基于通勤圈识别的大城市空间结构优化——以武汉市中心城区为例

研究通勤圈对于进一步认识大城市空间结构的运行特征和提升空间绩效具有重要作用。以武汉市为例,利用手机定位服务(LBS,location based service)数据识别武汉市中心城区主要通勤圈的空间分布;在对通勤圈的圈层结构、内部构成及外部形态进行测度的基础上,分析了基于通勤圈的通勤强度空间分布、大城市中心城区空间结构布局与运行特征之间的关联及其内在原因。研究发现,中心城区通勤圈空间分布呈以"通勤中心"为核心、相对集聚的"多中心"结构;通勤圈的内部结构呈圈层式扩张,且"飞地"和跨区通勤现象明显;随着通勤圈空间范围扩大,职住偏离指数、主要土地使用要素指标与交通环境要素指标均随之降低;通勤圈的大小和形态取决于其内部用地构成、用地混合度及通勤走廊主导交通方式的运送速度和效率;交通方式系统供给与基于通勤圈的3类通勤出行需求的"错位"布局降低了中心城区空间结构的运行绩效。在此基础上,提出了以准确识别通勤圈空间分布与内在结构为基础,优先完善中心城区内部交通系统组织、适度拓展中心城区跨通勤圈客流通道以逐步扩大通勤圈服务范围、审慎发展快速路系统的面向大城市空间运行绩效提升的优化策略。

COMMUTING CIRCLE-BASED SPATIAL STRUCTURE OPTIMIZATION OF MEGACITIES: A CASE STUDY OF WUHAN CENTRAL CITY

Studying the commuting circle is of great significance for further understanding the operational characteristics of spatial structure and improving spatial performance of mega-cities. This paper identifies the spatial distribution of main commuting circles in Wuhan central city by using LBS(Location Based Service) data. According to the measurement of the circle structure, internal composition, and external form of the commuting circle, the paper analyzes the relation between the spatial distribution of the commuting circle-based commuting intensity and the spatial structure layout and operation characteristics of the mega-city, as well as its internal causes. The study finds: the spatial distribution of commuting circles in the central city is a relatively concentrated "multi-center" structure with the "commuting center" as its core; the internal structure is spread in a circle and the "enclave" and cross-region commuting are obvious; with the expansion of the commuting circle, the occupational and residential deviation index, the main land use factor indicators, and the traffic environment factor indicators drop; the size and form of commuting circles depend on its internal land use composition, land mixing degree, and the speed and efficiency of commuting corridor-dominated transportation mode; the "dislocation" layout of the transportation mode system supply and three types of commuting circle-based commuting travel demand reduces the operational performance of the spatial structure of the central city. Accordingly, based on the accurate identification of the spatial distribution and internal structure of commuting circles, the paper proposes an optimization strategy for improving space operation performance of mega-cities, by giving priority to improving the organization of the internal transportation system, appropriately expanding the passenger flow channel across commuting circles in the central city to gradually expand its coverage, and prudently developing the expressway system.