Sunday, April 6, 2008
Friday, April 4, 2008
Thursday, April 3, 2008
Theory of Land-Use Transport Interaction
Theory of Land-Use Transport Interaction
Theories on the two-way interaction between urban land use and transport address the locational and mobility responses of private actors (households and firms, traveller) to changes in the urban land use and transport system at the urban-regional level.
That urban land use and transport are closely inter-linked is common wisdom among planners and the public. That the spatial separation of human activities creates the need for travel and goods transport is the underlying principle of transport analysis and forecasting. Following this principle, it is easily understood that the suburbanisation of cities is connected with increasing spatial division of labour, and hence with ever increasing mobility.
However, the reverse impact from transport to land use, is less well known. There is some vague understanding that the evolution from the dense urban fabric of medieval cities, where almost all daily mobility was on foot, to the vast expansion of modern metropolitan areas with their massive volumes of intraregional traffic would not have been possible without the development of first the railway and in particular the private automobile, which has made every corner of the metropolitan area almost equally suitable as a place to live or work. However, exactly how the development of the transport system influences the location decisions of landlords, investors, firms and households is not clearly understood even by many urban planners.
The recognition that trip and location decisions co-determine each other and that therefore transport and land-use planning needed to be co-ordinated led to the notion of the ‘land-use transport feedback cycle’. The set of relationships implied by this term can be briefly summarised as follows (see Figure 1):
- The distribution of land uses, such as residential, industrial or commercial, over the urban
area determines the locations of human activities such as living, working, shopping, education or leisure.
- The distribution of human activities in space requires spatial interactions or trips in the transport system to overcome the distance between the locations of activities.
- The distribution of infrastructure in the transport system creates opportunities for spatial interactions and can be measured as accessibility.
- The distribution of accessibility in space co-determines location decisions and so results in changes of the land-use system.
The major theoretical approaches to explain this two-way interaction of land use and transport in metropolitan areas include technical theories (urban mobility systems), economic theories (cities as markets) and social theories (society and urban space).
Figure 1. The ‘land-use transport feedback cycle’.
Source: Michael Wegener, Franz Fürst ,Land-Use Transport Interaction:
State of the Art- Dortmund, November 1999
Tuesday, April 1, 2008
BRT Planning Guide
BRT Planning Guide
Distinguishing between accessibility and mobility
Distinguishing between accessibility and mobility
Understanding the distinction between accessibility and mobility is a crticial aspect in creating a sound and sustainable transportation policy.
- ‘Traffic’: in this perspective vehicle movement and speed are beneficial; congestion or inadequate roads are seen as the problem. The old roads-focussed approaches in rural transport could be seen as analogous to a traffic focus.
- ‘Mobility’: in this perspective it is the efficient movement of people and goods that is seen as beneficial or as they key aim of policy. This is much wiser than a traffic focus because at least it helps move attention to more efficient ways of moving people and goods. This would put a high priority on collective modes of transport (eg buses, rail).
- ‘Accessibility’ or an ‘access focus’: In this perspective it is the ability to REACH opportunities that is beneficial, not movement itself. In remote rural contexts gaining access to services, goods and contacts will often require a lot of mobility. However, in many urban contexts accessibility might involve very short trips. And in places like suburban USA policy to enhance accessibility might actually require that we reduce traffic or even reduce the need to travel (or reduce mobility).
In the rural transport context, an example would be non-transport interventions such as efforts to bring water supply and fuel supply to houses (instead of forcing people - especially women - to walk long distances for them). This is an excellent example of an effort to increase accessibility of services without the need to increase mobility.
With an accessibility perspective, both traffic and mobility are obviously still important. But they are seen as ‘means’ not ‘ends in themselves’. Other ways to enhance accessibility would include planning for proximity, improved communications systems, bringing services closer, etc.
Source: Paul Barter in the SUSTRAN mailing list.
