标题： 访问图：一种用于可及性分析的公共交通网络的新颖图表示 显示英文标题

标题： Access graph: a novel graph representation of public transport networks for accessibility analysis

摘要： 可及性，定义为活动空间分散机会之间的旅行阻抗，是公共交通（PT）使用的主要决定因素之一。深入理解其特性对于优化公共交通系统规划和设计至关重要。尽管这一概念已有数十年历史，并且有关可及性操作化和测量的文献众多，但尚缺乏统一的方法。为此，我们引入了一种基于节点间最短路径的公共交通网络的新图表示方法，称为可达图。最短路径通过车辆内时间加权的L空间和频率加权的P空间表示来计算，以确定一般化出行时间。如果两个节点之间的出行时间低于一定的阈值时间预算，则在可达图中存在一条边。在此表示中，节点度直接衡量在预定时间内可到达的节点数量。我们研究了可达图随阈值的变化，重点在于平均度和度分布。基于可达图的拓扑特性，我们定义了一组可及性指标。此外，我们提出了可达性公平性的指标。我们将该方法应用于全球51个地铁网络的数据集。在所有情况下，都观察到平均度随时间预算呈类似逻辑的增长，表明可及性具有普遍行为，并展示了所提出表示方法在统一可及性研究中的价值及其进行比较分析的潜力。我们认为可达图在推动可及性深入研究方面具有巨大潜力。 显示英文摘要

摘要： Accessibility, defined as travel impedance between spatially dispersed opportunities for activity, is one of the main determinants of public transport (PT) use. In-depth understanding of its properties is crucial for optimal public transport systems planning and design. Although the concept has been around for decades and there is a large body of literature on accessibility operationalisation and measurement, a unified approach is lacking. To this end, we introduce a novel graph representation of public transport networks, termed the access graph, based on the shortest paths between nodes. Shortest paths are calculated using the in-vehicle time-weighted L- and frequency-weighted P-space representations to determine generalised travel times. Then there is an edge between two nodes in the access graph if the travel time between them is below a certain threshold time budget. In this representation, node degree directly measures the number of nodes reachable within a predetermined time. We study the threshold-dependent evolution of the access graph, focusing on average degree and degree distributions. Based on the topological properties of the access graph, we define a set of accessibility indicators. In addition, we propose indicators of access equity. We apply the methodology to a dataset of 51 metro networks worldwide. In all cases, a logistic-like growth of average degree with time budget is observed, indicating universal behaviour of accessibility and exhibiting the value of the proposed representation for unified accessibility studies and its potential for comparative analyses. We see a great potential for the access graph to drive in-depth studies of accessibility.