In general, transport in the UK has been regarded as a well-regulated sector. It is not surprising, given the obvious potential for public harm, and the high profile of any errant behaviour or system failures. Vehicles, drivers, infrastructure, and service provision by operators are all subject to safety and customer protection regimes. But technology and business practice move on, generating new issues to be addressed. Generally, this happens on a rather piecemeal basis when new modes, technologies, or commercial models emerge, but not always then.

Accordingly, under the Boris Johnson government, the Department for Transport launched its Future of Transport Regulatory Review in 2020 in the form of a call for evidence, initially focused on three areas: micromobilty; flexible bus services; and Mobility as a Service. Other topics that have been considered under this broad initiative included the future of flight, and modernising road vehicle standards. There has also been a look at ‘regulatory sandboxes’ as a means to introduce temporary or specific place-based regulatory flexibilities to support innovation. Yet addressing such topics ad hoc seems to have so far yielded little in the way of useful regulatory advance in any of these fields, let alone others of concern such as secure digital payment systems, customer data protection, and standards of information provision, for example.

One area that has been subject to full consideration is the regulation of automated road vehicles (AVs), an area where the last government seemed to believe there to be a major new industrial development and employment opportunity. The Law Commission was asked to recommend a regime to govern responsibilities when vehicles are operating in driverless mode, whether as ‘robotaxis’ or individually owned vehicles. The outcome was the Automated Vehicles Act 2024, which had broad political support. There is now in place a comprehensive legal framework that developers, operators and insurers of AVs might see as helpful in making clear their legal responsibilities, which, however, might be seen as quite onerous compared with arrangements in countries where the main development of the technology is taking place, the US and China in particular. UK developers of AVs are limited in number and their commercial prospects are unclear.

To be sure, the regulatory regime being put in place for AVs is forward looking and intended to encourage innovation. But the implications for the wider transport system and the management of the road network as a whole, particularly in urban areas, are consequential matters that also need careful consideration, a topic recently reviewed by the International Transport Forum and the subject of an exploratory project report by the National Infrastructure Commission.

Another fast-moving technological development area is aviation. Here a comprehensive sectoral regime operated by the Civil Aviation Authority is well established to oversee safety, security, the efficient use of airspace for maximum public benefit, and to protect the consumer interest. The CAA has set up an ‘innovation hub’, the purpose of which is to create an environment where innovation in aviation can develop in line with the CAA principles. These include ‘pilotless‘ planes and drones. A recent review endorsed the view that CAA is a world class regulator that is fit for purpose, delivering high quality services to the aviation and aerospace industry and the consumer. Moreover, the CAA and DfT are consulting on the creation of a new UK Airspace Design Service that would act as a single guiding mind for modernising the design of UK airspace, exemplifying the CAA’s proactive approach to innovation.

A further sector-wide regulator is the Office of Rail and Road, which originally was solely charged with regulatory oversight of railways, including holding Network Rail to account for stewardship of its network, its funding, as well as protecting the consumer interest in respect of services provided by the train operating companies. The ORR carried out a consultation in 2015-16 on its approach to innovation, following a prompt from the government. The ORR has taken the view that innovation is led by the rail industry and where appropriate it would be supported by the overall regulatory framework, including the duty to promote improvements in railway service performance and promote efficiency and economy on the part of providers of railway services. So, compared with the CAA, the ORR’s approach is relatively passive.

Since 2014, the ORR also has some oversight of roads, but this is limited to the engineering performance and efficiency of National Highways in England in respect of its network, not to other roads. The ORR’s remit does not allow it to address the benefits to road users of new road investments – whether the outturn from investment in new road capacity meets expectations – nor whether the strategic road network is being efficiently utilised (unlike the CAA’s concern with the efficient use of airspace). Again, there is a lack of intention actively to foster technological innovation for the strategic road network, or to analyse and prioritise the optimal use of capacity, and identify where enhancement is most justified.

For road vehicles more generally, there are important examples of regulatory approaches that both drive and support technological innovation. Tackling the harms from tailpipe emissions of petrol and diesel enginned vehicles has been effected by regulations within the portfolio of the Department for Transport that have driven down emissions of air pollutants and by the ZEV Mandate, a legal requirement for a minimum percentage of each manufacturer’s new car and van sales to be zero-emission each year.  Regulations made by local authorities to create urban clean air zones (in London known as the Ultra Low Emission Zone) also help incentivise the switch to electric propulsion, a once-in-a-century transport technology innovation. While the propulsion systems and physical impacts of individual classes of vehicles are a DfT matter, concern for overall emissions and air pollution lie elsewhere – with the Department of Environment, Food and Rural Affairs (Defra) and Department for Energy Security and Net Zero (DESNZ).

When it comes to new modes of travel, the Department for Transport again seems to be following rather than leading, with actions in fits and starts, for example in making regulations allowing trials of rental e-scooters to be fast tracked and expanded in response to proposals from local authorities. The intention is to understand usage, safety, and environmental impacts, and to explore changing travel patterns since the coronavirus pandemic and as e-scooters become more embedded in public life. Only e-scooters participating in official rental trials may be used legally on roads. It is expected that a decision will be made in due course about legalisation of e-scooters as a vehicle class, and about the appropriate regulatory regime, which may include a requirement to park rental e-scooters in prescribed bays. E-bikes are already legal and treated as ordinary bicycles if of limited power, but the problem of inappropriately parked dockless rental e-bikes prompts complaints and pressure to regulate.

In contrast to the supportive approach to e-scooters, and a permissive approach to e-bikes, as innovative mobility technologies, there has been inaction in several other significant areas. This includes updating the historic taxi and private hire legal regime, with minimal recognition by the authorities of the merits of ride hailing as an innovative means of summoning a taxi, exemplified by Uber’s struggles to get acceptance in London. This involved a number of court cases, which found in favour of Uber, while the company lost some other cases concerned with the employment status of drivers, which nevertheless has not seemed to impact on the provision of the service. Uber’s digital request and booking/payment system has proved very popular with users as a better means of getting a taxi compared with licenced black cabs or conventional private hire vehicles, as well as being sufficiently attractive to drivers so as to offer customers an acceptable level of service. But this outcome was no thanks to a taxi regulatory regime having a remit to foster innovation. On the contrary, taxi regulation is historic, not modernised for the digital age, rightly concerned with the protection of customers, less defensibly having the effect of protecting the trade of established black cab drivers. There is a marked contrast between this reluctance to welcome innovative approaches to taxi services and the progressive stance towards automated vehicles, including robotaxis.

In terms of road usage, beyond the urban areas where e-scooters and ride hailing taxis operate, regulation of the inter-urban system roads is confined to vehicle and driving licence holding, vehicle type approval and performance – handled by a number of specific agencies like DVLA and DSA – with speed limits and other rules of the road embodied in the Highway Code – an historic regime that has not generally recognised advances in innovative technologies.

One technological innovation that has been widely adopted is digital navigation, applicable to all travel modes to replace conventional maps. In the road context, this is generally known as satnav and is offered by a number of providers including Google Maps and Waze via free-to-use smartphone apps, and others who provide input to equipment installed by vehicle manufacturers. A key element of many of these offerings is to indicate the fastest route in the light of prevailing traffic conditions. Digital navigation is changing the way drivers use the road network in three main ways: local users are attracted to new capacity on major roads, pre-empting the additional capacity intended for longer distance business users and so weakening the economic case for the investment; longer distance users can divert to local roads that offer faster journeys than on congested major routes, roads that are well suited to active travel; and predictive journey time information allows more efficient use of the network.

At present, provision of digital navigation is a free-for-all, funded by sales of direction-finding to businesses that wish to attract clients to their premises, as for Google Maps; or by the sale of services to vehicle manufacturers that fit navigation as original equipment, as for TomTom. Road authorities generally seem to be paying little if any attention to these developments. Yet there are opportunities being overlooked to make better use of the road network, both urban and inter-urban, including buses services.

Curiously, legislation has long been in place to allow providers of digital navigation to be regulated. This dates back to 1989 and requires what were then termed ‘dynamic route guidance systems’ that take account of traffic conditions to be licensed by the government. The intention was to facilitate the introduction of a pilot route guidance system, known as ‘Autoguide’, that had been developed by the government’s Transport and Road Research Laboratory and required roadside equipment to be installed – a good example of forward-looking regulation to support innovation. The licence could include conditions concerning the roads that should not be included in the route guidance, the provision to road authorities of information on traffic conditions, as well as the right to install roadside equipment. In the event, the Autoguide pilot did not proceed, due, I suspect, to the limited computing power available at that time. Nevertheless, the legislation has remained on the statute book although no licences have been applied for or granted.

The possibility of achieving more efficient use of the road network through provision of better information about traffic conditions to both road users and road authorities was recognised early on by John Wardrop, a traffic analyst at the then Road Research Laboratory, in a seminal paper published in 1952. He postulated two equilibria. The first states that, under equilibrium conditions, traffic arranges itself in congested networks in such a way that no vehicle can reduce its costs (time and money costs) by switching routes. For this to happen in practice, drivers would need to have perfect knowledge of all feasible routes and travel times. Digital navigation may be seen as improving such knowledge, thus enhancing network efficiency, yet with a number of independent providers that may offer conflicting advice, it is hard to assess to what extent increased efficiency is being achieved.

Wardrop’s first equilibrium assumes that road users make decisions without regard to the impact their choices may have on others – a ‘selfish’ equilibrium. According to his postulated second equilibrium, the average journey time would be at a (lesser) minimum if all users behave cooperatively in choosing their routes to ensure the most efficient use of the whole system. This would be the case if an omnipotent central authority could command them all which routes to take. Traffic flows satisfying Wardrop’s second equilibrium are generally deemed system-optimal, and the loss of efficiency from this to the selfish equilibrium is an example of what is known as ‘the price of anarchy’.

Economists argue that a more socially optimal outcome could be achieved if the costs imposed by the marginal road user on others, by adding to congestion, could be internalised by a congestion charge, thus modifying behaviour by reducing demand through higher vehicle operation costs. However, implementing road pricing is difficult in practice, and there are issues of equity, so a question worthy of investigation is to what extent a more socially optimal outcome could be achieved through flexing the routing advice offered by providers of digital navigation – ‘nudging’, not compulsion

The likelihood that improved operational efficiency could be achieved through digital navigation is suggested by the wide use of such routing and navigation systems by the competitive road freight sector. Everyday experience of online shopping indicates the use made by logistics businesses of digital technologies to manage, track and predict flows of goods, often offering delivery time slots of two hours or less, all done algorithmically. This points to techniques to achieve operational efficiency on congested road networks that might be extended to the generality of traffic in a way that could be far more cost effective and less carbon generating than civil engineering technologies.

The competing providers of digital navigation services are generally uncommunicative about their operations, while highway authorities appear to show no interest in the impact of this technology on the functioning of the road networks for which they are responsible. One kind of opportunity for mutual benefit would be when the network is under stress, for instance on the occasion of major incidents, peak holiday flows, bad weather and the like. It is probable, and certainly worth further investigation, that coordination between highway authorities and digital navigation providers could make better use of available capacity. There is also the possibility of improving operations at normal times, including avoiding routing through traffic via unsuitable minor roads. There is therefore likely to be scope for coordination that would improve outcomes for road users. This might be through the parties acting voluntarily for mutual benefit, or through the updating and implementation of the 1989 regulatory regime.

Although, by and large, the transport sector is functionally regulated to avoid calamity, there are obvious gaps that could usefully be filled to the benefit of users and to give innovators a sound basis upon which to progress their new ideas – or at least try them out with appropriate dispensation. This is particularly the situation in respect of the operation of the road network. As well as concern for safety and customer protection, all regulators should have a remit to encourage innovation that offers user benefits, since making effective use of existing infrastructure is preferable to creating new capacity, given the need to achieve the Net Zero climate change objective.

The new Labour government has set up a Regulatory Innovation Office, with the aims of supporting regulators to update regulation, speeding up approvals, ensuring different regulatory bodies work together smoothly, informing the government of regulatory barriers to innovation, and setting priorities for regulators which align with the government’s broader ambitions. This is an ambitious and potentially extensive agenda. Yet it will be disappointing if the emphasis solely on novel and exciting new technologies, a possibility suggested by one initial topic, the role of drones as a form of connected and autonomous vehicle technology – surely a rather niche market. In contrast, there is much scope for encouraging innovative approaches in the mainstream emerging transport technologies, where the new Office could hopefully play an influential role.

This blog post is the basis for an article that was published in Local Transport Today 0f 31 October 2024.

My new book, titled ‘Travel Behaviour Reconsidered in an Era of Decarbonisation’, brings together arguments and evidence that I have discussed briefly in my commentary columns in Local Transport Today and in previous books intended for non-specialists. This book, aimed mainly at professionals and academics, is fully detailed, evidenced and referenced, yet concise and (I hope) cogent, the core of which is a critique of orthodox transport economic analysis and modelling, plus proposals for fresh approaches. It is published by the UCL Press, part of my own institution, an academic open access publisher launched in 2015, that makes copies of its books free to download as PDFs and claims more than 10 million downloads so far. In this blog post I will outline the main themes of the book, as a trailer to encourage readers to access the full text.

I argue that the need to reconsider travel behaviour and its analysis is two-fold. First, decarbonising travel could be achieved both by new technology and by altering behaviour so that we make less use of the car. The question for consideration is whether such behaviour change is feasible in practice on a scale that would make a useful contribution.

Second, I argue that there is a need to reconsider the economic analysis of transport investment so that this reflects the observed travel behaviour of real people in the real world, as opposed to assumed behaviour of utility-maximisers functioning within constrained analytical frameworks, the orthodox practice.

Behaviour change

To set the scene, the first chapter of the book outlines the pattern of travel on Britain, largely based on findings of the National Travel Survey prior to the pandemic. (UK data is particularly extensive, but I refer to other countries where possible.) The main feature, of course, is the dominance of car travel, which brings with it a variety of problems familiar the LTT readers. Yet the attractions of the car tend to be underestimated by those who hope for a shift to public transport and active travel. The car provides convenient door to door travel over short to medium distances where road traffic congestion does not cause excessive delays and parking is available at both ends of the trip. These conditions may not be satisfied in city centres, where public transport can be provided most economically and where catchment areas, whether for schools or supermarkets, are tighter, making active travel more feasible. But beyond city centres – in the suburbs, towns and rural areas – alternative to the car are much less attractive and mode shift much more difficult to achieve.

Yet the car is not attractive just for its utility; there are also ‘feel good’ factors that prompt car ownership and car-dependent lifestyles. Witness that cars are parked for 95% of the time, a good economic argument for car sharing, but conversely an indication of the value placed on private ownership. Witness also the growth ownership of SUVs, not least in urban areas where there is little practical need for a large 4×4 in place of a traditional smaller hatchback. The motor manufacturers are naturally focused on satisfying such feelings; and governments are supportive of auto industries for reasons of industrial and employment policies.

In the third chapter of my new book, I outline the important consequences of the coronavirus pandemic, a ‘natural experiment’ that showed how digital access could substitute for physical access under ‘lockdown’. Yet once the restrictions were lifted, car use returned quickly to pre-pandemic levels, consistent with the attractions of the car for gaining physical access to people and places, activities and services.

Chapter 6 discusses the routes to transport decarbonisation. For surface transport, electric propulsion is by far the most important means, though the equivalent in aviation is much more difficult. Some analysts and policy makers argue for a substantial reduction in car use as well, for instance by 20% as soon as 2030. But because of the attractions of the car, and given the built environment we have inherited within which trip origins and destinations very largely arise, any such reduction reflects much wishful thinking. The best prospects are in city centres where rail in all its forms provides speedy and reliable travel compared with cars, buses and taxis on congested roads. But urban rail is costly and takes a long time to build. Cycling infrastructure is much cheaper and quicker to implement, but largely attracts people from public transport, not from their cars.

So the prospects seem quite limited for changing travel behaviour and reducing car use on a scale that would make a useful contribution to decarbonisation objectives. How did we get to this state?

Changing travel trends

The historic trends in travel behaviour, the successive changes that have occurred, and their implication for future demand, are at the heart of what the new book explores. The evidence presented in the second chapter suggests four eras of travel: first, early man came out of Africa to populate the habitable earth, walking for 3-4 hours a day, covering around 3000-4000 miles on average, hunting and gathering. Then, starting 12,000 years ago, settled farming communities came into being, when average daily travel time fell to about an hour a day, covering about 1000 miles a year at walking speed (horse drawn vehicles on poor roads were not much faster).

The third era began in 1830 with the opening of the first passenger railway, between Manchester and Liverpool, utilising the energy of coal to travel faster than walking pace. Oil in the twentieth century permitted mass mobility through the internal combustion engine employed for road vehicle propulsion, as well as air travel. And the modern bicycle harnessed human power for local trips at faster than walking pace. According to the National Travel Survey, the average distance travelled in Britain increased to reach about 7000 miles per person per year by surface modes by the end of the twentieth century, with average travel time invariant at an hour a day. But then growth ceased, in part the result of exhausting the scope for faster travel through refinement of established technologies. This was the beginning of the fourth era of travel, that driven by the need for decarbonisation.

Each of these past innovations in transport technology based on fossil fuel energy led to a step-change increase in the speed of travel, and in turn to increased distance traversed in the long-run invariant hour a day of daily travel. Hence the benefits of faster travel were taken in the form of greater access to people and places, employment, services and activities, to family and friends, with the enhanced opportunities and choices that improve our quality of life.

In contrast, the new transport technologies seem unlikely to result in increases in speed of travel or of access. Electric propulsion is important for decarbonisation but does not increase the speed of travel. Digital platforms, exemplified by the access readily provided to car travel by the likes of Uber, and digital navigation, known in the road context as satnav, improve the quality of the journey without increasing speed. And automated vehicles on roads shared with conventional vehicles seem unlikely to permit faster trips. So these, the main new technologies, will not increase access benefits to users of transport networks.

A second reason why the growth of average daily distance travelled ceased to increase at the turn of the century, is evidence that those with the availability of a car in the household or good public transport services have arguably adequate levels of access, choices and opportunities, such that there is no need to travel further. Hence demand can be said to be saturated, a general feature of mature markets, and with no reason why travel should be an exception. However, travel to permit access has two distinct characteristics. First, improved access to any given class of destination is subject to diminishing returns, a standard economic concept. And second, access increases with (up to) the square of the speed of travel, reflecting elementary geometry. The combination implies that per capita travel demand for the purposes of access may be expected to saturate, consistent with the findings of the National Travel Survey and other sources.

While per capita travel has ceased to grow, the UK population is increasing, which requires consideration of how this may propel travel demand growth. Much would depend on where the growing population would be housed: new homes on greenfield sites would increase car use, whereas accommodating population growth within existing urban areas would point towards improvement of public transport services to meet the associated transport needs. The scale and location of new homes is currently a major issue of national policy, yet to be settled.

So the fourth era of travel is characterised both by the lack of new technologies to travel faster, and by substantial travel demand saturation, both helpful to implement transport decarbonisation. Yet population growth accommodated on greenfield sites is unhelpful. Overall, the scope for a significant reduction in travel demand seems quite limited.

Appraisal and modelling reconsidered

The second core theme of my book – decision-making processes for transport investment – leads to a fairly detailed critique of conventional transport economic appraisal which is based on the supposition that the saving of travel time is the main benefit of investment in new capacity. My conclusion is that it has not been possible to achieve a self-consistent methodology in this territory even after some sixty years of effort. One consequence is a mismatch between the policy objectives of many high-profile investments and the conventional estimation of economic benefits, which is therefore suitably massaged to align with the policy.

At the same time, there has been growing general recognition that the main benefit of investment that allows faster travel is increased access. However, attributing monetary value to access has proved difficult conceptually, and has not been successfully developed into a methodology for practical application. Besides, as noted above, travel demand for the purposes of gaining access is subject to saturation, quite unlike demand based on the supposition of time saving, which means that the latter cannot be a proxy for the former.

Identifying the benefits of investment as enhanced access creates problems for transport modelling, another issue I explore in some depth in the new book. Transport models to justify major investments typically comprise two parts: a variable demand multimodal traffic model, the outputs of which are inputs to an economic model that allows estimation of monetary benefits, comparing the with- and without-investment cases, and hence yielding the benefit-cost ratio, important for the decision to invest. Yet benefit in the form of increased access cannot be accommodated by the economic model as it exists, on account of the assumption of transport economists that time savings are the main benefit. This therefore requires the traffic modellers to constrain model outputs to a counterfactual case in which travel time is saved, rather than used to travel further for greater access, disregarding the increased vehicle-mile-related externalities and land use change that arise in reality. So transport modelling as currently practiced does not provide a secure basis for the estimation of investment benefits, nor of carbon and other externalities.

Fresh approaches

Pulling all these threads together, the final chapter of my book suggests some fresh approaches to travel analysis and transport policy, to respond to the methodological shortcomings of conventional appraisal and modelling that I identify, and to the need to make progress towards the Net Zero objective. I suggest a presumption that Britain has a mature transport system comprising the road and rail networks, consistent with travel demand saturation as discussed above. This is already the case for urban roads, where, in the last century, investment in increased capacity in the form of both new (often elevated) highways and enlarged carriageway for vehicles took place in response to growing car ownership; whereas more recently the trend has been to recover such capacity for active travel and prioritised bus routes. Demand for vehicle travel on urban roads must now be managed within constrained capacity.

There is a good argument for treating the interurban road network as mature, so not aiming to invest to increase capacity generally, hitherto justified by notional travel time savings. There may be benefits from particular investments associated with land use change; for instance, were a third runway at Heathrow airport to be built, investment in surface transport infrastructure would be needed to cope with increased passenger numbers, the resource implications of which should form part of the cost of the project as a whole.

More generally, location-specific road investment to make land accessible for development could be justified where the decision to develop is made jointly by planners, developers and transport authorities and where the developer contributes to the cost of the infrastructure. The case would be based more on commercial considerations than on orthodox welfare economics, although carbon emissions and other externalities should be taken into account.

Cessation of investment in a national road construction programme would be a big shift of policy politically, although this is what the Welsh government decided two years ago. But there is still widespread support for road investment among most politicians, national and local, the latter because the funds provided by central government are seen as ‘free money’. It is widely supposed that increasing road capacity reduces congestion, improves connectivity and boosts economic growth, although the basis for this supposition is tenuous. And of course, the construction industry and the consultancies that benefit from the funds that flow are also supportive. Nevertheless, there is a strong case for a switch in effort from costly investment in new civil engineering structures to making best use of the physical infrastructure we have. Economic analysis and modelling would then focus on the efficient management and use of the network, closely linked to the operational analysis of the road network in real time, a topic that has been neglected hitherto. To do this we now have the opportunity to take advantage of digital technologies that are already in wide use and are both scalable and relatively low cost.

Transport economic analysis has focussed on individual projects. In contrast, it has always been difficult to articulate an economically persuasive strategic case for a programme of transport investment. Regarding the transport system as substantially mature changes the main challenge from justifying a collection of investment projects to reconciling transport operations with the Net Zero objective.

The key elements of a strategy, whether of a particular sector or of transport provision as a whole, are:

  • the switch to zero-emission vehicles for surface transport;
  • employment of digital technologies to optimise network operations;
  • and financial support for public transport.

Alongside these, any investment in new capacity should now be specifically justified case by case to support economic development, such decisions being taken jointly with planners and developers, and schemes funded in part by the developers, as beneficiaries.

Active travel is not included in my key elements of strategy, although it is a good thing in many respects, including health and environmental benefits – I myself am a cyclist. But I see limited scope for getting people out of cars onto bikes. Copenhagen is a city famous for cycling, but car mode share is only slightly less than in London, while public transport is half that in London. So you can get people off buses onto bikes, but harder to get them out of cars, even in a small, flat city with excellent cycling infrastructure and a strong cycling culture.

One reason is that in Britain 80% of carbon emissions from car journeys arise from trip of more than 5 miles, and 95% from trips of more than 2 miles, so only limited opportunity to get switch to cycling and walking respectively. I don’t therefore see promotion of active travel as a central
element of a national transport strategy, although in cities with crowded public transport it may have more attractions, as in London, albeit with some loss of farebox revenue.

POSTSCRIPT

The new government’s policies: do they meet the need?

The manuscript of my book was completed before the General Election, which has led to a new focus on the basis of transport decision-making and the sources and allocation of funding. The new Labour Chancellor Rachel Reeves soon cancelled the proposed Arundel Bypass on the A27 and the tunnel adjacent to Stonehenge on the A303, as well as some minor rail schemes, laying the blame at the budget deficit.

Louise Haigh, the new Transport Secretary, has meanwhile been required to undertake a review of £800m of unfunded commitments in her department and a basis of prioritisation of projects, suggesting shortcomings in its system of controls. A new Office of Value for Money is to be established to identify areas where the government can reduce or stop such problems or improve the value of spending.

The government also intends to establish a National Infrastructure and Service Transformation Authority (NISTA), comprising the National Infrastructure Commission and the Infrastructure and Projects Authority, to drive more effective delivery of infrastructure across the country and support a 10-year infrastructure strategy. A seasoned transport and railway professional, Lord Hendy, has been given the rail policy brief, and a junior minister at the Department for Transport, Lilian Greenwood, the title ‘Minister for the Future of Roads’. All this suggests that there may be changes from past policies in the offing, in a direction that could be consistent with the arguments I have been making.

Such new approaches inevitably raise questions about the competence of the Department for Transport that cannot just be attributed to misjudgements by past Conservative ministers. A point of comparison is Transport for London, which is generally agreed to be a world leading planner and provider of regional public transport and major roads. TfL has a good vision of how London’s transport system needs to develop, aiming to implement the Mayor’s Transport Strategy and consistent with his responsibilities for housing, the environment and for London’s economy. This vision involves major investments in rail, low-cost investments in active travel, plus operational improvements across the board. Such a vision requires validation of individual investments – the ‘vision and validate’ approach.

But here it is important to recognise that decision makers do not simply bring an open mind to consider a portfolio of potential investments from which they might choose. Generally, those in charge – senior and experienced people – will have a pretty good idea of what investments they would like to make, and can justify. They seek validation from analysts – modellers, planners, economists, engineers. Validation includes securing good value for money and complying with all legal requirements. It is thus not often that major misjudgements occur in the choice of projects pursued. The popularity of the new Elizabeth Line, formerly known as Crossrail, is a good example of what has been achieved, despite overruns of construction time and budget. Other successful projects have been the introduction of the Congestion Charge and the upgrade of erstwhile ‘Cinderella’ rail lines into the London Overground.

In contrast to TfL, the Department for Transport has had neither a vision nor a strategy, nor has been a ‘driving force’ in the proposal/selection and delivery of the potential ‘best’ schemes, or the promulgation of effective ‘system management’ concepts. What it has had are problems with the major sectoral ‘wish list’ expenditure programmes for road and rail, the economic benefits of which it has found difficult to convincingly justify, both at programme level and for individual projects, but creating huge pre-emptive budget requirements. It has overseen serious cost overruns on HS2, had many setbacks and criticisms in the courts in the face of litigation by those objecting to road schemes. And it has struggled to reconcile the impacts of a large road investment programme with the Net Zero climate change objective, having its overall decarbonisation plans for transport twice rejected in the courts.

My book discusses many of the proposed investments supported by the Department as case studies in the application of a defective appraisal methodology, including the virtually impossible to justify Stonehenge A303 tunnel, questionable smart motorway schemes (a programme cancelled by the previous government as the result of public anxieties about safety, but falling well short of expectations economically), HS2 (now truncated), and the extended saga of a third runway at Heathrow. In some cases, the analysis was forced to comply with a prior policy decision, in others key strategic economic benefits were poorly treated or disregarded.

There is now surely a good case for an independent review of transport investment appraisal and modelling to identify a fit for purpose methodology for an era in which the high-level strategic priority is decarbonisation. I hope my book might provide useful evidence and argument were such a review to take place.

My new book is available at https://uclpress.co.uk/book/travel-behaviour-reconsidered-in-an-era-of-decarbonisation/ free to download as a PDF.

This blog post was the basis of an article in Local Transport Today of 5 September 2024.

The National Infrastructure Commission published its Second National Infrastructure Assessment on 18 October. The Commission’s objectives, set by the Government when it was established in 2015, are to support sustainable economic growth across all regions of the UK, improve competitiveness, improve quality of life, support climate resilience and transition to net zero carbon emissions by 2050, all within a specified long-term funding envelope for its recommendations.

The NIC’s remit is to issue a comprehensive analysis of the UK’s infrastructure requirements once every five years. This covers all economic infrastructure sectors, setting out recommendations for transport, energy, water and wastewater, flood resilience, digital connectivity and solid waste. The Assessment takes a 30-year view of the infrastructure needs within UK government competence and identifies the policies and funding to meet them.

First, I will look at some of the key conclusions and recommendations concerning transport from the NIC’s analysis, which should be fairly uncontentious, at least for transport planners and practitioners:

  • The public transport networks of England’s largest cities under-perform relative to comparable European cities. Initial priorities for investment should be in Birmingham, Bristol, Leeds and Manchester and their wider city regions, to prevent growth being constrained. The scale of capacity increases required justifies investment in rail- or tram-based projects. The government should make financial support conditional on cities committing to introduce demand management measures to reduce car journeys in city centres, and cities should provide a contribution of at least 15-25% to the funding of large projects, whether from fiscal devolution or transport user charging.
  • Transport budgets should be devolved to all local authorities responsible for strategic transport so that all places are able to maintain existing infrastructure – for example improving the condition of road surfaces – and invest for local growth. This will also help places develop locally led infrastructure strategies through which transport investment can be considered against long term goals and planned alongside housing and land use development.
  • For the national road and rail networks, the government’s first priority should be to maintain existing networks by investing adequately in maintenance and renewal, including ensuring resilience to climate change impacts.
  • In order to align the processes of road and rail capital investment, the government should set a long-term investment pipeline across road and rail around an indicative total budget envelope and with clear common strategic objectives. This should incorporate a strategic vision for the main transport corridors that includes both road and rail, ensuring that they are considered together and not separately.

The NIC goes on to say that the cancellation of HS2 beyond Birmingham, which happened only at the beginning of October, after the Assessment had been completed, leaves a major gap in the UK’s rail strategy around which a number of cities have based their economic growth plans. A new comprehensive, long term and fully costed plan is needed, says the Commission, to set out how rail improvements will address the capacity and connectivity challenges facing city regions in the North and Midlands. Who could argue with that?

More problematic, in my view, is the NIC ‘s proposition that the government should plan and invest in enhancements to the road network, targeting under-performing sections that can facilitate trade in goods, and provide better connections between cities to facilitate trade in services, observing that it is not clear that this happens at present. Accordingly, the NIC has developed a portfolio of road enhancement options, based on a connectivity metric developed by consultants, that gives each place in Britain a score to denote how well connected it is to other places, calculated by taking the average travel time between a given place and other places in Britain, and weighting them by population and distance, which are useful indicators of likely demand for travel between places. This approach is used to identify the worst performing routes on the network with substantial demand potential between key cities and towns (see map in illustration). The portfolio has been developed within a proposed budget for road investment to cover the next 20 to 30 years.

In support of its proposals for road investments, the Commission states that better connectivity will help improve trade efficiency, making it easier for businesses to move freight and trade goods and services. However, the evidence for this is problematical. For instance, one source cited by the NIC concludes that for an inter-regional transport investment, economic activity may shift either to the lower productivity region (the periphery) or to the higher productivity region (the core), the outcome depending on the underlying economic conditions and the type and scope of the investment. This is known as the Two-way Road Effect.

The emphasis of the NIC ‘s analysis is on trade in goods and services, only indirectly on non-business travel. Yet adding capacity to road and rail routes accommodates and generates more use of all kinds. On motorways, for instance, there is evidence that the increased capacity arising from converting the hard shoulder to a running lane results in local users, commuters and others, diverting to take advantage of a faster journey, pre-empting capacity intended for longer distance business users. A low connectivity metric score may well arise from delays due to morning and evening traffic congestion, indicating the existence of substantial car-based commuting. This suggests that enhancement of capacity could be expected to further increase in use by commuters, with little benefit to trade in goods and services. So, I would contend, the NIC’s approach to connectivity is too simplistic.

A further problem with the NIC’s analysis is that although it recognises that road investment will need to be compatible with plans to decarbonise transport, it concludes that the additional emissions from its proposals will not themselves substantially alter the scale of the challenge (which must therefore be borne by the plan to achieve widespread vehicle electrification by 2035). This conclusion is based on embracing the Department for Transport’s projections of road traffic demand growth of 10-28% by 2035 (as indicated in the DfT Decarbonisation Plan), while a road enhancement programme over that period would be expected to increase demand by only around 0.6 to 1.3% (based on historic evidence from a number of studies).

However, the rule of thumb, based on general experience, is that we cannot build our way out of congestion, so any increase in capacity will result in more journeys (good for trade), it will also mean more traffic, resulting in more carbon emissions – at least until fossil fuels are eliminated from road transport – and restoring congestion to what it had been (not good for trade). The Commission’s analysis, suggesting that the additional carbon emissions from its road investment proposals are relatively small, is unconvincing. What is missing is an estimate of the total additional carbon emissions from its programme of road investment, to be compared with the DfT Decarbonisation Plan projection of 620-850 MtCO2 savings from vehicle electrification between 2020 and 2050. If the total additional carbon emissions from the proposed road investments turns out to be relatively small, this implies relatively little benefits to trade; if they are large relative to the impact of vehicle electrification, then the pathway to net zero is put at risk.

A lacuna in the Commission’s analysis of transport infrastructure investment more generally is the failure to consider the application of digital technologies, both to the highway network and the vehicles using it, to enhance the performance of the system overall. The exemplar for this is the application of digital signalling on the railways that allows shorter headways between trains at peak times, thus increasing the capacity of existing track.

Conclusion

I had high hopes for the NIC as an alternative source of policy advice and appraisal methodology when it was set up in 2015. Its analysis of rail investments for the Midlands and North of England offered fresh thinking and was influential in shaping the Government’s plans published in 2021. But the Commission’s proposals for road investment are disappointing, both as regards methodology and conclusions. I suspect at least part of the problem is that its efforts are spread across the whole range of infrastructure investment it is required to cover, so that there is too little capability for deep thinking about how the road network functions and how additional capacity impacts on performance. The NIC needs to develop better models, methodologies and data sources if it to offer fresh thinking for road investment and challenge conventional wisdom and assumptions. If not to provide fresh thinking to that hitherto applied by the DfT, what is the purpose and benefit of the Commission?

Moreover, the Commission was badly unsighted by the Prime Minister’s announcement of the truncation of HS2. The failure of the Government to engage with it on such a major decision prompts a question about the purpose and status of the Commission. The politically-driven redistribution of the funds allocated to HS2 to local transport schemes is quite contradictory to the long term analytically-driven approach that is the remit of the NIC. So, while in principle, analysis of long term requirements for infrastructure investment must be right, in practice short term budgetary constraints and political priorities can render the long view nugatory. One has to ask whether there is a future for the NIC.

A Labour government might well be more sympathetic to the NIC’s role, given that the party in opposition in 2012 established a review of infrastructure planning under Sir John Armitt, now chair of the NIC. That review indeed proposed a National Infrastructure Commission be established. Labour has plans for major capital investment to support the transition to net zero, so having a source of independent advice on such expenditure may be continue to be attractive.

Indeed, there may be a case for merging the NIC with the Climate Change Committee, given the overlap of functions and their cross-departmental approach to future demand and supply. Yet as long as individual departments and their ministers retain responsibility for their budgets and spending plans, with the associated tendency to take a short term view, the strategic may continue to be subordinate to the politically pragmatic.

This blog post was the basis for an article in Local Transport Today of 28 November 2023

The Prime Minister, in his speech to the Conservative Party Conference on 4 October, announced the truncation of the iconic HS2 rail route, originally promoted as a means of levelling up the regions beyond London by halving journey time between city centres. The intention is now for high speed trains to run only between Euston and Birmingham, reverting to lower speeds on existing track to further destinations.

The economic case for HS2 was always problematic. It got worse as costs rose. The initial cost of the full Y network, comprising both the legs to Manchester and to Leeds, was put at £37 billion (2009 prices), but by the time of publication of the Full Business Case in 2020, this had risen to £109 billion (2015 prices), with further cost escalation in prospect due to inflation and real cost increases as earlier optimism bias became exposed. In July 2023 the Infrastructure and Projects Authority gave the project a red rating, meaning that successful delivery appears to be unachievable without rescoping.

So, it is not wholly surprising that Rishi Sunak pulled the plug. Yet London’s Crossrail scheme, renamed the Elizabeth Line on opening, also overran substantially both time and budget. But once opened, the design has been widely admired and performance has surpassed expectations. So, did the Prime Minister lack the courage to adhere to the strapline on his lectern when making his announcement: ‘Long term decisions for a brighter future’?

To avoid the charge of chopping HS2 to save money, the PM announced a whole raft of alternative transport projects, ranging from a metro for Leeds to more funds to fill potholes, most of which were already planned. However, a major rail investment has been replaced in part by a miscellany of road schemes, unhelpful for achieving Net Zero but consistent with the Government’s recent downplaying of urgency of this objective. And if the expenditure profile of the aggregate of these alternatives matches that of the abandoned section of HS2, then it would be many years before their benefits are realised.

The Government established the National Infrastructure Commission in 2015 to advise it on the UK’s main infrastructure needs. The Commission is shortly to publish its second National Infrastructure Assessment outlining a strategic vision over the next thirty years. The Commission has been unsighted by the HS2 announcement, which its Chair stated to be ‘deeply disappointing’.

The truncation of the largest single transport investment, planned over many years, will not reflect favourably on the UK’s ability to execute large infrastructure schemes on which a dynamic economy depends. Nor will an announcement at a party conference of a huge switch of resources from a major strategic investment to a diversity of lesser schemes seemingly designed to spread benefits thinly where these may have greatest political advantage.

There has long been an argument that better regional rail links for cities in the Midlands and the North would be offer greater economic benefits that North-South links. But any major shift of resources deserves more extensive consideration by those affected than has occurred in the present case, where the Prime Minister has wanted to make a break with his Conservative predecessors who had endorsed HS2.

The Department for Transport has issued a draft National Networks National Policy Statement (NNNPS) for consultation . It covers major investments on the road and rail networks in England. The draft is intended to replace the version issued in 2015, before the government’s commitment to Net Zero and publication of the Transport Decarbonisation Plan. The House of Commons Transport Committee has announced an inquiry into this draft.

The DfT states that the 2015 NNNPS shall apply to projects already selected for public examination, so the new NNNPS will apply only to applications accepted after it is implemented, following the consultation. It therefore looks as though the Lower Thames Crossing tunnel, which has been accepted by the Planning Inspectorate for consideration, will be subject to the old guidance, despite construction being deferred by two years as announced in the recent Budget, which seems odd.

The purpose of such National Policy Statements is to provide guidance for decision-makers on the application of government policy when determining development consent for major infrastructure. The intention is to remove the need for consideration of fundamental national policy questions at planning inquiries. Those subject to this guidance are the scheme promoters (National Highways for most road proposals), planning inspectors, and the Secretary of State when granting Development Consent Orders.

The important question is how investment in new road capacity could be reconciled with the government’s legal commitments to achieve Net Zero greenhouse gas emissions by 2050, meeting the requirements of both the Climate Change Committee’s Sixth Carbon Budget that has been agreed by the government and the intentions of the DfT’s Transport Decarbonisation Plan. (Rail, already substantially electrified, is less of a problem.)

The draft opens by rolling the pitch, stating that the government sees a compelling need for the development of national networks (para 3.22), such that there is a presumption in favour of granting Development Consent Orders (para 4.2), while at the same time recognising the need to move away from ‘predict and provide’ (para 3.44). This is very different from the new approach of the Welsh government, which does not see a compelling need to develop its national road network.

Scheme proposals are to be supported by assessments of whole life carbon emissions, to ensure minimisation as far as possible (para 5.29). The draft states that, in reaching a decision, the ‘Secretary of State should be content that the applicant has taken all reasonable steps to reduce the total greenhouse gas emissions from a whole life carbon perspective. However, given the important role national network infrastructure plays in supporting the process of economy wide decarbonisation, the Secretary of State accepts that there are likely to be some residual emissions from construction of national network infrastructure’ (para 5.36). Moreover, a net increase in operational greenhouse gas emissions [from more traffic] is not, of itself, reason to prohibit the consenting of national network projects or to impose more restrictions on them in the planning policy framework (para 5.37). So in policy terms, additional road capacity is more important than decarbonisation.

Importantly, the application for development consent orders applies to individual schemes. There appears to be no requirement to estimate the impact on carbon emissions from an investment programme, such as the planned five-year Road Investment Strategy 3 (RIS3) due to start in 2026. Accountability scheme by scheme is not so very different from the present practice whereby National Highways argues that each individual scheme makes only a de minimus contribution to national carbon emissions, which can therefore be disregarded.

The DfT’s Transport Decarbonisation Plan made broad-brush estimates of carbon reduction from policies and programmes, for instance 1-6 MtCO2e from increased active travel over the period 2020 to 2050, and 620-850 MtCO2e for electrification of cars and vans over the same period. It is inconsistent not to recognise offsetting carbon increases from investment in new road capacity, likely to fall somewhere between the above ranges, and certainly not de minimis for the programme as a whole.

There is also a problem of modelling future carbon emissions arising from road investment. Transport models are complex and opaque, with many parameters, the value of which requires expert judgement. In consequence, the are two types of protagonist: experts who have a good working understanding of transport models because they earn their living from building and running such models; and non-experts, who are interested in the output of models but are not able to understand the assumptions, simplifications and judgements that the experts must make. Non-experts include decision makers in national and local government who have prior expectations of the economic value of particular road schemes, and whose test of a good model is that it delivers outputs, comparing with- and without-investment cases, consistent with these expectations. Other non-experts are those opposing road schemes at public inquiries, who are faced with modelled outputs as part of the promoter’s proposal that are not open to detailed scrutiny. Inspectors at planning inquiries are also non-expert in this sense.

The NNNPS requires projects to be supported by a local transport model, but planning inspectors and the Secretary of State do not need to be concerned with the national methodology and national assumptions around the key drivers of transport demand (para 4.7). In practice, most schemes on the Strategic Road Network employ local versions of a set generic traffic and economic models, typically SATURN for network traffic modelling, the outputs of which are inputs to the TUBA economic model. So, as it appears, consideration of the predictive validity of these models for projecting carbon emissions need not be considered either at a public inquiry or by the Secretary of State. One can understand why a planning inspector should not be burdened with a task for which they are not professionally trained. Nevertheless, the question is where in the decision-making process the validity of the supporting modelling might be assessed.

The need to assess the predictive validity of transport models is pointed up by the failure of standard models to project fairly short-run traffic flows in two cases of motorway widening, on the M25 and the M1, as I have recorded previously. This does not increase confidence in the ability of such models to project economic benefits and carbon emissions out to sixty years.

One particular problem of transport models is that they are largely used to justify new investment, in which context the saving of travel time is supposed to be the main economic benefit. Yet average travel time, as estimated by the National Travel Survey, has changed very little over fifty years, excepting the period of the coronavirus pandemic. The implication is that people take the benefit of faster travel as enhanced access to desired destinations, people, places, activities and services, for the opportunities and choices on offer. Travelling further, rather than using travel time savings for more productive work or agreeable leisure, means more externalities related to vehicle-miles travelled, carbon emissions in particular.

Modellers who aimed to model such access benefits, and the resulting changes in land use and value, would not be appreciated by the economists who are wedded to travel time saving as the main economic benefit of investment, nor by decision-makers who are well used to conventional economic investment appraisal. So modellers must fix their assumptions, simplifications and parameters to get outcomes that satisfy a ‘realism test’ of prior expectations, subject to conformity with unspecified standards of professional respectability.

The upshot is that the modelling of the impact of new road investments will systematically underestimate carbon emissions from the additional (induced) traffic. This makes it easier to appear to comply with the pathway to Net Zero, but means that the outcome is likely to fall short of that pathway.

Some further light is shed on this matter by the cost-benefit analysis the DfT has published in support of options to implement the Zero Emissions Vehicle Mandate, the legislative framework to fulfil the government’s objective to phase out the sale of internal combustion engine cars and vans by 2030. The need for this cost-benefit analysis is not stated, since the timing of the phase out is largely for negotiation between the government and the motor manufacturers. Perhaps the Treasury wish to be assured that this route to decarbonisation represents good value compared with other possible decarbonisation measures. Or perhaps the DfT economists wish to parade their competences after cost-benefit analysis failed to be supportive of a number of major rail and road investments.

The modelling assumes that that the switch to ZEVs could result in increased mileage per ZEV driver because electricity as fuel is cheaper than petrol or diesel (which begs the question of whether some new charge for EVs might be introduced, as I have suggested). This extra driving, a ‘rebound effect’, is supposed to lead to more congestion delays, with a very substantial cost impact: for a central sensitivity case of the preferred policy option, the abatement cost of the ZEV Mandate for cars and vans estimated as £12/tCO2e excluding the rebound effect, and £100/tCO2e including it (Tables 61 and 62).

So, the DfT thinks it would be much more costly to reduce CO2 emissions by means of the Mandate if the lower operating cost of EVs led to greater distances travelled. However, in my view, rebound of the magnitude modelled is unlikely, quite apart from the possibility of a road user charge for EVs. The per capita distance travelled by car depends on three main factors: speed of travel, time available for travel, and household car ownership. None of these are affected by the switch to electric propulsion. Vehicle operating costs have a second order impact at best, witness the growth of SUV ownership despite higher fuel use.

Paradoxically, the DfT modellers postulate additional traffic from reduced vehicle operating costs arising from electrification (mistakenly, in my view), while being in denial about the additional traffic arising from road users taking the benefit of investment in increased capacity as enhanced access involving more travel (again mistakenly).

The ZEV Mandate cost-benefit analysis states that the preferred policy option is expected to achieve emission savings of 415 MtCO2e in the period 2020-2050 (Table 29). This is substantially less than the savings from switch to electric propulsion of car and vans of 620-850 MtCO2e projected in the Transport Decarbonisation Plan, mentioned above. No clear explanation for this discrepancy is given; it may be because the present Mandate is for the period to 2030, with a further Mandate promised for 2031-35; or it may reflect the sensitivity of model outputs to input assumptions.

More generally, modelling for the ZEV Mandate exemplifies how modelling outputs can be very sensitive to input assumptions that are made in the absence of firm evidence of future travel behaviour. This is a caution that applies to most transport modelling, not least to the projections of transport sector carbon emissions to support decisions necessary to achieve reductions required by the legislative framework to achieve Net Zero.

We have been before in a situation in which there have been doubts about approaches to transport economic analysis endorsed by the DfT. Good work was done by SACTRA – the Standing Advisory Committee on Trunk Road Assessment – an independent body created by the DfT, that issued two influential reports in the 1990s. One confirmed the importance of induced traffic arising from new road construction, a view that had been resisted by the DfT since such traffic added to congested and reduced travel time savings. The other report recognised the wider economic impacts of investment, beyond the conventional time saving, vehicles operating costs and those externalities to which monetary values could be attached; estimation of such wider impacts, such as agglomeration effects, now forms part of the standard approach to investment appraisal.

Although SACTRA, by its very name, was intended to remain in existence, at least until formally stood down, it seems to have fallen into that state by not receiving new commissions. There is a need, in my view, to reconstitute it, or some similar body of independent experts, to look at the suitability of the current body of official guidance on transport economic analysis and modelling in an era when decarbonisation is a national policy priority. As it is, however, the people in DfT and their consultants, who naturally wish to please their clients, are talking to each other in an echo chamber, from which interested outsiders are excluded.

Other departments do better. The Treasury’s model of the UK economy has long been available to independent forecasters. The Energy Department collaborates with academic energy modellers and makes available the online Mackay Carbon Calculator that allows users to explore the options for reducing carbon emissions. Modelling of the coronavirus pandemic was largely carried out collaboratively by academic groups whose models and outputs were public for all to debate. And the modelling of climate change is carried out openly, collaboratively and internationally as input to the reports of the Intergovernmental Panel on Climate Change.

Th DfT instigated a move to update the National Transport Model to generate a new version, NTMV5, intended to be open to other users, but this seems not to have worked out in that the National Road Traffic Projections 2022 employed the previous version (as I have noted). The DfT should explain what went wrong, and should engage openly with those beyond the Department and its immediate advisers on how best to model the decarbonisation of the transport sector.

This blog post is the basis for an article in Local Transport Today 23 May 2023.

My written evidence to the House of Commons Transport Committee inquiry into the National Networks National Policy Statement is based on this blog.

The Department for Transport has recently issued a new set of National Road Traffic Projections (known as ‘forecasts’ in the past, ‘projections’ perhaps indicating rather less commitment to the findings). These apply to England and Wales and look ahead as far as 2060. The new projections are derived from the DfT’s National Transport Model (NTM), which has been developed and updated since the 2018 forecasts –  so it is claimed, but see below.

The projections relate to a set of Common Analytical Scenarios, developed by DfT with the aims of better assessing uncertainty in scheme appraisal. There is a Core Scenario plus seven variants illustrating differences in economic growth, regional distribution of population, behavioural change, new technology and decarbonisation. Except for the Behavioural Change scenario, the other variants were created by changing some of the Core Scenario assumptions. For the Core Scenario, relationships between the key drivers of demand and road traffic are broadly assumed to continue in line with historical trends.

A noteworthy feature of the new projections is that traffic is expected to grow in all scenarios, by between 8% and 54% to 2060. This contrasts with the widely held view that car use needs to be reduced to meet the Government’s commitment to Net Zero by 2050, although this is not the DfT’s view. Projections of CO2 reductions to 2060 range from 38% to 98%, depending on scenario.

The Core Scenario is based on ‘existing firm and funded policies only’ and projects a 22% increase in traffic to 2060 and a 42% decrease in carbon emissions. Yet Net Zero by 2050 is surely a firm government commitment. The DfT published its Transport Decarbonisation Plan in 2021 which projected that this would be achievable, implying that future funding and policy development would need to constrain carbon emissions from road traffic to that indicated by the low carbon scenario projections. In which case, one might wonder why publish high carbon projections that go less than half way to achieving Net Zero.

This notion of ‘existing firm and funded policies only’ is stated as encompassing published plans or funded policies. So perhaps the civil servants are drawing attention to the shortcomings of the Transport Decarbonisation Plan, which was pretty vague about the details, particularly about the achievement of behavioural change. Carbon emissions under the Core Scenario are projected to fall initially quite rapidly, but then level off, apparently because ‘the details of future car and LGV regulations to reduce CO2e emissions beyond this point have yet to be finalised.’ (para 4.15 of the NRTP). Certainly, the details of the ‘ZEV Mandate’ remain to be settled – this is intended to oblige manufacturers to sell a specified increasing proportion of zero emission vehicles during the transition – a relevant factor may be the availability of battery production in the UK, which may require government financial support. Perhaps ministers are having a wobble about this Mandate, leading the civil servants to point up the implications for Net Zero of a weakening of policy intent. Nevertheless, it all seems very odd. If no new cars and vans propelled solely internal combustion engines are to be sold after 2030 (hybrids after 2035), then the normal turnover of vehicles would mean continuing decarbonisation until all internal combustion engine vehicles are scrapped (the average age of car at scrappage is around 14 years).

Congestion delays are projected to increase by between 4% and 59% by 2060, depending on scenario, which would provide a justification for creating more capacity. So another possible explanation of the ‘firm and funded’ qualifier is that no account has been taken of a future road investment programme, in particular RIS3 for the period 2025-2030, currently being planned.

In contrast to the Core Scenario, there are three scenarios that project carbon emissions reducing to near zero by 2050. The Vehicle-led and Mode-balanced Decarbonisation Scenarios assume high and fast uptake of EVs and other zero emission vehicles ‘in line with the government’s stated ambitions to end the sale of diesel and petrol cars, vans, HGVs,
and buses/coaches.’ (para 4.48). The Technology Scenario adds a high uptake of connected and autonomous vehicles.

A further scenario of interest is a Behavioural Change Scenario, involving new ways of working, shopping and travelling. This reflects past falling trends in driving licence holding by young people and in trip rates for most purposes, as well as coronavirus pandemic-induced changes in behaviour that are assumed to continue. Some of the latter assumptions are quite striking: 40% reduction in education trips by 2041, 39% in commuting, 41% in personal business, and 55% reduction in visiting friends and relatives (para 3.37). While it is welcome that the DfT is addressing the scope for changes in travel behaviour, these particular assumptions seem on the high side. Nevertheless, the impact of these behaviour changes is surprisingly small – only to level off the growth of car traffic, with van traffic increasing by 45% to 2060 (para 4.39), to compensate for car trips not taken. Car carbon emissions are similar to those of the Core Scenario, indicating that behavioural change in itself is expected to make minimal impact.

The new traffic projections adhere to the traditional practice of predicting demand for road travel driven predominantly by changes in travel costs, population and economic growth, 90% of demand growth being attributed to these factors. A large number of other factors are considered, which is appropriate since they are relevant. The outcome is an extremely detailed formulation of a set of scenarios, which therefore avoids criticism that potentially important factors have been disregarded, but it is then hard to see the wood for the trees.

Big picture

So, let’s stand back from the detail, to see the big picture, which in my view is this: the National Travel Survey has found a gradual decline in per capita travel since the turn of the century, including decline in the average number of trips taken and in distance travelled by car (prior to the pandemic) (see Chart above). This followed rapid growth in car use in the last century, mainly the result of increasing car ownership. But household car ownership has stabilised, with some three-quarters of households owning one or more cars or vans. There was a clear break in trend at the turn of the century, which implies a change in relationships between the determinants of demand and growth of car use. Accordingly, for modelling purposes, such relationships (known as elasticities) need to be forward-looking; assuming continuity of historic trends, as does the Core Scenario, is inappropriate.

The average distance travelled per capita by car depends mainly on three factors: speed of travel, time available for travel, and level of car ownership. The first two seem unlikely to change in the future, and while there has been growth of the number of cars owned within car-owning households, the second or third car tends to be used less than the first. The impact of economic growth and income growth on per capita car use is a second order effect, seen mainly as the purchase of larger, more expensive and fuel-consuming vehicles, notably SUVs. The unvarying travel time constraint, of about an hour a day on average, limits the distance that can be travelled, irrespective of income. The DfT Projections assume that three-quarters of the projected traffic growth is driven by increases in GDP and reduced costs of driving (para 4.7), which seems improbable.

That leaves population growth, which the new traffic projections take from the Office of Budget Responsibility as an overall 4% increase by 2060, and which therefore would have a very small impact on travel demand. The consequences for road traffic growth would depend on the extent to which the additional inhabitants were accommodated in new homes on greenfield sites where car use would be the norm; or at higher density within existing urban areas, where public transport would be relevant. Unfortunately if understandably, the Regional Scenario considers accommodating the population growth in regions beyond the Wider South East, which may be relevant to the Levelling Up agenda but has little impact on overall traffic or carbon emissions.

So, I would not expect much future change in either per capita car use or total road traffic, based on recent trends. This conclusion is at odds with the DfT modelling and so raises questions about the validity of the NTM, which has been in use for over twenty years in a series of versions. The version cited in the new projections is NTM version 2 Rebased (NTMv2R), which is unexpected since a new version, NTMv5, was announced in 2019.

Modelling regressed

NTMv5 was developed as a spatially detailed model to complement NTMv2R by providing additional capabilities for assessing the impact of major new road schemes, packages of transport improvements or spatially based charging arrangements. One particular purpose was to develop scenario-based traffic forecasts arising from changes in population, travel trends, GDP, car ownership, fuel price and road tax. Accordingly, it is surprising that NTMv5 does not appear to have been used to generate the new traffic projections.

One possible explanation is that a peer review of NTMv5 by experienced practitioners made a considerable number of criticisms. The reviewers advised caution in application of the model, primarily due to the focus of the NTMv5 being on the more strategic highway network, whereas many of the potential applications relate to urban travel policy and public transport interventions. In particular, the reviewers were critical of the treatment of urban traffic, observing that the assumed relation between traffic speed and demand growth lacked validity, and that the range of policies aimed at reducing urban car use were not taken into account. Besides, it was noted that the DfT’s car ownership model has not recognised that ownership in dense urban areas has been declining for many years in response to increasing population density, notwithstanding rising incomes. The reviewers concluded that the model could not be safely used to examine policies that relate specifically to London, and queried whether this might apply more generally to rapidly growing dense urban areas across England. They took the view that the model should be suitable for use in forecasting the growth of road traffic in most areas other than those adjacent to or within major urban areas, which is a pretty major qualification.

So perhaps the DfT was unable to rectify NTMv5 to respond to these criticisms, and hence reverted to NTMv2R, which had previously been used to prepare the 2018 National Road Traffic Forecasts. This version was also the subject of peer review, the reviewers noting problems with modelling traffic in London and other conurbations where non-car modes are most competitive. The 2018 Forecasts predicted substantial traffic growth in London, but admitted that this was likely to be over-forecasting because travel behaviour in London and relationships between key variables and road traffic demand can be different to the rest of the country, due to a high use of public transport and significantly higher congestion on roads. This was recognised as known issue with the NTM, which it was intended would be addressed in the future (para 4.33 of 2018 forecasts). However, it is not clear whether this has been done, prior to preparation of the new projections.

There is bound to be feedback from congested road capacity to travel demand. In the ‘vision and validate’ approach, nowadays effectively adopted by cities, the vision of the balance between the twin functions of roads – movement and place – means that travel demand must be managed. This contrasts with the earlier ‘predict and provide’ perspective, where forecasts of traffic growth led to proposals to increase road capacity. If our vision now includes Net Zero, the presumption of increased road capacity is problematic, and the modelling should take account of capacity constraints on demand for road travel. Given that over 80% of the UK population live in urban areas, models need to be responsive to urban traffic conditions.

The validity of the NTM is therefore questionable. The modelling suite used to prepare the present projections is complex and opaque, hence it is not possible for those other than DfT modellers and their consultants to understand what has been achieved and what has not. The peer reviews provide an exceptional opportunity to look under the bonnet, and what was found make one doubt whether the NTM in its various versions is reliably roadworthy. And that’s before the problems associated with specifying scenarios to reflect policy uncertainties.

One intention in creating NTMv5 was to make this important model transparent to external stakeholders, which NTMv2R is not. Lack of transparency and accessibility contrasts unfavourably with the online Carbon Calculator of the Department for Business, Energy and Industrial Strategy, open to all.

Projecting future road traffic volumes is not an end in itself, rather it serves policy purposes. Projections of growth of both traffic and congestion delays would help justify a further major road investment programme. Projecting carbon reductions of 98% meets the Net Zero objective. Arguably, the modellers have struggled to reconcile both policy requirements, but have fallen short.

This blog was the basis for an article in Local Transport Today 24 January 2023.

The House of Lords Built Environment Committee is carrying out an inquiry into public transport in towns and cities. I was invited to submit written evidence, which is now published.

My conclusions:

For public transport in towns and cities to be improved, the share of car travel needs to be reduced, to lessen both competition for passengers and road traffic congestion.


To reduce car use, better public transport is needed, which requires both local government to take overall charge of services and to have a sustainable source of funding beyond the farebox.


There are no new technologies that will make much difference.

The Department for Transport (DfT) has started planning its third Road Investment Strategy (RIS3), a five-year investment programme for the Strategic Road Network (SRN) for the period 2025-2030. The approach is conventional – a programme of projects, with little overview of how societal objectives will be advanced by the likely substantial expenditure. Yet there are five major issues that need to be addressed for the programme as a whole.

First, there is a need to reconcile the government’s Net Zero objective with the carbon emissions from both the tailpipes of the additional traffic arising from increased road capacity and the embedded carbon in the cement, steel and asphalt used in construction. Recent presentations by the DfT’s Transport Appraisal and Strategic Modelling (TASM) division indicated an intention to tackle this issue at scheme level, but this is misconceived. What matters is the overall contribution of RIS3 to carbon emissions and how this is to be offset or otherwise justified.

Second is the question of how RIS3 advances the government’s Levelling Up agenda, where the recent, well-received White Paper identified twelve medium-term ‘missions’ to be pursued across all departments. The one specific to transport states: ‘By 2030, local public transport connectivity across the country will be significantly closer to the standards of London, with improved services, simpler fares and integrated ticketing.’ Although the rate of progress implicit in ‘significantly closer’ is vague, the direction of travel is clear and the objective is not in dispute.

There is no mention of investment in the SRN in the Levelling Up White Paper. This is appropriate since there is, if anything, an inverse relation between the performance of the road network and economic prosperity across the nation, given that delays on the SRN due to congestion are greater in London and the South East than in other regions of England.

The implication of the White Paper approach is that there should be a substantial switch of DfT funds from road investment to improve public transport beyond London, if the Department is to play a full role in supporting the government’s the Levelling Up agenda. Yet the Department’s recently issued Levelling Up Toolkit is essentially a pro forma for a box-ticking exercise aimed at justifying investments already forming part of agreed expenditure programmes. There is palpable inconsistency here.

Third, we have the problem of the safety of smart motorways. These require conversion of the hard shoulder to a running lane as an economical means of increasing capacity without the expense of rebuilding bridges. Generally, new roads are safer than older roads, which meant that adding road capacity yields a modest safety benefit. But this is not obviously the case for smart motorways, and there has been considerable pushback from the public and the House of Commons Transport Committee. As a result, the DfT has paused the roll out of new smart motorways until five years of safety data is available for schemes introduced before 2020. A decision on the generic safety of smart motorways will be an important factor in developing RIS3.

Fourth, and less recognised, there is a question about the economic benefits from additional road capacity. There are two published evaluations of smart motorway schemes where the traffic flows after opening were very different from those that had been forecast. For the M25 Junctions 23-27 scheme, the traffic flowed faster one year after opening but subsequently delays reverted to what they had been before opening on account of greater traffic volumes than forecast. For the M1 J10-13 scheme, traffic speeds five years after opening were lower than before opening. Since the main economic benefit of road widening is the saving of travel time, both schemes had negative benefit-cost ratios (BCR) at outturn.

Examination of the reports of the traffic and economic modelling of these two schemes showed substantial time-saving benefits expected for business users, offset by a small amount of increased vehicle operating costs (VOC) arising from additional traffic volumes. There were also time savings to non-business users (for commuting and other local travel) but these were entirely offset by increased VOC – because these were local trips that rerouted to the motorway to save a few minutes of time, at the expense of additional fuel costs.

The scope for rerouting local trips to take advantage of increased motorway capacity is likely to be underestimated in modelling. Local users have the flexibility to vary routes whereas long distance business users will stay on the motorway unless there is a major holdup. Moreover, the general use of digital navigation in the form of Google Maps and similar offerings makes choice of minimum time options commonplace.

Even when the outturn total traffic flows are a reasonable match to those forecast, the scheme economics could be much worse than predicted if there is more local traffic, and hence less long distance business traffic, than projected. Traffic and economic modelling involve recognition of different classes of road user with different values of travel time: cars, LGVs, HGVs, business, local commuters, and other local users. However, the monitoring of outturn traffic flows does not distinguish between these classes of users. GPS tracking make such distinctions possible.

The DfT has emphasised the importance of evaluation of outturns of investments. Yet the failure to appreciate the need to break total traffic flows down into the segments that had been modelled reflects a serious professional shortcoming. As a result, we cannot be at all confident that investments to increase SRN capacity do more than facilitate rerouting of short trips by local users, of nil economic value. Likewise, we do not have the kind of detailed evaluation data that would allow traffic models to be better calibrated for future use.

The fifth issue for RIS3 is that the widespread use of digital navigation by drivers prompts questions about the continued focus of DfT and National Highways on major civil engineering expenditure. Contrast the aviation sector, where new runways or terminals are occasional efforts, not regular business. The main focus of airlines and air traffic control is to improve operational efficiency, to sweat the assets employing the techniques of operational research. We have a mature road network in Britain. It’s time to focus on operational efficiency. Yet it seems not to occur the National Highways that working with Google Maps, TomTom and other providers of digital navigation services would be a cost-effective means of improving the performance of the network.

More generally, the DfT is trapped in its box labelled Transport Analysis Guidance (TAG), a thousand pages of prescription to which more text is added when some new issue or policy arises, such as Net Zero, Levelling Up, inequalities or gender. The task for those promoting a scheme is to tick all the boxes and flex the modelling to generate BCRs that represent good value for money. Evaluation of outturns is inadequate to distinguish between success and failure.

Although the DfT pays lip service to the need to think at the strategic level, the TAG framework does not facilitate this in that the detailed analysis is at project level. Other interested parties do not challenge the Department’s approach. The consultants and local authorities do not bite the hand that feeds them. The professional societies, institutions and think-tanks do not engage. The National Audit Office carries out good analysis of road investments on occasion, but not systematically. The Office for Rail and Road scrutinises the management of the SRN, including how well new investments are delivered, but does not see its role as enquiring into how investments benefit road users. This is quite unlike the regulators of other infrastructure industries – electricity, gas, water, telecoms – that are focused on how consumers benefit from investment.

The DfT is stuck in its box and seems unlikely to break out. The best bet for a strategic view of RIS3 may come from the National Infrastructure Commission, which has begun the development of its second National Infrastructure Assessment. The Commission’s advice was the basis of the government’s £96 billion rail investment programme for the North and the Midlands. This required fresh thinking about the benefits of transport investment at the level of the whole programme, an approach clearly needed for RIS3.

This blog post formed the basis of an article in Local Transport Today of 25 March 2022.

The House of Lords Environment Committee is carrying out an inquiry into public transport in towns and cities. I was asked to provide a submission, as follows.

The scope for public transport in cities and towns depends importantly on the level of car use, both because the car competes for passengers and because car traffic impedes the progress of buses, lessening their attractiveness.

The car is the dominant means of travel in Britain and other developed economies. It offers efficient door-to-door travel over short to moderate distances where traffic congestion does not lead to unacceptable delays and where parking is available at both ends of the journey. Public transport does not offer an attractive alternative to most car drivers in these circumstances. However, in urban areas where congestion causes delays and where parking is costly and limited, alternatives to car travel become attractive. To grow public transport use in towns and cities, it is necessary both to improve bus and rail services and constrain car use.

Urban travel and traffic

It is necessary to recognise that our availability of time always constrains the amount we can travel. There are many activities that we need to fit into the 24 hours of the day, and on average we spend just an hour on the move. This limits the build-up of road traffic congestion, which arises in areas of high population density and high car ownership where there is not enough road space for all the car trips that might be made. If traffic volumes grow for any reason, delays increase and some potential car users make other choices. We may change the timing or route of a car journey, or the travel mode where there are alternatives available, or a different destination such as an alternative shopping centre, or not to travel at all, for instance by shopping online.

Road traffic congestion is therefore self-limiting. We know from experience that we cannot build our way out of congestion by adding road capacity, since this allows previously suppressed car journeys to emerge, restoring congestion to the previous level. Conversely, if urban road space is taken away from cars in order to create bus or cycle lanes, then initially congestion will increase. But the additional delays will induce some car drivers to make alternative choices and congestion will revert to what it had been. The overall impact of reducing urban road space is to reduce the share of journeys by car.

Accordingly, it is difficult to reduce the intensity of traffic congestion, but it is possible to reduce the amount of congested traffic by reducing road space available to general traffic, which can be publicly acceptable if alternatives to the car are provided. This is what has been happening in London over many years, as the population has grown, as there has been large investment in public transport, and as there has been a reduction in road space available for cars. Private transport use fell from 48% of all trips in 2000 to 37% in 2019, while public transport use grew from 27% to 36% over the same period. Cycling increased from 1.2% to 2.4% while walking held steady at 25%. The London Mayor’s transport strategy, published in 2018, ambitiously aimed to cut private transport use to 20% of all trips by 2041.

Creating cycles lanes reduces the space available for cars but in itself it does not get people out of their cars. Copenhagen is a city famous for cycling, with 28% of journeys made by bike. Yet car traffic is only slightly less than in London. Aside from cycling, the other big difference is that public transport accounts for only half the proportion of trips compared with London. The experience of Copenhagen indicates that we can get people off buses onto bikes, which are cheaper, healthier, better for the environment and no slower in congested traffic. Yet buses are an efficient way of using road space to move people in urban areas, with diesel engines being replaced by electric or hydrogen propulsion to cut carbon emissions. We would like to get drivers out of their cars onto bicycles, yet this has proved difficult, even in Copenhagen, a small flat city with excellent cycling infrastructure and a strong cycling culture.

Looking across a range of European cities, we find very diverse patterns of journeys by the different travel modes, reflecting, history, geography, size and population density. But we do not find cities with high levels of both cycling and public transport.

Policy options for towns and cities

British cities tend to have lower population densities than European counterparts on account of our preference for low-rise housing with gardens; this means that public transport is harder to deliver cost-effectively. British cities vary considerably as regards use made of public transport. Two otherwise seemingly similar cities, Brighton and Bournemouth, have very different shares of commuting by public transport – 23% and 7% respectively. Nevertheless, there are two broad policy options available to all towns and cities, for local decision:

  • whether to push back the cars to increase street space for engagement by those on foot, with active travel and public transport as the alternative to the motorised mobility, as successfully implemented in London;
  • or whether to accommodate car travel, as has been the practice in the past and as remains popular with many residents.

Pushing back the car requires improving the public transport alternative. Urban rail is fast and generally reliable, but costly to implement. It can provide an attractive offering, as for instance London’s Overground, created from existing underused tracks, and Nottingham’s tram network where an extension was financed from the proceeds of the local Workplace Parking Levy. Bus Rapid Transit on dedicated traffic-free routes is a less costly alternative to new rail, for example the Cambridgeshire Guided Busway. Buses on roads with general traffic, whether in bus lanes or not, offer a less attractive alternative to motorists – a chicken-and-egg situation.

Integration of public transport across the modes increases its attractiveness, as do the innovations adopted in London, including cashless ticketing with daily or weekly capped charges, and extensive real-time information about services available through mobile phone and other devices. The ability of city regions to take responsibility for public transport, on the London model, will be an important means to improve public transport where adopted.

The recent well-received Levelling Up White Paper identified twelve medium-term ‘missions’ to be pursued across all departments. The one specific to transport states: ‘By 2030, local public transport connectivity across the country will be significantly closer to the standards of London, with improved services, simpler fares and integrated ticketing.’ Although the rate of progress implicit in ‘significantly closer’ is vague, the direction of travel is clear and the objective is not in dispute. However, as well as devolving relevant responsibilities to city regions, it will be necessary to allocate additional funds on a sustainable basis. The experience of relying on private sector bus companies has shown that a high level of service cannot be sustained by commercial financing.

It would be worth considering the example of the French ‘versement transport’, a hypothecated urban regional payroll tax levied on the total gross salaries of all employees of companies of more than 11 employees, which was originally intended to raise capital for investment in local public transport infrastructure, but is more and more used to cover its operating expenses.

New technologies

There are four new technological developments affecting road transport:

  • Electric propulsion, being adopted for buses, eliminates tailpipe emissions of pollutants and carbon, but does not otherwise change the nature of the service.
  • Digital platforms are having a big impact on retail businesses. For transport, booking of rail and air travel has been transformed. Ride-hailing, exemplified by Uber, has made a major impact on the taxi business. There have been trials of Demand Responsive Travel whereby smartphone apps are used to book a trip on a minibus that operates a flexible route to meet demand, but the economic viability of this mode is not yet generally established.
  • Digital navigation, typified by Google Maps’ routing recommendations, is changing how the road network is used, but is not relevant to buses on fixed routes.
  • Vehicle automation may offer the prospect of driverless buses, but whether this would be feasible in city traffic is far from clear, as is the cost of the technology and the support it might need. Driverless trains are possible on systems constructed for that purpose, such as the Docklands Light Railway, but an attendant rides on every train to oversee safety and security.

In short, it seems unlikely that public transport will be transformed by new technologies.

Summary

For public transport in towns and cities to be improved, the share of car travel needs to be reduced, to lessen both competition for passengers and road traffic congestion.

To reduce car use, better public transport is needed, which requires both local government to take overall charge of services and to have a sustainable source of funding beyond the farebox.

There are no new technologies that will make much difference.