The House of Commons Transport Committee is holding an inquiry into zero emission vehicles and road pricing. I submitted evidence set out below.

Main points

  • There is a case for road pricing both to replace fuel duty revenues lost as ZEVs replace conventional vehicles and to help manage road traffic congestion.
  • The charge for road use might comprise two elements: one generating a revenue stream for the Exchequer and another for the local authority, which would allow substantial devolution of responsibilities for transport provision.
  • There would be attractions in the incremental introduction of national road pricing, building on the successful congestion charging arrangements in London.

Rationale for road pricing

The move to ZEVs will result in the loss of revenue from road fuel duty, as well as from VED were ZEVs to remain zero rated. Revenue from the former amounts to some £28 billion a year and from the latter some £6 billion. This prompts consideration of some form charging for road use to make up the loss.

The case for zero VED for electric vehicles (EVs) is to incentivise their uptake, a reason that will become irrelevant as the capital cost of EVs falls and as sales of new conventional vehicles are phased out. So, in due course VED could be applied to road vehicles generally, and if set at a rather higher rate could cover the annual cost of capital and current expenditure on national and local roads of £8 billion, obviating the need for road pricing to ensure that drivers pay for the roads they use.

One argument some make for road pricing is that without fuel taxation or a similar charge related to distance travelled, the running costs of EVs would be substantially lower than that of conventional vehicles, which would result in more miles travelled and thus more congestion, carbon emissions and other externalities. One scenario of the Department for Transport’s (DfT) 2018 Road Traffic Forecasts illustrates this expectation[1]. However, in recent years the average distance travelled by car has remained stable, being limited by the time available for travel, the speed of travel and the proportion of households owning cars, none of which have increased in this century. It is therefore not to be expected that the replacement of the internal combustion engine by the electric motor would have much impact on vehicle use.

Another argument for road pricing is to alleviate road traffic congestion, the intention of the London congestion charge. Experience has shown that reduction of congestion is quite limited at the level of charging typically employed, particularly in a prosperous city like London where many are able to afford the charge[2]. Charging for road use benefits those who can readily afford to pay by displacing those who are less able, generating increased inequalities in use of the road network that historically has been a relatively egalitarian domain. Nevertheless, congestion relief is in principle a possible aim of the road pricing regime, although the magnitude of the charge would need to reflect both the level of congestion and affordability in the locality if congestion is to be effectively ameliorated. Related to this is charging polluting vehicles, as in London’s Ultra Low Emission Zone (ULEZ), the rationale for which will diminish over time as EVs are increasingly used, yet which may remain relevant in respect on non-tailpipe particulate releases from vehicles.

Revenue from the London congestion charge and the ULEZ are retained by the city authority, as are charges for low emission zones planned elsewhere, ring-fenced for expenditure on transport services, and likewise revenues from parking charges. A national scheme for road user charging might comprise revenues both for the Exchequer as well as for local authorities, the latter setting levels of charges to reflect local conditions, including congestion and other environmental impacts of traffic, as well the need for revenues for road maintenance. There would be attractions in allowing local authorities to set their share of the road user charge to cover the full cost of local transport provision, obviating the need for grants from the DfT (other than perhaps for ‘rebalancing’ purposes). The Exchequer element of the charge could depend on the type of road, for instance higher for motorways that are funded nationally, and could vary by region to aid ‘rebalancing’ policies.

Introduction of road pricing

There would be attractions in introducing road pricing for EVs alone, on the rationale that they should pay their fair share of the costs of the road network that conventional vehicles are paying via fuel duty. However, the lower operating costs of EVs are a necessary incentive to purchase while capital costs remain higher. As capital costs fall, as is expected, scope would develop to charge users of EVs by introducing a road pricing regime from which conventional vehicles were exempt.

Introduction of general road pricing on top of fuel duty would be invidious for lower income motorists who are likely to continue to use conventional vehicles for longer than the better off. Accordingly, one possibility would be to introduce a general road pricing system but crediting conventional vehicles with the fuel duty they pay. This is the basis of a voluntary pilot scheme in Oregon[3]. Because this scheme is voluntary, uptake is incremental, in contrast to an obligatory scheme that would have to be imposed all at once.

It is worth considering options for incremental roll-out of national road pricing, given the potential difficulties of overnight national implementation of charging and enforcement technologies. In London, the existing congestion charging system functions sufficiently well and is publicly acceptable, but its scope is limited by the fixed charge for entering the charging zone.

There are a number of incremental developments of the London scheme that might be feasible:

  • Encourage participation via a smartphone app by offering a discount from the standard daily charge;
  • Take advantage of location awareness of smartphones to identify when the user is both in a vehicle registered for the charge and in the charging zone, backed up by camera enforcement as at present;
  • Encourage entry and exit from the charging zone outside times of peak congestion by offering a discount from the standard daily charge;
  • Increase the standard charge but offer discounts to encourage use when and where traffic is less congested;
  • Extend the charging to other areas of London where congestion is a problem;
  • Make the charging and enforcement systems available to other cities that wished to manage local traffic, incentivised by the revenues that could be used to provide alternatives modes of travel to the car.

Once a number of cities were using road pricing, there would exist the basis for national adoption in the form of an established charging system, which would need to be supported by the national roll-out of camera enforcement (unless a better enforcement system could be devised). This would be accompanied by the reduction and eventual abolition of road fuel duty, perhaps with the public assurance of no net increase in revenues from road users. There would need to be a daily penalty charge for those evading payment for road use, which, if not paid when requested, might be added to the annual VED charge, failure to pay which could result in clamping.

Whichever way to bring it about, a decision to adopt national road pricing would need to be strategic, commanding wide acquiescence, analogous to the decision to phase out internal combustion engine vehicles.

Conclusion

Adoption of a scheme of national road pricing would allow loss of revenue to the Exchequer from road fuel duty to be offset. A scheme that generated revenues for both central government and local authorities would allow substantial devolution to the latter of responsibilities for funding the provision of their transport services in the light of local needs. A national road pricing scheme might be developed incrementally from the congestion charging arrangements in London.

21 January 2021


[1] Department for Transport, Road Traffic Forecasts 2018, Scenario 7.

[2] Metz, D. Tackling urban traffic congestion: The experience of London, Stockholm and Singapore. Case Studies on Transport Policy, 6(4), 494-498, 2018.

[3] https://www.myorego.org/

Below are the main points and implications of my analysis of the outcome of widening of the M25 motorway between Junctions 23 and 27, published as ‘Economic benefits of road widening’, Transportation Research Part A, 147, 312-319, 2021. Available at https://authors.elsevier.com/a/1cqCk3Rd3uuBQe

  • The M25 motorway was widened between Junctions 23 and 27 as part of the Smart Motorway investment programme implemented by Highways England. Detailed traffic monitoring reports were published before the scheme was opened and for three years afterwards.
  • There was some increase in traffic speeds at Year One after opening, compared with Before opening, but this gain was lost subsequently account of increased volumes of traffic. At Year Three, average daily traffic was up by 16% compared with Before, and up 23% at weekends. This contrasts with an increase of 7% for regional motorway traffic growth.  
  • The conclusion of the Year Three monitoring report states: ‘These results show that increases in capacity have been achieved, moving more goods, people and services, while maintaining journey times at pre-scheme levels and slightly improving reliability.’ However, this could not have been the basis of the investment case, which in general suppose that travel time savings are the main benefit of transport infrastructure investment. Accordingly, reports of the traffic and economic modelling were obtained; these utilised the long-established SATURN and TUBA models.
  • The traffic model projected increased traffic volumes and speeds for the scheme opening year, comparing the ‘do something’ investment case with the ‘do minimum’ case without the investment. However, the increase in traffic volume was less than the observed outturn and the increase in speed forecast failed to materialise beyond the first year after opening.
  • The modelled economic benefits derived very largely from time savings for business users. There were also time savings for local users, commuters and others, but these were almost entirely offset by increased vehicle operating costs. This was the consequence of local users rerouting trips between unchanged origins and destinations to take advantage of short journey times made possible by diverting to the motorway, travelling somewhat greater distances.
  • The benefits forecast for business users were the main input to the economic appraisal that generated a benefit-cost ratio of 2.9, which was the basis for the investment decision. However, the time savings benefits did not materialise beyond the first year after opening, on account of the additional traffic above forecast.
  • The nature of this additional traffic cannot be deduced from the traffic monitoring. It is likely that much, possibly most, comprises local trips rerouting, of no net economic benefit; indeed, these trips would be of negative benefit on account of the additional externalities (carbon etc) arising from the increased distance travelled. The outturn BCR must be much less than the forecast 2.9, possibly even negative.
  • This M25 case is likely to be typical in that the Strategic Road Network comes under greatest stress in or near major urban centres where local traffic competes for carriageway with long distance users. Highways England has 10 smart motorway schemes in its current investment programme, with an average BCR estimated as 2.4. This likely reflects considerable optimism bias in the modelling.
  • The modelling to support decision making distinguishes between different classes of road user, yet the traffic monitoring does not allow such a distinction. The monitoring is therefore of limited use in refining the models and countering optimism bias. What is needed is monitoring of representative samples of road users over time to see how their travel behaviour changes as the result of the road investment. Such longitudinal studies, as they are known, are common in the areas of health and social sciences, but almost unknown for travel and transport.

Recent revisions to the road traffic statistics appear to show that there has been a substantial growth of motor vehicle traffic on GB minor roads in recent years, from 108 to 136 billion vehicle miles between 2010 and 2019, an increase of 26%. Traffic on major roads rose from 197 to 221 bvm over the same period, an increase of 12%.  (DfT Road Traffic Statistics TRA0102).

Road traffic statistics are based on a combination of automatic and manual traffic counts. Major roads are well covered in that traffic in all links is counted on typical days, although not every link in every year. Given the vast number of minor roads, however, it is only possible to count traffic at a representative sample of locations every year, and the observed growth is applied to minor road traffic overall. Estimates from a fixed sample may drift over time such that the sample becomes less representative of the changing minor road network. To account for any errors incurred in the fixed sample, the sample is revised through a benchmarking exercise every decade, involving a much larger sample of locations.

The most recent minor roads benchmarking exercise was published in 2020, based on 10,000 representative locations. Overall, the benchmark adjustment for 2010-2019 was 1.19, which is the factor to be applied to 2019 data from the original sample to bring this to the observed traffic level. Data for minor roads traffic for intermediate years are adjusted pro rata, to avoid a step change in the reported traffic data. There is significant regional variation in the adjustment factor, from 1.35 for Yorkshire to 1.09 for East of England, with London at 1.32. For B roads the factor is 1.25, for C roads 1.17; while for urban roads, 1.22, and for rural roads, 1.15. Applying the regional weightings yields an increase in traffic on minor roads of 26%, as noted above, whereas the increase based on the original sample would have been 6%.

The previous benchmarking exercise published in 2009 found a smaller overall adjustment factor of 0.95, with a regional range of 0.81 to 1.08.

The substantially greater adjustment required following the recent benchmarking, compared with the earlier exercise, suggests that there has been a real change in use of minor roads, beyond errors arising from drift in the sample. Importantly, had the increase in minor road use been spread evenly across the national road network, the traffic estimation based on the sample would have been close to that from the benchmark exercise. Hence the major difference between sample and benchmark indicates considerable heterogeneity of minor road traffic growth. Moreover, the fact that the sample failed to detect the traffic growth suggests either that the process for establishing the sample was deficient in some way, or that significant changes occurred in use of minor roads over a decade.

DfT statisticians have created a revised minor roads representative sample (4,400 locations) from the latest benchmark data, which will be used for the coming decade. It would be desirable to have comparative analysis of the previous and the new samples, to gain insight into what has been happening on the minor road network. Regrettably, the statisticians only report findings, and do not attempt to explain them, which leaves uncertainty as to the nature and cause of the reported changes to traffic volumes. The representative nature of the new sample must be questionable if the reasons for the failure of the previous sample to reflect reality are not understood and addressed.

Transport for London has recognised this uncertainty. The recent Travel in London Report 13 discusses the implications of the minor roads traffic correction (p92). The revisions mean that, for 2018, the DfT estimate of vehicle kilometres was 20% higher than previously reported last year (and included in Travel in London Report 12). The previous estimate suggested a fall of 1.8% in vehicle kilometres in London between 2009 and 2018, whereas the revised series now suggests an increase of 17.9% over the same time period, this change wholly arising from revisions to the minor road estimates. TfL notes that it is currently working through how the DfT have made this assessment, and also what this could mean for London data sets. For the moment, TfL is relying on its own traffic monitoring data, although it does not report traffic on minor roads separately.

The National Travel Survey could provide a cross-check on the traffic data. Average distance travelled by car/van driver decreased from 3388 miles per year in 2010 to 3198 miles in 2019, a decline of 5.6% (NTS0303). The GB population grew from 60.95m in 2010 to 64.90m in 2019, an increase of 6.5%. The net increase in car use of about one percent is inconsistent with the new road traffic statistics which show an increase in traffic for all roads of 17% over the same period. The NTS employs a fresh sample of respondents each year, so sample drift should not be a concern. However, it is not clear that the travel diary technique would pick up rerouting to minor roads, given that respondents are asked to provide their own estimates of distance travelled for each trip.

Possible causes of increase in traffic on minor roads

One factor contributing to the growth of traffic on minor roads is the increase in van traffic, including that arising from the growth of online shopping with home deliveries. The number of vans (light commercial vehicles) registered in Britain increased by 28% between 2010 and 2019. Total van traffic increased by 34% over this period, with an increase of 49% on urban minor roads compared with 10% on urban ‘A’ roads, although ‘delivery/collection of goods’ was less important in respect of journey purpose than ‘carrying equipment, tools or materials’. However, in 2019 van traffic amounted to 15% of traffic on urban minor roads, and 19% on rural minor roads, cars being responsible for 82% and 78% of traffic respectively. So, the growth of van traffic on minor roads is responsible for only part of the overall traffic growth on these roads.

Another possible explanation of the apparent large growth of traffic on minor roads is the widespread use of digital navigation (satnav) that offers routes that take account of traffic conditions and estimated journey times. Such devices make possible the general use of minor roads that previously were largely confined to those with local knowledge. This is likely to occur when major roads are congested and represents an effective increase in the capacity of the road network, so generating additional traffic – the converse of the ‘disappearance’ of traffic when carriageway is reduced. Increased use of minor roads is problematic when policy is concerned to decarbonise the transport system and to promote active travel, which these roads facilitate.

The possible role of digital navigation might be investigated by an analysis of the correlation of the upward adjustment factor for each minor road sample location with traffic volumes on nearby major roads – to test the hypothesis that there would be more use of minor roads in areas where major roads were most congested. If so, this factor should be taken into account when setting up the new minor roads sample for the coming decade.

The use of digital navigation has been growing and may continue to grow in the future. A better understanding of the phenomenon would be important for forecasting road traffic growth by means of the National Transport Model and models at regional level and below.

A further possible cause of the changed distribution of traffic on minor roads arises from intentional interventions aimed at reducing such traffic. It has long been the practice to discourage ‘rat running’ on urban minor roads by means of suitable physical control measures, as are used in low-traffic neighbourhoods (LTN). Such measures would reduce traffic in certain locations while possibly increasing it in others through diversion. Some locations in the minor roads sample may be so affected. If LTNs and similar measures increase over time, the sample may become increasingly unrepresentative, a factor that should be taken into account in setting up the new sample. However, the net effect of intentional interventions would be to reduce traffic overall, so this cannot account for the reported growth of traffic on minor roads.

The growth of minor road use by through traffic apparently facilitated by digital navigation would strengthen the case for implementing LTN measures. Alternatively, or additionally, the providers of digital navigation might be encouraged to omit routes that direct through traffic along minor roads.

More generally, the impact of digital navigation on the functioning of the whole road network seems likely to be significant and therefore worthy of investigation.

The above considerations prompt a number of questions:

  1. How reliable are the statistics for motor vehicle use of minor roads, given the apparent sensitivity to the sampling of locations?
  2. How reliable are the NTS findings for car use?
  3. What information is available on the likely causes of the increase of traffic on minor roads?
  4. What is known of the impact of digital navigation on the road network?
  5. What are the implications of digital navigation for transport and traffic modelling?

Summary

The reported increase in motor vehicle traffic on minor roads over the past ten years is substantial and locationally heterogenous, for reasons that are unclear. This lack of understanding raises methodological questions about the sampling of minor roads. The reported increase in traffic is not consistent with the findings of the National Travel Survey, as well as being of concern to Transport for London. While interventions to reduce traffic on urban minor roads may increase the heterogeneity of the sample, they would not increase the volume of traffic. Hence this increase is most likely due to the growing use of digital navigation devices that allow minor roads to be used by those without local knowledge. This has implication for transport modelling as well as for policies to decarbonise the transport system and encourage active travel.

This blog post is the text of an article published in Local Transport Today 19 March 2021

I have a new paper on how time constraints affect our travel behaviour. The link to the journal is here. Some copies are free to download here. The manuscript is here. The abstract is below.

Considerable observational evidence indicates that travel time, averaged across a population, is stable at about an hour a day. This implies both an upper and a lower bound to time that can be expended on travel. The upper bound explains the self-limiting nature of road traffic congestion, as well as the difficulty experienced in attempting mitigation: the prospect of delays deters some road users, who are attracted back following interventions aimed at relieving congestion. The lower bound implies that time savings cannot be the main economic benefit of transport investment, which means that conventional transport economic appraisal is misleading. In reality, the main benefit for users is increased access to desired destinations, made possible by faster travel, which is the origin of induced traffic. Access is subject to saturation, consistent with evidence of travel demand saturation. However, access is difficult to monetise for inclusion in cost-benefit analysis. Consequential uplift in real estate values may be a more practical way of estimating access benefits, which is relevant to the possibility of capturing part of such uplift to help fund transport investment that enhances such access.

The Climate Change Committee has published a comprehensive and impressive analysis of how to achieve net zero carbon emissions by 2050. This includes a detailed treatment of surface transport, currently responsible for 22% of UK Greenhouse gas emissions, the absolute amount having changed little since 1990, stable in the range 110-120 MtCO2e annually. Cars account for 61% of surface transport emissions. Three options are proposed to secure emissions reduction:

Reducing demand for car travel by a variety of social and technological changes, including increased home working, online shopping, increased car occupancy though shared mobility, a shift to active travel and public transport, and more fuel-efficient driving.

Improving conventional vehicle fuel efficiency through regulation of road vehicle performance, use of biofuels, and more rail electrification.

Widespread deployment of electric vehicles (EVs) with the uptake of new battery EVs to reach 90-100% by 2030, in line with the government’s intention to phase out sales of new conventional cars and vans by that date. Driving range is expected to improve as battery technology advances. Sufficient charging infrastructure would be needed for the 30% of car users without access to off-street parking, as well as rapid charging for longer trips. The electricity supply system will need reinforcement.

The CCC has modelled the quantitative requirements associated with these options to show that it is possible to reduce surface transport emissions to 32 MtCO2e in 2035 and to 0.9 MtCO2e in 2050. The largest contribution comes from EVs. There are of course multiple uncertainties, many of which have been modelled.

The question is to what extent it will be possible to follow this emissions reduction pathway without measures beyond those already planned. Will it be necessary to create stronger incentives, for instance through more subsidy for EV charging facilities, or by making conventional vehicles more costly to operate through increased taxation? Changing relative prices can be a powerful incentive to change behaviour. It has not been helpful that public transport fares have risen much faster in recent years than the cost of motoring, in part due to a freeze on the rate of road fuel duty since 2010, reflecting perceived political sensitivities.

I am not optimistic about the practical possibilities that would increase the cost of car use, even for the virtuous cause of tackling climate change. We will have to make the most of regulation, the costs of which are more opaque, to effect the necessary changes.

The RAC Foundation has published a report on how information can be conveyed to drivers via connected vehicles. This assessed representative possibilities including In-Vehicles Signage (IVS) to display road signs and warnings to the driver inside the vehicle, and Green Light Optimal Speed Advisory (GLOSA) which tells drivers what speed to adopt to pass through the next set of traffic signals on green. The report discussed the obstacles to implementing these technologies, which it suggested arise mostly from organisational, institutional and human issues.

What was not adequately considered was the elephant in the room – the existing digital navigation (satnav) services, whether available free of charge as smartphone apps (Google Maps, Waze and others) or embedded as an integral part of the vehicle equipment. While the report mentions satnav devices as already providing some signage information, it envisages that a key element of the IVS concept is the ability for highway authorities to communicate directly with drivers, so that they can give them information they want them to receive (for example hazard warnings), as opposed to a satnav provider generating messages themselves.

Yet given the widespread use of digital navigation, it seems likely that the prime deciders of what information is conveyed to drivers will continue to be the satnav providers, not the highway authorities. The latter would need to make timely information available to the former if drivers are to benefit. But while highway authorities are subject to statutory regulation, providers of digital navigation are unregulated and are free to choose what information to provide to road users.

More generally, digital navigation has transformed how very many motorists use the road network, particularly for occasional, as opposed to regular, journeys. A choice of routes is offered at the outset of the trip, with estimated journey times, which mitigates the main perceived problem with traffic congestion – the uncertainty of time of arrival. Alternatives may be offered en route in response to the build-up of congestion. However, because the service providers of digital navigation are very secretive about their methodologies, we have little idea of the impact of their guidance on the overall functioning of the road network. For instance, we do not know if the rerouting in response to a crash on a motorway is optimal for users of the whole road network, or for drivers responding to the advice, or for neither.

There have been many anecdotal reports of digital navigation resulting in problematic use of minor roads (‘rat running’). While traffic on A and B class roads in London has been broadly stable since the mid-1990s, traffic on C roads, which had also previously been stable, increased from 5.4 billion miles in 2009 to 9.3 billion in 2019, suggestive of substantial impact of digital navigation devices.

There is clearly a case for better coordination between satnav providers and highway authorities to optimise the impact of digital navigation for all road users and to minimise environmental harms. There is in fact a legal basis for achieving this, although it has not been put into practice. The Road Traffic (Driver Licencing and Information Systems) Act 1989 requires dynamic route guidance systems that take account of traffic conditions to be licenced by the Secretary of State. This was enacted to facilitate the introduction of a pilot route guidance system that had been developed by the Transport Research Laboratory (then part of the Department for Transport), which in the event was not taken forward. A licence could include conditions concerning roads that should not be used and information to be supplied about traffic conditions.

There is a need for a review of the impact of digital navigation on the functioning of the highway system with a view to identifying ways of benefiting road users. It is very likely that exploiting digital technologies would be far more cost effective than employing costly civil engineering technologies to increase capacity.

The main focus of recent interest in the area of ‘Connected and Autonomous Vehicles’ has been autonomy – driverless cars – where both tech companies and auto manufacturers are attempting to get the technology to the point where it could be used on real roads. In contrast, while the idea of connected vehicles has been around for some years, progress has been slow. There are two kinds of connectedness: vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I); collectively V2X. A recent US webinar and report provided some illumination.

The main motivation of V2X is to improve safety, a real issue in the US where more than 6000 pedestrians a year are killed in traffic-related incidents. The aim is to enhance visual line of sight communication by using other parts of the electromagnetic spectrum.

There are two means of connectivity: WiFi based on a dedicated short-range communications (DSRC) standard approved in 2010 but with little implementation by manufacturers; and a cellular connection (C-V2X), based on smartphone technology, which could connect vehicles directly, independent of the base stations used for normal voice calls. Initially, 4G technology is being used, with the intention to move to the much faster 5G as that is rolled out. The hope is that vehicles will also be able to sense the presence of pedestrians by detecting their smartphones. The V2I capability depends on road authorities being willing to install connectivity in traffic signals and other roadside signs, which they may be reluctant to afford.

Deployment of V2X depends on whether this is mandated by national authorities. The Chinse government is supporting C-V2X. On the other hand, EU states voted against a proposal of the European Commission to adopt a WiFi standard, and the US government has also not supported a similar approach. In the absence of a policy mandate, deployment depends on consumer demand. The VW Golf launched in 2019 has WiFi V2X connectivity. Ford is planning to introduce C-V2X in 2022.

However, consumer interest and willingness to pay for a range of driver assistance and connectivity technologies has remained lukewarm for several years, with substantial levels of ambivalence and even scepticism towards these offerings. Enhanced safety, while desirable, may be insufficient a selling point. And having two technologies in use will not help.

Apart from safety, the other potential use of V2X connectedness would be to increase effective road capacity by permitting shorter headways between autonomous vehicles. This benefit depends on the implementation of robot-driven vehicles with faster reaction times than human drivers. Shorter headways would increase the risk of crashes. Crashes involving autonomous vehicles require allocating responsibilities for fault, more difficult where V2V communication is involved between vehicles of different make under different ownership. Moreover, the benefit from increased road capacity accrues to road authorities more than to road users, so the commercial incentive to develop V2V for this purpose seems quite limited.

Altogether, the case for developing vehicles connectedness does not seem strong.

The Department for Transport (DfT) is consulting on a new aspect of vehicle automation – the Automated Lane Keeping System (ALKS) . Already available are advanced driver assistance systems that include adaptive cruise control and lane keeping, to govern longitudinal and lateral movements, respectively. Inclusion of both would amount to SAE Level 2, referring to the generally accepted categorisation of vehicle automation.

The consultation concerns a proposal to permit a move to SAE Level 3, by relieving the driver of a light vehicle of responsibility for longitudinal and lateral control at speeds of up to 60 kph (37 mph) on motorways. This would allow drivers to attend to other tasks in heavy, slow moving traffic on modern roads not used by cyclists and pedestrians.

DfT hopes that automation will make roads safer, given that 85% of road collisions in Great Britain that result in injury involve human error. However, a requirement for the operation of ALKS is that the individual does not need to monitor the vehicle if, inter alia, the vehicle can ‘avoid collisions which a competent and careful driver could avoid’ (consultation document para 3.13). Presumably, moving at low speed on a traffic-congested motorway ensures that the probability of an injury accident is very low. Hence while ALKS in these circumstances would not improve safety, it would not be likely to worsen it.

The benefits to road users of low-speed ALKS are relatively modest, and vehicle manufacturers may not think it worthwhile developing this SAE Level 3 technology, with the costs involved that would need to be recovered from sales. However, the consultation raises the possibility of ALKS operation at up to 70 mph, a speed at which fatal and injury accidents occur and where a timely and effective response of the driver to a transition demand would be essential. Doubts about the feasibility of such a response deter many developers from pursuing Level 3 technology, preferring to jump to Level 4 where there is no role for the driver in a defined environment. On the other hand, Level 3 low-speed ALKS may be easier to deploy on motorways, as a first step to autonomy, than Level 4 technology at higher speeds.

The attractions for manufacturers of low-speed ALKS may depend on the prospects for eventually offering this technology for use on motorways at all legal speeds, which would be far more attractive for intending purchasers of vehicles but more a good deal more demanding technically. It would therefore be important for DfT to indicate the likely safety requirement for all-speed ALKS. This would need to be more stringent than the ‘competent driver’ requirement, to meet both high public expectations for transport safety when individuals are not in charge of a vehicle, as well as the aim that automation should make roads safer.

The Prime Minister has announced expenditure of £2bn to kickstart a ‘cycling and walking revolution’. While this reflects his personal predilection for cycling, as was evident when he was Mayor of London, there are two pressing policy imperatives. The coronavirus pandemic necessitates reduced occupancy of buses and trains, for which cycling and walking provide healthier alternatives. And in the longer term, active travel, as it is termed, has a part to play in plans being developed to decarbonise the transport system, as well as to improve urban air quality.

Cities are promoting active travel in response to the pandemic. Manchester has committed £5m to enable socially-distanced cycling and walking.    Sadiq Khan, the current Mayor of London, has reallocated road space with the aim of increasing walking five-fold and cycling ten-fold.

A ten-fold increase in cycling in London would take the present 2.5% share of journeys to the level found in Copenhagen, currently 28%, in a city that has excellent cycling infrastructure and a longstanding cycling culture. However, 32% of trips in Copenhagen are by car, only a little less than London’s 35%. Aside from cycling, the other big difference is public transport use: 19% of journeys in Copenhagen versus 36% in London.

This indicates that we can get people off buses onto bikes, which are cheaper, healthier, better for the environment, and no slower on congested urban streets. But it is harder to get people out of their cars, even in Copenhagen where everyone has experience of safe cycling. Features that make the car attractive include the ability to carry people and goods, including the stuff your lug around in the boot; and trips a bit long for a bike ride, or where you need to appear well dressed at the destination. And many people positively like cars and driving for feel-good reasons – witness the enormous choice of models, including the current fashion for high fuel consumption sports utility vehicles.

Cars typically are parked for 95% of the time, which makes an economic argument for those keen on sharing vehicles or journeys. But conversely, the willingness to pay substantial sums for an item used for only 5% of the time indicates the value people place on personal ownership and the mobility that this make possible.

The fundamental attraction of the car is the access it allows to people and places, opportunities and choices, at least when roads are not too congested and when it is possible to park at both ends of the journey. To achieve access to the wide range of destinations to which we have become accustomed, within the time available for travel during the busy day, the car is the most efficient mode of travel for moderate distances. If you live in a village without a car, and with limited or non-existent bus services, your opportunities and choices of work, shops and services are limited. Acquire a car and the possibilities are expanded substantially. Although there are many ideas and initiatives for replacing cars outside cities, the cumulative impact is unlikely to be transformative.

Where it is certainly possible to replace cars is in cities, where roads are congested and parking is limited. Car use in London was at its peak in the early 1990s, accounting for 50% of journeys. Subsequently the population increased while road capacity for cars was reduced to make room for bus lanes, cycle routes and pedestrian space, and at the same time there was substantial investment in rail capacity, all of which reduced car use to the current 36% of journeys. But beyond densely populated cities, the cost of urban rail is hard to justify, and buses on congested roads are not an attractive alternative to car use. On the other hand, buses on dedicated routes free of general traffic – Bus Rapid Transit – can be attractive as a lower cost alternative to rail.

The pandemic lockdown showed how we could make substantial changes to our travel behaviour, some of which are likely to be long-lasting – less travel for commuting, shopping and on business. Yet such decreases could well be offset by increases in other kinds of trips, reflecting our need to get out of the house and engage with the wider world.

There is much uncertainty about the extent to which we can count on changing travel behaviour to contribute to transport decarbonisation and improve urban air quality. We will therefore need to rely largely on technological change, by replacing oil as the main fuel for motive power – electrification of cars, vans and most trains.

Policy to promote walking and cycling is undoubtedly worthwhile and will yield both health and environmental benefits. Yet the attractions of motorised mobility and the experience of Copenhagen suggest that the main impact will be to attract people from public transport, rather out of their cars.

This blog was the basis for an article in The Conversation on 24 August 2020

Lynn Sloman and colleagues of Transport for Quality of Life (TQL) issued a report about carbon emissions arising from the Department for Transport’s second Road Investment Strategy (RIS2). Their detailed analysis reaches the conclusion that the increase in CO2 from RIS2 would negate 80% of potential carbon savings from electric vehicles on the Strategic Road Network (SRN) between now and 2032.

This conclusion struck me as surprising. Although annual expenditure on new capital projects for the SRN has been running at over £2 billion a year, civil engineering is very costly and we don’t get much extra capacity for our money. The recent rate of addition of lane-miles to the SRN has been 0.5% a year, which is less than the rate of population growth. So how could such a low rate of addition of capacity have such a large adverse impact on carbon emissions? We need to question the TQL calculations.

TQL argues that the RIS2 road schemes will increase carbon emissions in a number of ways, particularly by increasing speeds and inducing more traffic, both of which they believe are underestimated in conventional scheme appraisal. They therefore estimate the additional cumulative carbon emissions from these sources, both put at around 6 Mt CO2 for the period 2020-2032. But I wonder if there is not some overstating here, given that more traffic would tend to reduce speeds. For instance, for a scheme to widen part of the M25, I found that outturn traffic flows were higher than forecast, such that there was no increase in traffic speed.

TQL estimate that RIS2 would increase carbon emissions by 20 Mt CO2 for the period 2020-2032, including carbon from construction. This is then compared with the difference in carbon emissions between two scenarios from the DfT Road Traffic Forecasts 2018, the Scenario 1 reference case and Scenario 7 high electric vehicle case, which amounts to a reduction of 25 Mt, hence the conclusion that the increased carbon emissions would negate 80% of the benefit of the shift to EVs.

There are, however, problems with this estimate of carbon reduction from EVs. Scenario 7 assumes no tax on EVs to replace fuel duty, so that the cost of motoring decreases substantially (by 60% by 2050), hence a projected large increase in traffic compared with Scenario 1 (50% increase by 2050 compared with 35% for the reference case). Whatever the realism of the assumption about tax, such a large increase in traffic is implausible as the consequence of electrification. Average travel time has remained constant at about an hour a day for the past 45 years at least, hence to travel further it would be necessary to travel faster, which will not happen through a change in propulsion. The problem is that the Road Traffic Forecasts derive from the National Transport Model, which does not recognise travel  time constraints.

An assumption that electrification has no effect on traffic volumes would substantially increase the scale of carbon reduction under Scenario 7, to which could be added the benefit of bringing forward the phase out of non-electric cars and vans earlier than 2040, as assumed in that Scenario. And if we reduce the additional carbon from the RIS2 programme to allow for some overstating, then we could arrive at a less pessimistic conclusion than the TQL authors about the carbon impact of this programme on future overall SRN emissions.

Nevertheless, despite these caveats, I agree with the conclusions of the TQL report that RIS2 is anachronistic, and that cancellation would free up substantial investment for better uses, not least fast broadband to lessen the need for travel, both for commuting and on business. The SRN is under greatest traffic stress in or near urban centres during the morning and late afternoon peaks, when car travel to and from work interferes with long distance road users. The economic case for road investment needs to be reconsidered in the light of changes in daily travel prompted by the pandemic.