Urban Modality: Modelling and evaluating the sustainable mobility of urban areas in the city-region

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 transitability, 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.UrbanismArchitecture and The Built Environmen

Modeling level alignment at interfaces in molecular junctions

Molecular devices are planned as alternative solutions for heat dissipation problems and reliable fabrication of nano-scale devices. However, it also opens up possibilities of combining many other degrees of freedom into functional device design. While they introduce interesting opportunities for study, they also demand a versatile, scalable toolset. In this thesis we calculate the electronic transport through molecular devices using the DFT+NEGF technique. We model the interaction of the molecule with the electrodes surfaces taking into account different facts such as the gap reduction produced by the charge polarization on metallic surfaces, the spin states of the molecule and the hydrophilicity of the leads. We hope our contribution helps to improve the functional single molecule devices design.QN/Thijssen Grou

Analyzing the Configuration of Multimodal Urban Networks

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 multimodal 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 multimodal layers to describe the structure and configuration of a city-region.UrbanismArchitecture and The Built Environmen

Urban form and multi-modal mobility patterns

UrbanismArchitecture and The Built Environmen

Modality Environments: A Concept For Sustainability And Vitality In The Multi-Modal City

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.Spatial Planning and Strateg

Amsterdam and its Region as a Layering of Socio-Technical Systems

Space syntax reveals structure in the plans of cities. It misses however an explanation of how this structure arises and what it means. We argue political geographies are structured by the way we have constructed them historically as social organisation, and the means (technique) we have used. These structures depend on a layering of state of the art socio?technical networks constructed at different times in history. These networks internalise their own orders as particular ‘technological rationalities’ which give meaning to the objects subjects and practices they contain. They have also, as an aspect of these rationalities, a strongly normative character, fixing in place geographical entities like neighbourhoods, cities, regions etc. They fix these through the ‘structures of places’ they contain – networks of ‘isotopic’ locations (neighbourhood places; city places; regional places) whose scale and relation with places of other scales is fixed by the network involved and by the part?whole normativities of neighbourhood to city; city to region; etc. relations. This all constitutes a profound level of organisational order, embedded in the real world, that passes under the radar of reductive and ‘theoretical’ thinking. It is not so much pre?conceptual as about the historical and material realm in which geographical concepts and percepts arise. This level of order is what space syntax is in an indirect way finding. It is also a level of order we can use in a far more direct way as a means of modelling our built environment. This paper is an exploratory attempt to reveal the significant elements of this order in the case of Amsterdam, preparatory to modelling them. It begins by reviewing previous work done to show that what space syntax reveals is an effect of the interface of ‘neighbourhood’ and ‘city’ as these were realised technologically in urban infrastructures installed in the industrial era. It goes on to show pre?industrial and post?industrial Amsterdam are forms in their own right and that there are path?dependent processes of transformation between each of these forms. These processes of transformation establish articulations between these different forms, the articulations themselves becoming the vivid centres and the way the different forms (or layers) of the city work together. We conclude that the idea of modelling these human organisational orders embedded in infrastructures so as to reveal the active centres they produce in urban fabric seems plausible.UrbanismArchitectur

Patterns of sustainable mobility and the structure of modality in the Randstad city-region

UrbanismArchitecture and The Built Environmen

Central places and modality environments: An historical architecture of urban places

UrbanismArchitecture and The Built Environmen

Transport gap renormalization at a metal-molecule interface using DFT-NEGF and spin unrestricted calculations

A method is presented for predicting one-particle energies for a molecule in a junction with one metal electrode, using density functional theory methods. In contrast to previous studies, in which restricted spin configurations were analyzed, we take spin polarization into account. Furthermore, in addition to junctions in which the molecule is weakly coupled, our method is also capable of describing junctions in which the molecule is chemisorbed to the metal contact. We implemented a fully self-consistent scissor operator to correct the highest occupied molecular orbital-lowest unoccupied molecular orbital gap in transport calculations for single molecule junctions. We present results for various systems and compare our results with those obtained by other groups.QN/Thijssen Grou

The backbone of a City Information Model (CIM): Implementing a spatial data model for urban design

We have been witnessing an increased interest in a more holistic approach to urban design practice and education. In this paper we present a spatial data model for urban design that proposes the combination of urban environment feature classes with design process feature classes. This data model is implemented in a spatial database that becomes the backbone of a City Information Model (CIM), integrating urban neighbourhood formulation, design, and evaluation methods into a comprehensive urban design support system. We demonstrate its application to urban design analysis and evaluation through the development of a tool for AutoCAD Map 3D that is integrated with the PostGIS spatial database.UrbanismArchitectur