The Influence Of Traffic Network On Population Flow At County Scale

Population mobility is crucial to the sustainable development of urban clusters and can impact their economic and industrial layout,social and cultural environment,population distribution,and structure,and even alter regional urban and town systems’ structure and socioeconomic patterns.Population mobility within urban clusters promotes the flow of information,technology,capital,labor,and other factors,driving regional economic development.However,it can also bring negative impacts such as strained medical resources and employment difficulties.Therefore,a deeper study of interregional population mobility is needed to promote high-quality sustainable development of urban clusters.The development of transportation networks has shortened the spatial distance within urban clusters,strengthened internal connections,and enhanced the mega-cities’ ability to attract populations.However,the impact of different modes of transportation on population mobility varies.Studying the impact of transportation networks on population mobility helps us better understand the laws of population mobility and promote regional economic and social development.The Chengdu-Chongqing economic circle is the largest economic area in western China.The development of this region is of great significance for narrowing the development gap between eastern and western China,and the construction of transportation networks and orderly population flow play a crucial role in the development of the Chengdu-Chongqing region.The level of interconnectivity within the economic circle is constantly improving,and the demand for population mobility within the region is increasing.Guiding rational population flow is conducive to improving the problem of imbalanced development within the economic circle and promoting healthy and sustainable development of cities within the economic circle.There are three main shortcomings in current research.First,existing research focuses mainly on cities at the prefecture level and above,with relatively little research on population mobility at the county level.Second,when studying the impact of transportation networks on population mobility,distance impedance is mainly calculated based on geographical distance and highway travel time,with a lack of research on comprehensive travel time based on both highways and railways.Third,research on the impact of transportation networks on population mobility rarely considers the influence of both transportation links and impedance.This study proposes a set-based travel time model based on mobile signaling population flow data,passenger car transportation data,railway train data,statistical yearbook data,and geographic spatial data.This model is used to calculate comprehensive travel time based on highways and railways and to construct a transportation impedance network.Complex network methods are used to study population flow network characteristics and transportation link network characteristics.The gravity model and exponentialfamily random graph models(ERGMs)are used to study the impact of transportation impedance networks and transportation link networks on population flow.The main research results are as follows:(1)Population movements have formed two population flow centers in the central urban areas of Chengdu and Chongqing.Population movements are mainly between neighboring counties within the province,and administrative boundaries at the prefecture level have less impact on population movements than those at the provincial level.As the geographical distance increases,population movements gradually decrease.The characteristics of population movements also vary with the date.During weekdays and weekends,population movements mainly occur within urban subgroups,with short travel distances,while during holidays,population movements involve more long-distance and cross-regional movements.(2)The impact of permanent population and GDP on population movements is inconsistent.Cities with higher GDP have a greater attraction to population inflows,and permanent population is negatively correlated with population movements.Among economic factors,the proportion of the secondary industry has a significant negative impact on population outflow,in addition to the total GDP.(3)Time and geographic distance have a greater impact on population movements than provincial administrative boundaries,GDP,and population size,and are only weaker than the influence of the proportion of the secondary industry in the population outflow network.In ERGMs,the comprehensive travel time based on highways and railways has the strongest inhibitory effect on population movements,followed by highway travel time,and geographic distance has the weakest inhibitory effect,indicating that the comprehensive travel time based on highways and railways can better represent the distance impedance between cities.This is consistent with the fitting performance of the gravity model,where the three distances are treated as resistance.The structural characteristics of the transportation network have limited effects on the fitting of the gravity model,and in ERGMs,the influence of the transportation network on population movements is not significant,indicating that the influence of the transportation network on population movements still lies in the impedance network based on comprehensive travel time based on highways and railways.