title: An integrated material metabolism model for stocks of urban road system in Beijing, China.
abstract: Rapid urbanization has greatly altered the urban metabolism of material and energy. As a significant part of the infrastructure, urban roads are being rapidly developed worldwide. Quantitative analysis of metabolic processes on urban road systems, especially the scale, composition and spatial distribution of their stocks, could help to assess the resource appropriation and potential environmental impacts, as well as improve urban metabolism models. In this paper, an integrated model, which covered all types of roads, intersection structures and ancillary facilities, was built for calculating the material stocks of urban road systems. Based on a bottom-up method, the total stocks were disassembled into a number of stock parts rather than obtained by input-output data, which provided an approach promoting data availability and inner structure understanding. The combination with GIS enabled the model to tackle the complex structures of road networks and avoid double counting. In the case study of Beijing, the following results are shown: 1) The total stocks for the entire road system reached 159 million tons, of which nearly 80% was stored in roads, and 20% in ancillary facilities. 2) Macadam was the largest stock (111 million tons), while stone mastic asphalt, polyurethane plastics, and atactic polypropylene accounted for smaller components of the overall system. 3) The stock per unit area of pedestrian overcrossing was higher than that of the other stock units in the entire system, and its steel stocks reached 0.49 t/m(2), which was 10 times as high as that in interchanges. 4) The high stock areas were mainly distributed in ring-shaped and radial expressways, as well as in major interchanges. 5) Expressways and arterials were excessively emphasized, while minor roads were relatively ignored. However, the variation of cross-sectional thickness in branches and neighborhood roads will have a significant impact on the scale of material stocks in the entire road system.
authors.affiliation: State Key Laboratory of Urban & Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Urban & Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China. Electronic address: hudan@rcees.ac.cn.
authors.forename: Dan
authors.initials: D
authors.lastname: Hu
authors.affiliation: College of Resources and Environments, Southwest China University, 1 Tiansheng Road, Beibei District, Chongqing 400715, China.
authors.forename: Fuhua
authors.initials: F
authors.lastname: Zhang
authors.affiliation: College of Biological and Environmental Engineering, Zhejiang University of Technology, 18 Chaowang Road, Xiacheng District, Hangzhou 310014, China.
authors.forename: Guolong
authors.initials: G
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Urban & Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xiao
mesh_terms: D002681:China; D003252:Construction Materials / Q000191:economics / Q000706:statistics & numerical data*; D004784:Environmental Monitoring; D040362:Geographic Information Systems; D008962:Models, Theoretical; D014186:Transportation / Q000191:economics / Q000706:statistics & numerical data*; D014507:Urbanization
keywords: Bottom-up model; Infrastructure resource management; Material stock analysis; Road system; Urban infrastructure; Urban metabolism