Written evidence submitted by Professor Greg Marsden,
University of Leeds (SRI0010)

Introduction

I work on transport planning and policy with an expertise in understanding what policy change is required to enable the Department for Transport to bring forward a programme consistent with the Climate Change Committee’s Sixth Carbon Budget. I have advised DfT on one of the six pillars of its plan (Place-Based Decarbonisation) and played an important role in shaping Transport for the North’s Sub-National Transport Decarbonisation Strategy. My response relates specifically to point 7 on the call for evidence for this inquiry. I am not ideologically for or against any particular size of roads programme. My analysis relates purely to whether or not RIS2 and RIS3 are consistent with the decarbonisation imperative which the Government and the Department for Transport have committed to. The analysis shows that there is currently no credible pathway for the transport sector to meet the 6th carbon budget. On this basis, there is no justification for a major programme of new roads or road widening.

My Evidence

The question as to whether RIS2 or RIS3 are consistent with the wider transport decarbonisation goal cannot be answered just by looking at individual schemes and their appraisal from a carbon perspective. If there is a credible decarbonisation plan which plots a pathway of emission reduction consistent with the 6th Carbon Budget and the roads programme and the associated traffic growth that forms part of that is within that plan then carbon is not a constraint at a programmatic level.

In order to form an assessment of whether or not there is headroom for a roads programme and associated traffic growth it is necessary to compare the annual changes in emissions that will come as a result of technology and behaviour change. It is essential that this is done annually and that the cumulative effects are summed up because the 6th Carbon Budget is a total budget constraint. If progress is slow initially then there is no headroom later. Of course, by the mid to late 2040s we would hope that all of our transport technologies are either zero emission or close to this. Then, carbon would not be a constraint. However, paying attention to 2040 and beyond misses the point. The carbon budget constraint matters now and every year.

The Transport Decarbonisation Plan included the following set of potential pathways for the decarbonisation of transport. It is important to note that whilst the green range is quite wide, it is only values tracking very close to the most ambitious lower pathway which are in-line with the 6th Carbon Budget. Whilst it is not necessary for every sector to exactly track to the budget, transport is now the largest share of emissions – so if this sector falls short then it is to ask much more of other sectors.

The Transport Decarbonisation Plan set out over 200 pages of description of what would be done over the coming years. Much of it is very positive and good progress has been made in areas like setting phase out dates for fossil fuel cars. However, nowhere in the plan did it specify what the technology or traffic growth projections would be. The Secretary of State’s forward suggested that the aim was “to reduce urban road traffic overall” and that the pandemic offered “the opportunity for a reduction or at least a stabilisation, in traffic more widely” (p6). I asked the Department to provide the underlying data which had underpinned the Image above so we could understand the different scenarios and their implications. My request was refused. I submitted an FOI which was also refused. My appeal was upheld completely by the Information Commissioner. The Department subsequently appealed that decision too. However, before progressing to tribunal, the information was released to me in January 2023. It is important for the Select Committee to ask why this information was not released. The release of background assumptions has been a common practice in the past by the Department (I worked as a Committee Specialist for the Transport Committee between 2001 and 2003). As you will see from my analysis below, the numbers do not make easy reading and pose a direct challenge to the logic being applied elsewhere in the DfT about expanding the roads programme.

To analyse the implications of the data released, I have built a simple model of carbon emissions in the economy which I have tested and validated against recent results published in the National Road Traffic Projections 2022. The values from my model fall within less than 1% of those produced by the DfT over a 15 year period and I take them to be robust.

The first point to note about the DfT’s green policy trajectories is just how different their start point is following Covid. For their most ambitious pathway DfT assumed that in 2022 traffic would be 273 billion vehicle miles per year. In the least ambitious pathway it assumed 359 billion vehicle miles per year. The range is staggering, amounting to 126 billion vehicle miles per annum different. The latest calibrated estimate from the DfT for the 2022 outturn figures suggests around 341 billion vehicle miles, which is just short of the upper trajectory estimate for 2022.[1] So, we already start from a position which is not in-line with the Sixth Carbon Budget.

I have then assessed the following:

• Scenario 1 – What would happen if we project forward from the current traffic levels with the DfT core national road traffic projection 2022 scenario and current committed policy pathway for electrification/ultra low emission vehicles?
• Scenario 2 – What would happen if we project forward the 2022 traffic level with the very low traffic levels assumed in the most optimistic pathway in the Transport Decarbonisation Plan and current committed policy pathway for electrification/ultra low emission vehicles?

The model finds that both scenarios exceed the 6th Carbon Budget by hundreds of MtC. Both scenarios also fall outside the least optimistic projected emissions pathway (the top green fuzzy line) set out in the Transport Decarbonisation Plan[2] (which allows for a cumulative total of 1482 MtC).

Cumulative Surface Transport Emissions from 2019 to 2035

We can therefore conclude that, as things currently stand, using the assumptions which are required to be used in project appraisal, a roads building programme predicated on growth in traffic is not consistent with the Sixth Carbon Budget. It has been argued, by the DfT, during judicial appeals on RIS2, that any one individual scheme does not make a big difference to overall carbon in the UK (the de minimus argument). This seems to be an irrelevant argument as, at a programmatic level, planning for traffic growth on this scale is quite clearly inconsistent with our overall carbon obligations. This, it seems, is now directly traceable back to analysis which sits within the Department for Transport, whereas previously it has only been able to be argued by external experts who have run their own transport and energy models.[3] A different policy pathway is clearly needed and there is no headroom for a roads programme as things stand.

Assumptions

It is important to keep in sight the assumptions that are made in the DfT’s scenarios for the Transport Decarbonisation Plan.

On road traffic levels, in the most ambitious (low green curve) scenario they have assumed:

• Reduction of trip rates of 15% by the end of the pandemic which are then continued with further downwards adjustments
• Lower rates of driving license holding for younger people
• Increased car occupancy to 1.7
• Increased operational efficiency of HGV and LGV (i.e. less empty running so lower vehicle miles)

All of these assumptions would, of course, significantly reduce the need for a roads widening programme. Very little of the content of RIS2 could be seen to be contributing to these goals. Indeed, the lack of attention which National Highways gives to vehicle occupancy, whilst claiming to be focussed on efficient use of its network, has never been justifiable. Are these assumptions actually policy? If so, what else will need to happen to make them feasible (e.g. what accessibility changes will need to happen to allow people to do more whilst travelling less and for more younger people to meet their needs without a car?). What is National Highway’s role in promoting more efficient use of the vehicles that use its network (rather than focussing on the efficient management of inefficiently utilised vehicles).

On technology, there is a very big difference between what is currently accepted as committed policies and what the DfT assumes would happen to track on the lower green pathway. The Chart below shows the different assumptions.

Assumptions on the Proportions of Vehicle Miles Driven in Zero Emission Mode to 2037 (dashed lines are current committed policy and solid the maximum ambition scenario)

The Net Zero Strategy suggests the following by 2030 and 2035:

• 24% and 53% of the car fleet is zero emission
• 14% and 40% of the van fleet is zero emission
• 9% and 37% of the HGV fleet

In the very ambitious TDP scenario it is assumed that by 2035 79% of all vehicle miles travelled by cars and LGVs would be in purely electric mode and 40% of HGV miles in electric. Norway, which has been transitioning rapidly to electric vehicles, in 2021 still only had 21% of its cars as electric vehicles (data from ACEA). The UK believes it will have matched this by 2025 – but with nothing like the incentives in place in Norway. It is normally the case that new cars are driven further than older cars. However, to date this is appears to be less true of electric vehicles, more of which are performing the role of second car in a household. The DfT is still commissioning trials to work out what a suitable decarbonisation pathway for zero carbon heavy freight might be. Whilst I believe more can be done than the current committed policy pathway on technology uptake, it is important to note that even the current pathways are not risk free in deliverability or affordability. I see no credibility to the ambitious technology adoption curve put forward. This still leaves a gap to be addressed to put us on track with the carbon budget – technology will not be able to resolve the problem in the timescale necessary.

Summary

In short, the current traffic growth patterns which feature in the Transport Decarbonisation Plan and the latest National Road Traffic Projections are not consistent with meeting the requirements of the 6th carbon budget. Whilst it is possible to draw technology adoption pathways which reduce emissions towards the 6th carbon budget, these have no credibility. It would be wrong to plan to invest in new or expanded roads in the absence of a credible plan for decarbonisation. There are still huge gaps and uncertainties in many other aspects of the decarbonisation plan such as walking and cycling investment, post-Covid public transport recovery, increasing car occupancy, rail electrification. I would argue for a redistribution of the expenditure planned for RIS3 towards such goals. RIS3 should be entirely focussed on maintenance, adapting to technological advances in vehicles, reducing the carbon impacts of network operations (such as lighting, solar banks, charge points, multi-modal interchanges and tree planting) and safety schemes.

January 2023

Endnotes