The Impacts of Urban Densification on the Supply and Demand for Transport
Ying Jin, University Of Cambridge, Ian Williams, University Of Cambridge
In recent decades, strong growth has re-emerged in the inner areas of many large cities. We examine the empirical evidence on how urban densification has impacted on the demand and supply for transport in these cities and how transport models should be structured so as to represent the complex supply and demand interactions within them.
In the UK and Ireland in recent decades, strong population and employment growth has re-emerged in the inner areas of many of the more dynamic large cities. To support sustainability planning policy has encouraged this urban densification. We examine the empirical evidence on how urban densification has impacted on the demand and supply for transport in these cities.
We use a variety of national and city-specific data sources to examine how densification influences the evolution of the determinants of travel demand, including:
• the age, sex and socio-economic characteristics of urban residents;
• the travel demands of these residents i6n terms of mode and travel distance;
• levels of household car-ownership and where its trend is to decrease rather than increase;
• employment structure and the changes in commuter patterns to these workplaces.
We also examine how urban densification influences the costs and characteristics of the supply of travel across the modes. This includes analysing the extent to which increased travel demands from pedestrians, cyclists and bus users may lead to major reductions in the availability of road capacity for cars and so to increased road congestion, which in turn generates a change in the balance of attractiveness between cars and these alternative modes. We consider the ability of higher urban densities to support improved bus services through higher frequencies and better load factors, as well as supporting light rail or metro investments.
We discuss the extent to which current conventional transport modelling approaches contain appropriate structures to represent the complex supply and demand interactions across modes within these dense urban areas. This is linked to the need for land use models that could provide improved support for the travel demand estimation procedures.
Finally we consider the extent to which densification leads in practice to the types of transport sustainability gains that were envisaged.
Association for European Transport