Interaction of Transport, settlement structure and economy

Economic development, settlement structures and transport infrastructure are closely interrelated. Current decision support approaches in the field of transport policy, however, widely neglect these long-term interactions. The main aim of this project is to highlight, if and to what extent `wider` effects of transport policies remain unaccounted for in this way. The project comprises `cognitive` (knowledge about long-term developments) and normative aspects (integration of results in decision support approaches). We will address the former using a formalized modelling approach - in line with scientific consensus. We will further develop the cause-effect model of the existing land-useransport model MARS. A comparison of state-of- the-art theoretical approaches, such as `New Economic Geography`, and empirical studies for the specific study region Austria will provide the basis to do so. We will apply the further developed and fully quantified model to 2-3 case studies, including the emerging `twin city` region Vienna-Bratislava. The analysis will cover a comprehensive set of measures taken from transport, land- use and fiscal policies. In a second step we analyze how to exploit the model results in practical decision support making special allowance for issues of sustainable development. We will exemplarily highlight differences to current assessment methodologies based on the assumption of inflexible spatial structure for the case studies and discuss their implications for transport policy making. Finally, the project findings will highlight how transport policy can complement general economic policy in promoting sustainable economic development.

Transport and economic development are interrelated in various ways. While transport textbooks hold that transport is an activity derived from the dispersal of economic activity in space, the reverse causality is equally significant: Transport shapes the (economic) landscape as it determines the relative accessibility of locations and favours certain ways of doing business. This in turn has implications for transport. Long term-oriented transport policies should account for these linkages and be coordinated with related fields such as regional, environmental and fiscal policy. Applied formal models can contribute to the process in assessing the relative importance of (some of) the mechanisms. The project`s point of departure for this project is the observation that the state of the practice in transport modelling adopts a narrower scope, focussing on issues within the transport sector itself. To address this, the research approach was to extend the scope of the existing urban land-useransport interaction (LUTI) model MARS in substantive and spatial terms. LUTI models are established in transport and urban planning and address the complexity outlined above by explicitly modelling changes in land-use (or location) while their links to (spatial) economic theory are rather weak. To improve on the theoretical foundation of MARS, we carried out a comprehensive literature review covering fields such as regional science, urban & regional economics as well as more systems science-/mathematics- oriented literature. Two approaches we particularly focused on were the `new economic geography` with its roots in trade theory and regional economics and the self-organising city/region models by systems scientist P. Allen. Based on the review we translated the models into the system dynamics framework, developing stylized prototype models. Especially in the case of the neoclassical economics-based `new economic geography` this is quite an achievement given the marked divide between general equilibrium and system dynamics modelling. Our stylized models show that both approaches analyzed produce surprisingly similar relations between transport costs (in a broad sense) and spatial economic structures. In particular, both exhibit endogenous agglomeration following a decline in transport costs. Our work, however, also highlighted the intricacies of truly integrated multi-disciplinary modelling, which, in the end, prevented us from developing applied, large-scale versions of the theoretical models. In parallel, we developed a MARS model for Austria, making more evolutionary model improvements on an ad- hoc basis. This is innovative in that few LUTI models exist in such a polycentric, national-level setting. The model improvements address substantial issues that set the national level apart from urban settings, including the more substantial role of space in the migration and the much wider range of distances. We addressed those in explicitly distance-sensitive migration models and a structure that disaggregates individual zones into distance classes. Preliminary policy simulations show that, even when accounting for land-use changes, transport is relatively insensitive to changes in transport prices, whether they follow from intentional policies or from exogenous developments such as rising fossil fuel prices. An obvious field of application for the research carried out within this project lies in the preparation of `official` long term transport projections used in strategic policy making and various other purposes. Even though specific tools have yet to be developed, our work has at the very least highlighted the feasibility of a more holistic approach to model-based transport analysis.