WORLD leaders are currently facing three major concurrent policy dilemmas: how to manage climate change, how to advance equitable and environmentally-sustainable economic and social development, and how to manage unprecedented urbanisation.


Reaching a consensus to overcome these challenges is one of the major questions of our time. This month's COP 21 conference on climate change in Paris offers a further opportunity to reach agreements on key policies that will offer a sustainable and more environmentally-friendly future. Whether this is achieved remains to
be seen, but for many building and operating enhanced urban public transport infrastructure based on trains, buses and bikes is critical to solving each of these issues and should form a key element of any global strategy.

UCD The UN estimates that two-thirds of the world's population, or 6.3 billion out of 9.6 billion people, will reside in cities in 2050, so there is a pressing need to develop urban transport infrastructure which will serve their requirements effectively and provide the conditions for continuing economic development. In addition, transport in urban areas accounted for about 2.3 gigatonnes of CO2 in 2010, almost a third of all transport emissions. And with continuing rapid urbanisation, particularly in India and China, and rising car ownership, this figure is set to double by the middle of the century unless major changes in policy emerge.

Inspired by the 2012 Rio+20 voluntary commitment by eight multilateral development banks to provide $US 175bn towards more sustainable transport investments over the next decade and other voluntary commitments to expand public transport, the Institution of Transportation Studies at University of California Davis and the Institute for Transportation Development and Policy (ITDP), developed a study of how these issues might be addressed through investments in public transport.

A Global High Shift Scenario is the first study to consider how changes in major transport infrastructure and transit system investments worldwide would affect urban passenger transport emissions as well as mobility by different income groups. It provides an understanding of what these systems might look like, their potential impact, and, for the first time, an idea of what it could cost to implement the study's recommendations.

At the heart of the study are two scenarios. The first is a "baseline" scenario calibrated to International Energy Agency (IEA) 2012 Energy Technologies Perspectives 4°scenario, which is the expected future path for the world's development given current trends, and the second "High Shift" (HS) scenario which was specially developed for the study. HS considers the global outcome of implementing the policies and investments currently in place in countries with the most efficient urban transport systems. It emphasises far greater travel by urban public transport and non-motorised modes than in the baseline, and a decrease in levels of road construction, parking garages and other ways in which car ownership is encouraged.

To become an efficient, transit-oriented city, an urban area needs to provide a sufficiently high level of rapid transit services. As a result a key aspect of HS' projections is growth in urban rapid transit, particularly metros, light rail, commuter rail and bus rapid transit systems. To project the extent of these systems in cities by 2050, the study estimated their extent today and developed targets for their expansion and new construction up to 2050. An analysis of city size was conducted in conjunction with data on system location and extent to identify patterns, while incorporating a UN projection of total urban population by 2050 to extend the UN projection of city size by 2030 up to 2050.

To achieve a reasonable approximation of these services, the study identified the kilometres of urban rail and high-quality bus rapid transit trunk lines currently available and the frequency and capacity of these services. HS focuses in part on increasing the ratio of rapid transit kilometres per million urban residents (rapid transit per resident, or RTR) in emerging economies closer to the levels found today in advanced developed economies and further boosts in wealthier countries where it falls short of current global best practice.


For example, in China in 2010, the RTR was about five and is projected to grow to nearly eight by 2050 in the baseline, while in HS the RTR would grow to 21 by 2030 and to 43 by 2050. Similarly in 2010 the RTR in Brazil and Mexico was 8 and 5.7 respectively and is forecast to increase very slowly in the baseline. However, under HS it reaches 19 and 20 respectively by 2030 and 32 and 35 by 2050.

By comparison, the RTR in the United States and Canada in 2010 was 32, and in the European members of the Organisation for Economic Cooperation and Development (OECD), 84, the highest of any region, with both projected to remain flat under the baseline up to 2050, but to grow to 61 and 118 respectively by 2050 under HS. It is noteworthy that in the US existing rapid transit systems are relatively underutilised with low passenger loadings, which contributes to a very high car share. In HS, this performance aspect rises over time, contributing to much higher transit ridership, and is a shift which occurs to a lesser extent in all countries in HS.

To achieve the HS projection of urban passenger travel, the increase in travel by each mode was combined (with consideration given to how much each of these modes could logically increase given increases to the others, and considering the starting points) and then compared with total travel in the baseline, for each of the regions and countries in the IEA's Mobility Model (MoMo).

Growth rates in non-OECD countries were adjusted to support a target 50% reduction in private light-duty vehicle travel, except in the United States and Canada, where the 50% reduction is much greater than a plausible offset from increased transit and non-motorised transport.

These figures show that in 2010 residents of OECDs travelled almost twice as much as someone from non-OECDs, while by 2050 in HS, the travel per capita converges around 8000 passenger-km per person per year, suggesting more equal levels of mobility than exist today or in the baseline scenario.

HS' underlying analysis suggests that urban travel needs in most parts of the world can, in principle, be met with a combination of travel modes that cut urban light-duty vehicle (LDV) kilometers by half. The required extent and use of mass transit and non-motorised modes in all areas in 2050 does not exceed the use in certain areas of the world today. However, given the rapid urbanisation occurring between now and 2050, this will require public transport offerings to be typically 2-3 times higher in 2050 in HS than in the baseline, and in some regions many times higher than today in places where today's public transport levels of service are very low.

A key goal of the HS scenario is to improve the equity of mobility, which is achieved as all regions begin to converge toward 8000 passenger-km per capita per year by 2050, with Africa and parts of Asia achieving higher mobility rates in HS via investments in public transport that are closer to other world regions, especially for buses.

So what could HS mean for rail investment?

In the baseline, there is only slow growth in urban rail ridership around the world due to the construction of very few systems and greater emphasis on road investments. In HS, there is a steady growth in the number of rail systems and ridership to reach the desired levels. However, in many areas these do not match Europe and OECD Pacific. Metros and light rail feature more in OECD countries whereas BRT appears more in non-OECD countries, although all regions grow this to some extent. Commuter rail systems expand across the world as a key part of development strategies for metropolitan regions.

Cost estimates

The projections used to estimate system size required in HS were also used to develop infrastructure cost estimates. The findings show that for OECD countries the increase for each mode is significant, but not huge, apart from BRT which is tiny in 2010. However, in non-OECD countries, the required growth rates are far higher and would require major sustained investments over the coming decades.

The study subsequently estimated the major direct cost and investment implications of HS relative to the baseline from 2010 to 2050 in cumulative and annual fashion including all market costs to private users and agencies.

Overall the cost of the baseline is $US 500 trillion ($US 200 trillion in OECD and $US 300 trillion in non-OECD) whereas the costs under HS are about $US 400 trillion ($US 160 trillion in OECD and $US 240 trillion in non-OECD.) HS trims overall costs by approximately $US 110 trillion, or 22%.

The results indicate that in the baseline, investments in road and parking space dominates all other investments. However, in HS the number of roads and parking spaces drops dramatically while in the OECD between 2030 and 2050 infrastructure costs "go negative," reflecting a reduction in the need for roads due to less traffic.

These findings show that a high-transit, high non-motorised-vehicle scenario which provides similar mobility in passenger-km to a more car-dominated scenario is likely to be less expensive to construct and operate over the next 40 years.

Indeed, the study shows that unmanageable growth in motor vehicle use threatens to exacerbate growing income equality and environmental ills, while choosing a model that emphasises sustainable transport delivers access for all. In addition, it will also offer a significant reduction in CO2 and harmful emissions which will limit both the effects of global warming and improve public health.

The report's findings should help to support wider agreements on climate policy, where costs and equity of the cleanup burden between rich and poor countries are key issues. However, they emphasise it is only one example, and is not a prediction of the future. With the high rates of public investment required, HS may be extremely challenging to achieve. It will require very strong commitments from governments and funding agencies to build the systems, with the quality and capacity levels, envisaged in HS. As a result an important purpose of A Global High Shift Scenario is to serve as a basis of further studies to expand its findings and investigate how they might be achieved.


Three countries that stand out

  • United States: Currently the world leader in urban passenger transport CO2 emissions, with 670 megatonnes annually, the US is projected to lower these emissions to 560 megatonnes by 2050 because of slower population growth, higher fuel efficiencies, and the decline in driving per person that has already started as people move back to cities. But with more sustainable transport options outlined under HS, this would drop by half to 280 megatonnes.
  • China: CO2 emissions from transport are expected to mushroom from less than 200 megatonnes annually today to nearly 1200 megatonnes in 2050, due in large part to the explosive growth of China's urban areas, the growing wealth of Chinese consumers, and their dependence on automobiles. However, this increase can be slashed to fewer than 700 megatonnes under HS by developing extensive BRT and metro systems. Passenger-km does not drop significantly for China in HS and the latest data shows that China is already sharply increasing investments in public transport.
  • India: CO2 emissions are expected to leap from about 70 megatonnes today to over 500 megatonnes in 2050 because of growing wealth and urban populations. But this increase can be limited to only 350 megatonnes under HS by addressing crucial infrastructure deficiencies in India's public transport systems and slowing the growth in car use.