Journal Articles (peer-reviewed) by Jorge Gil
Networks and Spatial Economics, 2018
Over the last fifty years, research into street networks has gained prominence with a rapidly gro... more Over the last fifty years, research into street networks has gained prominence with a rapidly growing number of studies across disparate disciplines. These studies investigate a wide range of phenomena using a wealth of data and diverse analytical techniques. Starting within the fields of transport or infrastructure engineering, street networks have commonly been treated as sets of more or less homogeneous linear elements, connecting locations and intersecting at junctions. This view is commonly represented as a graph, which provides a common and rigorous formalisation accessible across disciplines and is particularly well-suited for problems such as flow optimisation and routing. Street networks are, however, complex objects of investigation and the way we model and then represent them as graphs has fundamental effects on the outcomes of a study. Many approaches to modelling street networks have been proposed, each lending itself to different analyses and supporting insights into diverse aspects of the urban system. Yet, this plurality and the relation between different models remains relatively obscure and unexplored. The motivations for adopting a given model of the network are also not always clear and often seem to follow disciplinary traditions. This paper provides an overview of key street network models and the prima facie merits of pertinent alternative approaches. It suggests greater attention to consistent use of terms and concepts, of graph representations and practical applications, and concludes with suggestions for possible ways forward.
Built Environment, 2020
The digitalization of the urban development process is driven by the need for informed, evidence-... more The digitalization of the urban development process is driven by the need for informed, evidence-based, collaborative and participative urban planning and decision-making, epitomized in the concept of Smart Cities. This digital transformation is enabled by information technology developments in fields such as 3D city models, Digital Twins, Urban Analytics and Informatics, Geographic Information Systems (GIS), and Planning Support Systems (PSS). In this context, City Information Modelling (CIM) has recently emerged as a concept related to these various technological driving forces.
In this article, we review the state of the art of CIM (definitions and applications) in the academic literature and propose a definition and a general conceptual framework. By highlighting how the different disciplines are related to each other within this conceptual framework, we offer a context for transdisciplinary work, and focus on integration challenges, for research and development, both in academia and industry. This will contribute to moving forward the debate on digitalization of the built environment development process in the field of Smart Cities.
Transportation Research Part D Transport and Environment, 2020
Transport infrastructure can create efficient connections in traffic systems, yet it can also cre... more Transport infrastructure can create efficient connections in traffic systems, yet it can also create barriers to movement on a local scale. In transport infrastructure projects there is a need for methods to quantify these barrier effects – also called severance – to assess their impacts on social inclusion, health and viability of businesses. This paper proposes four local accessibility indicators to measure direct barrier effects: Travel time, Choice, Catchment and Service efficiency. The indicators are tested in a case study where the consequences of placing a motorway and a railway in tunnels are assessed. The results show how local accessibility is affected in non-linear patterns. The paper contributes to accessibility literature by introducing direct barrier effects as an applied case of local accessibility, and demonstrates the potential of those indicators to quantify barrier effects. Finally, it offers accessibility as a theoretical framework for further developing theories on barrier effects.
Environment and Planning B: Urban Analytics and City Science, Dec 22, 2017
We propose a GIS-based method to enable the understanding of how global street-network properties... more We propose a GIS-based method to enable the understanding of how global street-network properties emerge from the temporal accumulation of individual street-network increments. The method entails the adoption of quantitative descriptions of individual street-patterns and of classification algorithms, in order to obtain numerically defined typomorphologies, which may then be statistically associated with the numerical outputs of street-network analysis. We apply the method to the case of Oporto Metropolitan Area, whose development we observed over 60 years. We isolate each increment of development entailing the creation of new streets (4208 objects), we quantify the morphology of their street-layouts, and we classify them into typomorphologies with clustering techniques. Through the investigation of the temporal and spatial frequencies of those typomorphologies, we assess their impacts on the street-networks of a set of selected civil-parishes of the metropolitan region, demonstrating that different typomorphological frequencies result in also different global street-network properties. We conclude by summarising the advantages of the method to generic urban morphological research and by suggesting that it may also contribute to inform bottom-up metropolitan spatial planning.
With increased interest in the use of network analysis to study the urban and regional environmen... more With increased interest in the use of network analysis to study the urban and regional environment, it is important to understand the sensitivity of centrality analysis results to the so-called “edge effect”. Most street network models have artificial boundaries, and there are principles that can be applied to minimise or eliminate the effect of the boundary condition. However, the extent of this impact has not been systematically studied and remains little understood. In this article we present an empirical study on the impact of different network model boundaries on the results of closeness and betweenness centrality analysis of street networks. The results demonstrate that the centrality measures are affected differently by the edge effect, and that the same centrality measure is affected differently depending on the type of network distance used. These results highlight the importance, in any study of street networks, of defining the network's boundary in a way that is relevant to the research question, and of selecting appropriate analysis parameters and statistics.
The present policy objective of sustainable urban development has created the need for methods of... more The present policy objective of sustainable urban development has created the need for methods of ex ante evaluation of local area development projects that assess the contribution of alternative solutions to the general sustainability goals. For this reason, we have seen the evolution of building energy assessment methods into sustainable neighbourhood assessment methods that are more integrative and contextual to accommodate the complexities of the urban scale. This article identifies and reviews a selection of sustainable urban development evaluation tools that are applicable to the early stages of urban design projects, to provide a clearer picture of the state of play to those needing to use such tools and those wanting to develop new ones. The review follows an analytical framework covering the format, structure, content and output of the tools, based on the recommendations of planning evaluation theory and the requirements of urban design practice. Since no single tool stands out from the review, the choice is not simple and there is scope both to further improve existing tools and develop new ones. The paper concludes proposing a strategy for the development of robust and compatible sustainable urban development evaluation methods based on four goals: collaboration, compatibility, customisation and combination.
, Oct 2014
This article proposes urban network models as instruments to measure urban form, structure and fu... more This article proposes urban network models as instruments to measure urban form, structure and function indicators for the assessment of the sustainable mobility of urban areas, thanks to their capacity to describe the detail of a local environment in the context of a wider city-region. Drawing from the features of existing street network models that offer disaggregate, scalable and relational analysis of the spatial configuration of urban areas, it presents a multi-modal urban network (MMUN) model that describes an urban environment using three systems — private transport (i.e. car, bicycle and pedestrian), public transport (i.e. rail, tram, metro and bus), and land use. This model offers a unifying framework that allows the use of a range of analysis metrics and conceptions of distance (i.e. physical, topological and cognitive), and aims to be simple and applicable in practice. An implementation of the MMUN is created for the Randstad city- region in the Netherlands. This is analyzed with network centrality measures in a series of experiments, testing its performance against empirical data. The experiments yield conclusions regarding the use of different distance parameters, the choice of network centrality metrics, and the relevant combinations of multi-modal layers to describe the structure and configuration of a city-region.
The use of typomorphology as a means of understanding urban areas has a long tradition amongst ac... more The use of typomorphology as a means of understanding urban areas has a long tradition amongst academics but the reach of these methods into urban design practice has been limited. In this paper we present a method to support the description and prescription of urban form that is contextsensitive, multi-dimensional, systematic, exploratory, and quantitative, thus facilitating the application of urban typomorphology to planning practice. At the core of the proposed method is the k-means statistical clustering technique to produce objective classifications from the large complex data sets typical of urban environments. Block and street types were studied as a test case and a context-sensitive sample of types that correspond to two different neighbourhoods were identified. This method is suitable to support the identification, understanding and description of emerging urban forms that do not fall into standard classifications. The method can support larger urban form studies through consistent application of the procedures to different sites. The quantitative nature of its output lends itself to integration with other systematic procedures related to the research, analysis, planning and design of urban areas.
ISSN 1302-8324, 2014
The sustainable mobility vision for city-regions proposes a more integrated and ‘seamless’ multi-... more The sustainable mobility vision for city-regions proposes a more integrated and ‘seamless’ multi-modal public transport system around quality neighbourhoods, shifting mobility to soft transportation modes and to public transport at various scales. Existing models of sustainable urban form address this challenge focusing on the location, density and diversity of activities, on the composition of the street layout, and on the presence of transport nodes and the quality of the public transport service. In order to better understand the relation between urban form and sustainable mobility patterns we propose to additionally measure the structure of mobility networks, including network proximity, density and accessibility, for different transport modes. The analysis of a multi-modal network model of the Randstad region in the Netherlands, integrating private and public transport infrastructure networks and land use information, reveals the structures of modality in the city-region. These structures are used to identify a typology of ‘modality environments’ that tested against travel survey data demonstrate support for specific patterns of mobility, i.e. walking, cycling, car use, local and regional transit. This classification can contribute to a new urban form based method for evaluating the potential of neighbourhoods for sustainable mobility.
Architecture and Modern Information Technologies, 2 (11), 2010
Urban planning and design has a considerable impact on the economic performance of cities and reg... more Urban planning and design has a considerable impact on the economic performance of cities and regions. It is a complex process that extends for a long period and involves many participants. The lack of integrated tools to support this process hampers the ability to maximize the response of plans to contextual conditions while using the least resources. This paper describes research that aims to develop such a tool, integrating formulation, generation, and evaluation capabilities. It is focused on the generation module which relies on the encoding of Urban Induction Patterns (UIP) using shape grammars. A grammar for the extension plan of the city of Praia is presented as one of the case studies used to support UIP definition and illustrate its application. The paper also discusses how the proposed tool can be used for developing and monitoring urban plans.
Book Chapters (peer-reviewed) by Jorge Gil
The Mathematics of Urban Morphology, 2019
Cities are complex, perhaps one of the most complex kinds of structure created by humans. Some ci... more Cities are complex, perhaps one of the most complex kinds of structure created by humans. Some cities have been planned to a large extent while others have grown organically. The outcome of planning and growth processes is the diverse morphological built form and street patterns observed in cities today. So far, in urban planning and history research, cities are classified as planned or organic, largely based on the visual assessment of their urban morphology. To understand cities and their characteristics, it is necessary to develop methods that quantitatively describe these characteristics and enable objective comparisons between cities. Using graph representations of the street network of cities, it is possible to calculate measures that seem to exhibit patterns with scale-free properties (Jiang in Phys A Stat Mech Appl 384(2):647-655, 2007). And thanks to progress in the field of complexity studies, it is also possible to test if and to what extent the distribution of a measure in a collection of elements fits a power law distribution (Clauset et al. in SIAM Rev 51:43, 2009). In this chapter, we show that the degree distribution of a city's street network seems to fit a power law distribution for cities that are considered to have mostly grown organically. On the other hand, cities that are planned to a large extent do not exhibit such a good fit. This result is relevant since a power law distribution is a signature of multiplicative growth processes. Furthermore, the result of the quantitative classification method correlates well with the results of earlier qualitative morphological classifications of cities.
OpenStreetMap in GIScience: Experiences, Research, Applications, 2015
This chapter presents the process of building a multimodal urban net- work model using Volunteere... more This chapter presents the process of building a multimodal urban net- work model using Volunteered Geographic Information (VGI) and in particular OpenStreetMap (OSM). The spatial data model design adopts a level of simplifi- cation that is adequate to OSM data availability and quality, and suitable to the measurement of the sustainable accessibility of urban neighborhoods and city- regions. The urban network model connects a private transport system (i.e. pedes- trian, bicycle, car), a public transport system (i.e. rail, metro, tram and bus) and a land use system (i.e. building land use units). Various algorithmic procedures have been developed to produce the network model, supporting the reproducibility of the process and addressing the challenges of using OSM data for this purpose. While OSM demonstrates great potential for urban analysis, thanks to the detail of its attributes and its open and universal coverage, there is still some way to go to provide the data quality and consistency required for detailed operational urban models.
Digital Urban Modeling and Simulation, 2012
Urban planning and design have a considerable impact on the economic performance of cities and on... more Urban planning and design have a considerable impact on the economic performance of cities and on the quality of life of the population. Efficiency at this level is hampered by the lack of integrated instruments for formulating, generating, and evaluating urban plans. This chapter describes the theoretical foundations of a research project, called City Induction, aimed at the creation of a model for the development of such an instrument, departing from existing theories, which are integrated through a discursive grammar. The proposed model is composed of three sub-models: (1) a model for formulating urban programs from the analysis and interpretation of the context, based on Alexander’s pattern language; (2) a model for generating urban plans that match the program, based on Stiny’s shape and description grammars; and (3) a model for evaluating urban plans, that can be used for analyzing, comparing and ranking alternative solutions, departing from Hillier’s space syntax. A common urban space ontology guarantees the syntactic and semantic interoperability among the three sub-models. This ontology will be used to structure and codify information into a Geographic Information System (GIS), which will be the kernel for the computer implementation of the larger model. A CAD system is used to construct 3D models from contextual information stored in the GIS. In short, following Stiny and March’s design machines concept, the goal is to create an urban design machine that is able to produce flexible urban plans at the site planning level.
Books by Jorge Gil
A+BE | Architecture and the Built Environment, Feb 2016
This thesis proposes a framework for evaluating the mobility potential and performance of urban a... more This thesis proposes a framework for evaluating the mobility potential and performance of urban areas in the city region, as an instrument to support urban development that contributes positively to regional sustainable mobility objectives. The research takes a quantitative approach, modelling and measuring the characteristics of a city-region and of its individual urban areas, in terms of travel patterns and socio- economic characteristics of the resident population, and in terms of built environment characteristics. It then explores how the built environment defines the affordances of urban areas for travelling by particular modes of transport, i.e. its walk-ability, cycle- ability, drive-ability and transit-ability, by developing a typology of what I call their ‘urban modality’. And finally the work combines this typology with the socio-economic characteristics of urban areas to determine their sustainable mobility potential and performance. It focuses on the case of the Randstad region of the Netherlands and its VINEX neighbourhoods, which are an emblematic example of new urban areas created under a policy programme with sustainable mobility objectives.
A key stance in this work is the understanding that the location of an urban area
in the region can be indicative of its population’s travel patterns, because the built environment (infrastructural) and socio-economic characteristics are interrelated
and present strong regional spatial patterns. What types of urban areas support sustainable travel patterns, and what are their spatial characteristics? How do new neighbourhoods compare to the best performing urban areas, and to other areas of the same ‘modality’ type? These are some of the questions addressed in this study. There are two main contributions of this research: the methods for building and analysing integrated multimodal network models, and the framework for contextual performance evaluation using urban area typologies.
The integrated multimodal network model combines the various mobility infrastructure networks and the buildings’ land use to create a detailed description of the region, using open spatial data and open source Geographic Information Systems (GIS) technologies. The network model’s spatial analysis covers local urban form indicators, such as street layout, network density and land use mix, as well as regional indicators of multimodal accessibility and network configuration (its structure), to give a holistic profile of urban areas across modes and scales of travel.
The analysis results go through exploratory data mining and classification procedures to identify urban form typologies of urban areas. It is shown that there is a relation between this ‘urban modality’ of urban areas and the travel patterns of their residents, measured as a set of sustainable mobility indicators related to mode share and distance travelled. For this reason, ‘urban modality’ offers the possibility for ex-ante evaluation of sustainable mobility potential of planned urban areas. Furthermore, when combined with the socio-economic profile of the resident population, ‘urban modality’ defines a context for the ex-post evaluation of sustainable mobility performance of existing urban areas.
The evaluation of suburban areas together with the more central historical urban areas gives invariably a high score in sustainable travel to the central areas, and rates the suburban areas negatively. On the other hand, the evaluation of sustainable mobility performance in the context of suburban areas of the same type allows the finer distinction of underperformers that have scope for improvement, and overachievers that provide examples of (relative) success. This contextual evaluation can become
a decision support instrument for “hard” and “soft” planning measures involving sustainable mobility targets.
Applying this method to the set of VINEX neighbourhoods of the Randstad leads to the conclusion that despite being planned following the same policy objectives, the neighbourhoods have different types of ‘urban modality’, thus present different levels of sustainable mobility potential. Neighbourhoods identified as underperformers within their context can be targeted for soft measures related to transport services, technology and individual attitudes to travel, to fulfil the potential of their ‘urban modality’ type. However, if this potential is not deemed satisfactory or if they already overachieve, only by retrofitting a set of infrastructure and land use characteristics will lead to a different ‘urban modality’ type, and a change in potential. Such a change can be lengthy, costly and sometimes impossible to implement ex-post.
The thesis is based on a collection of published articles in peer-reviewed academic publications, with the first and last chapters providing an overview of the research and of its findings, and defining the main narrative thread.
Conference Articles (peer-reviewed) by Jorge Gil
Angular segment analysis is one of the most fundamental analyses in space syntax practice that he... more Angular segment analysis is one of the most fundamental analyses in space syntax practice that helps understand movement, land-use and other socioeconomic patterns. It was initially applied in axial segment maps and later was used in road centre line maps as an attempt to overcome the 'segment problem' (Turner, 2005). Furthermore, the growing need to examine large urban systems has led to the wide use of road centre line maps instead of the previously hand-drawn axial maps. However, this transition to such datasets has lacked systematic studies on what is required to convert a road centre line map into a segment map, in order to produce reliable results of the angular segment analysis. To date, no consensual methodology has been developed within the space syntax community. This paper attempts to clarify what a road centre line segment represents spatially and suggests principles and rules to simplify a road centre line map to a segment map. Based on previous experience, the simplification mostly relies on the following two principles: reducing the number of nodes in the dual graph representation of a street network; optimising the angular change between adjacent nodes of the dual graph when space allows it. In addition to the above general principles, we discuss rules for special and complex cases, e.g. roundabouts, underpasses, bridges etc. To evaluate these rules and principles comparisons are carried out between traditional axial and RCL unsimplified and simplified segment maps, to develop a good understanding of how changes in dual graph representation of a street network can affect space syntax measure of 'choice'. Correlations of angular segment choice values are performed in order to evaluate which simplification technique can approximate better the axial representation of actual human activity. The results show that using a raw road centre line data set raises several inconsistencies in the analysis results, and the progressive application of the different simplification techniques brings these results closer to those of a traditional axial segment map, and thus to a better representation of socioeconomic activity. The purpose of simplification is to minimise inconsistencies to ensure maximum accuracy in the results of angular segment analysis.
This paper reviews an idea of vital local high-street places with their walking spaces and econom... more This paper reviews an idea of vital local high-street places with their walking spaces and economies founded in interfaces between neighbourhood and city (between walking and public transport/bicycle movement infrastructures). It then extends this idea to higher scales, considering interfaces between city and region, which have already been theorised as 'mobility environments' (Bertolini & Dijst 2003) focusing on places and modal transfer points in new regional cities of high mobility. High-streets and mobility environments are both central places and our way of describing them suggests a new definition of central places as interfaces between normative (but also technically-infrastructually supported) political spaces (neighbourhood, city and region). It also clarifies the role of scale in place theory and we will deal with this in a following paper. Here we introduce ideas of 'modality places' and 'modality environments'. The 'modality environment' is concerned with areal and network transportation forms in whole fabrics and resulting conditions of sustainability and urbanity. Modality environments are understood in terms of transportation networks and the social and functional factors (like sustainability and urbanity) they produce. Modality environments are seen as lived environments built around movement infrastructure grids that distribute everyday urban functions. Ideally modality environments would be simple clear grids that distribute all or close to all the functions of everyday life so that a walking grid or a bicycle grid that gets adults to work, their children to school and includes shopping and recreation would be walking or bicycle modality environments. They would be expected to have high levels of direct visibility-legibility in the way urban elements present themselves to a mobile community. Modality environments would also include the central places (like high-streets or mobility environments like stations) at which people would transfer to other modality environments.. We will use a notion of 'movement culture' to indicate the convergence of land uses and mobile communities mediated in information-rich networks. We are concerned first with how modality environments (for cycling or walking for example) may afford more sustainable lifestyles. We are concerned in addition with the ways they can be designed to include central places as zones of urbanity and vitality and as socially and culturally mixed centres. We start not with a principle of accessibility of/from nodes in an extensive space but with the idea that particular social and political territories (communities and polities) are already articulations of distinct modality environments. We demonstrate using the case of the Amsterdam metropolitan area.
For numerous reasons related to energy demand, emissions, public health as well as liveable and a... more For numerous reasons related to energy demand, emissions, public health as well as liveable and attractive cities, a frequently stated aim in contemporary discussions on urban development is to increase amount and modal share of bicycling. In recent years, space syntax based methods have shown to be useful for providing informed premises for these discussions. Combining space syntax analyses with data on locations of residents, workplaces and destinations opens the door not only for predictive modelling of route choice preferences but also the potential amount of bicycling along routes. Building on previous research, the research presented in this paper develops space syntax based measures expected to capture bicycling and evaluates these measures by comparing the analyses with empirical data from studies carried out in cooperation with the City of Gothenburg. Among the variables considered essential for bicycling and included in our GIS model are: the slope and curvature of routes, the width and surface type of bicycle lanes and the kind and amount of traffic along the route for modelling bicycling flow potentials is a measure termed origin-destination betweenness (OD-betweenness) is used and tested, examining different combinations of variables and threshold distances.
The empirical data consists of gate counts of bicycle traffic and detailed GPS-tracks mapping actual bicycling speeds of ca. 900 trips along a selection of bicycle routes. Using multiple regression analysis to model speed data, eight variables were found significant. In addition to slope and curvature of routes, the significant variables relate to proximity to traffic signals, degree of separation from pedestrians, density of entrances along the routes and quality of paving of the cycle lane.
Concerning bicycling flow potentials, the most significant variables in the multiple regression model were: OD-betweenness within 5km, segment angular integration within 10km, density of residents and people at work (students included) within 1 km and network betweenness within 3km.
Based on the results of the current project, a proposal for further research is to elaborate on the OD-betweenness analyses by including speeds and preferably traffic safety in the betweenness measure. By using time along segments instead of metric length for defining the analysis threshold (radius), it should be possible to have a new and improved generation of space syntax based accessibility analyses for bicycling studies. A working name for such a measure is “least impedance origin destination betweenness”.
Proceedings of the 11th Space Syntax Symposium, 2017
Cities are complex, perhaps one of the most complex kinds of structure created by humans. Some ci... more Cities are complex, perhaps one of the most complex kinds of structure created by humans. Some cities have been planned top-down to a large extent while others have grown organically on their own. The outcome of these planning and growth processes are the various morphological building and street patterns seen in cities. There are strong reasons to believe that the street system in a city has a crucial effect on land use and building development (Hillier, 1996). It is therefore essential to understand the complex street networks in our cities. This is not only to categorize cities but also to be able to switch-over our transport system towards a higher degree of sustainability. Despite extensive research in the fields of urban planning and urban history, there are still very few consistent ways of quantitatively describing and classifying cities. The perspectives used in research so far have mainly categorized them based on visual judgements of their morphology (Kostof & Tobias, 1991). It is problematic that classifications are mainly based on subjective judgement and lack a quantitative measure. To understand cities and their characteristics, it is necessary to find methods and measures that can describe these characteristics and also be suitable for comparisons between cities. By using space syntax methods, it is possible to find measures and properties of the cities' street networks, which sometimes seems to exhibit patterns with scale free properties (Jiang, 2007). Thanks to recent progress in the field of complexity studies, it is now also possible to test if and to which degree a network has scale free properties. One commonly used approach is to test whether the distribution of a certain property in a collection of elements fit a power law distribution(Clauset et al., 2009). The results of this study show that the degree distribution for a city's street network seems to fit a power law for cities grown organically. On the other hand, cities that are planned to a large extent do not have that good fit. This result seems sound, since a distribution that fits a power law is a signature of a multiplicative growth processes. Another interesting finding following this result, is that this way of quantitatively classifying cities seems to correlate well with earlier attempts of qualitative morphological classification.
Proceedings of the 11th Space Syntax Symposium, 2017
It has been argued that different urban configurations-planned vs. organic, treelike vs. grid lik... more It has been argued that different urban configurations-planned vs. organic, treelike vs. grid like-perform differently when it comes to the intensity and distribution of pedestrian flows, built density and land uses. However, definitions of urban configurations are often rather abstract, ill-defined and at worse end in fixed stereotypes hiding underlying spatial complexity. Recent publications define morphological typologies based on quantitative variables (e.g. Barthelemy, 2015; Serra, 2013a; Gil et al., 2012; Berghauser Pont and Haupt, 2010) and solve some of these shortcomings. These approaches contribute to the discussion of types in two ways: firstly, they allow for the definition of types based on multiple variables in a precise and repeattable manner, enabling the study of large samples and the comparison between both cities and regions; secondly, they frame design choices in terms of types without being fixed and so open up for design explorations where the relation between the variables can be challenged to propose new types. This paper explores the typologies defined by Serra (2013a) and Berghauser Pont and Haupt (2010) further, as these target two of the most important morphological entities of urban form, namely the street network and the building structure. The purpose is to gain a better understanding of how types are composed and distributed within and across different cities. The method is based on GIS and statistical modeling of four cities to allow for a comparative analysis of four cities: Amsterdam, London, Stockholm and Gothenburg. For the street network, we process the Road-Centre-line maps to obtain a clean network model, then run segment angular analysis to calculate the space syntax measures of betweenness at different metric radii, defining the " centrality palimpsest " (Serra, 2013a). For the building structure, we process elevation data to obtain building height, then run accessible density analysis for all building density metrics (FSI, GSI, OSR, L) using the Place Syntax Tool (Berghauser Pont and Marcus, 2014). The street and building types are defined using cluster analysis (unsupervised classification), following a similar approach to Serra (2013a). The result is a typology of street (´paths´) and building types (´places´), with different profiles of centrality and density across scales. The spatial distribution and frequency of these types across the four cities gives an objective summary of their spatial structure, identifying common as well as unique traits.
Proceedings of the 10th International Space Syntax Symposium, Jul 2015
With the growth of interest in the use of spatial network analysis to study the urban and regiona... more With the growth of interest in the use of spatial network analysis to study the urban and regional environment, it is important to understand the sensitivity of the centrality analysis results to the so-called “edge effect”. Most spatial network models have artificial boundaries, and there are some principles that can be applied to minimise or eliminate this effect. However, the extent of its impact has not been systematically studied and remains little understood. In this article we present an empirical study on the impact of different network model boundaries on the results of closeness and betweenness centrality analysis of a road network. The results demonstrate that the centrality measures are affected differently by the “edge effect”, and that the same centrality measure is affected differently depending on the type of distance used. These results highlight the importance, in any study using spatial networks, of correctly defining the network’s boundary in a form that is relevant to the research question, and selecting appropriate analysis parameters and statistics.
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Journal Articles (peer-reviewed) by Jorge Gil
In this article, we review the state of the art of CIM (definitions and applications) in the academic literature and propose a definition and a general conceptual framework. By highlighting how the different disciplines are related to each other within this conceptual framework, we offer a context for transdisciplinary work, and focus on integration challenges, for research and development, both in academia and industry. This will contribute to moving forward the debate on digitalization of the built environment development process in the field of Smart Cities.
Book Chapters (peer-reviewed) by Jorge Gil
Books by Jorge Gil
A key stance in this work is the understanding that the location of an urban area
in the region can be indicative of its population’s travel patterns, because the built environment (infrastructural) and socio-economic characteristics are interrelated
and present strong regional spatial patterns. What types of urban areas support sustainable travel patterns, and what are their spatial characteristics? How do new neighbourhoods compare to the best performing urban areas, and to other areas of the same ‘modality’ type? These are some of the questions addressed in this study. There are two main contributions of this research: the methods for building and analysing integrated multimodal network models, and the framework for contextual performance evaluation using urban area typologies.
The integrated multimodal network model combines the various mobility infrastructure networks and the buildings’ land use to create a detailed description of the region, using open spatial data and open source Geographic Information Systems (GIS) technologies. The network model’s spatial analysis covers local urban form indicators, such as street layout, network density and land use mix, as well as regional indicators of multimodal accessibility and network configuration (its structure), to give a holistic profile of urban areas across modes and scales of travel.
The analysis results go through exploratory data mining and classification procedures to identify urban form typologies of urban areas. It is shown that there is a relation between this ‘urban modality’ of urban areas and the travel patterns of their residents, measured as a set of sustainable mobility indicators related to mode share and distance travelled. For this reason, ‘urban modality’ offers the possibility for ex-ante evaluation of sustainable mobility potential of planned urban areas. Furthermore, when combined with the socio-economic profile of the resident population, ‘urban modality’ defines a context for the ex-post evaluation of sustainable mobility performance of existing urban areas.
The evaluation of suburban areas together with the more central historical urban areas gives invariably a high score in sustainable travel to the central areas, and rates the suburban areas negatively. On the other hand, the evaluation of sustainable mobility performance in the context of suburban areas of the same type allows the finer distinction of underperformers that have scope for improvement, and overachievers that provide examples of (relative) success. This contextual evaluation can become
a decision support instrument for “hard” and “soft” planning measures involving sustainable mobility targets.
Applying this method to the set of VINEX neighbourhoods of the Randstad leads to the conclusion that despite being planned following the same policy objectives, the neighbourhoods have different types of ‘urban modality’, thus present different levels of sustainable mobility potential. Neighbourhoods identified as underperformers within their context can be targeted for soft measures related to transport services, technology and individual attitudes to travel, to fulfil the potential of their ‘urban modality’ type. However, if this potential is not deemed satisfactory or if they already overachieve, only by retrofitting a set of infrastructure and land use characteristics will lead to a different ‘urban modality’ type, and a change in potential. Such a change can be lengthy, costly and sometimes impossible to implement ex-post.
The thesis is based on a collection of published articles in peer-reviewed academic publications, with the first and last chapters providing an overview of the research and of its findings, and defining the main narrative thread.
Conference Articles (peer-reviewed) by Jorge Gil
The empirical data consists of gate counts of bicycle traffic and detailed GPS-tracks mapping actual bicycling speeds of ca. 900 trips along a selection of bicycle routes. Using multiple regression analysis to model speed data, eight variables were found significant. In addition to slope and curvature of routes, the significant variables relate to proximity to traffic signals, degree of separation from pedestrians, density of entrances along the routes and quality of paving of the cycle lane.
Concerning bicycling flow potentials, the most significant variables in the multiple regression model were: OD-betweenness within 5km, segment angular integration within 10km, density of residents and people at work (students included) within 1 km and network betweenness within 3km.
Based on the results of the current project, a proposal for further research is to elaborate on the OD-betweenness analyses by including speeds and preferably traffic safety in the betweenness measure. By using time along segments instead of metric length for defining the analysis threshold (radius), it should be possible to have a new and improved generation of space syntax based accessibility analyses for bicycling studies. A working name for such a measure is “least impedance origin destination betweenness”.
In this article, we review the state of the art of CIM (definitions and applications) in the academic literature and propose a definition and a general conceptual framework. By highlighting how the different disciplines are related to each other within this conceptual framework, we offer a context for transdisciplinary work, and focus on integration challenges, for research and development, both in academia and industry. This will contribute to moving forward the debate on digitalization of the built environment development process in the field of Smart Cities.
A key stance in this work is the understanding that the location of an urban area
in the region can be indicative of its population’s travel patterns, because the built environment (infrastructural) and socio-economic characteristics are interrelated
and present strong regional spatial patterns. What types of urban areas support sustainable travel patterns, and what are their spatial characteristics? How do new neighbourhoods compare to the best performing urban areas, and to other areas of the same ‘modality’ type? These are some of the questions addressed in this study. There are two main contributions of this research: the methods for building and analysing integrated multimodal network models, and the framework for contextual performance evaluation using urban area typologies.
The integrated multimodal network model combines the various mobility infrastructure networks and the buildings’ land use to create a detailed description of the region, using open spatial data and open source Geographic Information Systems (GIS) technologies. The network model’s spatial analysis covers local urban form indicators, such as street layout, network density and land use mix, as well as regional indicators of multimodal accessibility and network configuration (its structure), to give a holistic profile of urban areas across modes and scales of travel.
The analysis results go through exploratory data mining and classification procedures to identify urban form typologies of urban areas. It is shown that there is a relation between this ‘urban modality’ of urban areas and the travel patterns of their residents, measured as a set of sustainable mobility indicators related to mode share and distance travelled. For this reason, ‘urban modality’ offers the possibility for ex-ante evaluation of sustainable mobility potential of planned urban areas. Furthermore, when combined with the socio-economic profile of the resident population, ‘urban modality’ defines a context for the ex-post evaluation of sustainable mobility performance of existing urban areas.
The evaluation of suburban areas together with the more central historical urban areas gives invariably a high score in sustainable travel to the central areas, and rates the suburban areas negatively. On the other hand, the evaluation of sustainable mobility performance in the context of suburban areas of the same type allows the finer distinction of underperformers that have scope for improvement, and overachievers that provide examples of (relative) success. This contextual evaluation can become
a decision support instrument for “hard” and “soft” planning measures involving sustainable mobility targets.
Applying this method to the set of VINEX neighbourhoods of the Randstad leads to the conclusion that despite being planned following the same policy objectives, the neighbourhoods have different types of ‘urban modality’, thus present different levels of sustainable mobility potential. Neighbourhoods identified as underperformers within their context can be targeted for soft measures related to transport services, technology and individual attitudes to travel, to fulfil the potential of their ‘urban modality’ type. However, if this potential is not deemed satisfactory or if they already overachieve, only by retrofitting a set of infrastructure and land use characteristics will lead to a different ‘urban modality’ type, and a change in potential. Such a change can be lengthy, costly and sometimes impossible to implement ex-post.
The thesis is based on a collection of published articles in peer-reviewed academic publications, with the first and last chapters providing an overview of the research and of its findings, and defining the main narrative thread.
The empirical data consists of gate counts of bicycle traffic and detailed GPS-tracks mapping actual bicycling speeds of ca. 900 trips along a selection of bicycle routes. Using multiple regression analysis to model speed data, eight variables were found significant. In addition to slope and curvature of routes, the significant variables relate to proximity to traffic signals, degree of separation from pedestrians, density of entrances along the routes and quality of paving of the cycle lane.
Concerning bicycling flow potentials, the most significant variables in the multiple regression model were: OD-betweenness within 5km, segment angular integration within 10km, density of residents and people at work (students included) within 1 km and network betweenness within 3km.
Based on the results of the current project, a proposal for further research is to elaborate on the OD-betweenness analyses by including speeds and preferably traffic safety in the betweenness measure. By using time along segments instead of metric length for defining the analysis threshold (radius), it should be possible to have a new and improved generation of space syntax based accessibility analyses for bicycling studies. A working name for such a measure is “least impedance origin destination betweenness”.
The multi‐modal network model of the Randstad includes the three main public transport networks, namely rail, tram and metro/light rail, and it is a simple topological undirected network where the stations or stops represent nodes in the graph and the mobility infrastructure defines the links. In order to create a multimodal network we introduce a fourth set of links representing modal interfaces that make the connection between the nodes of the different public transport modes. We then measure the degree, closeness and betweenness centrality of this network and correlate the results with the data of the 2008 Mobility Survey of the Netherlands, aggregated at neighbourhood level.
Although the centrality of the multi‐modal network does not fully explain the patterns of public transport use in the different neighbourhoods, it seems to offer a possibility of characterising those neighbourhoods in terms of their public transport use potential, i.e. to what extent they can be public transport ‘modal environments’. The realisation of this potential is dependent on other factors, and further work is required to understand what makes a walking and cycling or a car environment in terms of multi‐modal mobility networks.
Furthermore, it was found that topological centrality measures show a hierarchy in the multi‐modal network infrastructure, and that one should use different methods to analyse the different modes because they play different roles. Finally, it was found that, despite these differences, it is important to consider the network as an integrated multi‐layered system. How these layers are modelled and articulated should be subject of further research."
In order to better understand the complex relation between urban form and sustainable mobility patterns we build a descriptive, multi-modal network model of the Randstad region in the Netherlands, integrating private and public transport infrastructure networks and land use information. This detailed model allows the description of the urban areas in the city-region by measuring and quantifying urban form characteristics, such as network proximity, density, accessibility and centrality, for different transport modes. The resulting multi-modal network measures are then tested against travel survey data of the Netherlands. This analysis reveals the structures of modality in the city-region, which we call ‘modality environments’, that support specific patterns of mobility at different scales, i.e. walking, cycling, car use, local and regional transit, contributing a new urban form based method for evaluating the potential of sustainable mobility in the city-region.
Our research project aims to develop an urban design system using an urban ontology that can be applied to the formulation, generation and evaluation of urban plans. The purpose of this urban design system is: (1) formulation - to read data from the site context on a GIS platform and then generate adequate program descriptions, given the contextual conditions; (2) generation - to generate alternative design solutions that match the program, and (3) evaluation - to evaluate evolving design solutions against the program to obtain satisfactory results.
In this paper we present a methodology for data mining an urban Geographic Information System (GIS) data set, consisting of three main phases: representation, analysis and description. The process reveals a series of block and street typologies that highlight the different character of two neighbourhoods. This methodology is demanding in the preparation phase and requires a high level of GIS and statistics expertise in the analysis phase. However, it successfully addresses the complex multi-scale and multi- level nature of cities in a systematic way, providing a tool for systematic profiling of neighbourhoods, which is site and problem specific."
CIM is more than an amalgamation of all the BIM models in an urban area. CIM represents the higher level networks of infrastructure, governance and human activity that make up the urban environment; and ultimatelly it forms the structure that holds all BIM models together and supports their interactions. CIM allows the description, visualisation, quantifcation, analysis and monitoring of the urban environment to support urban planning and design from the very local to the regional. CIM meets the needs of the various stakeholders with specifc design and decision support tools, with different types of interface and output, but one information base. The backbone of a CIM is an integrated, cross-disciplinary, spatial data model, with granular and relational information based on open standards.
In this presentation I will illustrate the CIM concept applied to urban design with current examples from industry and research. In particular, I will present prototype implementations integrating network data models and analysis in CAD and GIS platforms, for neighbourhood design and evaluation of the Randstad region in the Netherlands, with a focus on sustainable mobility objectives.
However, we also witness in built environment education and practice a lack of awareness of such data and tools, and of the theoretical and technical skills to use them. The current design paradigm is strongly rooted in drafting and illustration methods eventually supported by information technologies of CAD, digital modelling and visualisation (Gil et al. 2010), which is evident in curricula, the design software features and job requirements.
Here, we present some results of the ‘City Induction’ research project that was aimed at prototyping the next generation of City Information Modelling (CIM) tools, integrating formulation, design, and evaluation methods into a comprehensive urban design support system (Duarte et al. 2012). We focus on aspects of data management, their application in prototype software tools and the lessons learned from a workshop with students and practitioners.
While big data sets are readily available, for them to be of use to urban design teams they must be managed properly due to their diversity and size. The backbone of a CIM system should be a spatial database platform implementing a data model designed specifically for urban design practice (Gil et al. 2011). Currently, there are no spatial data models offering an integrated set of relevant features, or the standards such as CityGML are strongly focused on data exchange and visualisation lacking features to support the design process itself.
We propose a data model that combines urban environment feature classes with design process feature classes and exemplify its implementation using data of the Randstad region in the Netherlands. This model can be useful in practice and education to provide guidance in data requirements, data management and use. We then demonstrate its application to urban design through prototype tools for Rhino and AutoCAD Map 3D that integrate with a PostGIS spatial database, and through the experience of using these methods in an urban design workshop with students and practitioners.
We conclude that there is currently a large gap in knowledge and skills to use these methods. But the response is very positive and proves to be an ‘eye opener’, with people facing a tough challenge of returning to ‘old’ methods. Thus, we identify some requirements for education and software development:
- Early contact of students with data collection and manipulation using digital tools;
- Integration of data management in design and teaching methods;
- Institute a specific role for data and map management in BE libraries;
- Develop support tools for data collection and pre-processing that comply with standards;
- Develop user-friendly tools to manage and analyse data;
- Ideally, integrate these platforms with design tools.
This project, studying the performance of TOD in the Randstad region of the Netherlands, takes advantage of recent advances in data collection and distribution and in open GIS and spatial analysis technologies to overcome some of the earlier critiques. It builds a descriptive, disaggregate, multi-modal network model of the region on the PostgreSQL / PostGIS database platform using various Open Data sources. The model integrates street network data extracted from OpenStreetMap (OSM); public transport networks data derived from the same OSM data, from the OpenOV project timetable data and from route maps in Wikipedia and the various network operators; and land use data extracted from the public Basisregister Addressen (BAG) data set of the Netherlands. The modelʼs smallest spatial units are respectively the street segments, the public transport stops and the individual buildings, and it is analysed using PostGIS, pgrouting and the R statistical platform, and the results visualised using QuantumGIS.
In this session I will be presenting some of the results, lessons learned from the process and current challenges of building such network models, focusing on issues of data quality, spatial modelling and analysis.
Keywords: urban design, ontology, pattern language, shape grammars, space syntax, GIS, CAD