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.

I previously noted publication by the Department for Transport of its Second Road Investment Strategy (RIS2). DfT has now issued an economic analysis that concludes that the new programme represents high value for money. I had hope that this document would provide substantiation of the £27 billion, 5-year road investment programme but I was disappointed.

The summary states that overall RIS2 is High Value for Money, meaning £2 return for every £1 spent (Benefit-Cost Ratio of 2). Yet new commitments of major capital enhancement schemes yield a BCR of 1.5, which is unimpressive. The analysis is minimal, offering no breakdown into individual schemes, where some might be expected to have a BCR of 1 or less if the average is 1.5.

These estimates are based on the now rather dated Road Traffic Forecasts published in 2018, which included five distinct scenarios, yet no indication is given as to how the BCR would vary with scenario. The estimates are also derived from new but unpublished regional traffic models, asserted to be ‘world leading’.

I previously pointed out a major discrepancy between traffic forecasts and post-opening outturn for the smart motorway widening of the M25 between Junctions 23 and 27. These forecasts were generated by a regional model of the kind now in general use by Highways England, based on SATURN software that originated in the 1980s. The purpose of these models is to estimate travel time savings that arise from adding carriageway, which feed into an economic model. Yet in the M25 case, no time savings were observed beyond year 1 after opening, putting the validity of such models  in doubt.

The new DfT analysis frequently asserts that its analysis is robust (15 times, in fact), which is usually a sign of intellectual insecurity. In fact, the analysis is pretty thin and seems intended to justify a road construction programme developed in earlier era, before we have had a chance to assess the impact of the coronavirus pandemic and what this might mean for travel demand and for public expenditure priorities, urban vs. inter-urban transport vs. broadband.

An on-line meeting organised by Local Transport Today on 19 June was concerned with the future of car travel after the coronavirus pandemic. I contributed the following thoughts.

The average distance travelled by car in the UK per person ceased to grow at turn of century, following strong growth in the last century. This phenomenon has been called ‘Peak Car’, but ‘Plateau Car’ would be a better term, given the 20-year flat trend. But with the coronavirus pandemic, we have three new influences that could affect the trend of car use in the longer run.

First, a natural preference for the car in place of public transport during the pandemic, which will add to road traffic congestion. Second, less road space for cars in urban areas to allow more room for active travel, both as response to the pandemic and to promote longer term reduction in carbon emissions and improve urban air quality; this also will tend to increase congestion, unless car users could be persuaded to switch to active modes. Third, less car travel due to more working at home, more video-conferencing, and more on-line shopping, accentuating recent trends; this would relieve congestion. We can’t yet estimate the likely magnitude of these influences, so can only speculate in broad terms how they may play out.

Might active travel substitute for some car use? The London Mayor aims to increase cycling 10-fold. That would take mode share to 30%, as Copenhagen, a city with comprehensive cycling infrastructure. Yet car use in Copenhagen only slightly less than in London, while public transport use half that in London – 18% mode share vs 37% in London.

It seems that people can be attracted off buses onto bikes, which are cheaper, healthier, environmentally better, and no slower in congested traffic. Yet this would reduce fare income to public transport and likely the level of service. In contrast, it seems harder to get people out of cars onto bikes, even in Copenhagen where most motorists have bikes at home.

The fundamental problem in getting people to travel by slower modes is the consequent reduction in access. The key historic transport innovations all increased access. Railways, the modern bicycle, motor car, motorised two-wheelers, each offered a step change increase in speed of travel and hence in access to people, places, opportunities and choices. Access increases with the square of the speed of travel. Comparing walking at 3 mph with urban car travel at say 20mph, a 7-fold increase in speed, yielding a 50-fold increase in access to desired destinations. Comparing cycling at 10mph with car travel – twice the speed giving four times the access. People have become used to the access offered by the car and most would be reluctant to settle for less by opting for slower modes.

To reduce car use, we need to offer a mode that is faster and more reliable than the car on congested roads, which is rail – interurban between cities, commuting into cities, and rail in all its forms within cities. Investment in rail in London has been important in reducing car mode share from 50% in early 1990s to the current 36%. But continuation of that shift depends not only on successfully tacking the coronavirus pandemic, but also continuing to invest in urban rail, which is very costly and so limits expansion of rail travel.

The other way of reducing car use is to lessen the need to travel for work. The pandemic has shown us how we can manage to travel much less, but this is undoubtedly suboptimal. The magnitude of the rebound remains to be seen. Investment in broadband could facilitate remote working and could be much more cost-effective than new road capacity.

 All in all, I do not expect to see a substantial change in per capita car use nationally, once the pandemic is behind us, but we could be at the start of a downward trend, reflecting less need to travel and some switching to other modes. It may turn out that we are now at the peak of car travel on a per capita basis, which should prompt review of all those ‘shovel ready’ schemes in the road construction programme.

As a means to decarbonise the transport system, the contribution of behavioural change is problematic to rely on because of the uncertainties of responses to both the easing of lockdown restrictions and policy interventions aimed at changing travel behaviour. This means that we need a strong commitment to technology in the form of electrification, both to cut transport carbon emissions and improve urban air quality.

The other new technology – automation – is not a solution to the problems we face. It will be difficult to deploy autonomous vehicles on the existing road network. The technology is expensive and the benefits limited, so that the appetite of consumers is uncertain. The car manufacturers will give priority of electric vehicles, leaving automation to be developed in the slow lane.

The Department for Transport recently issued a report concluding that the Second Road Investment Strategy (RIS2) represents high value for money. One might have thought that this 29-page RIS2 Analysis Overview would porvide substantiation of the £27 billion, 5-year road investment programme announced earlier. We are disappointed.

The summary states that overall RIS2 is High Value for Money, meaning £2 return for every £1 spent (Benefit-Cost Ratio of 2). Yet new commitments of major capital enhancement schemes yield a BCR of 1.5, which is unimpressive. The analysis is minimal, offering no breakdown into individual schemes, where some might be expected to have a BCR of 1 or less if the average is 1.5.

These estimates are based on the now rather dated Road Traffic Forecasts published in 2018, which included five distinct scenarios, yet no indication is given as to how the BCR would vary with scenario. The estimates are also derived from new but unpublished regional traffic models, asserted to be ‘world leading’.

I previously drew attention to a major discrepancy between traffic forecasts and post-opening outturn for the smart motorway widening of the M25 between Junctions 23 and 27. These forecasts were generated by a regional model of the kind now in general use by Highways England, based on SATURN software that originated in the 1980s. The purpose of these models is to estimate travel time savings that arise from adding carriageway, which feed into an economic model. Yet in the M25 case, no time savings were observed beyond year 1 after opening, putting the validity of such models  in doubt.

The DfT report frequently asserts that its analysis is robust (15 times, in fact), which is usually a sign of intellectual insecurity. In fact, the analysis is pretty thin and seems intended to justify a road construction programme developed in earlier era, before we have had a chance to assess the impact of the coronavirus pandemic and what this might mean for travel demand and for public expenditure priorities, urban vs. inter-urban transport vs. broadband.

The Department for Transport has initiated an exercise to assess how the transport system could be decarbonised, in line with the Government’s commitment to a net zero carbon target for the whole economy by 2050.

I have submitted some thoughts on behavioural aspects, including the scope for increasing active travel, decreasing motorised road travel and air travel, and the need to improve modelling to accomodate such behavioural changes.

The Department for Transport’s (DfT) second Road Investment Strategy (RIS2) was published at the time of the recent Budget, committing to spend £27.4bn over the next five years on the strategic road network (SRN). The stated main priority is to maintain the existing roads. Only where existing roads are ‘simply not up to the job’ is the Government asking Highways England to develop wider, realigned or, in a few cases, wholly new roads to keep people and goods moving. Yet expenditure on maintenance is expected to be £12bn, whereas capital enhancements are worth £14bn.

Investment

Prioritising investment is based on the 2018 Road Traffic Forecasts, projecting growth on the SRN in the range of 29% to 59% by 2050. This suites the civil engineers of Highways England who see their main purpose as building roads. However, as I have argued previously, the DfT traffic forecasts are very problematic and have generally proved to overestimate outturn traffic levels. Moreover, as I noted in chapter 2 of my recent book, the rate of addition of lane-km to the SRN in recent years has been less than the rate of population growth, despite the high levels of spend.

It is therefore not surprising that average delays on the SRN have worsened during the RIS1 period, growing from 8.9 seconds per vehicle mile to 9.5 seconds per vehicle mile. The DfT’s ambition for performance at the end of RP2 is to be no worse than at the end of RP1. This is a very modest aspiration, and contrasts with the aim of the previous road investment strategy (RIS1) of a free-flow core network with mile a minute speeds increasingly typical.

The new ambition is consistent with the document’s recognition that it is ‘widely accepted that it is not possible to outbuild congestion across the whole of the road network’. Accordingly, investment is to be focused on congestion hotspots, so that average network performance will be at least as good in 2025 as it is in 2020. Yet, as I have pointed out, adding capacity induces more traffic, so tackling congestion hotspots has little impact beyond perhaps shifting congestion to another part of the network.

Optimisation

One odd feature of this and similar publications of Highways England, is the disregard of digital route guidance (Google Maps, Waze and others) that is in very wide use by drivers, because they find it of benefit in optimising routes under congested conditions and in estimating journey times. Roadside variable message signs are an outmoded technology, providing too little information, too late to be of much use.

There is picture of a route guidance app on page 38 of the RIS2 document, but no mention of its relevance. There is a statement that ‘During RP2 Highways England will work with Transport Focus [a consumer body] to investigate future opportunities to make more granular information about delay on the SRN publicly available. We anticipate that this might include reporting on a regional basis, journeys between conurbations, and maps showing delay across the network on a link-by-link basis.’ Highways England seems totally out of touch with the real world.

Non-investments

The RIS2 mentions the outcome of a number of earlier ‘strategic studies’ that now seem unlikely to lead to much. For the M60 Manchester NW Quadrant, it is concluded that the transformational options identified by the study would have significant adverse impacts on local people and communities, and overall would not provide value for money. The proposed Trans-Pennine Tunnel, improving the route between Manchester and Sheffield, seems unlikely to proceed. The Oxford to Cambridge Expressway project has been paused to look at other options.

In contrast, the A303 Stonehenge Tunnel is to go ahead. Yet the National Audit Office found that transport and economic benefits accounted for only 27% of total benefits; the value of cultural heritage, based on a survey asking people what they would be willing to pay to remove the road altogether, was put by the DfT at 73%, and yet this yielded a benefit-cost ratio of only 1.15 , which in the event is likely to be worse because cost overruns. The NAO noted that the DfT has no plan for the corridor as a whole, and that all the other projects on the route offered poor value for money.

This critique of the A303 route can be generalised to the RIS2 as a whole. Although it is entitled a ‘strategy’, in reality it is a construction programme that is deficient in both economic justification overall and indication of spatial impact of economic benefits. What benefits might we expect, and where? We are not provided with more than vague aspirations.

 

 

 

 

 

 

 

 

 

The Office of Rail and Road (ORR) is responsible for overseeing the performance of Highways England (HE), a publicly owned company responsible for England’s strategic road network. ORR is consulting on how it should perform its role. I have responded as below:

HE is responsible for a substantial programme of investment in new and improved road infrastructure, each element of which is supported by cost-benefit analysis consistent with the Department for Transport’s Transport Analysis Guidance. The main economic benefit is assumed to be the value of the time saved as a result of investments which increase capacity and are intended to reduce road traffic congestion.

However, there are questions about the estimation of prospective travel time savings derived from the standard models used for traffic forecasts. For example, monitoring of the outcome of widening of the M25 between junctions 23 and 27 concluded 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.’[1] No travel time savings were observed beyond the first year after opening, in part at least due to increased traffic, notably an increase of 23% at weekends. These outturns were inconsistent with the forecasts of traffic volumes that were significantly less than observed, and with speeds that were projected to be higher with the road widening than without.[2] The higher speeds were the basis for estimates of travel time savings, leading to the DfT’s estimate of the Benefit-to-Cost ratio of 2.3, which justified the investment.

This example shows that there may be a substantial discrepancy between forecast and outturn traffic flows and speeds. That this is a general problem is indicated by the observed invariance of average travel time over the past 45 years, as found in the National Travel Survey.[3] This implies that the benefits of road investment have been taken, not as time savings, but as increased access to desired destinations, which results in more traffic. This additional traffic is known as ‘induced traffic’, the consequence of increasing capacity, which results in increased externalities related to vehicle-miles travelled, including congestion, carbon emissions, air pollutants, and death and injuries. While HE routinely monitors outcomes of schemes 5 years after opening, this may not be sufficiently long to observe the full extent of induced traffic.[4]

There is therefore reason to suppose that in general the outcome of road investment as experienced by users does not correspond to the rationale for the investment, which is principally to increase welfare and economic growth by reducing congestion and improving connectivity. This discrepancy should be of concern to the ORR.

[1] Smart Motorway All Lane Running M25 J23-27 Monitoring Third Year Report. Highways England. 2108.

[2] https://www.gov.uk/government/publications/vdm-used-to-estimate-traffic-volumes-and-travel-time-saved

[3] Table nts-0101-2018

[4] Sloman L, Hopkinson L and Taylor I (2017) The Impact of Road Projects in England, Report for Campaign to Protect Rural England

 

 

Transport for London has recently published its latest report on Travel in London. At 279 pages, this latest in an annual series is almost certainly the most detailed account of travel behaviour in any city in the world. All credit to TfL.

Table 2.3 shows trip-based mode share. Private transport (very largely car) was responsible for 48% of trips in 2000, declining to 37% in 2015, but thereafter stabilising. Public transport has been stable at 35-36% of trips since 2012, and walking at 24-25% since 2000. Cycling grew from 1.2% in 2000 to reach 2.5% 2018. So the declining trend of car use has ceased in recent years, but it may resume as new rail capacity is opened, particularly Crossrail (the Elizabeth Line). Nevertheless, the target reduction of private transport to 20% by 2041, a feature of the Mayor’s Transport Strategy, looks difficult to achieve.

Section 9.7 discusses the role of licenced taxis and private hire vehicles (PHVs), a topic of much current interest. Taxis (black cabs) have been in slight decline while PHVs have grown substantially in recent years, largely reflecting the entry of Uber into the market. A survey of PHV users in London found that the two main trip purposes were for a night out and to/from airports, but only 28% of PHV trips were for both outward and return legs. App-based PHV users were attracted by specific features: estimate of fare, time for driver to arrive, knowing details of car booked, and estimate of journey time. 30% of PHV users said they had not needed to buy, replace or own a car, which facilitates a shift from individual car ownership.

Assessment

While a long-term target for reduction in car use has merit in that it shapes shorter term decisions, no Mayor is likely to hold office for anything like the time to reach the 2041 target date. A shorter-term target would allow performance to be held to account. And while the recent experience of London is that a steady reduction in the share of trips by car is compatible with the economic, cultural and social success of the city, sustaining this in the longer term would depend on substantial investment in the rail system that provides a fast and reliable alternative to buses, cars and taxis on congested roads. The biggest challenge for TfL and the Mayor is to find means of financing this investment.