The projected climate impact of the Lower Thames Crossing is approximately 25% higher than anticipated in National Highways' abortive planning application two years ago, documents submitted for its new application show.
The government-owned company pulled its previous application for a development consent order (DCO) in late 2020, based on early feedback from the Planning Inspectorate (PINS) that it was likely to be rejected. At the time, National Highways said it expected the delay to be minimal - perhaps as short as 100 days.
National Highways finally submitted its new DCO application for the project - estimated to potentially cost up to £9bn - on 31 October and PINS announced late last month that it had accepted it for examination, having assessed the quality of National Highways’ various consultations.
The new application’s Environmental Statement – Climate states: ‘The total net GHG emissions over the appraisal period of the Project (construction stage plus 60-year operational phase from opening) are calculated to be approximately 6.596 million tCO2e [tonnes, carbon dioxide equivalent] with TAG GHG Workbook (DfT, 2022a) / EFT v11 (Defra, 2021).’
This refers to the official Department for Transport (DfT) methodology, using the latest government Emissions Factor Toolkit (EFT), taking into account anticipated changes in the emissions from road vehicles. It comprises construction emissions of approximately 1.763 million tCO2e and 4.8 million tonnes of operational emissions, almost all from road users.
This compares with a projected total of 5.273 million tonnes generated by the scheme over 60 years at the time of the 2020 DCO application. That estimate was based on 3.241 million tonnes of construction emissions, and 2.031 million tonnes of operational emissions, mainly from extra traffic.
National Highways did not dispute that its projection of the scheme’s carbon emissions is 25% higher, comparing the 2020 and 2022 applications.
However, a spokesperson told Highways that it should not be seen as having increased as the two calculations were based on different factors such as an updated design, refined construction methods and materials, and an updated traffic model, with operational emissions calculated using an updated EFT.
The spokesman added that the most recent version of the EFT does not reflect current UK Net Zero policy. He added that the 2022 DCO application includes a DfT-approved sensitivity test that takes the net zero policy into account, and results in a significant reduction in (projected) emissions during the operational phase.
The Environmental Statement concedes: ‘The Project cannot control the implementation of the policies related to reducing road-user emissions, as the levers to support the net zero trajectory in transport emissions are delivered by the Government.’
Andrew Kidd, outcomes director at Lower Thames Crossing, said: ‘The Government's ambitious plans to decarbonise cars and goods vehicles will make road transport net zero by 2050, and would cut the 60-year forecast of carbon emissions from Lower Thames Crossing traffic by at least 80%.’
The scheme’s updated Environmental Statement also suggests that the government-owned company has cut even more from the scheme’s construction emissions. Although this is based on a hypothetical situation where it imagines a before scenario where it uses none of a common cement replacement product - thus increasing the amount it can claim to cut carbon by.
Mr Kidd has told Highways that significant savings are anticipated from the use of ground granulated blast furnace slag (GGBS) – the widely used cement replacement. The latest environmental statement states that National Highways has assumed 65% GGBS replacement for ordinary Portland cement (OPC) in all main concrete grades and 50% for ground improvement.
It calculates a total saving of 402,000 tonnes CO2e, by using this GGBS, around a quarter of a million tonnes higher than two years ago.
National Highways confirmed that this compares the use of concrete made using a high proportion of GGBS as cement replacement (generally 65%), with concrete made without any cement replacement.
However, the 2020 DCO application also stated that the scheme would use 65% GGBS in precast concrete for tunnels and highways. It adds: ‘This goes beyond current typical practice of using approximately 50% GGBS.’
Based on this comparison with what National Highways said at the time was ‘current typical practice’, the 2020 assessment projected savings of 157,626 tonnes of CO2e.
Mr Kidd said: ‘Our focus is now on reducing carbon as we build the new road, and as Pathfinder scheme that is exploring carbon neutral construction, our aim is to take the best practice that exists in the industry today and then work with our delivery partners to push the boundaries and explore how we get to the lowest practical level of carbon emissions and set a new benchmark for the industry to build from.’
