Sustainable Urban Transport

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Sustainability in the Transport Sector

This article has been adapted from the GIZ Sourcebook on Sustainable Urban Transport.[1][2]

Based on a concept developed by the Toronto-based Centre for Sustainable Transportation, which has been adopted by the European Conference of Transport Ministers (ECMT) and numerous other relevant international organizations, sustainable transportation can be defined as follows:

A more sustainable transportation system is one that:

  • Allows the basic access and development needs of people to be met safely and promotes equity within and between successive generations. (Social dimension)
  • Is affordable within the limits imposed by internalisation of external costs, operates fairly and efficiently, and fosters a balanced regional development. (Economic dimension)
  • Limits emissions of air pollution and greenhouse gases (GHG) as well as waste and minimizes the impact on the use of land and the generation of noise.

In conclusion, low-carbon, sustainable transport reduces short and long term negative impacts on the local and global environments, has economically viable infrastructure and operation, and provides safe and secure access for both persons and goods.

Consequences of Unrestricted Car Use

High population density is desirable for several reasons:

  • Low cost, high-frequency transit systems will be viable;
  • Shorter travel times are achieved;
  • Mobility for non-drivers – the vast majority in developing cities – is enhanced, including mobility of the poor, children, and the elderly;
  • An abundance of people will fill public pedestrian spaces;
  • More efficient land use and infrastructure provision is achieved.

For these reasons and more, urban experts around the world concur on the desirability of density.

The unsustainable nature of car-based transport is illustrated by the fact that the problem gets worse as societies grow richer. Unless car us is severely restricted, as in Singapore, or in cities such as Tokyo and HongKong which provide a very low level of Central Business District parking spaces, society will be worse instead of better off with economic progress due to the following:

  • More traffic jams;
  • More noise;
  • More air pollution;
  • More health problems;
  • More low density city expansion and suburban development;
  • More regressive public expenditure on road building and maintenance that benefits primarily car-owning upper middle classes.

Car use in developing cities is very regressive: It absorbs massive public investments of road infrastructure building and maintenance, taking resourced away from the more urgent and important needs of the poor.

International experience has made it clear that trying to solve traffic problems by building more, bigger roads causes even more traffic. In the United States time lost in traffic increases every year, despite enormous highways. A new highway stimulates new development around it and particularly at it extremes, and thus generates its own traffic. This phenomenon is called “Induced traffic”: Increasing transport supply, e.g. by road widening, generates increased vehicle travel, or ‘induced traffic’. Such inducement effects are felt in the short term such as through longer and more trips, mode switching to cars, or different trip routes. More insidious are the long term impacts, such as higher car ownership and lower densities, as activities become more spread out.

Consider the case of a new 10-lane highway from the centre of a city to any location in its outskirts. Immediately after it is completed, new housing projects, shopping malls, and factories are built around the new road and in the countryside near its extreme. Ten years after the road is built, traffic jams are worse than ever. For traffic considerations, doubling the number of vehicles is the same as having the same amount of vehicles travel twice the distance.

Los Angeles, the archetypal experiment in building a car-oriented city and seemingly the role-model for some developing cities such as Bangkok, has found that road-building cannot solve congestion problems. The city now focuses on transit-oriented investments including Bus Rapid Transit, light and heavy rail, and car-sharing.

Yet, despite evidence that the road-building approach is regressive, inappropriate, and unsustainable for dense developing cities, it is an approach which continues to be followed throughout the world.


The advanced cities’ car-based suburbanised model is not working well. It is wasteful in physical and human resources, is not environmentally sound and leaves much to be desired in terms of human interaction. Developing cities still avoid the failings of advanced cities and create a different city model. It is still possible to think and act differently.

Further Information


  1. D. Bongardt, D. Schmid, C. Huizenga, T. Litman 2011, Sustainable Transport Evaluation, Eschborn, Germany
  2. E. Penalosa 2005, The Role of Transport in Urban Development Policy, Eschborn, GermanyfckLR