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RSSB Carbon Measurements Report | Summary & Key Findings

By Chloe Broom
26th February 2021

We worked with the Rail Safety & Standards Board (RSSB) to develop a standardised approach to GHG reporting in the rail industry and support the UK’s 2050 net zero target. The DECARB: Carbon Measurements Report was published in January 2021 and will help shape how this industry tackles climate change as a collective.

Making up 34% of the nation’s carbon footprint, the transport sector is the UK’s greatest source of greenhouse gas (GHG) emissions (BEIS, 2020). Given this, reducing emissions within the transport sector is critical for the national climate change strategy to reach net zero emissions by 2050 (BEIS, 2019). As rail has relatively low normalised emissions compared to other forms of transport (BEIS, 2019), modal shift to rail would significantly support the UK’s national climate commitments.

Despite rail’s position as one of the most carbon efficient means of mass transport when efficiently utilised, there is still significant room for improvement that requires a shift beyond business-as-usual carbon reductions in operations. Emissions are measured and reported in a variety of different ways within the sector, which has meant that historically it has been difficult to understand its climate impact.

Following the Minister of Transport’s challenge in 2018 for the rail industry to remove all diesel-only trains by 2040 and provide a vision for rail decarbonisation, the Taskforce responded with an appeal for a more comprehensive understanding of the rail sector’s carbon footprint. This project, entitled ‘DECARB – Carbon Measurements (T1197)’, is a result of this appeal and was commissioned by the Rail Safety and Standards Board (RSSB). The project was led by Carbon Intelligence and began in January 2020. It is part of the DECARBonising Rail Research programme (DECARB), which is a wider RSSB-led research programme supporting industry-wide decarbonisation efforts by addressing specific issues and questions that impact upon the industry generally.

T1197 aims to provide both an estimate of the rail sector’s carbon footprint, and an understanding of how reporting could be improved.



  • TT197 is looking to calculate a greenhouse gas (GHG) footprint for the UK rail sector. This is in response to Minister of Rail’s challenge to decarbonise the rail network, as well as the UK’s commitment to achieving net zero emissions by 2050.
  • To develop a standardised agreed methodology and set of metrics to apply across the whole rail industry to measure, manage and report emissions on a system-wide basis.
  • Implementing a system to better measure the footprint, will allow the industry to manage it, making an important step forward in working towards the UK’s net zero goal.


The interconnectivity of the rail industry presents a unique opportunity to develop a standardised approach for stakeholders to report their GHG emissions activity data in a collaborative and efficient manner. By doing so, this will streamline the process for rail to make its necessary contribution towards the UK’s statutory 2050 net zero GHG emissions target.


Key research findings

A principal output of this study is a calculation of a carbon footprint for the UK rail industry over the year from 1st April 2019 to the 31st March 2020. We have calculated that the rail sector emitted approximately 9.5 MtCO2e both directly from its own activities and indirectly through activities in its value chain. This figure is 66% greater than the 5.7 MtCO2e estimated previously (RSSB, 2010).

The graph below highlights the results of the project, breaking down rail emissions by stakeholder and subsequently by emissions activity.



Network Rail is the largest emitter in the industry, responsible for almost ⅔ of the total footprint. This is because they’re responsible for managing the infrastructure that the rail sector depends on, which emits a large amount of embodied carbon within its supply chain. Train operating companies (TOCs) and freight operating companies (FOCs) are the next highest emitters, mainly due to emissions from traction power.

Looking exclusively at emission sources, the following graph shows embodied carbon to be the largest source of emissions in the industry – those emissions associated with the extraction, manufacturing, transporting, installing, maintaining, and disposing of materials and products used in the railway infrastructure and other assets, followed by traction diesel / gas oil.


RSSB graph 2


Traction electricity is the third largest source of emissions. Note however that national grid emissions factors of accounting for electricity was used to calculate this figure and therefore does not consider renewable electricity procurement decisions.


Key research recommendations

The RSSB’s previous report on the rail industry’s carbon footprint (T913, 2010) stated that the “implementation of a carbon management framework is crucial to structure data collection and assign ownership of emissions”. Our analysis supports this finding, which indicates that the data collection and analysis process, with its gaps and inadequacies, demands excessive resources simply to manage.

We recommend that the industry should put in place a comprehensive and transparent reporting system to streamline the reporting process and free up resources which would be much better used to support initiatives to reduce emissions. As mentioned previously, the connectivity of the rail sector creates a unique opportunity to collaborate and maximise efficiency.

We make four key recommendations that aim to improve the accuracy of the carbon footprint of the rail sector in the UK, and in turn, drive down carbon emissions:

  1. Implement an emissions reporting system in line with the ‘guiding hand’ approach that adheres to the Greenhouse Gas Protocol Standards and to ISO 14064 principles of GHG accounting.
  2. We recommend that TOCs and FOCs should calculate their full Scope 3 footprints as a priority.
  3. As embodied carbon emissions within the supply chain are the largest source of emissions in the rail sector, stakeholders should place greater focus on reducing these emissions.
  4. We recommend that further investigation through granular data collation is conducted on depot emissions to understand whether depot emissions are significant, and if so, ensure these are addressed.


Download the full DECARB: Carbon Measurements Report here.

At Carbon Intelligence we are committed to supporting organisations measure and reduce their carbon emissions and develop a pathway to help them achieve their targets credibly.


Further resources