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 stimuate lift-off.

There is considerable interest in, and support for diesel scrappage schemes. The challenge is to target polluting vehicles making the biggest contribution to poor air quality. In my recent blog on air quality, I said that it would be hard to devise a scrappage scheme for the more polluting diesel vehicles. On reflection, I can see a way forward.

The Mayor of London has advocated a national diesel scrappage fund. Transport for London has developed detailed proposals that involve targeting small businesses, charities, schools, low-income households and the oldest taxis, at a total cost for London of some £500m. The recent Defra/DfT Technical Report on reducing NO2 levels considers a national diesel scrappage scheme aimed at all pre-Euro 6 diesel cars and vans, and also a scheme to replace non-compliant vehicles with battery electric vehicles. The former is extremely expensive, while the latter makes very limited impact.

I propose that a scrappage scheme could be integral to the  Ultra Low Emission Zone (ULEZ) proposed for London, which would naturally target the vehicles making the greatest contribution to poor air quality.

The ULEZ will generate net revenue that could be used to fund a scrappage scheme. The targeted vehicles would be those that pay the largest cumulative charges for entry into the zone, since these make the greatest impact on air quality. The formula might be a contribution of £X00 to scrappage for every £1000 of cumulative charges – a cash-back offer. The value of X could be adjusted in the light of experience of uptake.

Owners scrapping a car or van under the scheme would need to provide evidence that the vehicle had been scrapped. To discourage replacement by a further polluting vehicle, it might be a condition of the scrappage scheme that the owner would not be allowed in future to pay the standard charge for entry of a non-compliant vehicle into the ULEZ, and would therefore incur the penalty charge should this be done.

Over time, as non-compliant vehicles are scrapped, revenue from the ULEZ would fall, as would NO2 levels. Depending on how far the latter was from the statutory limit, the scope of the zone could be extended, whether to more recent vehicles or to a wider geographic area.

I suggest that TfL considers in detail how a scrappage scheme might work as part of a the ULEZ, and what incentives might be sought from the Government to adopt such arrangements.

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.


An excellent report on the impact of road investments has been commissioned by the Campaign to Protect Rural England from Lynn Sloman and colleagues. This report re-examines the outcomes of a number of Highways England road schemes, finding average increased traffic above control levels in the short run (3-7 years) of 7% and in the longer run (8-20 years) of 47%. This is clear evidence for substantial ‘induced traffic’ generated by new capacity. The CPRE study also find very limited evidence for benefits to the local economy from road investments.

These findings pose problems for the  Department for Transport’s WebTAG approach to the economic appraisal of road schemes, in which time savings to users is the dominant benefit. However, induced traffic tends to restore congestion to what it had been, lessening time savings. If induced traffic were properly taken into account, the apparent value of the investment would be substantially less. Moreover, the orthodox approach assumes unchanged land use, yet the CPRE report documents extensive land use change in four detailed case studies. Such changes have implications for local economies, not necessarily wholly advantageous if these take the form of low-wage employment in warehouses or car-dependent residential development.


The main policy objective of the current UK national road investment programme is to boost economic growth by improving inter-urban connectivity and reducing congestion. Each scheme of the programme must offer acceptable value for money on the orthodox approach to appraisal, yet this approach overstates benefits by underestimating induced traffic and disregards changes in land use made possible by improved access. We need an evidence-based approach to investment appraisal, in which careful evaluation of completed schemes of the kind commissioned by the CPRE informs appraisal of prospective investments.

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, Travel Fast or Smart?, 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 is available both in print and as an ebook from Amazon Books

Transport for London (TfL) has published an illuminating report on the topic of Land Value Capture (LVC) – the way in which transport investments could be funded from a share of the increased value of land and property that follows when access is improved as a result of the investment. This study was carried out in response to a request from the Government for detailed proposals.

The range of possible approaches to LVC is wide, and overseas experience is relevant. A conclusion is that of past projects, the Jubilee Line Extension to Docklands resulted in land value uplifts of 52% relative to controls, and the Docklands Light Railway extension to Woolwich, 23%. For eight prospective TfL projects costing around £36bn, land value uplifts could be £87bn. So plenty of value that could help fund these new investments.

The Annexes to the main report are interesting, particularly Annex 7, the literature review of the theory and practice of the relationship between transport and land value, a relationship which does not form part of the orthodox approach to cost:benefit analysis of transport investment. The orthodox approach is concerned with benefits to users, particularly time saved through faster travel. The orthodox view is that to include the uplift of the value of land made more accessible by the investment would double count benefits that accrue to users. However, the user benefits are notional, based on the outputs of transport models, whereas the land value uplifts are real and observable.


The TfL report is important, both to identify possible ways of using LVC to fund new projects, and also to assert the relevance of land value uplift as a measure of the economic impact of transport investments. Chris Grayling, Secretary of State for Transport, in a speech on 6 December 2016, recognised the case for LVC:

I want to look at innovative ways of funding infrastructure development. Often the opening of a new road or a new railway line or station can transform the value of development land. It is right and proper that the government gets back some of the value it has created to invest in infrastructure. We have seen this happen for Crossrail through the mayoral community infrastructure levy.

My new book, Travel Fast or Smart?, 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 is available both in print and as an ebook from Amazon Books

There is much current interest worldwide in the concept of Mobility-as-a-Service (MaaS), the aim of which is to provide seamless journeys using the most appropriate travel modes, routed and ticketed by means of a smart phone app. The MaaS provider ‘aggregates’ the services provided by transport operators (in the way that Amazon acts for retail product providers). MaaS is intended to be an attractive alternative to private car ownership. The Transport Catapult has recently published a report on the opportunities for MaaS in the UK. And the New Cities Foundation has addressed the role of public transport operators in its development.

There are many recognised technical and policy issues that need to be tackled, including managing the large amounts of data, and coordinating ticketing and payments on behalf of a multiplicity of operarors. However, there are two aspects that deserve particular consideration. The first is the ability of MaaS to cope with peak travel demand.

Peak demand

Daily travel demand is characterised by morning and evening peaks, and there are also seasonal variations. Peaks result in road congestion and crowding on railways. One approach would be to charge higher prices at times of greatest demand, with the aim of spreading the peak. This model has been adopted in the aviation sector, led by the low-cost carriers, and by Uber for urban taxis (and also in other sectors such as hotels). The railways offer off-peak discounted fares, but do not flex fares upwards to reflect actual peak demand.

However, unless peak pricing is part of the public transport provision (which at present it is not), the scope for coping with peak demand for multi-modal journeys is quite limited. This means that unreliability of travel time for each stage of a journey would present a scheduling problem.

While MaaS comprises a minority of all trips, congestion would be a given, and scheduling would need to allow for expected journey stage times plus a margin for uncertainty, with rerouting in the event of unexpected congestion. On railways, consideration would need to be given to offering alternatives to overcrowded trains. Such dynamic scheduling could be technologically challenging.

Were MaaS to grow to encompass a substantial part of travel demand, there may be scope for routing travellers to spread demand across the network in a way that optimises overall efficiency, simplest for routes that involve stages with assured reliability – rail, bus rapid transit, walking and cycling. There would also be scope to consolidate car trips by means of shared taxis, as with UberPOOL. However, such sharing, incentivised by lower fares, could attract passenger from buses, which could add to congestion.

If MaaS were to be a major intermediary in meeting travel demand, a significant operational issue would be whether to respond to peak demand for door-to-door travel by mobilising more taxis through surge pricing, as does Uber. Surge pricing to deter demand and increase supply is sensible in the absence of congestion, but may not be optimal under congested conditions. In the absence of surge pricing, demand would exceed supply and would be rationed by waiting in a virtual queue until a taxi becomes available. With surge pricing, there is a greater supply of taxis and so less waiting time, but journey times might be slower on account of increased congestion. Which approach would be optimal would require modelling.

Surge pricing works well for aviation, a closed system where an aircraft can only fly if it has airport slots allocated at trip origin and destination. But roads are an open system and hence prone to congestion at peak times in populated areas. MaaS would be more straightforward to implement in lower density areas, less so in urban centres, unless private cars were entirely replaced by a fleet of shared use self-driving vehicles, as has been suggested.

Who owns the platform?

The question of how MaaS can best cope with peak demand is linked to the second problem – the nature of the platform by means of which demand and supply are matched, prices set and revenues allocated. The central issue is familiar: benefits of competitive supply versus benefits of an integrated network. Experience is varied. In the case of buses, Mrs Thatcher’s government opened the bus services outside London to competition with minimal regulation, hoping to benefit users by on-the-road competition between private sector operators. This largely failed to materialise since such competition resulted in unattractive profit margins. In consequence, the present Government has introduced legislation that would allow other cities to adopt the successful London model, whereby an integrated public transport network is operated by a politically controlled public body, Transport for London.

For MaaS, the question is whether an open source public platform would naturally evolve on account of the superior benefits, as envisaged by the TravelSpirit collaboration. Or whether competition in the market between competing platforms would be the main driver, with perhaps a dominant platform emerging through economies of scale and scope.

A dominant private sector platform might need to be regulated to avoid market failure that allowed economic rents to be extracted at the expense of users. The MaaS provider would have access to all the data arising from use of the system. Fair sharing of this data with transport providers would help meet the needs of users. On the other hand, discriminatory sharing could increase returns to the provider.


Traffic congestion is the main problem of the road system. A key question is whether MaaS has the potential to lessen traffic congestion. If it does, then promoting MaaS could be a sensible transport policy, in which case a view would need to be taken of the relative attractions of competing platforms versus a single public platform.

In the longer run, developments in shared use driverless urban vehicles might achieve substantial mitigation of urban traffic congestion. Sharing of taxis would increase vehicle occupancy and hence efficiency of the road system; demand management could limit use of single occupancy vehicles under congested conditions; and the development of vehicle-to-infrastructure communications could permit flow management, analogous to air traffic control. In such circumstances, MaaS would be likely to be an integral part of an urban transport management system. However, development of such a system would be challenging in respect of technology, business models, institutions and public acceptability – hence the feasibility and timing is uncertain. In the meantime, development of MaaS in urban areas would need to cope with traffic congestion.








Yaron Hollander is an experienced transport modeller, previously at Transport for London and now an independent consultant. He has written and published a book for beginners, which I warmly recommend. The style is accessible, jokey even, with cute hand-drawn illustrations. I learned a lot both from the the main expository text, and also from Part II, which discusses critically the culture of transport modelling.

Yaron argues that models work best for short term predictions of small scale interventions, such as fine-tuning traffic signal timings. But in practice models are mostly used to support investments in long lived infrastructure: here the modellers may understand the shortcomings, which their clients may prefer not to recognise provided the model outputs justify the planned investment.

Highways England has a major development of modelling underway to justify intended investment in 100 inter-urban road schemes. This ambitious project involves using mobile phone data to identify origins and destinations of trips, and the application of of the very fast computation that makes computer games possible. However, I would be surprised if many of the model outputs failed to confirm the investment decisions, given the scope for judgement about model inputs reflecting future developments, particularly traffic growth.

My conclusion is that transport modelling as it has developed is decidedly problematic. Models generally serve to confirm prior expectations, rarely to illuminate decisions.

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.

My new book published on 1 September 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.

Three studies of prospective road investments in the North of England have been published recently. These illustrate some of the questions that arise when the aim is to boost economic growth by increasing road connectivity between cities.

M60: Manchester North-West Quadrant

The NW section of the M60 orbital motorway within Manchester is one of the busiest roads in the country, on account of the mix of local and strategic traffic. Traffic congestion, local air quality and noise are considered to inhibit economic growth.

A number of road schemes are proposed to improve matters: new outer orbital roads to divert strategic traffic from the inner orbital M60, plus improvements to enhance capacity of the M60 itself. The benefits have been assessed, according to standard practice, on the basis of the value of journey time savings, which typically are quite small – up to 5-12 min for strategic long distance users and up to 3-5 min for local users. The capital costs are estimated at around £14 billion.

A public transport only scheme has also been considered but rejected since it offered no journey time savings for road users.

Northern Trans-Pennine Routes

This study addresses the most northerly major east-west road routes in England, currently underused on account of poor journey time reliability, high collision rates, high proportion of Heavy Goods Vehicles and lack of alternative routes if diversion is needed due to poor weather or road works. Parts of these routes are still single carriageway. Capital costs are estimated at about £5 billion. No quantitative estimation of benefits has yet been made.

Trans-Pennine Tunnel

This scheme involves a ‘bold concept’ – building a tunnel under the Peak District National Park to improve road connectivity between Manchester and Sheffield, with journey time saving of up to 30 min. Depending on the precise route, the length of tunnel would be 12-20 miles, longer than most road tunnels in Europe, costing £8-12 billion. No quantitative estimation of benefits has yet been made.


The total cost of these three schemes is put at up to about £30 billion, which is twice the total investment planned under the current five year Road Investment Strategy. It is very hard to see how the economic benefits could justify such expenditure, not least because the evidence for benefits from improving the connectivity of cities around 50 miles apart in thin (see my discussion of Glasgow and Edinburgh, two well connected cities).

Moreover, standard economic analysis does not distinguish between benefits to commuters and to long distance users. As I have argued, in situations like the urban M60, where car commuters comprise 40% of morning peak traffic, it would be commuters that would take advantage of any increased capacity, leaving long distance users no better off – consistent with the maxim that you can’t build your way out of congestion.

Standard economic appraisal, based on time savings to road users, takes no account of the way transport investment makes land accessible for development and so contributes to economic growth. Such development results from investment in urban public transport, as for example at MediaCity in Greater Manchester. The rejection of public transport investment as a means of mitigating congestion on the M60 reflects this disregard of development in standard appraisal.

The construction costs estimated at this stage are not to be relied upon. Very likely ‘optimism bias’ is at work, underestimating costs and overstating benefits at an early stage, to ensure the project remains under consideration, consistent with a ‘bias to action’ on the part of promoters and their agents when there is an opportunity to spend other peoples money.

On the other hand, the estimates of fairly small time savings are consistent with the outcomes of previous road investments, raising a question about the nature and value of incremental investment in a mature road system that generally provides dual-carriageway or better connectivity to all major cities.

What is entirely missing from these studies of road investment is any consideration of how digital technologies might help meet the needs of users, technologies that can be far more cost-effective that the very expensive civil engineering technologies that have dominated thinking about the road system. This is in marked contrast to the railways where the virtues of the ‘digital railway’ are increasingly recognised.

There is too much wishful thinking about the economic benefits of investment in road infrastructure, particularly in the context of the ‘Northern Powerhouse’, the North of England seen as a region with unrealised economic potential. More rigorous analysis is needed, otherwise outcomes will be disappointing.