Ben Warren
Emissions Principal, Sustainable Development, RSSB
Rail is already one of the greener ways to move people and goods. But the infrastructure behind those journeys accounts for around half of the industry’s carbon footprint. We need to design new assets with carbon in mind.
We increasingly use whole-life carbon assessments to understand the emissions associated with new rail infrastructure.
But two teams assessing similar projects can reach different answers, simply because they have started from different assumptions.
That problem is simple: everyone needs to start from the same assumptions. That is not always happening.
How long will a bridge, track or station last? How often will equipment need replacing? Which emissions factors and assessment boundaries should be used?
Change the assumptions and the final carbon figure can change too.
Making assessments consistent
Established whole-life carbon frameworks do offer an overall approach. But they do not give us the rail-specific detail that is needed for consistency.
That matters. Different asset classifications, design lives, replacement rates, system boundaries, and emissions factors make results harder to compare. They also create uncertainty and duplicated effort.
Most importantly, inconsistency makes it harder to identify where we can reduce carbon.
Developing a coherent set of assumptions for greater value
The new RSSB Rail Infrastructure Carbon Conventions project aims to improve the consistency and quality of carbon assessments across GB rail.
As part of this, RSSB has recently commissioned Arup to work with industry partners to develop a common set of rail-specific assumptions and rules for whole life carbon assessments.
These assumptions will cover asset lives and replacement cycles, emissions factors, and benchmarks for construction and operational emissions.
This is not about making every project identical. Different schemes will always have different circumstances. It is about agreeing the common ground before calculations begin. And this is where the real value lies.
The conventions will help practitioners assess carbon more efficiently and confidently. Instead of reconciling different assumptions, they can focus on what matters: identifying carbon hotspots, comparing options, testing better design and construction choices, and supporting evidence-based decisions that reduce emissions.
Used alongside RSSB’s Carbon Management Tool, the conventions should make assessments quicker, more consistent, and easier to compare.
The conventions promise to shift whole life carbon assessment from a compliance exercise to a practical—and efficient—decision-making process.
This is important. Because before rail can decide how best to cut carbon, it needs to be confident that everyone is measuring carbon from the same starting point.