heat and cold. Climate change projections suggest we will be entering a period with increasing average and maximum daily temperatures, drier summers, wetter winters, sea level rises and increased storminess. With these weather changes brings an increase in flooding, earth slip and coastal storm surges, heat causes soil desiccation and track buckling, high winds result in debris falling onto track and snow and cold weather result in frozen points and blocked routes. Such weather events can cause significant disruption to the operation of train services and damage to rail infrastructure.

Over the last eight years the average annual costs attributed to weather impacts for the whole of the network was over £50 million, which is set to rise to £80 million per annum. In terms of delay minutes, weather and seasonal events on average caused 12% of all delays.

Infrastructure Projects (IP) is delivering the biggest investment in the railway since the Victorian era. When we design and build iconic new stations, signalling upgrades, electrification, track renewals and bridges the investment, design and construction decisions we make have an impact on the reliability of our assets to withstand future weather events. To maintain a resilient railway we need to understand the vulnerability of our rail assets to weather events and impacts of climate change and invest in making them more resilience to future weather events. If we fail to invest, design and build assets that are resilient to weather and climate change the level of performance costs, consequential costs of repairing the rail infrastructure and wider socio-economic impacts such as delayed services to our passengers will continue to rise.

Therefore to support the climate change challenge that faces the rail industry and our business Infrastructure Programmes has committed to:

“Understand the long term impact of climate change and innovate beyond Network Rail Engineering Design standards to eradicate service disruption caused by weather events.”

Lessons Learned

Whilst the TLP did implement a number of climate change interventions the target was introduced and considered late in the programme in 2012 therefore the scope of influence was limited. This was due to climate change not being considered a key risk when the initial sustainability objectives were set in 2006 as part of the Transport and works Act Order. Following revision of the TLP sustainability strategy in 2012 a climate change target was introduced to maximise the opportunity to incorporate climate change adaptations into the second phase of the TLP delivery as the business became more aware of the impact of this risk.

To support the NR IP business going forward with the delivery of its climate change commitments the following lessons learnt have been identified:

• Objectives and targets should be agreed early on in the project lifecycle and cascaded to the supply chain via the contract and procurement process.
• Investment, design and construction decisions should be undertaken on a whole life cost basis to encourage long term decision making and to identify funds to deliver adaptation strategies.
• Designers and engineers should be engaged early in the process. There was a lack of guidance from NR on the design standards that TLP should be working to verify that assets would be resilient to future changes in climate. As supply chain designers work to NR standards NR as a client will need to provide more guidance on design and engineering standards going forward.
• The route teams should be engaged to ensure that assets designed by IP meet the requirements as set out in their route weather resilience and climate change adaptation plans.

Flood mitigation study

The TLP also undertook a flood mitigation study to verify that the flood mitigation designs being undertaken were adequate and robust. The study was broken into two phases:

• Phase 1 – used Interactive Environmental Agency Flood Maps and modelling data from NR to create a Thameslink GIS map, which identified the impact of flooding from Reservoirs, Rivers and Surface Water upon the NR Assets such as stations, substations, tunnels, depots and sidings.
• Phase 2 – more detailed review of flood risk at five high risk locations to ascertain if sufficient flood mitigation measures had been incorporated into TLP’s original designs.

The report concluded that the risk of flooding was found to be acceptable. The risk of flooding from a 1 in 100 year storm is unlikely, albeit the possibility of flooding from a 1 in 30 year event does exist. However, when the presence of existing assets, such as track drainage is taken into consideration the flood provision for a 1 in 100 year storm the flood was deemed to be acceptable.

TLP has therefore designed its assets to withstand the impacts of a 1 in 100 year flood event thus protecting the safety and performance of the Thameslink Route.

With thanks

We would like to thank the following Network Rail project and suppliers:

• London Bridge Station Redevelopment team and WSP
• Track project team and Balfour Beatty Rail