Going green: at what cost?

Posted: 31 August 2017 | | No comments yet

With expectations constantly rising for a greener future, Professor John Miles highlights some of the financial implications and barriers of truly sustainable urban transport…

Going green: at what cost?

It has become very fashionable to write about sustainable transport and articles on the subject can be found in transport journals and popular interest magazines all over the world. The arguments that have created this high level of interest are simple and compelling.

The stage for bus, tram, and light-rail systems has been fundamentally reset by the arrival of the twin environmental imperatives of street-level air quality and global climate change. In addition, the arrival of ubiquitous hand-held communication devices, ‘big data’ technologies, and 24-hour social media, has introduced powerful traveller information services and changing patterns of social behaviour to the agenda. These forces for change are provoking a massive re-think of how we might provide better, more user-oriented, public transport services in the future.

The environmental and social considerations outlined above may have generated a general atmosphere of expectation, but when are we likely to see the results of these forces on our streets? In reality, the widespread rollout of new and sustainable transport models will depend more on the third leg of the sustainability argument than the first two legs; namely, financial sustainability. How long will it be before we can afford to go green?

The bus

The basic building block of urban public transport is the bus. It therefore makes sense to start our thinking with this mode of transport. What are the chances of something dramatic happening in the bus world within the next few years?

The vehicle of operator choice for many years has been, and still remains, the diesel bus. The reasons for this are simple and pragmatic: diesel vehicles are cheap, reliable, and allow unmatched levels of day-to-day operational flexibility. This is a very difficult combination to beat and, for this reason, the diesel bus remains by far the most common public service vehicle on our roads. However, it also represents one of the greatest contributors to poor urban air quality and, for this reason, is increasingly coming under attack.

There has been a great deal of publicity about clean diesel and hybrid buses, but an even better solution from the urban air quality point of view would be to introduce all-electric buses. These vehicles genuinely have zero tailpipe emissions, but are currently regarded by most bus operators as a step too far at this stage. The reasons for this are two-fold: the range limitations of battery powered vehicles and the cost of purchase.

However, things have developed rapidly over the past few years and the evidence on the ground is beginning to change. The advent of ‘opportunity charging’ (the ability to recharge a vehicle during the working day without interrupting the scheduled timetable) has transformed the range capability of all-electric vehicles. With a wellchosen combination of battery size in the vehicle and in-route charger power on the ground, all-electric buses with opportunity charging can now run daily duty cycles of 200 miles or more with route PVRs that match diesel fleets. To give added confidence, these vehicles can also come with 10-year warranties on the batteries. For routes with high annual mileages, this can enable the lifetime cost of operating an all-electric bus fleet to be less than that of operating a conventional diesel fleet. And, for those operators who do not wish to purchase and operate the necessary electric charging infrastructure, lease packages are now available that combine the lease of the vehicles with the provision and operation of the charging infrastructure. As operational experience increases and the cost of batteries continues its downward trend, the route mileage required to make the financial case for all-electric buses is likely to drop to a point where, within a decade, most routes in the UK could be operated more cheaply using electric buses than diesel buses.

First- and last-mile services on demand

An important part of making public transport services more attractive will be to address the user-convenience issue. Fixed route, fixed timetable services (like buses and trams) can never replicate the user-convenience associated with a private car, but their appeal might be much improved if they could be combined with on demand first- and last-mile services. This combination, enhanced by real-time journey planning services delivered via handheld devices, could enable future public transport systems to pick up travellers from near their front door, subsidy. With many small-to-medium sized cities experiencing chronic peak-hour congestion, a much lower cost mass-transit solution is urgently required.

The key to reducing the cost of mass-transit systems is to reduce the cost of the infrastructure. The cost of planning and installing fixed rails, overhead power catenaries, ‘stations’, and signalling systems represents, by far, the bulk of the overall system cost – the cost of the vehicles, by comparison, is relatively low. Part of the large capital cost arises due to the complexity of urban construction. The route clearance and (often) building demolition work required to create a new surface rail corridor through an urban quarter requires a great deal of public consultation and planning consent, even before the physical work begins. In addition to this, the disruption caused to local traffic during the period of construction represents further, often hidden, costs.

The Advanced Very Rapid Transit system (AVRT) represents some of the latest thinking in the field of urban mass transit. The concept, developed within the last few years at the University of Cambridge, makes use of modern electric and autonomous vehicle technologies by proposing a system that runs on rubber-tyred, steerable wheels through a network of small-bore tunnels beneath the city landscape. Despite the need to bore tunnels, AVRT is designed to have capital and operational costs that are approximately half that of traditional tram or light rail systems, making the system suitable for operational scenarios where user demand lies in the region of 1,000-3,000 passengers per hour in each direction.

Going underground within the boundaries of the city is expected to create far less public resistance during the planning stages of a new programme, and far less surface disruption during the construction stages of the programme. Recent concept definition studies in the City of Cambridge and its surrounding region suggest that AVRT could have a transformational effect on the city’s congestion problems and that it could be translated to other small cities with relative ease.

The shape of modern public transport systems has the potential to change rapidly in the coming decade. New technologies in the fields of battery electric vehicles and driverless vehicles are beginning to make their presence felt and a straightforward financial case for switching to all-electric buses is already here for some high-mileage bus routes.

The outlook for next generation solutions is very encouraging, with early driverless pod systems beginning to appear in several locations around the world, and radical new solutions for mass transit appearing on the drawing board.


Professor John Miles is CEO of eFIS (Electric Fleet Integrated Services), a company dedicated to accelerating the delivery of sustainable, low-carbon, public transport services through the development of new technical solutions and the provision of attractive financing packages. He has over 40 years of experience delivering high-tech projects in the fields of energy and transport, having previously been a Group Board Director at global consultants Arup. In addition to his role at eFIS, John is a Fellow of Emmanuel College, Cambridge, and is Professor of Transitional Energy Strategies at the University Department of Engineering.