中文摘要：

本文提出了一个适用于研究城市内部的个体或商业区位的微观可达性计算方法，该方法的核心是将研究区域进行等距的网格划分，通过计算每个网格的可达性指标，来研究整个区域的可达性的空间分布特点。在可达性计算中，利用网格内的道路密度和土地利用状态这两个因素来模拟计算每个网格的交通成本，引入了启发式A^＊空间搜索算法来计算网格问路径的交通成本，并且加入适当的启发信息，提高了搜索效率，使搜索结果更符合实际需求。最后，基于本文提出的方法，利用GIS二次开发工具ArcEngine开发了计算程序，收集了多源数据，以广州市商务区的可达性作为计算对象，进行了商务区的可达性和易达性案例计算。

英文摘要：

An accessibility computing method based on grid partition and heuristic A^＊ searching algorithms was put forward in the paper, which is used to research accessibility spatial distribution feature in the study area through computing each grid＇s accessibility. Traffic cost is an important element in accessibility computing. There are two approaches to stimulate grid traffic cost, one is approach of density of road network, and the other one is approach of relative spatial resistance for different land use status. The density of road network is anti-correlative with traffic cost. Land use has a close relationship with urban traffic, so grid relative traffic cost can be stimulated directly by integrating the two approaches, actual status of road and topological structure of road network was ignored. A computing formula of grid relative traffic cost was defined in the paper. The key point is how to compute traffic cost of grids path. Dijkstra algorithm makes sure to get the lowest traffic cost, but it must spend more searching space and time. Not only can A^＊ algorithms improve searching efficiency, but also can add some heuristic searching information to make searching result more reasonable. The key of the searching process is the definition of heuristic evaluation function H, which is responsible for estimating traffic cost from intermediate grid to target grid. Usually, marching from one spot to another is constrained by two factors： distance and arrival angle. So Euclid distance and marching arrival angle are adopted to evaluate traffic cost. In application, in order to make computing result accorded with practice, more heuristic information can be imported into computing process. For verifying our research, a software package was developed with C# language under ArcEngine9 environment. A case study was implemented by using the package. Accessibility of business districts was selected as computing object in Guangzhou city. The computing result by using the method can provide a quantitative refere