Environment and Planning B: Urban Analytics and City Science

Urban growth is one of the indicators that reflects human interaction with the environment and has a direct effect on land use change. Continuous demand for space in Nigeria’s urban markets to accommodate shops and other retail outlets used for informal economic activities is accompanied by a change of use. This study examined the impact of informal economic activities on change of use in Bola Ige International Market, Ibadan. The concept of informal economy and the bid rent theory provided the conceptual/theoretical framework for this study. Geographical Information System was used to capture the change of use between 2006 and 2016. Land used for informal economic activities increased from 39.45% in 2006 to 55.35% in 2016, signifying a 15.9% increase. This implies that other land uses have been illegally converted and encroached. Transportation land use decreased from 31.47% in 2006 to 30.28% in 2011 and to 28.73% in 2016. Land used for open space (including parking space, and open trading area) which was 26.7% in 2006 reduced to 20.24% and 11.05% in 2011 and 2016, respectively. Most of the green areas (62.1%) have been converted to informal trading spaces between 2006 and 2016. Illegal change of use was credited to harsh economic condition in the country, and the engagement of the unemployed and retirees in informal sector economic activities. It was suggested that urban managers in conjunction with informed activists, researchers and citizens need to formulate and implement planning regulations that will integrate informal economic activities.

Both pre-disaster approaches, e.g., mitigation and preparedness, and post-disaster approaches, e.g., response and recovery, play important roles to mitigate the damage from large-scale disasters. From the viewpoint of disaster response, there have been studies on evacuation guiding schemes and applications using evacuees’ mobile devices, e.g., smart phones. On the other hand, disaster preparedness has also been studied mainly on geographical information analysis, e.g., road blockage probability and people flow data. The road blockage probability is the probability that the corresponding road is blocked due to collapse of roadside buildings when an earthquake occurs. The people flow data express the people flow in usual time. In this paper, with the help of evacuation guiding schemes, road blockage probability, and people flow data, we propose a road network risk analysis approach that considers people flow in both ordinary and evacuation situations, which can be used to as a tool to strengthen the urban fabric for fostering better evacuees’ responses in disaster situations. First, the proposed approach derives ordinary road demand, which is the degree of road usage at a certain interval in an ordinary situation, from the people flow data. Then, it calculates evacuation road demand, i.e., the degree of road usage at a certain interval in an evacuation situation, by extending the edge betweenness centrality under the assumption that people located according to the ordinary road demand move to refuges along their evacuation paths. Finally, it detects roads with high risk of encountering blocked road segments by combining the road blockage probability and evacuation road demand. Through numerical experiments under a case study of Arako area of Nagoya city in Japan, we show the proposed approach can detect such high-risk roads. Furthermore, we show the detected roads spatially change according to the people flow in ordinary situations, evacuation behavior, and disaster occurrence time.

In this paper, we consider the question of what is ‘in’ a region, from an economic perspective, based on commuting data. This follows a long line of studies on labour market delineation, including the widely used ‘travel-to-work area’ approach. Using Combo, a network partitioning algorithm, we analyse commuting data from the 2011 UK Census in order to define a discrete set of regions. Our aim is twofold: to contribute to methodological advances in regional delineation, and to produce results that have real-world utility. Following the introduction, we review previous work, before describing our data and methods. Our approach produces 17 new ‘regions’ for Scotland, in contrast to the existing set of 32. Our view is that algorithmic approaches to regional delineation have much to offer in a policy setting, but this must be tempered by the fact that regions, however defined, are inherently political constructs.

Research applying residential property value as a socioeconomic status measure is increasing. The literature includes several measures of residential property value socioeconomic status, all of which highlight location as an important component. This paper examines the drivers of the location component of residential property value that form the basis of its application as a socioeconomic status measure. The metropolitan area of Adelaide, South Australia, is used as a study area to analyse the composition and context embodied in residential property location value. The focus of this paper is to provide an understanding of the drivers of residential property value calculated as the relative location factor, deliberately constructed to reflect the effect on value due to location. The analysis reduced the traditional composition measures of social structure into a smaller number of factors using principal component analysis and regressed these against relative location factor. A spatial lens was applied to the results using Moran’s I to visualise the composition and context influence embodied in relative location factor. The results provided a significantly enhanced understanding of both the composition and context of socioeconomic status wealth that may be a more suitable socioeconomic status measure than the traditional composition measures of income, education and occupation. This paper provides an original interpretation of the contribution and use of residential property location value enabling a broader understanding of socioeconomic status, concluding that relative location factor provided a more informed measure of socioeconomic status, capable of enhancing social science and health research and policy formation.

The streets in the traditional residential areas of severe cold cities in China often have openings leading to enclosed courtyards. These openings connect the street to the courtyard space, which affects the physical environment of the residential streets. This paper uses field measurements and numerical simulation to study the wind–sound environment in the street, comparing and analysing the effects of the existence, size and form of openings on the wind–sound environment in the street. The results indicate that both the average wind velocity and sound pressure level have some degree of reduction around the opening, with the difference of wind velocity reaching 1.0 m/s and the difference in sound pressure level reaching 0.5–1.6 dB. Additionally, the T₃₀ changes from 0.2 s to 0.4 s around the opening, while the average T₃₀ in the street also varies. Increasing the width of the opening by 1 m increases the influential range of the opening on the sound environment by 0.5–4 m. In contrast, the width of the opening has little effect on the sound pressure level and the T₃₀. Compared with an entrance of the same width, a gap intensifies the fluctuation of the local wind velocity and causes the average T₃₀ to reduce by 0.3 s. The results of this paper lay a data foundation for further studies on the optimized design of the physical environment in enclosed residential areas.

Attractions and hotels are the two most important elements in tourism activities. However, there is a lack of in-depth analysis of tourist mobility between hotels and attractions. Meanwhile, new means of data collection are opening up opportunities for disclosing the mobility patterns between hotels and attractions. This paper aims at analyzing the network structures and mobility models of tourist mobility from attractions to hotels (TMAH) and tourist mobility from hotels to attractions (TMHA), by using the user-generated content data collated from an open tourism web service. Then the differences between the two tourist mobilities are compared. Through the empirical study of Nanjing, it is found that the influence of distance on the two mobilities is different. The distance has a significant influence on TMAH, and the mobility conforms to the power law distribution. TMHA is more influenced by the ranks of hotels and attractions, and the mobility confirms to the gravity model. The highlight of this paper is to use the new network data to reveal the network structure and mobility laws of the special tourist mobility between hotels and attractions from the perspective of difference comparison.

Variability in spatial accessibility of emergency medical services has become a major concern in evaluating the quality of emergency medical services in China. Unlike some other public services, response time is critical in the provision of emergency medical services. Traffic congestion may significantly affect response time, especially in large cities. This study uses a transportation simulation model to estimate the travel time under free-flow and congested road conditions and measure the corresponding spatial accessibility of emergency medical services for various hours of a day in inner-city Shanghai. When traffic congestion is considered, the overall spatial accessibility is significantly reduced, and the effect is further magnified in certain congested areas. The results help policy makers in planning the emergency medical services resource that is sensitive to the spatiotemporal variation of its accessibility.

Models of street networks underlie research in urban travel behavior, accessibility, design patterns, and morphology. These models are commonly defined as planar, meaning they can be represented in two dimensions without any underpasses or overpasses. However, real-world urban street networks exist in three-dimensional space and frequently feature grade separation such as bridges and tunnels: planar simplifications can be useful but they also impact the results of real-world street network analysis. This study measures the nonplanarity of drivable and walkable street networks in the centers of 50 cities worldwide and then examines the variation of nonplanarity across a single city. It develops two new indicators—the Spatial Planarity Ratio and the Edge Length Ratio—to measure planarity and describe infrastructure and urbanization. While some street networks are approximately planar, we empirically quantify how planar models can inconsistently but drastically misrepresent intersection density, street lengths, routing, and connectivity.

The size and form of cities influence their social and environmental impacts. Whether cities have the same form irrespective of their size is still an open question. We analyse the profile of artificial land and population density, with respect to the distance to their main centre, for the 300 largest European cities. Our analysis combines the GMES/Copernicus Urban Atlas 2006 land use database at 5 m resolution for 300 larger urban zones with more than 100,000 inhabitants and the Geostat population grid at 1 km resolution. We find a remarkable constancy of radial profiles across city sizes. Artificial land profiles scale in the two horizontal dimensions with the square root of city population, while population density profiles scale in three dimensions with its cube root. In short, cities of different size are homothetic in terms of land use and population density, which challenges the idea that larger cities are more parsimonious in the use of land per capita. While earlier literature documented the scaling of average densities (total surface and population) with city size, we document the scaling of the whole radial distance profile with city size, thus liaising intra-urban radial analysis and systems of cities. Our findings also yield homogenous spatial definitions of cities, from which we can re-question urban scaling laws and Zipf’s law for cities.

Aside from modeling geometric shape, three-dimensional (3D) urban procedural modeling has shown its value in understanding, predicting and/or controlling effects of shape on design and urban planning. In this paper, instead of the construction of flood resistant measures, we create a procedural generation system for designing urban layouts that passively reduce water depth during a flooding scenario. Our tool enables exploring designs that passively lower flood depth everywhere or mostly in chosen key areas. Our approach tightly integrates a hydraulic model and a parameterized urban generation system with an optimization engine so as to find the least cost modification to an initial urban layout design. Further, due to the computational cost of a fluid simulation, we train neural networks to assist with accelerating the design process. We have applied our system to several real-world locations and have obtained improved 3D urban models in just a few seconds.

Planning has long been perceived as intervention in a complex spatial system that tends toward equilibrium. In this perspective, time is implicit and dynamic details do not matter. As a result, little has been said in the literature about planning behavior that takes into account time and dynamic details. Exploration into planning behavior is important in the face of complex systems that are path dependent and far from equilibrium. The purpose of the present paper is therefore to model normative planning behavior based on Savage’s (1954) utility theory, Marschak’s (1974) theory of teams, and Hopkins’s (1980) definition of plans (i.e. planning is an activity of information gathering and producing to reduce uncertainty), to interpret the planner’s behavior on plan making, implementation, and revision. This model fits well the emerging perspective of the city in that urban development is non-equilibrium. We first define a simplified planning environment in which there are only one planner and one actor with three worlds: the grand world, the planner’s world, and the actor’s world, the latter two being small worlds. The notion of small world was first proposed by Savage (1954) and provides a useful way of explaining planning behavior. In the small worlds, the planner and the actor simultaneously select optimal actions among a set in order to maximize their expected utilities. Due to the mathematical property of the small world notion, planning behavior thus defined can be formulated analytically so that the planning process can be depicted in a precise, concrete language. The model proposed in the present paper is normative in nature, emphasizing on how planning behavior should take place and providing insights into how that behavior actually does come about in reality. In its current formulation, the model is only a preliminary approximation of normative planning behavior, but prompts some research questions worth pursuing, such as how multiple planners and actors make and use plans in a more complex situation and what planning procedures would be effective through computer simulations in the face of complexity.