An interesting report, from a new organisation called Transport for New Homes, examines a number of greenfield housing developments in Britain, criticising most of them for generating excessive car dependence. This is in part due to location away from existing centres, and in part to disregard of public transport possibilities in the planning process. Generally, the arguments are well made. However, what is missing is survey evidence of the experiences and attitudes of occupants of these new houses. The BBC reports a couple of anecdotal examples of dissatisfaction of residents. Yet these may not be typical since those whose choose to live in such housing may prefer the car to the public transport, walking and cycling alternatives. After all, car dependent lifestyles are adopted by choice by many residents of cities where alternatives exist.

The developers of new greenfield housing construct new properties to sell, which they of course do, reflecting the need for new housing and the preferences of many for location away from traditional urban centres. The lack of public transport provision tends to arise from the relatively small scale of developments, in a context in which bus use is generally on the decline. The report discusses some developments of new urban quarters in the Netherlands, where the scale and location adjacent to existing towns means that good public transport provision is feasible. One example, Almere, is a planned city built on land reclaimed from the sea, which makes large scale development possible. In Britain, assembling land on that scale has not been attempted since the post-War new towns.

It would be worth considering innovative approaches to transport provision for greenfield housing developments, for instance as in Pinellas County, Florida, where residents can use a subsidised Uber service to reach the core bus routes – known as ‘micro-transit’.

An independent Commission on Travel Demand, funded by UK Research Councils, recently issued its report, based on evidence and expert advice. There is no single message, other than that there are more uncertain factors influencing travel demand than conventionally supposed. However, the report make ten sensible recommendations for better processes.

I was disappointed that the report did not consider two matters on which I had submitted evidence. One is that demand for any kind of product or service may saturate, that is, cease to grow once all needs are met. For instance, ownership of many household goods, such as washing machines, exceeds 90%, so that demand no longer reflects growing tes, but only replacement plus population growth. There is evidence consistent with saturation of demand for daily travel for many purposes. For instance, 80% of the urban population of Britain have a choice of three or more large supermarkets within 15 drive minutes of home, and 60% have a choice of four or more. If you have a choice of 3-4 supermarkets within 15 minutes drive, you may not be inclined to drive further to have a choice of a fourth or fifth, in which case your demand for travel to supermarkets is said to have saturated.

Second, given that average travel time has not changed for at least the last 45 years, as measured in the National Travel Survey, increased travel demand (distance per capita) must require faster travel. This is now hard to achieve, given high levels of car ownership and the limited scope for this to grow, plus a mature road network where congestion proves difficult to mitigate. We have High Speed Rail on the way, but rail is a minority of all trips, so HSR would be a minority of a minority, with little impact on average speed.

The travel time constraint, coupled with the speed constraint, means that travel demand per capita is unlikely to grow significantly in the future. Total travel demand will be driven by population growth, of course, although the pattern of demand will depend on where the additional inhabitants are housed: greenfield means more cars, urban at higher density implies investment in public transport.

I blogged some months back about a paper of mine published in a peer-reviewed journal. This was a critique of the orthodox approach to the cost-benefit analysis of transport investments, which focuses on the saving of travel time. My paper has prompted three senior transport economists to publish a response in the same journal. They say: ‘Metz makes some good points, but many of his key arguments are unsound.’ Naturally, I disagree with the latter proposition.

The three economists concede that the conventional approach to appraisal is weak on the spatial distribution of the benefits of investment, which is important to decision-makers. An example here is High Speed 2, the planned new rail route connecting London to the cities of the Midlands and the North. The strategic case for this very large investment is to boost the economies of these cities by improving their connectivity to the dynamic economy of the capital. However, the conventional economic case sees the benefit as largely time saving for business travellers, and is silent on its spatial distribution. What we need is economic analysis that quantifies the strategic case. This is lacking.

More generally, the purpose of the transport system is to move people and goods through space. Investment increases such movement, whether by increasing the speed of travel so that people go further in the time they allow themselves for travel, or by increasing capacity at existing speeds, so that more people are able to travel. In either case, an important consequence is change in land use and land value, reflecting the increased access made possible by the investment. Transport planners well understand how transport investment increases access and changes how land is used, whereas transport economists are fixated on notional time savings – notional because they are the output of models, not observed in practice. What we observe in the findings of the National Travel Survey is that average travel time has hardly changed over 45 years, despite many £ billions of transport investment justified by the value of supposed time savings.

Professor Peter Jones, my UCL colleague, has been leading an EU funded project concerned with urban mobility, past and future, in five Western European cities – Berlin, Copenhagen, London, Paris and Vienna. The report is now available, as is a short speech by Peter.

A trajectory is identified in which cities start by attempting to accommodate the car, see the difficulties in high density locations and so reallocate road space to walking, cycling and public transport, and subsequently move on to focus on place – the role of streets as public realm for non-mobility activities. The figure above shows how car use peaked and then declined in consequence.

Recognition of place as an important quality of urban streets presents a problem for conventional transport investment appraisal, which only recognises the economic benefits of increased mobility. The report advocates ‘vision and validate’ as an approach, as opposed to the traditional ‘predict and provide’, using cost-effectiveness analysis to justify investment to attain the desired balance between mobility and place.

This report is a valuable synthesis of a considerable amount of data and analysis highly relevant to how we think about the future of cities.


I have a new article that reviews the evidence for the success of congestion charging (aka road pricing, road user charging) in the three major cities in which it has been tried. In London, there was a marked reduction in both car traffic and delays when charging was introduced, but delays reverted to previous levels by year five. In Stockholm, a similar initial impact was seen, but there was no monitoring of delays subsequently.

Singapore has been successful in using electronic road pricing to maintain desired traffic speeds, adjusting charges up or down according to whether speeds have exceeded or fallen below targets. However, this is only possible because there is a very high charge for vehicle ownership, which has limited this to 100 cars per 1000 population, compared with 450 in the UK and similar or higher figures for other developed economies.

Road traffic congestion occurs in areas of high population density and high car ownership. There are more trips that could be made by car than are in fact made. Some people are deterred by the prospect of time delays and make other choices: a different time or mode of travel, or a different destination, or not to travel at all. Measures that deter some drivers, such as congestion charging, reduce delays when introduced, which makes car travel more attractive to those who are more time-sensitive but less cost-sensitive, so that traffic increases and delays revert to previous levels. Accordingly, congestion is both self-regulating and difficult to reduce.

Although economists believe that road pricing is the proper way to tackle congestion, in practice the level of charges to make a useful impact would probably be too high to be publicly acceptable.

I have long been skeptical about the case for a third runway at Heathrow. The argument in favour concerns the growth of demand for business travel, yet most passengers at Heathrow are on leisure trips, so there is plenty of scope for increasing business travel by displacing leisure travel to other airports in the London area with spare capacity. In a blog posted in 2015 I suggested that Emirates Airline might fly from Stansted to its Dubai hub if demand for flights from Heathrow could not be accommodated.

I was therefore gratified to read in the Financial Times that Emirates is indeed launching next month a daily service from Stansted to Dubai. Other airlines are offering services from Stansted to New York: Primera Air and Wow Air. Stansted hosted 190,000 flights in 2017 but could accomodate 274,000 on its single runway.

I have a new paper published in a special issue on the future of urban transport and mobility systems in the journal Urban Science. This is an open access journal, so the paper is available to all.

The question addressed is the likely impact on autonomous vehicles on urban traffic congestion, a ubiquitous problem that has proved difficult to mitigate. My analysis concludes that little is changed until fully autonomous  (‘driverless’) vehicles are on the streets in significant numbers. There would then be two main consequences. First, by dispensing with the driver, taxis and other public service vehicles would cost less, which would increase demand, drawing people from conventional public transport, but at the same time offering an attractive alternative to personal car ownership in urban areas. Second, individually owned driverless cars would at times travel unoccupied, for instance returning to home for use by others in the household, having taken someone to work. Such unoccupied vehicles would add to traffic and their use might need to be regulated if they worsened congestion, to give priority to occupied vehicles.

There is much uncertainty about the feasibility and timing of driverless vehicles in urban areas, but it is not too soon to begin thinking about how policy should best be developed, to secure benefits from the new technology and mitigate possible adverse impacts.

A recent transport innovation with potentially a big impact is the dockless bike – for hire in urban areas but not linked to a permanent location or installed by or with permission of the local transport authority. Dockless bikes are linked instead to an app on the mobile phone, which allows payment for use, and are installed by entrepreneurs who see a business oportunity.

Dockless bikes have made a striking impact in China, with large numbers flooding the market and huge surpluses piling up – literally, as recent photojournalism in The Atlantic magazine vividly illustrates. Presumably, economic considerations will restore a balance between supply and demand in due course.

A witty follow up article in Slate shows pictures of extensive arrays of dockless vehicles in the US – in this case parked cars.

Another stage on the long-running saga of expanding the capacity of London’s Heathrow Airport is marked by publication of a report from the House of Commons Transport Committee. This considers the Government’s Airports National Policy Statement, which endorses the proposal for a third runway at Heathrow. The Committee goes along with this, subject to quite a number of caveats about environmental impacts and costs.

What struck me were the weakness of the case for a third runway (the Northwest Runway, NWR), as revealed by the Committee’s findings:

Figure 3 on p17 shows that the main impact of the runway would be to increase the numbers of leisure travellers and international transfer passenger. The extra numbers of business travelers are very small, yet the case for the runway is mainly based on the needs of the UK economy.

‘The benefits and costs the NWR scheme are finely balanced. Even small changes in assumptions or methodology could mean that the monetised costs of expansion via a NWR would outweigh the benefits.’ (p19)

While Heathrow is ‘full’ in respect of aircraft movements and landing/takeoff slots, it is not yet full in terms of passenger throughput since each plane is on average only 76% full and is not always an  aircraft with the highest capacity (p40). Luton and Stansted have the equivalent of around one third of a runway to spare through to 2050. This means that passenger throughput for the London airports is forecast to rise by 27% out to 2050 without expansion at Heathrow (p42)

The forecasts  show that an expanded Heathrow would accommodate more than three times more outbound passengers than inbound passengers (p48), a net economic deficit to the UK.

The NWR scheme would only offer only one new destination to emerging and fast-growing economies when compared with no expansion by 2050 (p49).

Airport charges at Heathrow are the highest in the world (p82). Could a further runway be financed without increasing charges, which would erode the economic benefits and deter use?


I am struck by the weaknesses in the case for building another runway at Heathrow. A key question for the future will be the ability of the airport to finance construction from private sector investors at a cost – both construction and financing – which the airlines and their passengers will be willing to pay via landing charges. The proposal may achieve planning consent but could prove to be commercially unviable.

Professor Anne Graham and I submitted evidence to the Transport Committee, which argued that the market for air may be more mature than generally supposed, and hence demand growth may be less than projected, with consequences for the business case.


The Transport Committee of the London Assembly has published a report on future transport technologies in London, covering Connected and Autonomous Vehicles, App-based services (Uber and dockl;ess bikes) and drones. This is a useful review of the prospects for these technologies, which draws attention to aspects of governance and regulation where the existing framework is inadequate for innovative technologies.