“An analysis of carbon emissions following modal shift on to HS2 services”

We’re very grateful to Mark Brewer for sending us this research paper looking in to the various potential modal shift and carbon emission savings models that HS2 can produce, and what the timescales look like for each. This is really well thought out, fully referenced research and we’re really pleased to present it for your consideration.

The full paper is available here; we’ve reproduced the Abstract (aka the tl;dr in today’s parlance!) below to whet the potential reader’s appetite (emphases are ours). Enjoy!


“An analysis of carbon emissions following modal shift on to HS2 services”
–M Brewer MEng, 2021

1 – Abstract

There has been significant debate surrounding the possible carbon neutrality, or lack thereof, that High Speed 2 (HS2) is capable of delivering. A key sticking point has been found in the carbon analysis methods utilised by HS2 Ltd in building the business case for the project, with some results suggesting the line may not achieve neutrality inside its 120-year lifespan. This report covers an analysis into the modal shift opportunities and potential generated by HS2, with particular attention paid to the competition against aviation seen globally on medium distance intercity services. Three scenarios have been tested for this investigation, one in which nothing is built, one in which HS2 is built, and one in which a third runway is constructed at Heathrow to facilitate air passenger growth. As well as this a number of other variables have been assessed in order to create a clearer picture of the potential of the project, with population growth, green travel policy, and minor infrastructure advances all being incorporated into the analysis. The findings in this report have found that HS2 can become carbon neutral well before its end of life, while expansion of Heathrow consistently sees the worst emissions results across all cases. The line itself has been calculated to achieve neutrality against the do-nothing scenario in 72 years, implementing policy to dissuade  domestic air travel dramatically improves this, reducing the time expected to just 41 years. This report does however feature a relatively narrow scope, only looking at the passenger demand changes directly onto HS2 services and ignoring the wider capacity relief that is provided. These figures are therefore likely to be worst case estimates, with carbon neutrality expected to be achieved within four decades of opening of phase 1 in 2033.