Adapting to extreme weather: a civil engineering perspective

In recent years, the UK has faced unprecedented weather patterns, including record temperatures, strong winds, droughts, floods, and cold snaps. Climate change is causing these extreme weather events to occur more frequently and with greater intensity.

Climate change is one of the biggest challenges facing the railway today, and the UK is seeing direct effects of it on our rail infrastructure; in fact, 7% of delays and cancellations during CP6 were due to weather. The effects of extreme weather can lead to serious failures, such as landslips. A mitigation and preventative approach is hugely important to ensure the safety of rail users and avoid delays.

Drainage, earthworks and upgrades for structures impacted by flooding and other weather events are a key focus for CP7. Recognising the need to invest in resilience and adaptation, Network Rail has committed ￡2.8bn over the next five years in activities and technology that will help the UK's railways better cope with extreme weather events.

So how can civil engineering design help mitigate the long-term impacts of climate change? In this newsletter, we explore how we can design structures to withstand the severe weather anticipated in the future.

Preparing structures for unpredictable weather events

Climate change is reshaping the landscape of civil engineering, and by upgrading our strategies and designs, we can help ensure that rail infrastructure can withstand the challenges of the future.

During the design phase of a project, our focus is on creating robust structures that meet all requirements, including enduring extreme weather events. This is formalised within our design work by a statement of probability. For instance, a project may need to account for a ‘once in 40 years’ event or even a ‘once in 100 years’ event.

In the context of drainage design, this consideration can be extended to a ‘once in 200 years’ event, with additional safety factors specifically related to climate change. The percentage increase for these climate change considerations often varies by local authorities or specific employers, typically ranging from 20% to 30%.

If there is no clear specification in the design brief regarding the severity of events to be considered, we will make an informed assumption and present that to clients.

Comprehensive data is key for resilient infrastructure

What does a statement of probability mean? Historical records and statistical weather analysis can be used to create maps which specify for each geographical location what precisely constitutes a 40 year wind event, for example – such an event having a 2.5% chance of actually occurring next year in that location.

While weather-specific data is vital, it is also complemented by other data sources, such as ground investigation and hydrological analysis. Securing the right data to inform designs is central to our civil engineering approach, and we combine all information to deliver comprehensive solutions.

Designing solutions for diverse extreme weather challenges

The measures we implement depend on the type of extreme weather anticipated and the specific structure involved and will be individual to each project but as examples:

• For wind, we may require additional bracing struts, stronger walls, or more robust foundations.
• When it comes to snow loading, we carefully assess elements such as parapets that can cause snow to accumulate.
• Flooding, which is increasingly common due to climate change, can be managed with barriers and channelling solutions. Our team of engineers specialise in flood risk assessment and mitigation, ensuring our projects remain resilient against rising flood threats.
• Temperature extremes can cause a variety of problems both for built structures and during the build phase itself. Cold conditions and freeze/thaw cycles can severely damage structures, while high temperatures can adversely affect materials such as concrete.

We must also consider maintenance aspects, like protective coatings, to ensure longevity.

Responding to the impact of extreme weather now

While prevention is vital, the impacts of extreme weather are already being seen across the rail network.

In addition to upgrade projects, WCS is also involved in maintenance framework contracts, and we are regularly called on to consult on civil aspects of emergency works, so we are very familiar with the consequences of engineering failure, and the importance of avoiding this.

Our team has a depth of experience and is used to mobilising quickly to the site, as well as responding flexibly to issues and opportunities arising.

Get in touch

Delivering a more resilient network is a huge task. Overall, Network Rail manages 10,000 miles of track and several times as many rail journeys as many larger countries. The scale and diversity of conditions across the network, and of infrastructure that can be well over 100 years old, mean finding solutions in the rail sector requires a creative approach to overcoming challenges.???

WCS is committed to supporting the UK's transition to a more resilient and sustainable rail network. Our proven track record in delivering civil engineering solutions for significant infrastructure projects means we're well-placed to support the delivery of CP7 frameworks.

This article appeared first on the WCS website.

To find out what that expertise can deliver on your next project, please get in touch at (0)20 3581 7847, [email protected], or via our contact page.