S.T.I.T.: a System of Mathematical Models for the Simulation of Land-use and Transport Interactions
A Nuzzolo, P Coppola, University of Rome Tor Vergata, IT
In order to evaluate long-term impacts on travel demand due to changes in transport supply, it is not possible to disregard the effects that such changes have on ?land-use? and, indirectly, on travel demand. The problem of simulating such effects has been tackled by different modelling approaches, labelled in literature as ?integrated land-use/transport models? (Wilson, 1997).
The term ?land-use? covers a variety of topics including urban activities such as residing, and working, the outcomes of market processes such as property or land values, and so on. All these topics can be influenced by changes in transport supply, and may affect travel demand.
In this paper the focus is on the impacts that transport supply has on the distribution of urban activity locations (e.g. residents, services, commerce,?), and, consequentially, on travel demand (e.g. spatial distribution, modal split and so on). Emphasis is given to how zone accessibility impacts on residential and economic activities and on the competition among urban activities for the acquisition of urban spaces (mainly residents and other economic activities).
The analysis is carried on by means of models dealing with the complex interactions between transportation and urban activities. The overall modelling framework consists of three integrated sub-models:
· the Travel Demand sub-model, which, given the land-use pattern and the level of service of transportation system, simulates individual travel choices (such as tour frequency, trip distribution and mode choice) and allows to estimate the generalised travel cost between (o,d) pairs as well as zonal accessibility;
· the Residential Location sub-model which, given the generalised travel cost, the economic activities pattern and the housing market, simulates the residential location choice of each worker residing in the study area;
· the Activity Location sub-model which, given the accessibility of each zone and the residential location pattern estimates the amount of socio-economic activities located in each zone.
Individual choices of residential and activity location are simulated under the framework of maximum utility principles. The interaction between different individuals (i.e. resident, firms,?) is here simulated through a static (or equilibrium) approach. This approach seems more suitable for practical applications since equilibrium models are easier to be calibrated and implemented, with respect to more complex dynamic modelling framework.
The above models system has been applied to the urban area of Rome in order to predict the land use and the travel demand long-term variations, induced by changes in transport supply system. The results of such applications are discussed in the paper and compared with those carried out by means of traditional four-stages demand model calibrated on the same urban areas.
Association for European Transport