Paper presented at the 11th World Conference on Transport Research, University of California at Berkeley, 24-28 June 2007 1 SIMULATING INTERACTIONS BETWEEN LAND USE, TRANSPORT AND ENVIRONMENT Rolf Moeckel*, Björn Schwarze*, Klaus Spiekermann**, Michael Wegener** *Institute of Spatial Planning, University of Dortmund (IRPUD) **Spiekermann & Wegener, Urban and Regional Research (S&W) ABSTRACT The project ILUMASS (Integrated Land-Use Modelling and Transport System Simula- tion) embedded a microscopic dynamic simulation model of urban traffic flows into a comprehensive model system incorporating both changes of land use and the resulting changes in transport demand as well as their environmental impacts. The land use mod- elling is entirely microscopic and includes models of demographic development, resi- dential location, firm life cycles, business relocation and construction of dwellings and non-residential floorspace. To test the land use model the very detailed transport and environment models were temporarily replaced by an aggregate transport model and less detailed environmental impact models. The paper outlines the land use submodels and their integration into the ILUMASS model and presents selected scenario results and concludes with a discussion of the advantages and limits of microsimulation. 1. INTRODUCTION Rising energy prices and growing evidence of the role of greenhouse gas emissions for climate change have renewed the awareness of experts and policy makers for environ- mental issues. However, despite advances in resource efficiency and pollution control, continued growth in affluence leads to ever longer travel distances, energy consumption and greenhouse gas emissions. This has renewed the interest in integrated models of urban land use and transport. There is growing consensus that the negative environ- mental impacts of transport cannot be reduced by transport policies alone, but that they have to be complemented by measures to reduce the need for mobility by promoting higher-density, mixed-use urban forms more suitable for public transport. Urban modellers, have for a long time ignored ecological aspects of the processes simu- lated in their models and have only recently been prompted to redirect their attention from economic to environmental impacts of land use and transport policies. Existing land-use transport (LT) models are being augmented by environmental submodels to become land-use transport environment (LTE) models. However, today there exist no full-scale urban LTE models. The first pioneering efforts of extending LT models to LTE models have concentrated on environmental impacts of land use and transport and have ignored the opposite direction, the impact of environmental variables on land use and transport decisions. However, the quality of the environment of urban locations strongly affects their attractiveness in the eyes of investors, firms and households.