Environment and Planning B: Urban Analytics and City Science

Multiagent systems (MASs) constitute a powerful methodological platform for dealing with the decision-making process underlying individual travel behaviour. A major challenge is the implementation of a strong notion of agency, through the building of agents capable of drawing information from their environment, processing what is important, and engaging in activities. This paper explores this issue. The notion of mental worlds—that is, cognitive entities involving both syntactic and semantic components—is invoked for accounting the way in which individuals understand their environment. A MAS model (CogMob) is illustrated. It has been developed to simulate the application of a palette of cognitive strategies in urban mobility, that is, habitual behaviour: agents choose the most familiar route; learning by instruction: agents secure information about the less congested routes; reasoning: agents select the most convenient route from a set of those previously used; visioning: agents explore a novel route. CogMob has been implemented on a SWARM simulation platform and considers a fictitious urban environment. Some results of its application to simulate the use of the proposed cognitive strategies are compared and discussed briefly. Three (not unexpected) key findings emerged: (1) there is no single most effective strategy, (2) agents can modify their strategies to adapt to changing travel conditions, and (3) an agent's personality matters when the need to modify a strategy arises. It is submitted that these aspects may be of substantial importance in the drafting of transport policies. For example, they suggest that tailoring policies according to the personalities of agents can improve the effectiveness of certain mobility measures. They also indicate that adaptation of an agent's behaviour involves both syntactic and semantic components. Thus, greater attention should be paid to information-sensitive policy measures.

Validation of agent-based models (ABMs) of land-use change is a significant challenge in current spatial-modelling research and application. During the validation process, model performance and accuracy assessment depend mostly on pixel-by-pixel comparisons. However, in urban land-use planning problems the use of vector spatial data to develop ABMs is becoming more necessary. Hence, improved and robust validation approaches are required for vector-based ABMs. This study presents a novel validation approach for an ABM using vector-based geographic information system and Bayesian networks. The approach creates a unique-polygons map and an object-oriented database. Three indicator variables are calculated to assess the probability of agreement. The indicator variables are nodes in a Bayesian network that is used to evaluate the final agreement of each unique polygon. Further, an index of overall agreement is calculated. The approach was applied to a simulation outcome map generated by an existing Bayesian network-based agent-system (BNAS) model. The BNAS model simulation of land-use change for the year 2001 was compared with the actual land-use change for the same year using the proposed validation approach. The results obtained indicate that significant agreement between the maps was achieved. The approach is well suited for validating vector-based ABMs and can be used as an aid in model designs for improved model performance.

Cellular automata (CA) are an effective means of urban-growth simulation. Moreover, the development of a planning support system associated with the theory of artificial intelligence has recently become a new global challenge. In this paper we investigate a geosimulation model using CA based on the geographic information system (GIS) for visualising land-use patterns in urban partitions. Most recent simulation models using CA have been developed in regular grid nets or networks, where adjacent grids or networks in urban space are easily addressed. Our project explores how to utilise an irregular polygon dataset in a GIS database in order to deal with spatial microsimulation. A new concept used in this project takes into account the effects of urban planning, such as land-use zoning and street networks, at the level of parcels and blocks in urban space. Adjacent irregular parcels on both sides of a street are intended targets in the simulation. In this paper, a method of simulating land-use patterns in urban space after the implementation of land-readjustment projects is discussed.

Several attempts have already been made to use telecommunications networks for urban research, but the datasets employed have typically been neither dynamic nor fine grained. Against this research backdrop the mobile phone network offers a compelling compromise between these extremes: it is both highly mobile and yet still localisable in space. Moreover, the mobile phone's enormous and enthusiastic adoption across most socioeconomic strata makes it a uniquely useful tool for conducting large-scale, representative behavioural research. In this paper we attempt to connect telecoms usage data from Telecom Italia Mobile (TIM) to a geography of human activity derived from data on commercial premises advertised through Pagine Gialle, the Italian ‘Yellow Pages’. We then employ eigendecomposition—a process similar to factoring but suitable for this complex dataset—to identify and extract recurring patterns of mobile phone usage. The resulting eigenplaces support the computational and comparative analysis of space through the lens of telecommuniations usage and enhance our understanding of the city as a ‘space of flows’.

New techniques to measure 2D and 3D visibility over urban spaces are presented in this paper. The concept of the isovist, that is, the visible space from a vantage point, could help in providing a quantifiable basis for Lynch's urban analysis, as outlined in his book [Lynch, 1960 The Image of the City (MIT Press, Cambridge, MA)]. We also expand on the concept of 3D isovists and develop a new technique to calculate them on digital elevation models, whereby the same input information can be processed easily in pixel coordinates and in voxel space, that is, a 3D array of urban-visibility measures. The investigation of what we have called the ‘isovisimatrix’ seems to allow a very useful interpretation of visibility from a visual-perception viewpoint. The approach presented here suggests helpful applications for urban design, in particular for predicting the visual impact of new buildings on the physical context and understanding how open spaces may be used by people depending on visibility features.

Spatially associated patterns are often found in geographical phenomena, since nearby entities are often more related than distant ones. Such spatial association also changes over time; hence, the temporal aspect of spatial association needs to be examined using both spatiality and temporality. This paper describes a method of modeling the temporal signatures of spatial association, and thus of grouping similar changes. We employed a Moran scatterplot to assess the local characteristics of a spatial association and then extended it to a time-series Moran scatterplot quadrant signature (MSQS) to capture spatiotemporal changes in regions categorically. We used sequence comparison and data grouping techniques to classify similar regions in terms of the time-series MSQS. We tested the feasibility of the proposed method using a case study of a twenty-four-month (June 2004–May 2006) housing price index for sixty-nine administrative units in the Seoul Metropolitan Area, South Korea.

It has long been argued that the housing market is spatially compartmentalized within a metropolitan area. The argument has important implications for explaining how the housing market works—should the status quo be seen as an equilibrium state? Or if no equilibrium is reached, how do loosely interlaced submarkets function both independently and interdependently? We note that the body of literature has leaned toward testing the distinctiveness of housing submarkets given a priori housing submarkets. However, there seems to be a lack of interest in developing methods for deriving housing submarkets empirically. Fuzzy clustering is well suited to this problem, given that the boundary of housing submarkets is not often sharply delineated. The study applies a fuzzy c-means (FCM) algorithm to identify housing submarkets in the Buffalo–Niagara Falls region. The study is distinct from other FCM applications in three respects. First, we reflect on issues tied to choosing parameters of fuzzy clustering. Second, we introduce overlap measures to characterize the relationship between the clusters produced. Third, we evaluate the performance of fuzzy clustering in terms of hedonic prediction accuracy. Results show that stratified hedonic models predict house price better than a market-wide hedonic model. Fuzzy clustering solutions also yield better prediction, compared with hard clustering.

Besides the urban sprawl of housing, many regions suffer from an employment shift from city centres to the suburbs. A simulation model has been developed that analyses alternative strategies for limiting the suburbanisation of employment. It applies microsimulation by representing single businesses individually. The establishment, growth, decline, closure, and relocation of firms are simulated. The model was implemented in the urban region of Dortmund in Germany. Zoning, transport, and tax-related policies were tested and compared to estimate their likely success in fostering a more sustainable land-use development. The analyses reveal that a regionally coordinated approach would be the most successful policy option for reducing the urban sprawl of employment. Benefits and drawbacks of using microsimulation for business modeling are discussed.

The effect of weather elements on the incidence of different types of crime has been the focus of a number of research studies. However, the detailed geographical dimension of this relationship has been largely ignored. The aim of this paper is to broaden the research on weather and crime to consider the effect of weather parameters on the spatial arrangement of crime within an urban area of the UK. A novel combination of techniques that are capable of both evaluating statistically and visualising geographically the effect of weather variables on the incidence of one type of crime, namely calls for police service for disorder or disturbances, is presented. These techniques are examined in relation to the theories that have traditionally been put forward to explain such trends. We conclude that, in our study area, both temperature and humidity exert significant effects on the spatial patterning of incidents of disorder or disturbances. Rainfall, wind speed, and wind direction were found not to have a significant effect for this type of call for service. More research is needed to see how transferable these findings are to other geographical areas with different climatic regimes.

New Urbanism is often presented as an improvement over conventional suburban development along economic, social, and environmental lines. While the economic and social claims of New Urbanism have been investigated, relatively little work has examined the potential environmental impacts of New Urbanism as compared with conventional forms of suburban development. One of the challenges of studying the environmental impacts of New Urbanism is that it is still too early to evaluate adequately many sites, since most New Urban development is less than a decade old but it often takes several decades for vegetation and related ecological processes to establish. This paper attempts to address the gap in our understanding of New Urban environmental conditions by examining the relationship between residential-parcel vegetation abundance and specific components of residential form across the Greater Toronto Area (Ontario, Canada). While not explicitly comparing New Urban sites with other locations, this analysis illuminates how many New Urban design principles are related to vegetation conditions by focusing on those aspects of residential form that are addressed by New Urbanism—road pattern, neighborhood land use, and site-level characteristics—across a region with heterogeneous form. The results indicate that locations aligned with New Urbanism design principles do not necessarily support more vegetation than those areas based on more conventional suburban patterns, with many design principles having no relationship to vegetation abundance. The paper concludes by examining the planning implications of the results, and outlines future research needed to understand more fully the long-term impact of New Urbanism on local environmental conditions.