时空角度下极端天气的可达性指标比较

Comparison of accessibility indices for extreme weather events from spatiotemporal perspectives

为了确定不同可达性指标在极端天气下的性能,基于Hansen可达性指标,结合飓风“桑迪”期间纽约市曼哈顿区的出租车行程数据,从吸引系数和阻抗函数角度比较5类可达性指标,从时间和空间维度分析曼哈顿区的灾前、灾中、灾后可达性.比较结果表明,需求吸引系数体现灾害对出行距离的影响,比人口吸引系数更适合描述灾害场景的出租车流量变化特征;3类阻抗函数可达性的皮尔逊相关系数绝对值均大于0.8,但可达性的变化幅度不同;相较于累积机会型阻抗函数,使用重力型或混合型阻抗函数评估的灾害下可达性水平更符合现实情况.实验结果显示,使用需求吸引系数和重力型阻抗函数分析可达性能够体现灾害不同阶段的出租车流量和行程时间变化特征,极端天气对城市路网的影响存在显著时空异质性.确定可达性指标的适用条件有助于评估灾害下的路网性能和指导灾后重建工作.

The performance of various accessibility indices under extreme weather conditions was examined.Utilizing the Hansen accessibility index and taxi trip data from Manhattan during Hurricane Sandy,five types of accessibility indices were compared,focusing on attraction coefficients and impedance functions.The analysis included pre-disaster,during-disaster,and post-disaster accessibility in Manhattan,considering both temporal and spatial dimensions.Comparative findings indicated that demand attraction coefficients reflected the impact of disasters on travel distance,and aligned more effectively with taxi traffic flow changes during disaster scenarios than population-based coefficients.The absolute values of the Pearson correlation coefficients for the three types of impedance function accessibility were all above 0.8,albeit with varying degrees of accessibility.The gravity-type or the hybrid-type impedance function was found to offer a more realistic assessment of accessibility levels during disasters compared to the cumulative opportunity-based functions.Experimental results showed that the demand attraction coefficients and the gravity-type impedance functions captured the variations in taxi traffic flow and travel time characteristics during different disaster stages,while a significant spatiotemporal heterogeneity of extreme weather impacted on the urban road networks was observed.Identifying the applicable conditions of accessibility indices contributes to evaluating road network performance during disasters and guiding post-disaster reconstruction efforts.