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Implementing climate change allowances in drainage standards across the UK railway network

Implementing climate change allowances in drainage standards across the UK railway network (2015)

The UK is generally projected to experience increases in precipitation as a result of climate change. An important resilience action to mitigate the impacts from such increases is improvements in drainage management. Climate change resilience within Network Rail, the national railway infrastructure manager in Great Britain, is driven by corporate strategic objectives within the Network Rail Sustainable Development strategy. Recently, Network Rail published eight Route Weather Resilience and Climate Change Adaptation plans covering the whole rail network. The plans reflect upon the impacts from weather variability, regional climate change projections and actions being taken to increase resilience; including investment in drainage systems and implementation of an Integrated Drainage Management Policy.

Case Study Description

Challenges

The effective control of water is essential for the management of infrastructure to support safe and efficient railway services. Water has a role in many degradation mechanisms that affect infrastructure; such as the scour of bridges and embankments, and the long-term softening of materials that form the Track Support System. Drainage problems can result in speed restrictions or temporary closures of the line, as well as increasing maintenance costs.

In accordance with its Asset Management Capability report (Network Rail, 2014), Network Rail is addressing different climate-related challenges, including increases in average and maximum daily temperatures, changes in rainfall patterns and occasionally very cold winter conditions. NR's drainage policy is addressing some of them: in the last years, NR has developed a coherent policy across the drainage system and has started to improve the asset information held on the drainage system. Within the current Control Period (2014-2019, CP5), Network Rail will continue to pursue improved assets knowledge, and to seek a clearer understanding of how changes in rainfall intensity and frequency will impact on new asset specification and maintenance regimes.

Objectives

Climate change resilience within Network Rail, the national railway infrastructure manager in Great Britain, is driven by corporate strategic objectives within the Network Rail Sustainable Development strategy:

  • Understand the current weather resilience, and seek to optimise resilience and enhance adaptation capability;
  • Develop a thorough understanding of the potential impacts of climate change in terms of infrastructure performance, safety risks and costs;
  • Embed climate change adaptation within asset policies and investment decisions;
  • Communicate the role the rail network plays in supporting weather and climate resilience across Great Britain, and support efforts to increase national resilience.
Adaptation Options Implemented In This Case
Solutions

To be effective, railway drainage systems need to be designed and built to appropriate standards, maintained regularly and, when required, improved. The revision and implementation of the drainage standards is a key asset management instrument within Network Rail's drainage policy. The drainage standards adopt a precautionary approach, by increasing the design flow and providing further capacity in new and refurbished drainage systems. The implementation of climate change allowances is a part of the solution for Network Rail to increase weather and climate change resilience. Asset policy revision, technology adoption and root cause analysis are also essential actions.

Network Rail developed its current Railway Drainage Systems Manual in 2010. The document set standards that include allowances for impacts from future climate in the design of railway assets. For new and remediated railway drainage, a 20% increase in the estimated present day design flow for design event return periods is added. This addition is consistent with the recommendations for climate change allowances for flood and coastal risk management provided by the UK Government, and more specifically by England’s Environment Agency.

The drainage standards are applied across the network; however the location-specific nature of weather impacts will require analysis and response at route level to ensure investment in drainage is cost effective. The Scotland Route Weather Resilience and Climate Change Adaptation Plan (Network Rail, 2014) reports on some concrete actions already undertaken:

  • The flood site at Dalmarnock Station has been remediated through major works by providing an attenuation system.
  • The flood site at Drem station has been remediated under a Business Plan with a new pipe work and an attenuation pond.
  • Remediation of the flood site at Penmanshiel siphon is still ongoing. Initial remediation was provided through enhanced inspection and cleaning. A major works scheme to raise the wall heads of siphon chamber and install new screens has being completed. Further enhancement to provide an attenuation pond is planned during CP5 (Control Period (2014-2019).
  • Improved drainage management capability is also being achieved by Network Rail through new mobile works tools and improvements in NR's drainage competency during 2014.

Drainage standards are also applied in new projects, such as the 30-mile "borders rail" project, linking Edinburgh to Tweedbank. This is the longest domestic railway being constructed in the UK in the last 100 years, and is expected to open in Summer 2015 (Borders Railway, 2014). Network Rail is further strengthening its drainage policy in CP5. It has developed a coherent policy across the drainage system, and improved the asset information held on drainage system. In future, Network Rail will seek a clearer understanding of how changes in rainfall intensity will impact on new asset specification and maintenance regimes.

Relevance

Case developed and implemented and partially funded as a CCA measure.

Additional Details

Stakeholder Participation

Network Rail presents progress to railway industry stakeholders through many forums. The delivery of drainage plans is specifically monitored internally and by the Office of Rail Regulation. Network Rail liaises with England, Wales and Scotland environment agencies.

Success and Limiting Factors

Success factors include: (i) Long-term vision and strategy; (ii) Collaborative relationships with stakeholders; (iii) Robust asset management policies and compliance processes.

The main limiting factors are related to the complexity and extension of the British rail system. Upgrading of current drainage conditions to the new standards will need to be accommodated to the availability of resources, and action will have to be prioritised accordingly. Furthermore, the decisions taken may have system wide implications, as activity on one asset group (such as track, for drainage), may impact on another part of the overall railway system (e.g. signalling).

Legal Aspects

Network Rail operates under a Network Licence which sets out the conditions under which it must operate. In particular, Licence Condition 1 sets out Network Rail's core obligations to secure the operation, maintenance, renewal and enhancement of the network in order to satisfy the reasonable requirements of persons providing services to railways and funders. This condition also includes some specific obligations for Network Rail to produce a delivery plan, establish and maintain route utilisation strategies (RUSs) and develop asset management policies and criteria to maintain, renew, replace, enhance and develop the assets. Although there are no specific provisions within the Network License on climate variability and climate change, it can be understood that its purpose to secure the operation and the improvement of the network in accordance with best practice includes the need to adapt to changes in climate.

Implementation Time

Implementation started in 2011 and is continuing in the current Control Period 2014-2019.

Life Time

60 years, in accordance with the drainage standard.

Reference Information

Contact

Kate Avery
Network Rail
E-mail: kate.avery@networkrail.co.uk

Source
UK Network Rail and Borders Railway

Keywords

Asset management, railway, standards, water drainage

Sectors

Disaster Risk Reduction, Transport

Climate impacts

Flooding

Governance level

National

Geographic characterization

Europe

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