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.
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.
Sci Total Environ. 2014 Feb 1;470-471:883-94. doi: 10.1016/j.scitotenv.2013.10.041. Epub 2013 Nov 6.
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.
快速的城市化进程极大地改变了城市物质与能量代谢。作为基础设施的重要组成部分，城市道路在全球范围内得到了快速发展。对城市道路系统代谢过程进行量化分析，特别是对其存量的规模、组成和空间分布进行分析，有助于评估资源占用和潜在的环境影响，并改进城市代谢模型。本文构建了一个涵盖所有类型道路、交叉口结构和附属设施的综合模型，用以计算城市道路系统的物质存量。该模型采用自下而上的方法，将总存量分解为多个存量部分，而不是通过投入产出数据来获得，从而提供了一种促进数据可用性和理解内在结构的方法。与 GIS 的结合使模型能够处理复杂的道路网络结构并避免重复计算。以北京市为例，得到以下结果：1）整个道路系统的总存量达到 1.59 亿吨，其中近 80%存储在道路中，20%存储在附属设施中。2）碎石沥青是最大的存量（1.11 亿吨），而沥青玛蹄脂碎石、聚氨酯塑料和无规聚丙烯则占整个系统较小的组成部分。3）过街天桥单位面积的存量高于整个系统中其他存量单元，其钢材存量达到 0.49 t/m²，是交叉口的 10 倍。4）高存量区域主要分布在环形和放射性快速路以及主要的交叉口。5）快速路和主干道得到了过度强调，而支路和小区道路则相对被忽视。然而，分支和小区道路的横断面厚度变化将对整个道路系统的物质存量规模产生重大影响。
