Ben Warren, Emissions Principal, RSSB, reflects on rail’s decarbonisation commitments, arguing that carbon information should be used to improve project decisions rather than simply informing reports.
Britain’s railway industry has a strong story to tell on decarbonisation. As the most energy-efficient mode of long-distance transport, rail will continue to play a central role in a low-carbon transport system.
But when we talk about rail’s carbon footprint, we often focus on moving trains. That overlooks a significant part of the challenge. Around half of the sector’s greenhouse gas emissions come from the materials used to build, renew, and maintain the railway, particularly steel and concrete. Many of those emissions are determined by design decisions made long before construction begins.
Too often, carbon assessments are carried out after key decisions have already been made. By that stage, many of the biggest opportunities have been lost. Carbon information needs to shape decisions throughout project development, not simply record outcomes at the end.
The need for different decisions
The rail industry has made important commitments on decarbonisation, but ambitions alone will not reduce emissions.
The greatest opportunities are found early in the project lifecycle. Decisions about whether an asset is required, how much material is needed, what can be reused, and how it will be maintained over its life can have a greater impact than selecting a lower-carbon product later in the process.
This is particularly true for concrete and steel. Reducing demand through better design, asset management, and more efficient use of existing infrastructure can often deliver greater savings than material substitution alone.
Organisations across the construction sector increasingly recognise that embodied carbon is not simply a materials challenge. It is a design challenge. The most effective projects consider carbon alongside cost, performance, and operational requirements from the outset.
What this means in practice
Frameworks such as PAS 2080 provide a structured approach to managing whole-life carbon. Network Rail’s Rail Enhancements Hierarchy offers a practical example of how this thinking can be applied.
The first question should always be whether an intervention is needed at all.
In my experience, the biggest carbon savings rarely come from specifying a different material. They come from challenging scope and reducing the amount that needs to be built.
This sequence matters. Buying greener steel, specifying lower-carbon concrete, or requesting environmental product data are all worthwhile actions. But they come too late if the asset is unnecessary, oversized, or difficult to maintain.
The Carbon Management Tool
This challenge is one of the reasons RSSB has developed the Carbon Management Tool, which is available free to Britain’s rail industry.
The purpose of the tool is not simply to calculate and measure emissions. It is designed to help organisations make better decisions by providing a consistent approach to assessing carbon across the asset lifecycle and identifying opportunities for reduction.
For suppliers, contractors, consultants and designers, the benefits are practical. The tool can help teams quantify the carbon impact of different options, demonstrate the value of lower-carbon solutions to clients, and respond more consistently to carbon requirements in procurement and project delivery.
A tool alone will not reduce emissions. However, it will help organisations compare options, identify areas of greatest impact, and understand the carbon implications of different choices at an earlier stage. That creates opportunities to reduce material use, lower costs, improve project outcomes, and build stronger evidence for investment decisions.
Too often, carbon assessment is treated as a compliance exercise. To deliver meaningful reductions, it needs to become part of day-to-day decision-making.
What happens next?
The central message is straightforward. Rail cannot rely solely on its environmental advantages as a mode of transport. We purchase millions of tonnes of materials every year, and the decisions we make about those materials have a significant impact on our carbon footprint.
The industry’s decarbonisation ambitions will ultimately be delivered through thousands of decisions made by clients, designers, engineers, contractors, suppliers, and asset managers. The organisations that can demonstrate lower-carbon solutions, reduce material demand, and provide credible carbon information will be increasingly well placed to win work and support their customers’ carbon objectives.
That means making emissions visible, comparable and actionable. It means using carbon information to improve decisions rather than simply produce reports. It means challenging scope before materials, considering whole-life impacts, and learning from previous projects.
If we can do that consistently, carbon assessment becomes more than a reporting requirement. It becomes a practical tool for delivering a lower-carbon railway while helping organisations improve efficiency, demonstrate value, and stay competitive in a changing market.
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