Search Results (9)

Exploring key impact factors and their effects on urban residents’ transport carbon dioxide (CO₂) emissions is significant for effective low-carbon transport planning. Researchers face the model uncertainty problem to seek a rational and better explanatory model and the key variables in the model set containing various factors after they are arranged and combined. This paper uses the Bayesian Model Averaging method to solve the above problem, explore the key variables, and determine their relative significance and averaging effects. Beijing, Xi’an, and Wuhan are selected as three case cities for their representation of developing Chinese cities. We found that the initial key factor increasing transport emissions is the high dependence on cars, and the second is the geographical location factor that much more suburban residents suffer longer commuting. Developing satellite city rank first for reducing transport emissions due to more local trips with an average short distance, the second is the metro accessibility, and the third is polycentric form. Key planning strategies and policies are proposed: (i) combining policies of car restriction based on vehicle plate number, encouraging clean fuel cars, a carbon tax on oil uses, and rewarding public transit passengers; (ii) fostering subcenters’ strong industries to develop self-contained polycentric structures and satellite cities, and forming employment and life circle within 5 km radius; and (iii) integrating bus and rail transit services in the peripheral areas and suburbs and increasing the integration level of muti-modes transferring in transport hubs. The findings will offer empirical evidence and reference value in developing cities globally. Full article

The present study illustrates a simplified procedure identifying population sub-centers over 50 years in three Southern European cities (Barcelona, Rome, Athens) with the aim to define and characterize progressive shifts from mono-centric structures towards a polycentric spatial configuration of (growing) metropolitan regions. This procedure is based on a spatially-explicit, local-scale analysis of the standardized residuals from a log-linear model assessing the relationship between population concentration and the distance from a central place in each metropolitan region, under the hypotheses that (i) a mono-centric spatial structure is characterized by a linear relationship between the two variables and that (ii) population sub-centers—considered early signals of a more polycentric regional structure—are characterized by high and positive regression residuals. Results of this study indicate that the three cities have experienced distinctive urbanization waves influencing the overall metropolitan configuration, with variable impact on the original mono-centric structure. Population sub-centers include (i) peri-urban municipalities around the central city and more remote towns situated in rural districts (Barcelona); (ii) scattered towns at variable distances (20–30 km) from the central city (Rome); (iii) fringe municipalities and peri-urban locations in flat districts, 10–20 km away from the central city (Athens). These results may indicate a distinctive evolution path toward polycentric development in the three cities, more evident in Barcelona and Rome and less evident in Athens. The proposed methodology can be generalized and adapted to discriminate population from employment sub-centers in metropolitan regions all over Europe. Full article

Dasymetric mapping of high-resolution population facilitates the exploration of urban spatial feature. While most relevant studies are still challenged by weak spatial heterogeneity of ancillary data and quality of traditional census data, usually outdated, costly and inaccurate, this paper focuses on mobile phone data, which can be real-time and precise, and also strengthens spatial heterogeneity by its massive mobile phone base stations. However, user population recorded by mobile phone base stations have no fixed spatial boundary, and base stations often disperse in extremely uneven spatial distribution, this study defines a distance-decay supply–demand relation between mobile phone user population of gridded base station and its surrounding land patches, and outlines a dasymetric mapping method integrating two-step floating catchment area method (2SFCAe) and land use regression (LUR). The results indicate that LUR-2SFCAe method shows a high fitness of regression, provides population mapping at a finer scale and helps identify urban centrality and employment subcenters with detailed worktime and non-worktime populations. The work involving studies of dasymetric mapping based on LUR-2SFCAe method and mobile phone data proves to be encouraging, sheds light on the relationship between mobile phone users and nearby land use, brings about an integrated exploration of 2SFCAe in LUR with distance-decay effect and enhances spatial heterogeneity. Full article

An emerging polycentric spatial structure in China’s mega cities has been confirmed in the literature, but few studies have addressed the linkage between the change in spatial structure and urban development policies. Using Beijing as a case study, this paper examines the role of urban polycentric planning in the polycentric evolution process from a morphological perspective. We observed that urban polycentric planning significantly promoted the emergence of a polycentric urban form in Beijing’s metropolitan area from 2001 to 2010. Firstly, most of the planned subcenters were identified as real employment subcenters by a relative threshold method in 2001 and 2010 and comprised the majority of the employment subcenters. Secondly, the planned subcenters significantly increased their employment share and influence on employment and population distribution from 2001 to 2010, and their performances referring to these aspects were much better than the unplanned subcenters. Thus, our findings provide evidence that changes in urban spatial structure can be strongly affected by urban development policies, although it is determined by market forces in theory. Full article

In recent years, increasing attention has been paid to the urban spatial structure in developing countries. In China, studies have shown that many mega cities or big cities have been transformed into polycentric spatial structures. However, polycentric spatial structures’ impact on urban development requires further empirical research, including in relation to land price, commuting, and population distribution. Taking Beijing as an example, this paper discusses employment subcenters’ rise and evolution on residential land prices. Using the land transaction data for 2001–2013, this paper analyzes the residential market characteristics in terms of their temporal and spatial variation and studies the impact of employment subcenters on residential land prices using a Hedonic model of Beijing city for 2001–2004, 2005–2008, and 2009–2013. This paper finds that (1) Beijing’s employment subcenters increased from one in 2001 to four in 2004 and six in 2008, while the spatial distribution was diffused from the center of the city to the suburbs; (2) Beijing’s main center’s influence on residential land price is on the decline, while that of employment subcenters is on the rise, although their influence and scope of influence remain limited; (3) the impact of different employment subcenters on land prices is significantly different. The impact of Zhongguancun is very significant, while that of other employment sub-centers is relatively limited, particularly the “new town” employment subcenter. Based on this, this paper argues that with the development of subcenters of employment, their influence on urban development will become increasingly obvious. Therefore, urban policy-makers need to consider this influence and make corresponding strategic adjustments. Full article

Decentralization and polycentric spatial structure strategies are important ways to alleviate urban disease in China. However, whether the urban spatial structure is meeting expectations is still unknown. Taking the Beijing Metropolitan Area as a case, the author adopted a non-parametric method to identify the subcenters, then an employment density model was used to analyze the spatial changes of employment and the employment centers’ impacts on the urban spatial structure. The results show that the Beijing Metropolitan Area was undergoing processes of employment decentralization, the monocentric structure was obvious throughout this time, but the polycentric model prevailed. The spatial structure of the Beijing Metropolitan Area was characterized as depicting “all centers aggregation” and the spatial structure of the central district of Beijing can be described as “subcenter agglomeration” between 2004 and 2013. The spatial structure became increasingly polycentric in the Beijing Metropolitan Area, but became more scattered in the central district. Full article

Urban spatial structure evolution, when using employment as the proxy, can be explained by the change of employment distribution. In this study, we measure the 361 US metro areas (metros) by employment shares, in five submetro sections (i.e., main-center, sub-centers, non-center clusters, non-cluster urban areas, and rural areas), and explore the spatial patterns of submetro growths. We use recognized methods to delimit urban and rural areas, identify employment centers with relative thresholds, and categorize the metros into three (i.e., small, midsize, and large) categories. Then we use descriptive statistics to determine the dynamics of employment growth in the five submetro sections. The results suggest that metros’ spatial structures and growth patterns vary greatly across different size categories. We found that (1) small metros tend to have growth in the main-center or non-cluster urban areas; (2) midsize metros may be in the critical period of forming sub-centers, which also may be an effective way to curb urban expansion into rural areas; and, (3) the five submetro growths in large metros tend to be positively associated with one another, except for the main-center. Full article

The standard method of identifying subcenters is due to Giuliano and Small. While simple, robust and easy to apply, because it uses absolute employment density and employment cutoffs, it identifies “too few” subcenters at the metropolitan periphery. This paper presents a straight forward modification to this method aimed at remedying this weakness. The modification entails using cutoffs that decline exponentially with distance from the metropolitan center, thereby giving consideration to the employment density of a location relative to that of its locality. In urban studies, there is a long history of estimating employment density “gradients”, the exponential rate at which employment density declines with distance from the metropolitan center. These density gradients differ substantially across metropolitan areas and across time for a particular metropolitan area. Applying our method to Los Angeles, Calgary and Paris, we have found that using cutoffs that decline exponentially at one-half the estimated density gradients achieves an appealing balance between subcenters identified close to the metropolitan center and those identified at the metropolitan periphery. Many other methods of subcenter identification have been proposed that use sophisticated econometric procedures. Our method should appeal to practitioners who are looking for a simple method to apply. Full article

The spatial structure of Beijing has changed dramatically since the reforms of the late 1970s. It is not clear, however, whether these changes have been sufficient to transform the city’s monocentric spatial structure into a polycentric one. This paper uses 2010 enterprise registered data to investigate the spatial distribution of employment in Beijing. Using a customized grid to increase the spatial resolution of our results, we explore the city’s employment density distribution and investigate potential employment subcenters. This leads to several findings. First, Beijing still has strong monocentric characteristics; second, the city has a very large employment center rather than a small central business district; third, five subcenters are identified, including four in the suburbs; and fourth, a polycentric model that includes these subcenters possesses more explanatory power than a simple monocentric model, but by only four percentage. We conclude that the spatial structure of Beijing is still quite monocentric, but may be in transition to a polycentric pattern. Full article