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The need for electrification to reduce both carbon emissions and harmful particulate emissions from diesel traction is certainly a priority but is far from the only emissions issue. Network Rail’s Environmental Sustainability Strategy considers that its carbon footprint has three categories of emissions: those the company emits directly, indirect emissions from energy it purchases and those over which it has influence such as supply-chain activities. This last category, which includes traction energy, is 96% of the company’s carbon footprint.
This also includes the carbon embodied in infrastructure projects for which the Rail Safety and Standards Board (RSSB) has developed its Rail Carbon Tool which can assess low-carbon options and calculate the carbon footprint of rail projects. This tool has been used to show that emissions savings from electrification projects recoup their embodied carbon in typically five years.
Climate challenge
Ensuring that the railway is resilient to climate change is a particular challenge as earthworks were mostly cheaply built over 150 years ago when there was little understanding of soil mechanics. Since then, much has been done to enhance asset and weather management regimes to improve infrastructure resilience.
Although climate change presents significant risks, it is arguable that the risk of biodiversity collapse is even greater. The 52,00 hectares of land owned by Network Rail provide ecological connectivity at a landscape scale. The sustainability plan aims to work in partnership with neighbouring landowners to create a railway estate lined with species-rich grassland, hedges, and well-managed trees and to improve conditions for fragmented populations of rare and threatened plants and animals. The sustainability strategy aims to ensure that there is no net loss of biodiversity across the network by 2024 and requires a net gain by 2035.
A beaver tunnel beneath the railway
With Network Rail spending £7bn a year on its supply chain and generating 2.1 million tonnes of waste each year, minimising such waste and the sustainable use of materials is a key aspect of its sustainability policy. This aims to reuse, repurpose, or redeploy all surplus resources, minimise use of resources, design out waste and plastic pollution, and embed circular economy thinking into the industry. The company aims to reuse, recycle, or redeploy all non-hazardous infrastructure materials by 2029.
A circular economy seeks to move away from disposal towards a system of designing out waste, keeping products and materials in use for as long as possible, reusing, recycling and repurposing materials at the end of their life rather than throwing them away. A good example is the reuse of track materials.
Over the last 10 years, Network Rail’s High Output Ballast Cleaning System has recovered 2.6 million tonnes of track ballast for reuse back onto the track, saving £9m in material costs. When used track ballast cannot be reused, the rejected ballast is transported by rail to one of Network Rail’s nine aggregate handling depots. These depots process used ballast material as well as redundant railway sleepers and rail from track renewal projects for reuse, either back into the railway, in land reclamation or sold on for reuse in heritage railways or construction.
Adding social value
Social responsibility is perhaps a not-so-obvious aspect of sustainability. Network Rail has the potential to affect the lives of its seven million neighbours for good or bad. Good environmental practice to, for example, reduce noise nuisance is an obvious requirement. Yet rail can also benefit local communities. The Rail Social Value Tool, provided by RSSB, has been developed to assess this in accordance with HM Treasury Green Book principles and will be fully launched this year.
The intention is that, by measuring such added social value, more informed decisions about services and infrastructure improvements can be made. As an example, it is estimated that community rail volunteers generate a social value of £28m a year.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.