Long-term Impacts of Urban Land-use and Transport Policies: Simulation and Assessment
F Russo, G Musolino, Mediterranea University of Reggio Calabria, IT
The work focuses on long-term impacts of urban land-use and transport policies. Simulations are performed through a land-use transport interaction model, while policies assessment is performed by means of a set of sustainability indicators
Transport systems affect economy and planning of an urban area, conditioning households and firm location choices, production levels, trade patterns, land use. Conversely, socio-economic system affects transport demand.
Starting from the 1990s, some urban Land-Use Transport Interaction (LUTI) models, such as TRANUS (de la Barra, 1989), MEPLAN (Echenique and Hunt, 1993), IRPUD (Wegener, 1998), DELTA (Simmonds, 2000), were developed in literature to simulate long-term dynamics of transport and activities interactions.
They simulate transport and activity systems by means of market mechanisms, where demand and supply interact, providing prices and quantities simultaneously. In the transport model, users behaviour is simulated through demand models which estimate emission, mode, time-of-day and path choices. These choices are driven by utilities, which include transport costs provided by a network model. Demand-supply interaction is simulated through an assignment model, which estimates transport costs and flows on the network. If the available supply (transport facilities and services) is limited, congestion costs arise. In the activity model, population, employment and economic actors behaviour is simulated, through an activity generation model which estimates demand (consumption) levels of activities (population, employment, land, ?.) and an activity location model which simulate where activities supply (production) is located across zones. Location choices are driven by utilities, consisting of a supply price, transport cost and other attributes. Demand-supply interaction leads to the estimation of supply prices and quantities in each zone. Due to supply constrains (e.g. limited available land), a rent can be generated.
The work was carried out in the behalf of a two-years research project, which had the following general objectives: formalization of a LUTI model and description of all components and connections (Russo and Musolino, 2007); model specification and application in an urban area, definition of land use and transport policies; simulation and assessment of their long-term effects.
The paper presents the results of different urban policies simulation and assessment in the town of Reggio Calabria (Italy): land use, transport infrastructure and service, transport regulation and pricing policies. Long-term interactions between transport and activity systems simulation is performed through an urban LUTI model, while policies assessment is performed throught a set of key indicators able to provide disaggregate measures related to the three dimensions of sustainability (environmental, social and economic).
The study area includes the municipality of Reggio Calabria, where the activity system is segmented in sectors to match available census residential and employment location data. Inter-dependencies between activity sectors are simulated through a Social Accounting Matrix (SAM), where some coefficients are fixed (e.g. those connected to employment of economic sectors) and others are price elastic (e.g. those connected to available floorspace consumption).
From inter-zones activity flows, transport demand is estimated through a three-step system of demand models that simulate emission, mode and path choices. Transport supply has two available transport modes: private and transit. The supply model for private modes is a congested network model, while transit services are represented through a line-based not-congested network model.
Several land use and transport policies are simulated and compared with a reference scenario and their long-term effects are assessed through the estimation of a set of sustainability indicators.
The paper will be articulated in three sections. The first describes the system of models for simulation of land-use and transport interactions. The second illustrates the results of policies definition, simulation and assessment. The last concludes with considerations about successful policies to enhance the long-term sustainability of an urban area.
de la Barra T. (1989). Integrated land use and transport modelling. Decision chains and hierarchies. Cambridge University Press.
Echenique M., Hunt J.D. (1993). Experiences in the application of the MEPLAN framework for land use and transport interaction modelling. Proceeding of the 4th National Conference on the Application of Transportation Planning Methods. Daytona Beach, Florida. USA.
Russo F., Musolino G. (2007). Urban land-use transport interaction modelling: state of the art and applications. In Brebbia C.A. (ed.), XXIII Urban Transport, WIT Press, pp. 525-534.
Simmonds D. (2000). The objectives and design of a new land use modelling package: DELTA Technical Report. David Simmonds Consultancy. Cambridge.
Wegener M. (1998). The IRPUD model: overview. http://irpud.raumplanung. uni-dortmund.de/irpud/pro/mod/mod_e.htm.
Association for European Transport