公交模式对公共服务设施可达性的影响

利用python程序语言开发了基于百度地图导航服务的批量路径时间查询平台,并结合最邻近设施时间和累积机会成本方法度量了居住单元与中心商业区（CBD）、与行政服务中心、与大型医院、与火车站、与飞机场的可达性;然后,着重对比分析了2种公交模式（有/无地铁）下公共服务设施可达性的差异。实验结果表明：① 与基于ArcGIS网络分析法等传统方法相比,基于“门到门”互联网路径规划服务API方法计算的出行时间成本能够较为精确、便捷地用于度量公共服务设施的可达性,避免了人工构建复杂路网数据集的工作量,而且更具时效性;② 融入地铁网络的公交模式不同程度上提升了居住单元至公共服务设施的可达性,尤其是地铁沿线“廊道”以及重要交通设施（如地铁站点）邻近区域最为显著;③ 居住单元至邻近CBD的可达性变化显著集中于0~30 min,30 min时间阈值内公交（有地铁）模式下累计的人口和面积分别是公交（无地铁）模式的1.7倍和2.2倍;④ 居住单元至邻近火车站的可达性变化显著集中于0~30 min以及30~60 min,30 min时间阈值内公交（有地铁）模式下累计的人口和面积分别是公交（无地铁）模式的8.9倍和3.0倍,60 min时间阈值内累计的人口和面积分别是公交（无地铁）模式的1.5倍和1.9倍;⑤ 居住单元至邻近飞机场的可达性变化显著集中于60~90 min以及90~120 min,90 min时间阈值内公交（有地铁）模式下累计的人口和面积分别是公交（无地铁）模式的12.6倍和6.6倍,120 min时间阈值内累计的人口和面积分别是公交（无地铁）模式的2.0倍和3.6倍;⑥ 居住单元至所属行政中心、至邻近大型医院的可达性在各个时间间隔及阈值范围内亦有相应幅度的改善。此外,运用本文的技术方法还可获得更完整、真实的其他交通模式（如汽车、电动车、自行车、步行等）接入城市公共服务设施的情形,为进一步研究非汽车模式下城市公共服务设施的可达性提供参考,促进城市公共交通可持续性的发展。

Accessibility of Public Service Facilities as Influenced by Public Transport Modes

Spatial accessibility analysis is recognized as an efficient way to assess the convenience of residents in accessing public service facilities by different travel modes. To this end, analyzing the travel time between residents and public service facilities is essential part of accessibility analysis. However, most studies used rough estimates of travel distance/time by ArcGIS network analysis tools, especially for public transport modes. To calculate travel time more accurately, this study used Python language to develop a platform to extract the traffic trip data including travel times and distances based on the Baidu map navigation API (Application Program Interface) service. The nearest facility method and the cumulative opportunity cost and isochronal method were applied to measure and compare the disparity of accessibility to Nanjing's central business districts (CBDs), administrative service centers, large hospitals, railway stations, and airports in different public transportation scenarios (BTT and MTT). The results show that: ① A door-to-door approach in travel time calculations for public transport modes according to up-to-date schedules based on internet map service is more accurate and convenient compared with the traditional ArcGIS network method. ② The metro network system has obviously improved the accessibility from residential areas to urban public service facilities, especially the "corridors areas" along the metro lines or bus routes and the areas close to the important transportation facilities, such as metro stations. ③ In the MTT scenario, the changes of the accessibility from residential areas to CBDs were significantly concentrated in 0-30 minutes; the cumulative population and area within 30-minute time threshold are respectively 1.7 times and 2.2 times those of the BTT scenario. ④ The changes of the accessibility from the residential cells to the nearest railway station were significantly concentrated in 0-30 minutes and 30~60 minutes; the cumulative population and area within 30-minute time threshold were respectively 8.9 and 3.0 times those of the BTT scenario. The cumulative population and area within 60-minute time threshold were respectively 1.5 times and 1.9 times those of the BTT scenario. ⑤ The changes of the accessibility from residential cells to airports were significantly concentrated in 60~90 minutes and 90~120 minutes, and the cumulative population and area within 90-minute time threshold were respectively 12.6 and 6.6 times those of the bus scenario; the cumulative population and area within 120-minute time threshold were 2.0 and 3.6 times higher than in the BTT scenario. ⑥ The changes of the accessibility from residential cells to administrative centers and large hospitals were also available to promote at various time interval periods. In addition, this paper can obtain more complete and real route time access to urban service facilities for other modes of transportation (e.g., cars, electric vehicles, bicycles, walking), and also provides reference for further studies to promote the sustainable development of public transportation.