THIS SUMMER was the 20th anniversary of a letter signed by 28 professors in the field of transport – including myself – that was sent to the then Secretary of State for Transport, Alastair Darling, in 2002. It was prompted by a dissatisfaction with the government’s transport policy of the time for overlooking instabilities in the treatment of supply and demand, and the neglect of important potential consequences. This was well recalled in LTT850 (see link) which noted that the thrust of the argument was that there would need to be ‘active policy intervention to manage the demand for road space at congested times and places’, without which the benefits of new infrastructure would be eroded by extra traffic. Alongside this there was a strong suggestion that to manage demand, users would need to be charged the full costs that each journey imposes on society, most importantly to levy a congestion charge on road users, to reflect the cost of time delays imposed on other users.

Our most pressing concern nowadays is the need to decarbonise the transport system, but it doesn’t seem to have been a hot topic 20 years ago amongst the academic community judging by the content of the letter. Might we professors be forgiven for not mentioning this at all? Well, on the one hand we were simply reflecting the popular issues of the time. But weren’t we also, perhaps, the very people who should be spotting the emerging problems we now face? After all, Tesla, the pioneering electric car company, was founded in 2003.

But this glaring omission apart, how valid were their other expressed concerns and projections, viewed with the benefit of hindsight?

The professors expected that the strong growth in road traffic seen through most of the 20th century, if it continued, would negate the benefits of investment in transport infrastructure. This was a view widely held. Kwasi Kwarteng, then a back bench MP, now Chancellor of the Exchequer, authored a book in 2011 titled ‘Gridlock Nation’, which predicted that the country would grind to a halt without unleashing the possibilities of new technology and political reform.

In the event, gridlock has not occurred. As it happened, the professors’ letter was sent at the time when it soon became apparent that per capita of surface travel by all modes had ceased to grow, as did per capita travel by car – although it took some time to appreciate this break in the historic trend. A number of factors contributed. The proportion of households owning cars plateaued at 75% of all households. It was not possible to travel faster on the roads, given safety concerns, speed limits and prevailing traffic congestion. Continued investment in strategic and major roads added too little capacity to do more than keep up with population growth, and so did not relieve congestion. The fashion for enlarging road capacity for cars, in urban areas, had reached its end, replaced with a tendency to increase space for buses, pedestrians and active travel, so discouraging car use. And most of us had sufficient mobility, based on the car or good enough public transport, to meet our needs for access to people and places, opportunities and choices.

Control, by pricing, and restriction, of parking has been in place since the middle of the last century, though without much obvious impact on demand, but congestion charging for moving vehicles, meanwhile, has not been employed in Britain beyond a small zone in Central London. It has not been necessary because congestion of moving traffic is effectively self-limiting. Time always constrains our travel behaviour. If traffic volumes grow, congestion and the associated delays increase. So some potential drivers make other choices – of time of travel, route, mode, destination, or not to travel at all. And the congested equilibrium is restored – not an ideal situation, but not intolerable.

I believe, we professors were rather wide of the mark in our analysis of the problems of the transport system two decades ago, and in identifying the best solutions. It is then worth asking what the academics have contributed to understanding and resolving these problems since then?

From the perspective of academic transport economists, congestion charging would, as they put it, “internalise an externality”, in this case by reminding individual motorists through their pocket of the cost of the delays imposed on other road users by their decision to embark on a car journey. With congestion charging, we would face the full cost of our decision, and some of us, particularly those with lower incomes, would decide the trip would be too costly and so would vacate the road network for the benefit of others.

But is congestion charging really the best tool for the job? There is a cost of inequity occurring here, which is usually recognised by a willingness to use some of the revenues of congestion charging in a redistributive way to improve public transport. However, inequity is increasingly recognised as a problem of the wider society, and a full economic analysis would arguably now put a value on the cost of inequity, as a ‘social’ externality created by congestion charging. It is, of course, possible that the efficiency benefits of charging would be substantially offset by the costs of inequity generated – which might help explain the lack of progress in implementing road user charging thus far.

So, I believe, we professors were rather wide of the mark in our analysis of the problems of the transport system two decades ago, and in identifying the best solutions. It is then worth asking what the academics have contributed to understanding and resolving these problems since then? The answer is rather depressing, in my view, and suggests a lack of identification of, and attention to, some of the key emerging issues of our time in relation to transport.

What should we be focusing our research on today? There is plenty of brain power available, surely, with the number of professors either directly or closely related to transport now going well beyond 100. The most obvious topic deserving of attention is how to advance the Transport Decarbonisation process, in particular to understand the realistic opportunities to achieve behavioural change, an aspect where there is too much wishful thinking. I wrote in LTT826 about the experience of Copenhagen where excellent cycling facilities attract people off the buses, not out of their cars.

Sustainable scenarios for aviation is a neglected area, where behavioural change possibilities are especially important, given the difficulty of technological decarbonisation. I co-authored a 2017 paper on the characteristics of the ‘infrequent flyers’, the half of the population that never or rarely travel by air, to assess this group as a possible source of future demand growth.

‘Integrated transport’ is a slogan without much substance. We have the impressive Swiss system of urban and rural buses linking with rail, working to a frequent timetable. Developing models for public transport integration in Britain would be more useful than modelling the impact of autonomous vehicles, a currently fashionable research topic.

Transport’s role in Levelling Up, and in equality and equity more generally, is a matter of current interest, yet our understanding is insufficient to identify much in the way of policy response. A recent report from the International Transport Forum was titled ‘Gender Equality and the Role of Women in Decarbonising Transport’ and looked for overlaps between two distinct agendas, without (to my mind) settling whether gender equality is helpful for, or a distraction from, the decarbonisation challenge.

More generally, we academics need to be active in spotting outliers of coming change, emerging challenges and new approaches to analysis. As one example, I summarised the findings of my paper on the impacts of Digital Navigation - the combination of satnav, digital mapping and route guidance algorithms – in LTT847 (see link), a technology in widespread use that, nevertheless, has hardly been studied. The use of GPS tracking offers a vast data set of trip data – origins, destinations, routes, times of day, prevailing traffic conditions, estimated and outturn journey times – processed by machine learning by the businesses that offer Digital Navigation services. This represents a new and powerful approach to transport modelling that could both better project and evaluate the outcomes of investments in infrastructure.

In my judgement, the contribution of academic researchers to addressing the problems faced by the transport sector, and to help influence decision makers, has been decidedly disappointing, with only a small fraction of published papers really having any prospect of influencing and improving either policy or practice. Yet there is scope for making much greater impact if we address two questions, in the right order: first, ‘What’s going on here?’, and then, ‘What can we do about it?’ Analysis first, and only then advocacy.

Further contributions on the issues raised are welcome. Please send to hello@lttmagazine.co.uk