My new book, Travel Fast or Smart?, is one in a series of short books on policy and economics topics described as ‘essays on big ideas by leading writers’. My contribution is a critique of the inconsistencies of transport policy in recent decades, which I attribute to the shortcomings of conventional transport economic appraisal in identifying the benefits that arise from investment.  This book is available both in print and as an ebook from Amazon Books

There is much current interest worldwide in the concept of Mobility-as-a-Service (MaaS), the aim of which is to provide seamless journeys using the most appropriate travel modes, routed and ticketed by means of a smart phone app. The MaaS provider ‘aggregates’ the services provided by transport operators (in the way that Amazon acts for retail product providers). MaaS is intended to be an attractive alternative to private car ownership. The Transport Catapult has recently published a report on the opportunities for MaaS in the UK. And the New Cities Foundation has addressed the role of public transport operators in its development.

There are many recognised technical and policy issues that need to be tackled, including managing the large amounts of data, and coordinating ticketing and payments on behalf of a multiplicity of operarors. However, there are two aspects that deserve particular consideration. The first is the ability of MaaS to cope with peak travel demand.

Peak demand

Daily travel demand is characterised by morning and evening peaks, and there are also seasonal variations. Peaks result in road congestion and crowding on railways. One approach would be to charge higher prices at times of greatest demand, with the aim of spreading the peak. This model has been adopted in the aviation sector, led by the low-cost carriers, and by Uber for urban taxis (and also in other sectors such as hotels). The railways offer off-peak discounted fares, but do not flex fares upwards to reflect actual peak demand.

However, unless peak pricing is part of the public transport provision (which at present it is not), the scope for coping with peak demand for multi-modal journeys is quite limited. This means that unreliability of travel time for each stage of a journey would present a scheduling problem.

While MaaS comprises a minority of all trips, congestion would be a given, and scheduling would need to allow for expected journey stage times plus a margin for uncertainty, with rerouting in the event of unexpected congestion. On railways, consideration would need to be given to offering alternatives to overcrowded trains. Such dynamic scheduling could be technologically challenging.

Were MaaS to grow to encompass a substantial part of travel demand, there may be scope for routing travellers to spread demand across the network in a way that optimises overall efficiency, simplest for routes that involve stages with assured reliability – rail, bus rapid transit, walking and cycling. There would also be scope to consolidate car trips by means of shared taxis, as with UberPOOL. However, such sharing, incentivised by lower fares, could attract passenger from buses, which could add to congestion.

If MaaS were to be a major intermediary in meeting travel demand, a significant operational issue would be whether to respond to peak demand for door-to-door travel by mobilising more taxis through surge pricing, as does Uber. Surge pricing to deter demand and increase supply is sensible in the absence of congestion, but may not be optimal under congested conditions. In the absence of surge pricing, demand would exceed supply and would be rationed by waiting in a virtual queue until a taxi becomes available. With surge pricing, there is a greater supply of taxis and so less waiting time, but journey times might be slower on account of increased congestion. Which approach would be optimal would require modelling.

Surge pricing works well for aviation, a closed system where an aircraft can only fly if it has airport slots allocated at trip origin and destination. But roads are an open system and hence prone to congestion at peak times in populated areas. MaaS would be more straightforward to implement in lower density areas, less so in urban centres, unless private cars were entirely replaced by a fleet of shared use self-driving vehicles, as has been suggested.

Who owns the platform?

The question of how MaaS can best cope with peak demand is linked to the second problem – the nature of the platform by means of which demand and supply are matched, prices set and revenues allocated. The central issue is familiar: benefits of competitive supply versus benefits of an integrated network. Experience is varied. In the case of buses, Mrs Thatcher’s government opened the bus services outside London to competition with minimal regulation, hoping to benefit users by on-the-road competition between private sector operators. This largely failed to materialise since such competition resulted in unattractive profit margins. In consequence, the present Government has introduced legislation that would allow other cities to adopt the successful London model, whereby an integrated public transport network is operated by a politically controlled public body, Transport for London.

For MaaS, the question is whether an open source public platform would naturally evolve on account of the superior benefits, as envisaged by the TravelSpirit collaboration. Or whether competition in the market between competing platforms would be the main driver, with perhaps a dominant platform emerging through economies of scale and scope.

A dominant private sector platform might need to be regulated to avoid market failure that allowed economic rents to be extracted at the expense of users. The MaaS provider would have access to all the data arising from use of the system. Fair sharing of this data with transport providers would help meet the needs of users. On the other hand, discriminatory sharing could increase returns to the provider.


Traffic congestion is the main problem of the road system. A key question is whether MaaS has the potential to lessen traffic congestion. If it does, then promoting MaaS could be a sensible transport policy, in which case a view would need to be taken of the relative attractions of competing platforms versus a single public platform.

In the longer run, developments in shared use driverless urban vehicles might achieve substantial mitigation of urban traffic congestion. Sharing of taxis would increase vehicle occupancy and hence efficiency of the road system; demand management could limit use of single occupancy vehicles under congested conditions; and the development of vehicle-to-infrastructure communications could permit flow management, analogous to air traffic control. In such circumstances, MaaS would be likely to be an integral part of an urban transport management system. However, development of such a system would be challenging in respect of technology, business models, institutions and public acceptability – hence the feasibility and timing is uncertain. In the meantime, development of MaaS in urban areas would need to cope with traffic congestion.








My new book published on 1 September is one in a series of short books on policy and economics topics described as ‘essays on big ideas by leading writers’. My contribution is a critique of the inconsistencies of transport policy in recent decades, which I attribute to the shortcomings of conventional transport economic appraisal in identifying the benefits that arise from investment.  This book, Travel Fast or Smart?, is available both in print and as an ebook from Amazon Books

The House of Commons Transport Committee is carrying out an inquiry into urban traffic congestion. I submitted evidence and appeared at an oral evidence session along with other experts.

Traffic congestion occurs in densely populated areas where car ownership is high. There is too little road space to meet all potential demand for car travel while maintaining reasonable flow. Accordingly, many possible car trips do not take place. People are deterred by the prospect of uncertain delays in congested traffic, so they change the timing of their trip, or the destination (alternative shops, for example), or the mode of travel (rail often faster than a car on congested roads), or decide not to travel at all (by working at home, for instance).

The implication of such suppressed demand for car travel is that measures to lessen congestion may have little impact. A congestion charge, as in Central London, would deter some drivers, but they would be replaced by others able to bear the cost who previously would have been dissuaded by the congestion delay. Increasing road capacity, while generally not feasible in urban areas, is seen by many as a solution beyond. However, this permits more and/or longer car trips, the extra traffic thereby restoring congestion to what it had been – hence the maxim that you can’t build your way out of congestion.

Congestion is self-regulating in the long run. As traffic builds up, speed drops and journey times increase. Some drivers opt for alternatives of the kind mentioned above, and congestion stabilises. Urban Traffic Management systems, which operate through adjusting the timing of traffic signals, help to prevent gridlock. However, congestion can be exacerbated in the short run by temporary blockages such as street works or major construction, and also while adaptation takes place to new permanent structures such as cycle lanes.


There is little that can usefully be done to mitigate urban traffic congestion. On the other hand, the growth of urban car traffic can be contained by not increasing road capacity for cars, and indeed can be reversed by subtracting from such capacity. This is the experience of London Congestion Charging, which returned congestion to past levels and yet traffic volumes are lower than they were – because the Mayors took the opportunity offered by the Congestion Charge to take road capacity away from conventional traffic in favour of pedestrians, cyclists and other uses.




The Independent Transport Commission (ITC) has updated its earlier report on trends in road and rail travel, On the Move, to 2014. This is based on detailed analysis of National Travel Survey data by Peter Headicar and Gordon Stokes.

A key finding is that per capita distance traveled has been decreasing significantly over the past decade and is now 10% lower than in the mid-2000s. As author of a book (and this blog) entitled ‘Peak Car’, I was gratified to read that individual car driving mileage per adult has declined significantly over the period 1995-2014 (see Figure).

The main purpose of the analysis was to identify trends rather than the causes behind them, but the authors believe that attitudinal factors are becoming increasingly significant as drivers of travel. The ITC’s 2015 attitudinal research indicated that cars are increasingly viewed as ‘appliances not aspirations’, especially by young people, while public transport is being seen more favourably.
This report of the ITC provides valuable analysis of the Department for Transport’s National Travel Survey, well worth reading by those who follow the debate about the future of car use. This detailed consideration contrasts with the rather limited account provided by the Department itself.
The present study is consistent with the proposition that travel behaviour changed significantly as we transitioned from the twentieth century to the twenty-first.

My new book published on 1 September is one in a series of short books on policy and economics topics described as ‘essays on big ideas by leading writers’. My contribution is a critique of the inconsistencies of transport policy in recent decades, which I attribute to the shortcomings of conventional transport economic appraisal in identifying the benefits that arise from investment.  This book, Travel Fast or Smart?, is available both in print and as an ebook from Amazon Books.

Three studies of prospective road investments in the North of England have been published recently. These illustrate some of the questions that arise when the aim is to boost economic growth by increasing road connectivity between cities.

M60: Manchester North-West Quadrant

The NW section of the M60 orbital motorway within Manchester is one of the busiest roads in the country, on account of the mix of local and strategic traffic. Traffic congestion, local air quality and noise are considered to inhibit economic growth.

A number of road schemes are proposed to improve matters: new outer orbital roads to divert strategic traffic from the inner orbital M60, plus improvements to enhance capacity of the M60 itself. The benefits have been assessed, according to standard practice, on the basis of the value of journey time savings, which typically are quite small – up to 5-12 min for strategic long distance users and up to 3-5 min for local users. The capital costs are estimated at around £14 billion.

A public transport only scheme has also been considered but rejected since it offered no journey time savings for road users.

Northern Trans-Pennine Routes

This study addresses the most northerly major east-west road routes in England, currently underused on account of poor journey time reliability, high collision rates, high proportion of Heavy Goods Vehicles and lack of alternative routes if diversion is needed due to poor weather or road works. Parts of these routes are still single carriageway. Capital costs are estimated at about £5 billion. No quantitative estimation of benefits has yet been made.

Trans-Pennine Tunnel

This scheme involves a ‘bold concept’ – building a tunnel under the Peak District National Park to improve road connectivity between Manchester and Sheffield, with journey time saving of up to 30 min. Depending on the precise route, the length of tunnel would be 12-20 miles, longer than most road tunnels in Europe, costing £8-12 billion. No quantitative estimation of benefits has yet been made.


The total cost of these three schemes is put at up to about £30 billion, which is twice the total investment planned under the current five year Road Investment Strategy. It is very hard to see how the economic benefits could justify such expenditure, not least because the evidence for benefits from improving the connectivity of cities around 50 miles apart in thin (see my discussion of Glasgow and Edinburgh, two well connected cities).

Moreover, standard economic analysis does not distinguish between benefits to commuters and to long distance users. As I have argued, in situations like the urban M60, where car commuters comprise 40% of morning peak traffic, it would be commuters that would take advantage of any increased capacity, leaving long distance users no better off – consistent with the maxim that you can’t build your way out of congestion.

Standard economic appraisal, based on time savings to road users, takes no account of the way transport investment makes land accessible for development and so contributes to economic growth. Such development results from investment in urban public transport, as for example at MediaCity in Greater Manchester. The rejection of public transport investment as a means of mitigating congestion on the M60 reflects this disregard of development in standard appraisal.

The construction costs estimated at this stage are not to be relied upon. Very likely ‘optimism bias’ is at work, underestimating costs and overstating benefits at an early stage, to ensure the project remains under consideration, consistent with a ‘bias to action’ on the part of promoters and their agents when there is an opportunity to spend other peoples money.

On the other hand, the estimates of fairly small time savings are consistent with the outcomes of previous road investments, raising a question about the nature and value of incremental investment in a mature road system that generally provides dual-carriageway or better connectivity to all major cities.

What is entirely missing from these studies of road investment is any consideration of how digital technologies might help meet the needs of users, technologies that can be far more cost-effective that the very expensive civil engineering technologies that have dominated thinking about the road system. This is in marked contrast to the railways where the virtues of the ‘digital railway’ are increasingly recognised.

There is too much wishful thinking about the economic benefits of investment in road infrastructure, particularly in the context of the ‘Northern Powerhouse’, the North of England seen as a region with unrealised economic potential. More rigorous analysis is needed, otherwise outcomes will be disappointing.



My new book published on 1 September is one in a series of short books on policy and economics topics described as ‘essays on big ideas by leading writers’. My contribution is a critique of the inconsistencies of transport policy in recent decades, which I attribute to the shortcomings of conventional transport economic appraisal in identifying the benefits that arise from investment. A column in The Spectator magazine of 26 September described my book as ‘excellent throughout’. My book, Travel Fast or Smart?, is available both in print and as an ebook from Amazon Books.

The National Infrastructure Commission has issued a report on the corridor connecting Cambridge to Oxford via Milton Keynes, in response to a request from the Government for proposals to optimise the potential of this knowledge intensive cluster that competes on a global stage.

The Commission’s national remit does not extend to housing. Nevertheless, its central finding in the present study is that a lack of sufficient and suitable housing presents a fundamental risk to the success of the area. Investment in infrastructure, including enhanced east-west transport links, can help to address the challenges, but it must be properly aligned with a strategy for new homes and communities, not developed in isolation. This means local authorities working in partnership, and with national government, to plan places, homes and transport together.

The Commission recommends that planning for the East West Rail route and the Oxford-Cambridge Expressway should be taken forward urgently, as investments that will deliver substantial national benefits and, if designed properly, can provide the foundations for the corridor’s long-term prosperity: unlocking housing sites, improving land supply, and supporting well-connected and sensitively designed new communities, whilst bringing productive towns and cities closer together.


The Commission’s recognition of the importance of planning transport investment to unlock land for housing and to facilitate access to employment is very welcome. However, the orthodox approach to transport economic appraisal focuses on time savings to travellers, which is unhelpful in making decisions about best value for money in this context. A new approach to appraisal is needed.

The Commission’s recommendations for strengthening rails links within the corridor are more persuasive than those concerning road improvements. Increased road capacity in an area of housing development would result in roads filling up with commuter traffic, consistent with the maxim that we can’t build our way out of congestion. Conventional economic appraisal of road investments does not distinguish between benefits to different classes of road users – commuters, long distance business, freight etc. Yet such understanding is important if road investment is not to disappoint.


I have a new book published on 1 September, one in a series of short books on policy and economics topics described as ‘essays on big ideas by leading writers’. My contribution is a critique of the inconsistencies of transport policy in recent decades, which I attribute to the shortcomings of conventional transport economic appraisal in identifying the benefits that arise from investment. A column in The Spectator magazine of 26 September described my book as ‘excellent throughout’. My book, Travel Fast or Smart?, is available both in print and as an ebook from Amazon Books.

Nottingham is a city unique in Britain in that it has taken advantage of national legislation, the Transport Act 2000, to introduce a Workplace Parking Levy. The consequences have been outlined in a helpful brief prepared by the Campaign for Better Transport.

Nottingham is a medium sized city with two universities and a tram system. The Levy was implemented in 2012 and applies to employers providing 11 or more parking places for employees, who must pay £375 per place per year. There are 42,000 workplace parking spaces in the city, of which 25,000 are chargeable. Operation of the levy is quite low cost.

The direct impact of the levy is to reduce car commuting, reinforcing the declining trend in car traffic shown in the Figure. The revenue of £25m raised in the first three years is ring-fenced for transport improvements, the indirect impact, for instance to help fund doubling to coverage of the tram network.


Big cities like London, with dynamic economies and growing populations, are experiencing a declining share of journeys by car, as they invest in rail for speedy and reliable travel for commuters. A declining share for the car is associated with increasing prosperity, at least in big cities. But what of smaller cities? Do they do best by attempting to accommodate the car, the traditional approach? Or should they push back the cars, which impede economic, cultural and social interactions that make cities good places to live?

Nottingham’s experience suggests that bearing down on car commuting may make a useful contribution, even though it requires brave politicians to push through a Workplace Parking Levy against the inevitable initial opposition. The Levy has particular virtues: it impacts only on residents, not on visitors from out of town, who may have available competing  destinations for shopping and leisure activities; and because it reduces car commuting, it makes more road space available for buses at peak times.

Encouragingly, Nottingham ranked top in 2016 in the National Highways & Transport Network Satisfaction Survey carried out in 106 local authority areas by Ipsos MORI.



I have a new book published on 1 September, one in a series of short books on policy and economics topics described as ‘essays on big ideas by leading writers’. My contribution is a critique of the inconsistencies of transport policy in recent decades, which I attribute to the shortcomings of conventional transport economic appraisal in identifying the benefits that arise from investment. A column in The Spectator magazine of 26 September described my book as ‘excellent throughout’.

The Office of Rail and Road has responsibility for monitoring Highways England’s delivery of the Government’s Road Investment Strategy. This involves investment in England’s Strategic Road Network of £15bn over five years, with more to follow. The ORR has been consulting on how to carry out this task. My response to this consultation is as follows.

The economic rationale for investment in the road network is to generate benefits for users, including in particular the saving of travel time. It would therefore be appropriate for the benefits to users of Highways England’s investment programme to be evaluated as part of ORR’s monitoring process.

In general, traffic congestion on the Strategic Road Network (SRN) arises in or near populated areas, where local traffic adds to long distance traffic; remote from such areas, the traffic generally flows freely. From the perspective of orthodox transport economics, a congested road is an opportunity to invest by adding capacity. But how do road users experience the benefit?

Highways England has evaluated the outcome of ‘major schemes’ five years after opening. It finds that average time savings are small, 3 minutes at peak periods.[1] The economic case for investment depends on multiplying such small time savings by a large number of vehicles (and by monetary values of time saved). Nevertheless, it is relevant to ask how road users experience such small time savings.

While a few minutes time saving would not be material for long distance users, it could be significant to local users on short trips, in particular by allowing more opportunities and choices when changing job or moving house. Indeed, it seems likely that the main benefit of investment in additional capacity on the SRN would accrue to car commuters.[2]

It would therefore be important to understand the nature and distribution of the benefits of the investment schemes of Highways England, as experienced by different classes and locations of road users.

Transport Focus commissioned an Independent Analytical Review for a Road User Satisfaction Survey in 2015. This recommended the development of a continuous online survey of satisfaction using a representative panel of road users. Repeated surveys of a panel would allow trends in satisfaction to be monitored over time. Transport Focus is currently piloting this approach.[3]

Such a survey technique could in principle be used to track the subjective user experience of improvements to the network as a whole. Moreover, relating user experience to specific investments would allow the benefits of these to be understood, as experienced by different classes of road user.

Another approach, also using a volunteer representative panel, would involve monitoring individual travel patterns, based on mobile phone GPS location. This would provide an objective measure of changed travel patterns as the result of investment, and would allow identification of which users benefit, both as regards location, journey purpose and socio-economic characteristics.

Average travel time has been measured for the past 40 years by means of the National Travel Survey. It is noteworthy that average travel time has remained unchanged at about an hour a day, despite many £billions of investment in the road network. This indicates that there are no time savings to users in the long run. There is a therefore a question about the nature of long run benefits, which are mainly to be seen as changes in land use and land value, as land is made more accessible for development that can contribute to economic growth. Travel time savings are therefore short run and their duration needs to be monitored.


Given the very large expenditures planned for the SRN, it is important to understand the nature and distribution of the benefits of investment. There is an opportunity for the ORR to improve value for money by taking an analytical approach – tracking the experience of road users as this is improved by investment in the road network. Both subjective and objective change should be monitored, to understand the nature and distribution of the benefits of investment.
















I have a new book published on 1 September, one in a series of short books on policy and economics topics described as ‘essays on big ideas by leading writers’. My contribution is a critique of the inconsistencies of transport policy in recent decades, which I attribute to the shortcomings of conventional transport economic appraisal in identifying the benefits that arise from investment.

The Transport Committee of the London Assembly is holding an inquiry into growing traffic congestion in London. The evidence I submitted is below.


Although London’s population has been growing quite rapidly, road traffic in London has not increased over the past two decades, both cars and all motor vehicles, as Department for Transport statistics show (see Figure).

Road traffic growth has been inhibited by the retention of London’s historic street pattern, more road space allocated to buses, cycles and pedestrians, controls on parking in inner boroughs, and congestion charging. The public has accepted constraints on road traffic growth because of investment in public transport, particularly rail, which generally provides speedy and reliable travel for commuting and for work-related journeys in central London. As the population has grown, car use, as a share of all trips, has declined from a peak of 50% in 1990 to 36% currently, projected to decline to perhaps 27% by mid-century with continuation of present policies.

Mitigation of Traffic Congestion

Average travel time is invariant as measured in the National Travel Survey: over the past 40 years, it has remained steady at about an hour a day nationally, 1.1 hours in London. Accordingly, traffic congestion is self-limiting: as traffic speeds fall, journey times rise, and flexible road users change the timing, mode or destination of their trips. Gridlock can generally be avoided through Active Traffic Management measures.

The origin of the recent observed increase in congestion is unclear: it could be a short-term response to particular developments, such as the Cycle Superhighways or the construction boom, with congestion expected to lessen in time as the more flexible road users adjust.

Of the of possible means for mitigating congestion:

  • Investment in rail to accelerate mode shift is likely to have the biggest impact.
  • Flexible road users could be encouraged to avoid peak congestion by providing them with good information on expected journey times via mobile phone apps. This would reduce congestion for those whole are less flexible.
  • A workplace parking levy might be beneficial, particularly by generating funds to support investment in public transport.
  • More bus priority measures, including Bus Rapid Transit, would increase the speed and reliability of buses, thus attracting people from cars.
  • It would be worth investigating the scope for fine-tuning road layouts, on-road parking restrictions, permitted turns and Active Traffic Management, based on suitable traffic modelling methodologies.
  • Car sharing in place of personal ownership results in people making less use of the car, which is helpful.

Other possible means for mitigating congestion seem less attractive:

  • The extension of congestion charging to the Western zone in 2007 and its subsequent withdrawal in 2011 had little impact on congestion. A substantial increase in the charge would pose problems of public acceptability.
  • New road infrastructure, such as the proposed East London River Crossings, would add to traffic without reducing overall congestion. We know from experience that we can’t build our way out of congestion (and understand why).
  • Regrettably, investment in cycling infrastructure is unlikely to get people out of their cars. In Copenhagen, 30% of all trips are by bike, but car use at 33% is only a little less than London: walking and public transport take the hit. However, investment in cycling infrastructure would reduce crowding on public transport. (Relevant to Q4,14)
  • Driverless cars, as being developed by Google for instance, are essentially taxis with robot drivers. More use would be made of such taxis if they were cheaper, as they might be if robots replaced human drivers, which would increase demand. Parking requirements for privately owned cars might reduce in residential districts and in off-street car parks, but not for on-street parking in central areas, so the impact on congestion seems unlikely to be substantial.

Increased vehicle occupancy

One longer term approach to mitigating congestion would be to encourage increased vehicle occupancy. For instance, UberPOOL offers ride sharing for people going in the same direction, sharing the cost. In the long run we might envisage a system of driverless shared-occupancy taxis. This could be facilitated by (a) demand management measures to prioritise shared over single occupancy (as High Occupancy Vehicle lanes on US freeways or the exemption of taxis from congestion charging in London); and (b) traffic management that takes advantage of developing vehicle-to-infrastructure communications to smooth flows and avoid conflicts (analogous to Air Traffic Control). While implementing a system of this kind would face formidable challenges – technological, institutional, commercial, public acceptability – it offers the prospect of a more efficient road network that provides reliable, uncongested, door-to-door travel at the user’s time of choice.


Traffic levels in London as a whole are stable, despite population growth. Congestion is self-limiting, as flexible road users adjust to slower speeds. There is scope for accelerating the shift away from car use, without detracting from London’s success, particularly by further investment in public transport, which could ease traffic congestion. In the long run, driverless shared-occupancy taxis may allow a significance increase in efficiency of the road network.



I recently participated in a study visit to Copenhagen, organised by the Young Urbanist Network of the Academy of Urbanism. This proved to be an excellent opportunity to understand the impact of pro-cycling policies in Denmark.

The Bicycle Account records that Copenhagen is very friendly to cyclists, with 45% of all journeys to work or education made by bike, up from 36% ten years ago. For residents of the city, the figures are 63%, up from 52%.

It is interesting to compare Copenhagen with London as regards mode share for all trips: bike C 30%, L 2%; car C 33%, L 37%; walk C 17%, L 24%  ; public transport C 20%, L 37%. So compared with London, promotion of cycling in Copenhagen has reduced public transport use markedly, walking significantly and car use just a little.

The Bicycle Account estimates that there is a net socioeconomic benefit of DKK 1.62 per km (£ 0.18) for a cycle trip during rush hour, in comparison with the journey not having taken place. The main benefits are convenience (time saved) followed by health. For a car, there is a loss of DKK 5.63/km.

The main feature of cycling in the city and beyond is the general provision of dedicated cycle lanes, located between the pavement and the carriageway, separated by kerbs from both. Only on residential roads or narrow historic city centre streets do cyclists have to share space with cars. In addition, there are traffic signals for bikes with give them a head start (typically 6 seconds). Car drivers defer to bikes when they need to cross a cycle lane.

I took the opportunity to try the electric bikes available for rental on the streets, equipped with an iPad-like display for login, payment and satnav route. This behaved like a normal bicycle, with a boost from the power-assist – very pleasant.  These electric bikes seem aimed at tourists since residents all have bicyles and the city is flat, so little need for a power-boost.

The question I had in mind at the start of this trip was: how can we get people out of cars onto bikes? – something that seems difficult in Britain. What I learned is that, with vision and perseverance, and in particular by segregating cyclists from general traffic, it is possible gain a very substantial share of trips for bicycles, but largely by switching from public transport and walking. It is still hard to get people out of their cars, even in such a cycle-friendly city as Copenhagen.

The article below appeared in Local Transport Today 699, 10 June 2016. It was prompted by discussions at a workshop event organised by colleagues at the Transport Institute of University College London, who are carrying out a study for the Department for Transport of social and behavioural impacts of autonomous vehicle.

There is much interest in the possibilities for autonomous vehicles, in particular driverless cars. Focus is mainly on technological feasibility, role of the driver, risks and insurance. What has not yet been sufficiently considered is the implications for traffic. How much difference would autonomous vehicles make?

There are two broad routes to driverless cars. Mainstream auto manufacturers are equipping vehicles with devices that assist the driver. Adaptive Cruise Control automatically adjusts the vehicle speed to keep a safe distance from the vehicle ahead. Lane Keeping systems alert the driver if the car is drifting out of its lane and assist in steering back. Self-Parking systems allow a vehicle to park hands-free. Such devices are contributing to a reduced role for the driver, which ultimately could lead to driverless vehicles. The crucial transition is from high automation to full automation. Because many manufacturers, BMW for instance, market their cars on performance, they are likely to encourage hands-off-the-wheel only in situations where there is little challenge to the keen driver – such as long motorway trips or slow-moving urban traffic. Otherwise, driving is to be enjoyed.

Google’s pods, lacking a steering wheel, exemplify the other route – the great leap forward to full driverless. While these electric vehicles could be privately owned, they seem particularly suitable for shared ownership, given that they are, in effect, taxis with robot drivers. Taxis are popular, and we would make more use of them if they were cheaper, which they might be if robots replaced humans. This could increase demand, adding to traffic congestion in urban areas. But possibly the technology might allow the safe distance between moving vehicles to be reduced, packing more into the available carriageway.

The main impact on traffic of shared driverless cars is likely to be via parking. Privately-owned cars are generally parked for 95% of the time, seemingly an inefficient use of resources. Sharing would allow more time in use and so fewer parked cars. But the main impact on road space would be in the suburbs and car parks, not city centre streets where congestion is most acute and where parking is limited to avoid impeding traffic.

Driverless vehicles would contribute to congestion when they are on the move empty, as do black cabs plying for business. Programming your personal driverless car to cruise round the block empty while you transact business in a shop – in effect ‘parking’ on the move – would need to be regulated, possibly banned, in city centres (although this could lessen the attractions of driverless vehicles). A two-car family might economise with one driverless car, taking the breadwinner to work, then returning for use by the house wife/husband and children, before collecting the worker at the end of the day. But this would double the number of work trips, adding to traffic.

Altogether, it seems likely that the overall impact of driverless cars would be to increase urban traffic. It would be desirable model traffic flows under a variety of driverless scenarios to understand better the implications, since there may be conflicting policy objectives.

The UK Government is keen on driverless cars. The ministerial introduction to the Department for Transport’s 2015 action plan, The Pathway to Driverless Cars, starts: ‘Driverless vehicle technology has the potential to be a real game changer on the UK’s roads, altering the face of motoring in the most fundamental of ways and delivering major benefits for road safety, social inclusion, emissions and congestion.’ The Chancellor of the Exchequer, in his 2016 Budget, made a point of announcing trials of driverless cars on the Strategic Road Network by the end of 2017.

It could turn out, however, that benefits of autonomous vehicles on inter-urban roads could be offset by increased traffic on urban roads. One way of mitigating such traffic would be to increase vehicle occupancy significantly. This may be possible though what might be termed the ‘shared-squared-driverless’ mode, involving both shared ownership and shared use.

So rather than one or two occupants, the aim would be to fill the vehicle at peak times with passengers travelling in the same direction. This would reduce urban traffic congestion through high occupancy requiring fewer vehicles, with one study suggesting that this could remove 9 out of 10 cars in a mid-sized European city. Uber has introduced uberPool, a shared taxi service with lower fares, and uberHOP, which facilitates sharing along commuter routes at peak times. Their success will depend on the ability to match enough passengers going in the same direction, and also on the willingness of people to share.

If priority were given to shared-squared-driverless vehicles through road pricing or similar demand control measures, it might be possible to avoid urban traffic congestion while offering speedy and reliable door-to-door travel. This would be facilitated by some central oversight of such vehicles to minimise conflicts and maximise efficient use of the road network (analogous to air traffic control). The outcome could allow the car to compete with rail in urban areas, in terms of speed and reliability, and could help cities without rail infrastructure better to meet the mobility needs of their citizens. However, the technological, institutional and commercial challenges to the shared-squared-driverless concept are substantial, and practical feasibility is unclear.

Colin Buchanan’s seminal report, Traffic in Towns, was published 50 years ago, decades before the possibility of driverless cars. How much difference would autonomous vehicles make to urban traffic congestion? In the medium term, congestion could worsen, unless action were taken to regulate the movement of vehicles without occupants. In the longer term, the possibility of higher vehicle occupancy offers the prospect of mitigating urban traffic congestion.