Operation and construction measures for ensuring climate-resilient railway infrastructure

Railway represents an energy efficient transport mode with a comparatively small environmental impact, which favours railway transport in the implementation of the long-term neutral-carbon transport strategy. This is also related to the potential of rail to mitigate climate change, since the growth of rail transport would result in a reduction in greenhouse gas emissions. However, this potential can only be realized if railways are adapted to withstand impacts associated with climate change.

One of the most critical vulnerabilities in the railway transport system is the low flexibility of both infrastructure and operations in the event of disturbances. The rail transport system also depends on other types of infrastructure. For instance disturbances in the power supply due to extreme weather events directly influence the functionality of the railway transport system. Due to the long lifetime of rail infrastructure, which is expected to operate at full capacity for more than 50 years (and even longer, for some installations), it is appropriate to integrate climate change aspects into the long-term railway planning, design and management process. The Rail Adapt Report vision (UIC, 2017) considers the adaptation process of railway as part of the business as usual development scenario so that the cost of adaptation has only a marginal impact of the financial performance of a railway company.

Climate change risks for the railway industry have been thoroughly described by the ARISCC project (Adaptation of Railway Infrastructure to Climate Change), implemented by the consortium led by UIC (International Union of Railways). The outcomes of ARISCC comprise natural hazard maps and the guidance document on integrated natural hazard management on railways. The identified climate change effects affecting railway can be distinguished into three main categories, each requiring specific sets of adaptation measures:

• Extreme weather events, such as heavy rain (and associated flooding), high wind speeds, storms, cyclones, severe winter weather, etc. According to Defra´s 2011 Transport Resilience Review both infrastructure and operational resilience should be developed in particular using available network redundancy and redirection routes, and should be complemented with effective systems to restore services and routes to normal conditions. Communication with stakeholders to minimize the impact of disruption on people and businesses is also essential.
• Slow onset events having gradual impact on the railway transport, like the increase of air temperature or sea level rise. Adaptation response should be implemented within long-term transport development strategies.
• Other natural hazards triggered by climate change, including landslides, rock falls, avalanches, decrease in embankment stability etc. Structural protection measures combined with vulnerability assessment and disaster risk reduction systems would suitably respond to such challenges.

The “Guidebook for Enhancing Resilience of European Rail Transport in Extreme Weather Events”, produced by the MOWE-IT project, splits responses to extreme weather events into long-term planning measures, actions to be taken immediately before the event and recovery actions. The guidebook “Urban Rail, Climate Change and Resilience”, developed by the International Public Transport Union (UITP), focuses on adaptation responses to prevent and restore damages caused by climate hazards on individual sub-systems of city railway, such as: power supply, tracks, rolling stocks, stations, tunnels, level crossings and maintenance facilities. The main recommendations provided by these resources include:

• Incorporate climate change projections into the design and capacity of drainage to cope with projected future flooding frequency and magnitude. In the UK for example, the drainage standards include allowances for impact from future climate in the design of railway assets: for new and remediated railway drainage, a 20% increase in the estimated flow is added.
• Improve wind resilience of catenary masts and keep areas close to tracks and catenaries free from hazardous objects. Even though many operational failures are caused by trees fallen to track or catenaries, vegetation is often used as a buffer zone for noise and pollution along railway tracks and also to protect the track from direct insulation. Ecosystem based measures increasing resilience to wind (e.g. trees able to withstand high wind speeds) should therefore be preferred.
• Install spare and emergency capacity for the safety and operational systems (pass-by trucks, switches, operation on opposite lane) to back up the capacity affected by extreme weather.
• Develop strategies minimizing the impact of operational failures caused by extreme weather conditions (special timetables, rerouting models), and provide replacement of services if needed (e.g. bus transport)
• Provide real-time information to passenger and maintain communication with important institutions

Increase in temperature may not be seen as a major problem for railway transport in regions which are already coping with such conditions (southern Europe); however, in Northern Europe resilience to high summer temperatures should be increased. Rail buckling, increased risk of fires of vegetation, installation of cooling systems and other systems for passenger comfort are concerns relating to heat in the future railway transport system. The respective adaptation responses should combine technical solutions (e.g. increased heat resistance of switches and the safety system), ecosystem based measures (e.g. vegetation protecting from direct sun) and monitoring and early warning systems.

Another aspect of rail vulnerability relies in reduced soil stability triggered by climate change impacts, such as heavy precipitation or temperature fluctuation. The occurrence of landslides, rock falls or avalanches, affecting mainly mountainous areas, imposes the need for the implementation of structural protection measures, such as dikes and embankments. These measures may have multiple benefits as they may protect also settlements or other infrastructure such as roads or energy supply networks. As the implementation of structural measures for the whole railway system of mountain countries is often not feasible for both economic reasons and aspects of nature and landscape protection, there is a strong need for additional (non-structural) risk reduction measures, such as the provision of early warning systems, traffic redirection, etc., above mentioned.