Urban  (U) Session 4

Abstract: Study of urban systems---how they form and develop---constitutes an important portion of human knowledge, not only because it is about our own physical space of daily living but also for understanding the underlying mechanisms of human settlement and civilisation on the Earth's surface that may be fundamentally similar to other forms of organisation like biological cells in our body or animal colonies. Among the physical features of an urban system, the complex patterns delineated by the physical locations and shapes of urban entities like buildings, parks, lakes or infrastructure can provide us with the comprehension of its current status of development or even the living condition of people inside it. In this study, we explore the spatial patterns encompassed in urban systems by analysing the pattern of spatial distribution of transport points in their public transport network of 73 cities around the world. The analysis reveals that different spatial distributions of points can be quantified and shown to belong to two main groups in which the points are either approximately equidistant or they are distributed apart with multiple length scales. The first group contains cities that appear to be well-planned, i.e. organised type, while the second consists of cities that tend to spread themselves over a large area and possess non-uniform spatial density of urban entities at different length scales, i.e. organic type. In addition to public transport network, we also look at the distribution of amenities within each city to investigate the relation between these two types of urban entity, and find that it possesses universal properties regardless of the city's spatial pattern type. This result has one important implication that at small scale of locality, the urban dynamics cannot be controlled even though the regulation can be done at large scale of the entire urban system. Close

Abstract: Power-grid nodes are coupled oscillators in electric power systems. In the normal operational state of power grids, the phase frequencies of the power-grid nodes are synchronized. The synchronization is self-sustained such that it recovers the synchrony against small perturbations. However, large perturbations can break the syncronization, and the synchronization stability varies for the topological position of nodes and the network parameters such as transmission strength. In this study, we investigate how the synchronization stability undergoes transition according to the network topology and the transmission strength between nodes. We track the stability transition by using Kuramoto-type model as a function of the transmission strength. Based on the transition shapes of the synchronization stability, we reveal the width of the transition curve is correlated with community consistency that represents how consistently a node associates with other nodes. In addition, we find that the transition shapes are distinguished by few patterns. Through the analysis of 598 isomorphically distinct topologies, we classify the transition patterns into four groups. Neither macro- nor micro- network characteristics well predict the transition patters. However, we find that the pathway-based nodal centrality such as betweenness is a good indicator for the synchronization stability transition. Close

Abstract: Interactions and movements in urban systems are controlled by their transport networks. For these systems to function efficiently, there is a need to build a robust network. We present here how we can couple land use and network structure to model the travel demand of stations in a transport network. This gives us insights as to how transport networks should evolve with changing land use patterns. We apply the model to the Singapore Rapid Transit System (RTS). We find that considering network structure and using the entropy of the gross plot ratio as the potential measure of how likely a commuter will be attracted to travel to specific areas, the model predicts the data well with a correlation of 0.76. Close

Abstract: Within the realm of urban studies and spatial planning, the concept of self-organization receives increasing attention in understanding spatial transformations and related planning interventions (De Roo et al, 2012; Portugali, 2011). In exploring the potential of self-organization, various scholars however introduce diverging interpretations of the concept, consequentially leading to different interpretations of what the concept of self-organization can offer to planners. In the first part of the paper, we show that these different interpretations have their foundation in two distinct epistemic positions: One is a critical-realist interpretation of complex adaptive systems (Byrne, 2005), resulting in a planning focused on pattern recognition and formulating guiding conditions (Portugali, 2011; Rauws, 2015). The other includes a post-structuralist interpretation of emerging assemblages (Cilliers, 1998; DeLanda, 2006), leading to a planning focused on personal style and situational behavior (Boonstra, 2015). Although both contribute to further explications of what self-organization can offer to planners, the potential synergies between the two epistemic positions has so far remained unexplored. Therefore, the second part of the paper explores their complementary in dealing with urban transformations and discusses how to turn them into consistency with one another – meaning how they can mutually reinforce each other without losing their individual epistemic strengths. Based on this exploration we suggest a style of spatial planning in which the planner is able to act adaptively and differentiate in style in response to the situation at stake, among others by means of pattern recognition. On a conceptual level the paper shows how planner scholars can make sense of the diversity of ongoing processes of self-organization in the context of spatial transformations. Close

Abstract: The planning and realization of transport infrastructure occurs in a continuously changing environment. The climate changes, our economy is circulating, environmental requirements and restrictions grow and our society becomes more energetic and participative. Dealing with these changes is a major challenge in infrastructure planning and implementation nowadays. Traditionally, infrastructure planning focused on modelling and forecasting future developments based on historical data and socio-economic scenarios. Complexity and dynamics of infrastructure and its environment are reduced to something concrete and manageable. In practice, this leads to a reactive way of working. With the emergence of complexity theory and the realization that the object of planning behaves as a complex system, a system of many actors with mutual reciprocal relationships, the emphasis in infrastructure planning is shifting from pre-scribing to creating a context that allows and stimulates variation to occur. Planning becomes more adaptive and aims the ability to develop variation and choosing the "best fits" given changing circumstances. This is a major transition in the context of traditional infrastructure planning with its specific institutional design and specific relational and contractual characteristics. Considering the infrastructure sector as a complex adaptive social system, the paper analyses adaptability from a complexity theory perspective and confronts this with current practice in (Dutch) infrastructure planning, implementation and exploitation through the analysis of cases. Focus is thereby on conditions that allow variation through interaction between related actors in the system. As most important relations, the public-public and the public-private relationships are analysed. From the confrontation of theory and practice dilemmas for further discussion are formulated and recommendations are made - to infrastructure authorities and markets involved in infrastructure development - how to facilitate the above described transition from the traditional technical-rational planning to a more adaptive planning. Close