两步移动搜寻法及其扩展形式研究进展

Research progress of the two-step floating catchment area method and extensions

两步移动搜寻法是公共服务设施空间可达性研究中的重要方法,在国内外公共服务设施布局研究中得到了广泛应用,且发展出了众多扩展形式。但国内研究中对两步移动搜寻法尤其是其扩展形式的应用还较为有限。本文对两步移动搜寻法的主要扩展形式进行系统梳理和总结,将国内外研究中提出的两步移动搜寻法扩展形式归纳为基于引入距离衰减函数的扩展、对搜寻半径的扩展、针对需求或供给竞争的扩展以及基于出行方式的扩展4类,并分析了各种扩展形式的优缺点、适用情景以及未来可能改进方向。旨在为相关研究的方法选择提供参考,促进两步移动搜寻法及其扩展形式在国内相关领域的应用和发展。

Two-step floating catchment area（2SFCA） method is an important method of research on spatial accessibility to public services,which has been widely applied in studies on the spatial layout of public service facilities.Various extensions of 2SFCA have been developed.However,the application of the 2SFCA method and especially its extensions is still very limited in China.Thus,this study systematically summarizes the major extensions of the 2SFCA method.Such extensions found in existing literature can be classified into four categories.The first category focuses on the distance-decay function,replacing the dichotomous distance-decay form of the original 2SFCA by a multilevel discrete form as in the Enhanced 2SFCA,or continuous forms such as in the gravity-style,Gaussian-style,and Kernel-density-style distance-decay functions.The second category deals with the delimitation of catchment areas.The original 2SFCA form adopts a buffer-ring（BR） method delineating the catchment areas as concentric circles with certain radii of physical distance or travel time.A number of extensions have improved the BR method,including the Variable 2SFCA,the Dynamic 2SFCA,and the Multi Catchment Sizes 2SFCA.Moreover,a novel nearest-neighbor（NN） method for delineating the catchment areas by identifying a finite number of nearest facilities for each demand node has been proposed.The third category strives to improve the accuracy of 2SFCA by accounting for the competition among demand nodes or among supply nodes.The initial extension of this category is the Three-step Floating Catchment Area（3SFCA） method,following which other extensions such as the Modified 2SFCA and the Huff 2SFCA are proposed to make further improvements.The fourth category extends the travel means of the demand side,including the Multi-mode 2SFCA taking into account various potential transportation modes,and the Commuterbased 2SFCA integrating service visits and commuting behavior.The advantages and disadvantages,scenarios appropriate for their application,and potential improvements in the future of these extensions are also discussed.This study can contribute to the choice of method in relevant studies and promote the implementation and development of the 2SFCA method and extensions in relevant research fields in China.