In this blog we introduce a new two-year research project, funded by the UK Economic and Social Research Council and the Indian Council of Social Science Research. The project is an interdisciplinary collaboration between Greg Marsden (ITS University of Leeds), Louise Reardon (INLOGOV, Birmingham), Sanjay Gupta (SPA, Delhi), Ashish Verma (IISc, Bangalore) and the World Resources Institute and will examine the urban mobility implications of India’s on-going Smart Cities Mission.
The negative outcomes of India’s current urban transport systems are a cause for concern. The World Health Organisation has identified India as home to 10 of the world’s 20 most polluted cities, while also experiencing 150,000 road traffic deaths per year (some six times higher per head of population than the UK). There are also major social inequities that directly or indirectly arise from the uneven allocation of transport resources in India’s urban areas. To date, the emphasis in Indian cities has been on expanding mobility through new, large transport infrastructure projects. These projects benefit high income people most but do little to address the existing inequities in delivery of transport services where there has been a decline in the overall coverage of public transport and a rise in private motorised transport. Redesigning urban governance, including transport governance, has therefore been identified as a critical element of progress in delivering more inclusive and sustainable cities in India.
Congestion and Pollution in Delhi (source: NOMAD)
Previous research has identified that limited powers, resources and capacity at a local level have contributed to a failure to plan adequately for the exponential growth in vehicular traffic, and to service new formal and informal migrant communities in rapidly growing Indian cities. The need for improvements to transport service quality, innovation and easier access to the financing necessary for such improvements has increased the importance of industry and other private sector actors as key agents of change alongside the state. These processes bring with them new challenges around how best to manage the balance of responsibility and resources between national, regional and local government levels. Moreover, how best to govern through an increasingly complex set of actors and how to effectively steer the competing interests of different stakeholders.
in 2015 the Indian national government sought to address these governance challenges launching the Smart Cities Mission; a competition for funding for 100 cities in India for the period to 2019/20. In the government’s own words, the initiative is ‘bold’, aiming to go beyond what has been achieved before at the local level. The focus of the initiative is on promoting cities that provide core infrastructure, a good quality of life and a clean and sustainable environment, through the application of ‘Smart’ Solutions. Urban mobility is one aspect of the Smart Cities Mission (alongside water supply, electricity supply, sanitation, affordable housing, safety and security and health and education). In relation to transport specifically, Smart Cities aim to promote a variety of transport options including Transit Orientated Development, public transport, last mile para-transport connectivity and ‘walkable localities’. There is certainly a broad range of options from what might be seen as basic essentials to ‘smart’ and the tone set by the branding of the initiative is itself an interesting question.
Whilst the interpretation of what policy mix might achieve these features and at what scale (pan-city, new development, retrofit or redevelopment) is to be decided on by each City, the implementation of the Smart Cities Mission at the City level must be done by an organisational arrangement called a Special Purpose Vehicle (SPV) created for the purpose. The SPV will ‘plan, appraise, approve, release funds, implement, manage, operate, monitor and evaluate the Smart City development projects’. Within this context then, the Smart Cities Mission provides a major opportunity to understand the aims and processes of governance reform and contribute knowledge on the extent to which these reforms impact transport governance and in turn are capable of achieving a significant improvement in the mobility system to promote more sustainable and inclusive development.
The project will undertake a comparative analysis of four case study sites: Bangalore, Jaipur, Ranchi and Bhubaneshwar, each of which have their own history or previous urban transport governance reform. The project, will trace the impacts of transport governance reforms through to the impacts on the economic prosperity and quality of life of citizens both through changing processes and outcomes. It will also critically develop the multi-level governance framework approach in an Indian context, particularly understanding the evolving role of Special Purpose Vehicles in urban reforms. The project has a strong emphasis on engagement with practitioners and academics from across India and the UK and we would be pleased to hear from anyone who has an interest in these themes and in making a difference to urban transport reform in India.
Interested in what you have read here? We have a two-year post doctoral position available based at the University of Leeds to conduct the primary research (see here for details). There will also be shorter posts available in Delhi and Bangalore.
Greg Marsden & Louise Reardon
Image Source: NOMAD [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)%5D, via Wikimedia Commons
Today’s press release from the British Retail Consortium showed a 6% year on year fall in footfall for March. It is not just the lousy weather we had in March, although it was so wet that even duck footfall fell, this is part of a longer term reduction in people accessing town centres (around 1.4% per year). As the Figure below shows using data from the National Travel Survey, the frequency of shopping trips and overall distance travelled to shops has declined for two decades.
The Decline in Shopping Trips and Distances
The normalisation of on-line shopping is obviously one factor here. On-line shopping is growing at around 10-12% per year and now represents almost 17% of total UK retail sales. The rise in on-line has coincided with a 30% decrease in physical shopping trips over the past decade and a 16% decline in distance travelled. In recent work undertaken as part of the DEMAND Centre, we found that many goods have become predominantly on-line purchases or are heading that way as shown below.
Purchasing Patterns for Different Goods
Importantly, the decline in shopping trips is just one of many categories of trips which have been declining over the past twenty years (pre-dating mass internet shopping). We have been so fascinated in the transport sector in explaining travel growth as the economy has grown that we have overlooked the fact that when the underlying conditions in society shift then travel might reduce. On 3rd May the Commission on Travel Demand will be launching its report “All Change? The Future of travel demand and the implications for policy and practice”. It will explore further why these trends have happened and how we might understand them so that we can look forward and plan for travel futures differently (or indeed plan for different travel futures).
The report will debate policy futures. The question which high streets face is why are people going to go there? Increasingly it has to be because they are nice places to be and they are places where a mix of activities can be undertaken in a clean and vibrant environment. So, transport planners, if we need to create great places then how do we value place? It seems that some of the logics which brought us to where we are today might need to be rethought very quickly if we are going to put form over function and ensure a good balance of activities remains in out cities. That may require upsetting some applecarts which have been cemented in place. The Commission report we hope will spark that debate. If you want to be part of it then please sign up to the event now!
Greg Marsden is the Chair of the Commission on Travel Demand
In the next week the Commission on Travel Demand will have its final evidence session on ‘decision-making’. In advance of that and my talk at the Landor Local Transport Summit I wanted to share some thoughts about why demand policy seems to have slipped off the transport agenda. This seems particularly troubling given the really limited progress which seems to be being made on climate change emission reduction and air quality.
Nothing about this image screams “lets not worry about travel demand”. The 2015 National Road Traffic Forecasts showed an increase of between 19% and 55%. The CCC works on a central or most likely projection from the Department. Looking at the NRTF this would be the scenario with growth of 34%. On these grounds alone, demand matters. For every % over the core scenario the significance of the amber and red areas in the CCC graph is magnified and for ever unit under it is reduced.
However, we do not have a clear policy on travel demand. This, I believe, stems in part from the economic traditions underpinning transport analysis. Here, demand is a measure of consumer preferences in transactions with more demand general seen to be a good thing (subject to the caveats of well performing markets and full externalities being paid which we seem happy to hold out as a possibility. Sometime).
Demand is also rather curiously, yet rather importantly, held to be somehow ‘out there’ and independent of policy. By this, I mean that our approach to looking at demand in the future tends to try and hold policy constant and ask what impact important exogenous variables could have such as oil price, GDP and population. Only then do we look at the extent to which this demand might be accommodated or not. This is worldview one or the “two moons” part of the figure below.
Three worldviews of demand and policy
This might be an overly tough critique of the way of things today. It could be argued that in oil price sensitivities there are assumptions of pricing policy from government and it is also the case that some policies are seen to be able to impact on demand – such as the Committee on Climate Change’s assumption that behaviour change could reduce travel demand by 5%. This corresponds to worldview 2 or the very partially overlapping moons.
However, is that all that matters? If we look again at the NRTF, the highest growth scenario identified could only meaningfully be brought about if the growth in demand were supported by the same kind of infrastructure or supporting policies that were in place in the last period where such growth was seen back in the 1980s and early 1990s.
Similarly, Scenario 3 assumes a continued reduction in trip rates. Not all of this has been the result of transport policy for sure. However, it is easier to imagine this scenario unfolding in a policy setting where much greater attention was given to localisation, virtual communication and trip chaining through densification of activities than it is in a world where the focus is on very significant investment in major inter-urban infrastructure.
Demand has to be more strongly shaped by policy than is currently considered or allowed to be seen to be. That is part of the explanation as to why different countries have different levels of per capita travel. It is perhaps convenient, more than realistic to hold the position that demand futures are somehow independent of policy futures (see Foresight in Action for a great short read on this). It means you may not need a policy on demand reduction because it is not something you have agency over. This fallacy can be picked apart by looking ahead. There are clearly policy choices to be made about how we welcome autonomous vehicles to our roads, how we regulate mobility service providers such as Uber and Lyft and what kind of a service Mobility as a Service can become. It is not all determined by policy – but it is not free from policy. It also will not be allowed to unfold the same way in every city or country. That will clearly affect the services provided, how they are used and what they get used for – i.e. demand. This is the third world view of more highly overlapped circles in the diagram. This recognises the inter-relationship between demand and policy. As the framework conditions of policy shape the demand that develops so too does policy respond to the levels of demand which emerge. This can work to drive up or bring down demand.
I started out by suggesting that it is imperative that we act to reduce demand if we are to meet our climate objectives. To end on a positive note, IF we accept that policy matters to shaping demand then we can plan by asking questions that start with “What kind of a future do we want to create?” rather than starting with “What kinds of demand do we need to accomodate?”. I’m looking forward to hearing more about what needs to be done to change rather than reinforce the current pathway.
Having just spent the best part of two hours schlepping in and out of York through race day traffic for a 2 minute radio interview on transport spending in the North I thought I’d share the thoughts I didn’t get time for.
First up, is the spend on transport in different parts of the UK fair? The chart below is taken from data summarised in the IPPR North’s assessment of the NIC and HM Treasury infrastructure pipeline for those projects that can be classified to a region.
Per Capita Spend on Transport Infrastructure from 2016/17
Arguments can be had about what is in and what is out. Revenue spend is not included, for example, which is also lower in the North. The picture is clear, however, and has been so over a long period. More money gets spent in London and on investments connected to London than for cities in the North.
Why does it happen and is it actually just the outcome of different needs in different places? Andy Burnham hits the nail on the head when he wrote in the Guardian about his time in the Treasury. The way transport projects are assessed are to look at the benefits of investment versus the costs. In general the benefits are greatest where congestion is highest, flows are highest and issues such as overcrowding and unreliability are worst. The reality is that these problems are, on average, worse in the more crowded South East than the North. On top of this, recent focus on identifying wider economic benefits such as agglomeration of knowledge industries are also likely to be stronger in and around London. So, whilst doing work in London and the South East can be much more costly due to the lack of space and need to work underground, the benefits are such that more investments come out on top from there than from the North.
There are other factors at play. Almost twenty years of Transport for London and the Mayor have led to a focused set of planning activities with a delivery body and financing regime to support that. Devolution in the North is still in its infancy. Whilst I am a big supporter of it there are major challenges to pan-regional action for an agency like Transport for the North. Investments in one part of the region relatively disadvantage another. It is a huge region and tensions exist. Whilst there is talk now of speaking with one voice, this will take time to be an effective voice.
However, my view is that we have a Henry Ford problem. He is attributed as saying “If you always do what you always did, you’ll always get what you always got”. It will matter much less what the leaders of the North ask for if the process for deciding what makes for good value for money remains as it is in Whitehall.
Does it matter? It matters for the quality of transport service people experience. The journey times between Leeds and Manchester by rail are about 50 minutes for a 40 mile journey. You can get from central London to Peterborough (80 miles) in 45 minutes and Winchester (70 miles) in just over an hour. Our major cities of the North do not have good connectivity and there is little redundancy when either the M62 or the transpennine rail line goes wrong.
What options exist for change? There are different options each with benefits and disbenefits. One argument would be to hand a bigger chunk of resources to Transport for the North and let them decide how to spend it. If a funding settlement could be agreed then that would certainly place a responsibility for achieving best value out of that firmly with the Northern leaders. However, Transport for the North is not an elected body and so there would need to be some pretty heavy checks and balances in place to ensure that the spend did not just end up as pork barrel politics or there would need to be a shift to far greater direct accountability.
The problem could also be solved out of Whitehall. One option would be to have a national transport strategy. Yes, that’s right, a national transport strategy. Don’t get me wrong, they have not always been particularly effective but we have not had one since the coalition of 2010 (see forthcoming article with Jon Shaw, Iain Docherty and Jillian Anable – come on reviewers!). However, it seems clear that to address the infrastructure shortfall of the North requires a very deliberate policy around what constitutes good connectivity and journey quality between our major cities. This does not mean that everything we have in place today gets revisited. Projects to support growth will continue to remain important but if we leave it to the current process and keep the commitments vague then we may end up continuing to get what we always got. As an aside, a national transport strategy might also do some really important joining up of other major agendas such as road safety, total electrification of the car fleet and how we take a longer term view on resilience which is also subject to regional disparities.
The opening plenary session at Modelling World asks whether rapid change means new models? In advance of my talk there I reflect on this question drawing on the work of the Commission on Travel Demand and the DEMAND Centre.
The first part of the question implies that we are in a world of rapid change. The rise of Uber, increasing autonomy of vehicles, electrification, on-line shopping… the list goes on. Change is happening for sure – but how rapid it is and how much of it is defined by changes to transport technologies seems much more open to question. I argue here that there are a number of trends, many of which our traditional approaches to understanding demand did not anticipate, that have been on-going slowly but for a period of time. Even when we see significant technological change coming to transport this will take some time to happen and when it does it will do so in ways which we currently would not anticipate. There is time to reflect on what sort of changes these new systems might engender but there is a need to start now given that we can be trying to support decisions that meet the needs of users 20 and more years into the future.
The second part of the question asks whether we need new models. Here I will argue that is the range, scale and nature of the uncertainties that should pre-occupy the discussion about the need for new models rather than a concern with rapidity of change. I will suggest that decision-making processes needs to accept that there does indeed exist a range of potentially different, yet still plausible, futures for how we get around in order for the focus of model development to address these challenges in a meaningful way. Models are decision-support tools and if we consider the questions which they are supporting to be different to those we have been examining then adaptation and/or innovation will be necessary. I will discuss why that is currently a challenge.
So, how rapid might change be and change in what? Looking back over the past decade, at an aggregate level as captured by the NTS for England, we have seen a decline in trip rates, trip distance and, more recently, the amount of time spent travelling.
Figure 1: Declining per capita annual travel trends (Data from NTS0101 2016 release)
There have been various important studies looking at the reasons behind these changes (see RAC Foundation, Independent Transport Commission and Department for Transport for start points). Some of the change is attributed to later uptake of driving licenses amongst younger people, some to rising insurance costs, increasing urbanisation, the changes to company car tax rules and a shift to virtual activities. However, none of these provides a complete explanation (see the work of Noreen McDonald), nor should we expect to find all of the answers within the transport sector. For example life expectancy is increasing by around 3 months each year and the average age at which women have their first child has risen by around one year each decade since 1975. If we look at wider social change which will impact on traffic patterns in the long-run then decisions such as raising the pension age, reducing pension levels, tightening immigration, healthcare innovations and continued growth in the pace and quality of communications infrastructure are all going to be very significant for mobility, but we cannot anticipate all of these changes by calibrating on historic data.
One interesting pattern to be emerging more strongly appears to be the decline in traffic in major urban areas excluding motorways (see Figure 2). People here seem to be able to assemble their patterns of mobility to meet their needs in less car intensive ways. Some of this results from growth in housing and employment in city centres which are associated with lifestyles which are less car dependent. Will these trends continue? Will they apply largely to those households without children? Does it mean car later rather than car never? Will car later mean car less (less intensive use of cars when they are owned)? It is in answering these sorts of questions that it becomes relevant to understand how Uber or Car Clubs are being incorporated into the everyday mobility patterns of people in different places. Many transport systems work much better with higher densities of demand and we might expect greater divergence in the degrees of multi-modality of people in different areas.
Figure 2: Changes in motor vehicle kilometres by area of Greater Manchester (1996 = 100). Source: TfGM submission to the Commission on Travel Demand
Given some of the gaps in understanding of how travel patterns have been changing, it seems important to try and understand how any new mobility options might be being accommodated in how people conduct their everyday life. If there is already evidence of travel being put together in different ways to those expected then we should avoid simply bolting on new elasticities and modal preference constants as a means of representing these changes. Questions such as whether people will send children to school in autonomous pods seem at least as important as to whether they can surf the web whilst on the motorway and therefore have a different time penalty on travel. It is important to remember that early adoption is not the same as mass adoption and we should be investing more now in understanding how they might influence what people do.
We should also be mindful of the longer term trends which were shown in Figure 1. Why will new technologies encourage people to start making more trips or to travel for longer? What will they stop doing if they are spending longer in vehicles? Whilst the substitution narrative is appealing it is unlikely to represent the full range of adaptations that occur (Did people use mobile phones just to make calls they used to do on their landlines?). There is also a tendency and a temptation to focus on the importance of the changes to transport modes and to forget that the other influences which have seemed so important to recent trends may continue or change in equally important ways. Will these changes accelerate or slow the adoption of some innovations as their mobility needs they might fulfil change? All of this poses some really interesting challenges to one of the key tenets of our approach to modelling and evaluation which is a reference case or business as usual. This would seem to be becoming more unusual.
So, to the second question, do we need new models? The answer to this, in the light of the potential for a quite different type of transportation system and ways of living, would seem to be a self-evident yes. How could modellers fail to try and incorporate and represent some of these changes? However, I would argue that we need to ask what we are using our models for before we jump in to improving them. All models are attempts to represent a complex world in as simple a way as is effective. Whereas the dominant influences of the decades up to 2000 could be seen to be those surrounding the growth of automobile use this is no longer the case. Given the range of uncertainties there seems to exist a range of future pathways which could diverge (and have already done so) from previously anticipated travel demand growth pathways. What does better modelling mean?
I am currently working with Glenn Lyons to draw the work of the CIHT Futures project together with that of the Commission on Travel Demand. One of the key areas we are grappling with is what models are being used to inform. As in Figure 3, we would suggest that what we need to aim for is a set of tools which provides insights about a range of plausible futures (left most image) – i.e. the dots are spread quite wide but around the centre of the target. This would imply that we take decisions that are robust in a range of futures (or that decision-makers understand that there would be circumstances where a particular course of action was not sound). If it is accepted that there is a lot of uncertainty then to continue to focus on one future and to develop our tools solely with the aim of testing lots off sensitivities around this creates an impression of accuracy which could be misleading (the centre image). The image to the far right would be some kind of Nirvana of great foresight. Outturn results of existing exercises suggest that we have never really lived there.
Figure 3: What are we aiming for?
So, I would suggest that there are parallel (but not unconnected) streams to be pursued in the future development of modelling. The first is a strand which develops a range of plausible demand futures. These will each develop different notions as to how society will change and how new technologies might become embedded within that. Where there is a need for more in-depth modelling then this will involve further development of modelling tools. This may be relatively minor such as understanding how smart technology impacts on interchange or more fundamental such as developing models around on-demand mobility access rather than car ownership. However, there will be a need to take an honest look at the requirements which the different futures suggest in order to determine whether current tools will continue to remain fit for purpose in representing these. Again here, there will be a growing need for transparency in terms of areas of limitation and uncertainty in how these different socio-technical futures are able to be represented by the tools at hand.
However, not all of the innovation or case for change can rest with the modelling community. Models are developed to find answers to policy questions. The current emphasis on being able to justify the number of jobs which a scheme will create or the degree to which agglomeration benefits or land value uplift will accrue itself implies a clear handle on these relationships and how they will evolve in the future. I think even here policy is running ahead of where experts in those fields believe the evidence is today. If the policy-making environment is not able to relax its obsession with a single BCR approach (down to the nearest decimal point) and consideration that the main way of supporting growth is delivered by the type of investments which supported the current travel paradigm then it is difficult to see why the mainstream modelling community would shift its developmental focus. It is necessary for there to be sufficient professional consensus, and then policy acceptance, that some kind of scenario based approach to policy making is a necessary part of the decision-making process before the door to more significant change can be opened.
So, to come back to the question posed by the plenary, does rapid change mean new models? It is not the rapidity but the breadth and scale of the changes to how society operates and the kind of mobility systems that might exist to support this that matters. Acceptance of a wider palette of futures and a need for a different approach to decision-making seems critical to the extent to which the demands on the modelling community are incremental or more fundamental. I am delighted to see this debate alive and kicking as I believe that if we do not get to grips with the real changes that are happening and what they mean for transparent decision-support then, at some point, our professional credibility will be challenged and potentially undermined.
This article is reproduced here with the permission of Landor as part of Modelling World 2017
This week saw the first evidence session of the Commission on Travel Demand bringing together stakeholders from local and national government, academia and industry to discuss approaches to understanding demand in the sector. It ended with a debate on whether forecasting as had its day. The motion was defeated but that is not the same as saying we don’t need to re-examine the practice of thinking about travel demand in the future.
Robin Hickman shared the following image on uncertainty, time and techniques that match to the space you are operating in.
In the transport sector we largely deploy forecasting and, even where we use scenarios to think about different policy options, we return to making our decisions based on estimates of demand derived from a forecasting approach. Such an approach seems likely to risk biasing prioritisation of options towards those that are most compatible with the trends which underpin the forecasts. That is a problem if the futures really are potentially significantly different from where we are today.
It seems critical therefore to understand whether there already have been some important structural changes to travel trends which we have missed and whether there are likely to be more which fundamentally change how mobility is tied in to how society works. The evidence session shared several examples of trends which seem to be somehow significantly different to previous decades whether that is between central, inner and peri-urban areas or between different groups in society or for different journey purposes but what there is less evidence on is why that is happening. As an example, the chart below comes from evidence submitted to the Commission by Transport for Greater Manchester showing very different trends in traffic inside, outside and on the motorway network.
Some of the gap between projections and outturn was attributed to it being impossible to correctly foresee the ‘input conditions’ (wealth distributions, oil prices and congestion effects) and that structurally things aren’t perhaps so different. Even were that to be the main explanation, that line of thinking could marginalise whether the changes that result then create a different pathway for society as a result of the new conditions. Some of the change was attributed to completely new ways of doing things such as retail and work which is having a profound impact on what we travel for and how we might value travel in different activities.
It is important to make headway on these arguments. Despite there being widespread acceptance that in some way things are different this does not mean that there is acceptance amongst those taking decisions that this actually makes a difference to how we should take decisions. The assumption that demand in the future will be best supported by the assumptions of links between capacity growth and GDP growth remains intact and the attraction of a single central point forecast also remains strong. Greater clarity on the extent and reasons for an underlying change to how demand is evolving that challenges the current view would be necessary to convince that business as usual planning assumptions are built on sand.
Whilst I think there is a strong case to change the way we approach long-term planning I think we need to proceed with caution and build the arguments very carefully. In the debate I argued that forecasting is not dead. I did so for several reasons (other than that the purpose of a debate is to mount a coherent argument for whatever you are given to discuss!):
- There remain many decisions in the transport sector which are more short term in nature and/or which get revisited over time and therefore can be adapted. Longer-term uncertainty here is less important (see the earlier diagram)
- The approach to forecasting allows one to see how different explanators are changing over time and provide a baseline from which to understand stability and divergence from trends (incidentally no-one argues that forecasting is perfect and that it could not be improved)
- Even if we determine that other approaches would be better for longer-term decisions (and there does seem great potential here) there remain risks that those approaches would be hijacked to support the political will of the day as some critics suggest has happened with our current approach. There would need to be more work done to underpin the analytical rigour which supported decision-making in a world where more pluralistic futures were accepted (and there are examples being deployed in other sectors that may help).
- In short, we must not confuse the practice of decision-making that has built up around forecasting with the benefits that can be derived from the development and appropriate use of forecasts. They should be part of a toolkit of futuring rather than the only tool.
So, to conclude, there seems to be a growing body of evidence that suggests that there is a change in the role of mobility in society and therefore a level of uncertainty in future demand which goes beyond whether or not we have used the right GDP and oil price assumptions in a forecast. The future policy picture for mobility looks certain to add further uncertainty with the increasing automation of transport and changes to mobility service provision. Still greater change can be expected outside of the transport system which will also have profound impacts on what we travel for, where, when and how. That will be true whatever approach we adopt to decision-support and decision-making.
One of the uncertainties that we certainly face is whether decision-makers are ready to not just recognise this but to accept that it matters. A key challenge for research and practice is whether we can prove the need for change, persuade them of the evidence and provide tools which help them to understand and communicate this uncertainty to the various constituencies and systems to which they are accountable.
In this second post about the work of the Commission on Travel Demand I will explore the challenges posed by the quote from the scientist Nils Bohr that headlines this article.
Lets start by looking at the state of practice in the UK. All major infrastructure schemes are subject to an economic appraisal with an appraisal period of 60 years (which is 30 years longer than it used to be a decade ago). We produce long term estimates of demand using the National Trip End Model and a suite of other tools such as the National Transport Model and the Passenger Demand Forecasting Handbook. However, the demand futures upon which decisions are based are largely determined by what are deemed to be ‘reasonable assumptions’. The case for HS2 for example includes the following acknowledgment: “Despite the economic downturn there is little evidence to suggest the recent strong growth in long distance rail travel is about to stop. We therefore assume further growth in long distance rail travel but on a conservative basis that growth will stop in 2043” (HS2 Ltd 2011)
It’s a truism that the only thing we will know about any forecast is that will be wrong but that is not particularly helpful. So what is our history on forecasting? Phil Goodwin has long established the tendency of forecasts from the days of Roads for Prosperity to tend to overestimate road traffic with, at best, demand following the low growth ‘option’ as shown in Figure 1.
Figure 1: A history of forecasting difficulties for car traffic (Image courtesy of Phil Goodwin)
It is not that transport forecasters are bad at forecasting, it is just difficult to anticipate how the various variables in the models might move and which important variables that are not in the current approach will start to matter more. As an example, the National Infrastructure Commission is currently consulting on what the most likely population estimates will be. They review forecasting accuracy as shown in Figure 2. Look familiar? Clearly if the population forecasts are wrong then so will the travel forecasts be given the importance of population growth to total demand growth in our current approaches.
Figure 2: Previous ONS projections versus actual population 1955-2014 (Source: National Infrastructure Commission, 2016)
So, how do we deal with uncertainty about the factors that have underpinned our approaches to demand forecasting such as oil prices, population, income changes. The Department for Transport has been developing the National Transport Model to try and consider those trends which might be important. It led in 2015 to the production of five ‘scenarios’ of travel demand futures. They are not scenarios in the true sense of the term, more sensitivity tests on oil price, economic growth and the extent to which declining trips rates might persist. These are shown in Figure 3.
Figure 3: Range of potential demand futures from National Road Traffic Forecasts (DfT, 2015)
This shows us that there is a range in 2040 traffic levels between the highest and lowest projection of 100 billion vehicle miles. Yes, 100 billion vehicle miles. That is 40% of the miles on our roads today. How do we deal with this kind of range of uncertainty? Currently we don’t, we adopt a preferred ‘scenario’ and continue with our demand analysis on the basis that this is the future under which all projects should be assessed.
None of the above allows for the changes to mobility that will come from social change such as the radical reshaping of the retail sector or changing travel expectations for the over 65s. Nor does it consider the transport system changes such as the introduction of TNCs such as Uber and Lyft, vehicle automation or electrification of the fleet which are being aggressively promoted.
An alternative to simply adding more and more sensitivity lines that incorporate these factors is to try and develop scenarios which capture a plausible set of alternative futures under which decisions can be evaluated. Glenn Lyons and the New Zealand Department for Transportation underwent such an exercise producing a set of four scenarios (see Future Demand where Figure 4 is drawn from – well worth a read). The scenarios were then quantified and the headlines shown below.
Figure 4: Different demand scenarios for New Zealand: Source Lyons et al, 2014
Here again however the range of possible futures goes from a growth in traffic of +10% to –62%.
So, one of the questions we need to ask is whether the relatively near future of 2040 is so uncertain that we have to present decision makers with a range of outcomes which are this wide? Are there not some aspects of everyday life which root some parts of travel demand and are harder or slower to change? Which aspects, which areas, which communities are most and less open to change? Buchanan was surely faced with uncertainty on a level that parallels that which we face today as Traffic in Towns was assembled in the early 1960s. Many of the key insights were right or close approximations as to how demand might play out.
So, we must find a way forward which accepts that there are some demand uncertainties but which provides insight as to what and how much and equally importantly why? Some of these uncertainties are not somehow ‘out there’ waiting to happen but will be created by policy pathways we choose. Which aspects of future demand are most amenable to influence by transport policy and which will happen anyway? I hope the Commission will make progress through the call for evidence and our first three sessions on these questions so that we can move forward the debate on what this really means for decision-making.