Research from our fellows

February 4, 2021

When in a hole stop digging. All local road schemes promoted by local authorities must be cancelled

Professor John Whitelegg was appointed FIT Senior Fellow in 2020.

Road safety

On 2nd February 2021, Herefordshire Council cancelled the Hereford Bypass on climate change, cost and the availability of more effective non-road building alternatives to achieve wider Council objectives including the reduction of congestion in Hereford.

The Herefordshire recognition that building new roads does not pass climate change, cost and the availability of alternatives test is not evident across all local authorities. In reply to a Freedom of Information request dated 4thAugust 2020 the DfT supplied a list of all the approved Large Local Major (LLM) road schemes. The total cost of these schemes was £6.986 billion (Note 1).

New roads are recognised as a significant source of additional carbon emissions (Sloman and Hopkinson, 2020; Mottschall and Bergmann, 2013, Chester and Horvath, 2009).

“A road scheme increases carbon emissions in several ways. There is significant embodied carbon in the steel, concrete, asphalt and other raw materials used to build it. If there is extensive land clearance and many mature trees are felled, a carbon ‘sink’ is lost.

“The construction impacts of road building arise from land use changes (e.g. site clearance and loss of trees, disturbance of soil); embodied emissions associated with the materials (e.g. steel, concrete, asphalt); fuel, electricity and water associated with plant and equipment used in clearance and construction; travel of construction workers to the site; and transport of construction materials and waste. These emissions are generally estimated using the Highways England Carbon Tool (published in 2015 and updated in 2019) and guidance set out in a British Standards Institute specification”

“Construction carbon ranged from 60-730 tCO2e per £1 million expenditure, with an average of 456 tCO2e per £1 million”

Sloman and Hopkinson, 2020

Embodied carbon associated with road construction has been presented at the public inquiry into the M4 relief road in South Wales, Whitelegg (2017), Anderson (2017)

A Freedom of Information request to the UK National Infrastructure Commission (Note 3) requesting a copy of guidance on the estimation of embodied carbon from the full life cycle of road building produced the response:

“The National Infrastructure Commission (NIC) does not hold information within the scope of your request. The NIC has not developed a methodology for estimating the carbon impact of adding additional road capacity.”

FOI request to the National Infrastructure Commission. Submitted 5th December 2020. Reply received 15th December 2020 (Ref No NIC2020-27)

Freedom of Information requests were sent to 59 English local authorities in the DfT list of LLMs. The request was for information on the embodied carbon associated with the full life cycle of construction. Four replied with data on tonnes of CO2eq embodied carbon, 41 replied saying “we do not have this information”. Replies are still awaited from 14 local authorities.

The lack of attention to the development of a robust evaluation methodology for the estimation of the carbon impact of road building and its c£34 billion budget is a significant failure of national transport and climate change policy and contrary to the spirit and purpose of declaring a climate emergency.

The German federal environment ministry (Umweltbundesamt) has published a robust methodology (Mottschall and Bergmann, 2013).

Embodied emissions are the full supply chain emissions associated with the initial creation of an asset. Typically this includes emissions from: raw material acquisition, transport, processing and manufacturing of building materials; distribution of materials to site and energy used on-site in assembly. In the infrastructure sector these are commonly referred to as capital carbon emissions to accord with the concept of capital cost. (Scott, Giesekam, Owen and Barrett, 2015)

Embodied carbon is sometimes referred to as “capital carbon”.

“Capital carbon. PAS2080 defines capital carbon as GHG emissions that can be associated with the creation, refurbishment and end of life treatment of an asset. This follows for all infrastructure sectors which have similar sources of capital carbon. This includes the emissions associated with the use of materials, such as concrete and steel, the use of construction plant, such as excavators or tunnel boring machines, and the transport of materials and plant to construction sites. This will occur for all construction activities be they directed to new build, maintenance or refurbishment. Capital carbon emissions also arise at end of life and are associated with demolition, waste processing and any final treatment/disposal. Carbon emissions from transportation which occurs as part of any of these activities is considered to be capital carbon

British Standards Institution, PAS 2080:2016 Carbon Management in Infrastructure

A group of researchers at Leeds University have developed a methodology for the National Committee on Climate Change to provide an estimation tool that can be used to quantify embodied carbon in infrastructure projects (Scott, Giesekam, Owen and Barrett 2015).

Embodied emissions do not include operational emissions. These are the CO2 emissions generated by the traffic using the new road and taking into account the evidence around “new roads generate new traffic” (SACTRA, 1994).

Embodied greenhouse gases can be estimated by a methodology that is in the public domain and described in the Leeds University report. This is the top-down, environmentally-extended input-output analysis (EE-IOA). The key finding of the Leeds team is that the carbon intensity, spend and embodied emissions can be estimated using the EE-IOA methodology to produce an average value (kgCO2e/£) of 0.98.

“EE-IOA generates an emissions intensity factor for the emissions embodied in UK construction per pound spent on the construction sector’s output (kgCO2e/ £), which we take as representative of the emissions intensity of infrastructure. This relates to all the physical goods and services required along the construction sector’s supply chains, whether produced in the UK or abroad.”

Scott, K., Gieskam, J., Owen, A and Barrett, J (2015) Embodied greenhouse gas emissions of the UK National Infrastructure Pipeline (NIP), University of Leeds

The total cost of the LLM road schemes supplied by the DfT is £6.986 billion (Note 1).

Referring to the above table from the Leeds University report we can see that the calculation produces an estimate of embodied kgCO2eq of 0.98 per £spent (2021 estimate). I therefore calculate that the embodied CO2 associated with the DfT list of LLM schemes is 6.986 billion x 0.98kg = 6.846 billion kgs or 6,846,280 tonnes (Note 2).

This additional burden of 6,846,280 tonnes of CO2 is an avoidable and unacceptable move in the wrong direction. Decarbonisation and dealing with climate change requires a reduction in carbon and not a policy that increases those emissions by 6,846,280 tonnes of CO2eq.

The incompatibility of projects that generate extra carbon with a clear policy to reduce carbon was one of the reasons quoted by the Inspector, Michael Ellison, at the Thames Gateway Bridge public inquiry in his report rejecting the proposal in 2007. The inspector recommended that the TGB should not go ahead.

“Global warming and climate change. The estimated proportion of all greenhouse gas emissions in the UK that comes from transport varies according to the views of different estimators, but is generally thought to lie in a range between about 21% and about 32%. Private cars account for about 10% of UK carbon dioxide emissions. (9.379) Carbon dioxide reduction from transport is possible to the level required by national policy, but it would require behavioural change. TfL’s evidence is that the scheme would result in the emission of an additional 55,000 tonnes of carbon dioxide in 2016. (9.380) TfL respond that this is only an increase of 0.4% across the study area. Even if it were doubled, it would be less than 1%. (9.381) It seems to me that even a small increase offers no assistance in achieving a reduction to which the Government has made a commitment. (9.382)

“On the other hand, I consider that the proposed TGB would not comply with national planning policy on transport, and it would result in a negative contribution to the Government’s commitment to reducing greenhouse gases (9.427).”

Inspector: Michael Ellison MA Assistant Inspector: John Watson BSc FIHT MICE MCMI, Thames Gateway Bridge (2007) Inspector’s Report

All road schemes promoted by local authorities should be cancelled. All the funding allocated to these road schemes should be redirected towards evidence-based zero carbon interventions that reduce the need to travel and maximise the potential for active travel and modal shift in favour of walking, cycling and public transport.


Anderson, K (2017) Climate change and the case against the M4 relief road, World Transport Policy and Practice, v23, 3-4, 69-76

BSI (2016) British Standards Institution, PAS 2080, Carbon Management in Infrastructure. Download here.

Chester, M V and Horvath A (2009) Environmental assessment of passenger transportation should include infrastructure and supply chains, Environ. Res. Lett. 4 024008. Download here.

Mottschall, M and Bergmann, T (2013) Infrastruktur und Fahrzeuge des Strassen-, Schienen- und Luftverkehrs sowie der Binnenschifffahrt in Deutschland, Arbeitspaket 4 des Projektes “Weiterentwicklung des Analyseintrumentes Renewbility”. Download here.

SACTRA (1994) Trunk Roads and the Generation of Traffic, the Standing Advisory Committee on Trunk Road Assessment, Department of Transport. Download here.

Scott, K., Gieskam, J., Owen, A and Barrett, J (2015) Embodied greenhouse gas emissions of the UK National Infrastructure Pipeline (NIP), University of Leeds

Sloman, L and Hopkinson, L (2020) The carbon impact of the national roads programme, Transport for Quality of Life”. Download here.

Thames Gateway Bridge (2007) Inspector’s Report. Download here.

Whitelegg, J (2017) Evidence on embodied carbon to the Public Inquiry into the M4 relief road in South Wales. Download here.

Note 1

The full list of road building projects can be seen here.

Note 2

This estimate is based on the scientific method produced by Leeds University researchers. It is based on an average value of kgCO2eq/£ and it is in the nature of averages that some projects will be above the average and some below.

Note 3

Freedom of Information request to the National Infrastructure Commission. Submitted 5th December 2020. Reply received 15th December 2020 (Ref No NIC2020-27)

“Please let me have a copy of the methodology you use to estimate the carbon impact of new road building. The carbon impact of adding road capacity/providing new roads and bypasses is normally summarised under 2 headings: 1 So-called embodied carbon which is the carbon content of all materials used in road construction e.g. cement, concrete, steel, asphalt and the carbon burden associated with plant and equipment used in construction and the carbon generated by all the HGV activity in delivering and removing raw materials, soil and rocks 2 Carbon in use. What is the carbon total over the planned life time of the road that is a direct result of fuel use by vehicles using the new road? This would take into account the research on induced traffic from SACTRA and carbon emissions for all vehicles types including cars, LGVs and HGVs over the life time of the road and any assumptions you are making about the replacement of fossil-fuelled vehicles by electric/hybrid/.”

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