HIMMELI - Heuristic three-level Instrument combining urban Morphology, Mobility, service Environments and Locational Information Morphologically structured agent based simulation model of urban retail system Sanna Iltanen Tampere University of Technology, Finland COST TU1002 WG Meeting Edinburgh 13.10.2011

EVOLUTION OF RETAIL SERVICES MODEL PRINCIPLE The holistic model of the urban retail system which utilises the accessibility measures in multiple ways The model combines approaches of urban morphology, spatial interaction modeling and agent based modeling techniques Model structure: INPUT OUTPUT MODEL retail services EVOLUTION OF RETAIL SERVICES households transportation system

theoretical framework Network city theory Model framework Dupuy ’s triple layered network Households Retail Units / Types (Daily/Specilaty) Road Network

theoretical framework Gabriel Dupuy’s three level network theory defines the overall framework for the model The urban morphological methodologies is exploited to define the retail unit typologies and in handling the infrastructural networks The interaction principles in the model are derived from the tradition of spatial interaction modeling Agent based modeling enables the observation of spatial self-organization of retail units based on local interactions The bottom up approach allows also the observation of emergent phenomena and relates the model to the complex system theory

Model flowchart Initialisation Phase Simulation Phase Input data Get network data & calculate travel cost matrix Get retail unit typology & locations Get household typology & locations Calculate Accessibilities Simulation Phase Calculate utilities for households simulation cycles Update retail unit accounts Remove unprofitable retail units Create new retail units

ACCESSIBILITY IN THE MODEL Simulation Phase ACCESSIBILITY FUNCTIONS TRAVEL COST MATRIX Acc R-R accessibility from retail unit to all other retail units 2. Production & consumption level Acc Hh-R accessibility from household location to retail unit affects to utility 1. Agent level Acc network Accessibility as a network property affects on locations of new retail units 3. Infrastructural level

INDICATORS At current stage the focus is on roadnetwork mean depth of road centre line network (or integration) travel cost in terms of distance (meters) travel cost in terms of time (minutes) The travelcost matrix (of discrete space) enables combination of several accessibility levels (e.g. road network based, public transportation based, walkability based).

input census data of households (grid format database, three income brackets) register database of companies (classification based onNACE Rev.2) road network database or general travel cost matrix

output dynamics: the spatial self-organization of retail system temporal behavior of the system: stable / periodic / chaotic / complex Scenario 1 Scenario 2 Scenario N …

USEFULNESS IN PRACTICE The model increases understanding of the feedback loops and cumulative influence of boundary conditions related to infrastructure, mobility and service typologies The model allows observation of possible development paths of the system as one of the attributes is changed Possible phase transitions in spatial distribution of (retail) services can be anticipated

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