Department of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China.
Engineering and Technology Research Center of Rail Transit Line Safety and Disaster Prevention, No. 3 Shangyuancun, Haidian District, Beijing 100044, China.
Sensors (Basel). 2021 Mar 20;21(6):2179. doi: 10.3390/s21062179.
Urban rail transit (URT) systems are often regarded as the backbone of their respective city. The evolutionary features of URT systems have attracted much attention in recent years, but their evolution and their distinct function in contrast to other transit modes have seldom been investigated, especially quantitatively from the perspective of work-residence separation. Accordingly, we propose a framework for exploring the evolution of URT topological networks and demand-weighted networks, comparing the different impacts of all transit modes on work-residence separation. In this study, a URT passenger flow assignment model was formulated on the basis of travel cost function and an improved logit model was proposed that takes into account the heterogeneity of passengers. This model was used to generate a section load, which is regarded as a weight and able to reflect the residents' demand for travel by URT. Then, the fractal dimensions for a non-weighted network and demand-weighted network are proposed and their indications for transportation explained. Finally, the Beijing Subway System (BSS) is used as a case study by employing fifty years of network data and ten years of smart card data. Using fractal approaches, the different characteristics illustrated by the two networks were investigated and the reasons behind the observed patterns explained. In addition, the spatial features of the rail network, in terms of fractal indictors, were compared with population distribution and urban mobility for all modes, extracted from phone data as a proxy. Thus, the relationship between the residents' travel demand and traffic supply can be revealed to some extent. The main finding of this work is that demand must be taken into account when analyzing the fractal features of a transport network, lest the demand side be separated from the supply and important issues missed such as inconsistencies between demand and supply. Additionally, the role of rail transit in work-home imbalance can be investigated in the context of urban mobility for an entire city.
城市轨道交通（URT）系统通常被视为各自城市的骨干。近年来，URT 系统的演进特征引起了广泛关注，但它们的演变及其与其他交通方式的明显区别尚未得到充分研究，特别是从工作-居住分离的角度进行定量研究。因此，我们提出了一个探索 URT 拓扑网络和需求加权网络演变的框架，比较了所有交通方式对工作-居住分离的不同影响。在这项研究中，我们基于旅行成本函数构建了 URT 客流分配模型，并提出了一种改进的对数模型，考虑了乘客的异质性。该模型用于生成一个路段负荷，作为权重，可以反映居民对 URT 出行的需求。然后，提出了非加权网络和需求加权网络的分形维数，并解释了它们对交通的指示意义。最后，以北京地铁系统（BSS）为例，利用五十年的网络数据和十年的智能卡数据进行研究。采用分形方法，研究了两种网络的不同特征，并解释了观察到的模式背后的原因。此外，还从手机数据中提取了人口分布和所有模式的城市流动性作为代理，比较了轨道网络的空间特征与分形指标。因此，可以在一定程度上揭示居民出行需求与交通供给之间的关系。这项工作的主要发现是，在分析交通网络的分形特征时必须考虑需求，以免需求方与供给方脱节，并错过供需不一致等重要问题。此外，可以从整个城市的城市流动性角度研究轨道交通在工作-家庭失衡中的作用。
