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.

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 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.

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?

Assessment

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.

 

I was recently involved, as a member of an expert Panel, in a study, Older Canadians on the Move, carried out by the Council of Canadian Academies. This had been commissioned by the Federal Government and focused on measures that might be taken to improve the mobility of older citizens primarily for longer distance travel, local travel being the responsibility of lower tiers of government. Nevertheless, we did recognise that longer trips started locally and so were concerned with door-through-door journeys.

The Panel identified three pathways to help facilitate door-through-door journeys for older adults and improve the inclusivity of the Canadian transportation system: advancing human and social resources; advancing technology and infrastructure; and advancing policy. Each pathway has an important research and development and innovation component, whether it be through the development of new technologies or the testing and implementation of research-driven solutions in real-world settings.

I have also contributed a chapter to a book edited by Charles Musselwhite on Transport, Travel and Later Life, on the topic Future Transport Technologies for an Ageing Society: Practice and Policy. Let me know if you would like to see this.

In recent years there has been emerging evidence that the travel behaviour of young people has been changing, characterised by a shift away from car use. The UK Department for Transport commissioned a thorough study from researchers at the Universities of West of England and Oxford, comprising a literature review and secondary analysis of existing UK data sets.

The trend for young adults to drive less than previous generations began approximately 25 year’s ago. Driving licence holding by people aged up to 29 peaked in 1992-94, while car driver trips per person declined by 36% between 1995-99 and 2010-14. This decline is attributed to a variety of social factors outside transport, including more participation in higher education, more lower paid less secure jobs, and delay in starting families. Within the transport sector, the high cost of car ownership and more use of urban  public transport have contributed to declining car use. There is inevitable uncertainty about the future, but the authors conclude that is is difficult to envisage realistic scenarios in which all these future uncertainties combine in such a way as to restablish earlier levels of car use.
US experience
A recent survey of younger people (‘the millennials’, ages 18-34) in California aims to identify the factors that explain why they are found on average to drive 18% fewer miles than members of the previous generation. One report addresses lifestyle and attitudes, a second deals with residential location. Generally, the findings of the UK and US studies seem consistent.

Charles Musselwhite has edited a new book on transport and travel in later life. I have a chapter on Future Transport Technologies for an Ageing Society. I discuss how the new digital technologies are affecting both the transport system based on civil and mechanical engineering technologies, and how we choose to travel. There are a number of ways in which innovations would be of benefit to those in later life, and a number of policy approaches that would help achieve such benefits.

I was a member of a Commission on the future of London’s roads and streets convened by the Centre for London. Our report was launched yesterday.

This was a worthwhile exercise that stimulated thought and discussion amongst the expert members. The report will contribute to the actions that will be needed to implement the plans of the Mayor’s Transport Strategy. Some of the toughest issues concern the management of demand for both road space and kerb space while maintaining traffic flow and improving the quality of place in a city growing at the rate of about 100,000 people a year.

Travel time and congestion

Britain’s National Travel Survey has been monitoring our travel patterns for the past 40 years. One remarkable finding is that average travel time has held steady over this period at about 375 hours per person per year, close to an hour a day. There are only 24 hours in the day and many activities that have to be fitted in, leaving an hour or so for daily travel. The history of travel is largely about travelling faster as incomes have grown and technologies advanced, allowing us to go further in the same amount of time.

This travel time constraint is an important influence on road traffic congestion. As traffic builds up, speeds fall and trips take longer. This puts pressure on time available for travel and some road users change their plans – travelling at a less busy time, or to a different destination (where options exist, as for shopping), or by a different mode, or not to travel at all. So congestion is self-regulating, and gridlock is rare, particularly when an urban traffic management system is used to adjust the timing of traffic signals to make best use of road space, as in London.

Road traffic congestion occurs in areas of high population density and high car ownership. There is insufficient road capacity to accommodate all the trips that might be made. Many potential road users are deterred by the prospect of time delays. These suppressed trips mean that congestion is difficult to mitigate since measures aimed at reducing car use in effect create space for drivers previously deterred.

Policies that it is hoped would reduce congestion by getting people out of their cars tend to disappoint. Promoting walking and cycling is good for health and for the environment but has little impact of urban car use. Increasing road capacity induces more traffic, hence the maxim that you can’t build your way out of congestion, which we know from experience to be generally true.

Congestion charging

London pioneered congestion charging, aimed at reducing demand for car use in the central area. On introduction in 2003 there was a marked impact – both car use and delays were reduced. But when the charge was increased from £5 to £8 in 2005, there was no further effect, and over the next few years delays reverted to the previous level. So while congestion charging has generated useful amounts of revenue for investment in London’s transport system, it has been disappointing as a means of reducing congestion – because of the high potential demand from drivers willing to pay the current charge of £11.50. It seems likely that a substantially higher charge would be needed to make a significant impact on congestion in a city like London where many have high incomes.

When road users are asked why congestion is a problem, their main concern is the uncertainty of journey time. While it is difficult to reduce general delays arising from congestion, new technologies are able to lessen uncertainty. The route planning offered by smartphone apps such as Google Maps and Waze, and similar in-vehicle devices, takes account of traffic congestion in real time and proposes less congested routes, making better use of the road network. These apps also estimate journey time, which helps decide the best time to start a trip.

Performance of the route guidance apps would be enhanced by collaboration with road authorities. Transport for London’s 2017 Business Plan announced a new partnership with Google on its Waze technology that will see Google use TfL’s open data, while TfL uses the Waze crowd-sourced data on road conditions to help manage traffic around incidents and road closures.

These new technologies are helping us make better use of the road system within the limited time we can allow ourselves for daily travel.

 

 

The Department for Transport publishes passenger numbers for the English light rail systems, shown in the Figure. What is striking is the very different growth rates: buoyant for London’s Docklands Light Rail and Tramlink, and for the systems in Manchester and Nottingham; but relatively static elsewhere – West Midlands, Sheffield and Tyne & Wear.

Urban light rail offers speedy and reliable travel compared to cars and buses on congested roads. In a growing economy, we expect its popularity to grow, as we see in London and Manchester.

The light rail passenger number trends bear upon the general question of whether transport investment can foster economic growth, or whether it follows it. The different patterns observed tends to suggest that urban rail investment can contribute to existing economic growth but may not in itself stimulate lift-off.

Most air travel forecasts predict a long-term rise in demand, with limited consideration of any limits to growth. However for any given population there will be those who have not flown recently, as well as those who never have flown. For the UK, about half the population respond to travel surveys that they did not fly in the previous 12 months. We call these the ‘infrequent flyers’.

Little is known about this group, including  whether they are likely to fly in the future. Anne Graham, of the University of Westminster, and I recently published findings of an analysis of the characteristics of this group and the reasons for their travel habits, using a survey commissioned by the UK Civil Aviation Authority. We found that infrequent flyers make up a heterogeneous consumer group whose non-flying is influenced more by budget constraints and personal circumstances than specific aviation factors such as fear of flying.

The proportion of infrequent flyers in the UK population has remained stable over time. Our findings do not suggest that this is likely to change in the future, so the infrequent flyers are unlikely to be a source of future demand for air travel on account of their increased propensity to fly.

Our paper: Graham&Metz JATM Infreq flyers published