Bruce Schaller, an expert on urban transportation, has published an informative and insightful report on the impact in New York City of what he calls ‘Transportation Network Companies’ (TNCs) such as Uber and Lyft. Use of these providers of app-based ride services has grown rapidly, more than doubling in each of the past four years. This reflects the popularity of the services offered, which reduce anxiety, uncertainty and stress, not least by providing assurance of a vehicle in situations where hailing the traditional yellow cab may be problematic.

The contribution of the TNCs to congestion has been a matter of controversy. The present report confirms a previous study carried out by the NYC authorities which found that worsening congestion was driven primarily by increased freight movement, construction activity, pedestrian volumes and record levels of tourism, all of which put growing demands on the streets’ limited capacity. However, use of TNCs continue to grow, raising the question of their future impact on congestion.

A key question is whether TNC growth is making more efficient use of scarce street space by putting more passengers in each vehicle, as with UberPool which offers low fares for trips shared with others? Or does it add to traffic by diverting people from high capacity services such as rail and bus, for which evidence of a recent decline in ridership is suggestive? The available evidence as a whole is insufficient for a definitive answer, but the report suggests that diversion is likely to be more important, implying  that TNC’s add to congestion.

The report is concerned that TNCs are fundamentally undoing the cost incentives to use public transport. NYC taxi fares were traditionally set at about 4.5 times the subway fare to encourage the use of transit (public transport). However, as they cut fares, the TNCs are beginning the erase these disincentives to road vehicle use. These fares do not reflect the costs of time delays arising from congestion, hence there would be a case for some kind of congestion charging.


Congestion is self-limiting in that as traffic builds up, for instance from more TNC vehicles, speeds drop, trips take longer, and some road users make alternative decisions, for instance to travel at a less busy time, or to go to a different destination, or to use the subway. So it is not to be expected that growth of TNCs would worsen congestion in already congested parts of NYC. The switch of people from the subway to TNC services would be limited for the same reason.


The National Infrastructure Commission (NIC) has been issuing Discussion Papers for comment. I have previously blogged about the paper on technology.

Two further NIC papers are of interest: one concerns the relation between economic growth and the demand for infrastructure, where it is assumed that these are closely correlated. In my response (Metz NIC Econ growth 28-3-17 ) I argued that, for transport, this is far from the case, with demand saturation an important phenomenon.

The other discussion paper concerned the impact of population change and demography  My response (Metz NIC population 23-1-17 ) drew attention to the importance for transport infrastructure investment of where a growing population is housed : greenfield housing leads to road investment, urban densification requires investment in public transport.

My new book 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 National Infrastructure Commission has issued a discussion paper on the impact of technological change on future infrastructure supply and demand. I submitted a response (Metz NIC tech 9-1-17 ) in which I argued that the potential of digital technologies to increase the effective capacity of existing road infrastructure is not well understood. It would be worth the NIC commissioning an expert study, to consider the scope for a roads analogue of the Digital Railway, a concept that is gaining influence for rail infrastructure.

‘Transport modelling – fact, forecast or fiction?’ was the topic of a well-attended meeting of the Transport Planning Society at which I was a panelist. I argued that there was occurring quite a lot of change in travel behaviour as we moved into the twenty-first century – not least the Peak Car phenomenon – which made the task of the modeller more difficult. Modelling of any kind assumes continuity between past and future, that past relationships (estimated as elasticities) will apply in the future, subject to changes in parameters exogenous to the model, such as growth in GDP, population and oil prices. If behaviour is changing, the best approach is to widen the range of forecasts by adopting scenarios which allow the model to explore the impact of a wider range of travel behaviour. An example is the generation by Department for Transport modellers of road traffic forecasts based on five scenarios applied to the National Transport Model.

I also drew attention to the experience of the Actuarial profession, which after the failure of a life assurance company had prompted a government inquiry,  had put in place formal standards for actuarial analysis and a means for professional oversight of compliance. One standard deals with modelling, the language of which is quite general and would be relevant to other kinds of modelling, including transport modelling. So the actuaries’ arrangements show that it would be possible to put in place formal standards for transport modelling. However, for this to happen, there would probably need to be some kind of scandal, as happened to the actuaries.

One kind of scandal involving transport modelling has occurred in Australia, where a number of privately-funded toll roads have experienced usage far below the forecasts made when investors were approached to finance construction. This has resulted in litigation that in at least one case resulted in the transport consultant responsible for traffic forecasts paying out $200m. Were something similar to happen in Britain, I would expect a call to put in place standards for transport modelling.

My fellow panelists had their own concerns and solutions to achieve better transport modelling. My feeling from the meeting as a whole is that there is a needed to  review systematically the current state of the art and to identify ways to improve. I hope the Transport Planning Society might act as a thought-leader, given the centrality of modelling to planning.

The Transport Planning Society recently held a meeting on the topic of whether appraisal methods for new transport investments are fit for purpose.  I have been critical of the conventional methodology since it disregards changes in land use that result from the increased accessibility made possible by improved transport. I was a speaker at this meeting, see the video.

The discussion was lively, and I look forward to continuing the debate in other venues.

The Guardian reports the latest version of Google’s driverless car, a two-seater city car without a steering wheel. Taxi drivers are concerned that they might be displaced. That is possible since a driverless car is essentially a taxi with a robot driver. We would make more use of taxis if they were cheaper. But road transport would be be little changed, I suspect, with traffic congestion the main problem.

The Financial Times reports growing sales of electric bikes in Europe, 850,000 sales in 2012, and 400,000 last year in Germany. Manufacturers include Bosch, Daimler and BMW. In China, 30m are sold annually.

The electric motor kicks in when you start to pedal and then only with a force commensurate with your own efforts. Electric bikes overcome two disadvantages of ordinary bikes: hills and getting damp from sweat.I look forward to trying one.


The Independent Transport Commission has published a useful report on automated cars, authored by Scott Le Vine and John Polak of Imperial College London. The tone is generally agnostic: ‘The impacts will be mixed, some good and some bad, and there will no doubt be surprises and unintended consequences along the way.’

I am skeptical about the impact of driverless cars on the transport system. They would be essentially taxis with robot drivers. Taxis are useful, and we would make more use of them if vehicle automation brought down the costs, but the impact on road speeds and congestion does not seen likely to be large.