Re-thinking transport evaluation methods: do we have the best tools to help us make cities more sustainable?

Publication Type:
Conference Proceeding
Challenge and Opportunity-delivering sustainable development-Summary of Proceedings, 2004, pp. 1 - 28
Issue Date:
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Most planning and evaluation tools are derived from a theory that attempts to describe how the system in question works. The tools currently used to assess the relative merits of urban transport options are based on the logic of mainstream economic theory. But this theory is essentially a-spatial and therefore poor at describing all the changes that take place in an urban system once a new motorway or public transport link is opened. This paper investigates the way two different theories can be used to explain the phenomenon known as induced traffic growth - the sharp increase in road traffic that occurs after the opening of a new urban motorway. First, an explanation using standard supply and demand theory is used to explain the cause and consequences of the effect. Then, General Systems Theory is used to explain the same process. The first explanation renders the outcome in a way that is physically abstract, providing a number value. The second articulates the outcome using spatial data, illustrating both positive and negative changes to land use sectors and patronage on more sustainable transport modes. It is argued that the latter method provides greater insights into the real consequences of motorway building and induced traffic growth, and with it the basis for more useful transport planning and evaluation tools. The challenge for regional government is to recognize the shortcomings of current evaluation methods and reform them so that economic and environmental outcomes are more sustainable. This paper seeks to demonstrate the need for that reform and the direction it might take.
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