西北地区是丝绸之路经济带建设的境内外重要结合点。通过考虑各城市铁路交通流的异质性,以西北各市（州）主要城市为研究单元,重要高铁线路开通时间为断面,以2011、2015年和2019年为时间节点,利用列车频次可达性测度方法与标准引力模型,采用列车频次加权平均旅行时间以及经济联系总量和经济联系强度等指标,对其铁路可达性及城市空间相互作用进行分析。结果表明：（1） 铁路可达性及城市间经济联系强度整体上提升明显,高铁沿线更为显著,受列车频次的影响较大。（2） 全区铁路可达性总体上东西梯度差异显著,向西北方向逐渐递减。各省（自治区）局部表现为以省会城市为中心,以铁路枢纽城市为次中心的圈层结构。（3） 全区空间相互作用由传统的“极核式”转变为以枢纽城市为节点,以陇海线、宝兰线、兰新线等主干铁路为轴线纵向延伸的“点轴式”,进而初步形成一定的“网络式”格局。各省（自治区）内部“区域中心城市—外围城市—边缘城市”经济联系总量梯度结构明显。深入剖析地区可达性及经济联系分布格局,建议应该进一步加强铁路建设,尤其是扩大边缘地区铁路网覆盖面,统筹东西梯度发展,非高铁沿线城市需要加强与沿线城市的交通接驳建设,积极主动融入高铁网络。

Northwest China is an important juncture of the Silk Road Economic Belt. Considering the heterogeneity of railway traffic flow in different cities, with the main cities in the northwestern region as the research unit, and the important high-speed line openings in 2011, 2015, and 2019 as time points, using the accessibility of the train frequency measurement method and the standard gravitational model, and adopting the frequency-weighted average travel time of trains and the total economic ties and economic indices of the contact strength, the accessibility of railways and the urban spatial interaction are analyzed. The results indicate the following. (1) Railway accessibility and the strength of the economic connection between cities have significantly improved overall, especially along the high-speed railway, which is greatly affected by the train frequency. (2) Railway accessibility in the entire region has a significant gradient from east to west and gradually decreases in the northwest direction. In some provinces (autonomous regions), a circular structure is centered on the provincial capital city and sub-centered on the railway hub city. (3) The spatial interaction in the entire region has changed from the traditional “polar core” pattern to a “point-axis” pattern with the hub cities as nodes and the main railways, such as the Longhai, Baoji-Lanzhou, and Lanzhou-Xinjiang railways, as longitudinal axes, forming a “network” pattern. Within the provinces (autonomous regions), the “regional central city-peripheral city-marginal city” economic connection total gradient structure is obvious. It is suggested that railway construction be further strengthened; in particular, the coverage of the railway network in marginal areas should be expanded and the east-west gradient development should be coordinated. Cities along non-high-speed railway lines should strengthen their transportation connections with cities along the railway lines and actively integrate into the high-speed railway network.