This study employs prevalent international statistical standards to categorize urban rail transit into three types: metro, light rail, and tram. It presents a comprehensive statistical analysis of the current state of urban rail transit systems across the globe. As of the close of 2023, urban rail transit systems have been established in 563 cities spanning 79 countries and regions, with a cumulative track length exceeding 43,400.40 km. Subways, light rails, and streetcars account for 50.07%, 10.69%, and 39.24% of the total length, respectively. Notably, as of December 31, 2023, 66 cities in China (including Hong Kong, Macao, and Taiwan) have commenced rail transit operations, boasting a combined operational track length of 11,900.29 km, with Chinese mainland alone contributing 11,232.65 km to this total. In 2022, the metro systems in 183 cities across 59 countries globally handled a total of 58,652 million trips of passengers, representing an average ridership intensity of 0.81 trips per day per kilometer. Specifically, China's metro systems (including those of Hong Kong, Macao, and Taiwan) registered an annual passenger traffic volume of 21.251 billion trips. The study underscores the steadfast advancement of China's urban rail transit systems, which consistently lead the world in both network scale and passenger traffic. Through an indepth analysis of data subsequent to the release of Document 52 by the State Council, this study anticipates a resurgence of lowcapacity urban rail transit systems, particularly streetcars, in Chinese mainland, especially in the central and western regions, in a bid to drive environmentally sustainable urban development. Further, by drawing on data from major countries and cities worldwide, both preand postpandemic, the study predicts a return of passenger traffic in Chinese mainland to prepandemic levels by 2024-2025.

Addressing shortcomings in the current customer service system, including low awareness of passenger service needs, limited service channels, high costs, and inefficient operation control, this study starts by examining highquality and efficient travel demand in the modern era and analyzing diverse passenger group travel needs. We advocate for new service goals centered on timeliness, convenience, accuracy, and proactivity. The proposed smart passenger service architecture for urban rail transit embraces the multitude of online and offline demands, overcoming existing system limitations in data integration, equipment platform unification, service quality, and efficiency. Emphasizing adherence to passenger service schedules, it also prioritizes efficient lastmeter service delivery. By showcasing representative Beijing subway lines, we present a replicable technological system and application model that can comprehensively enhance the intelligent service and management processes of China's urban rail transit system.

This paper provides a comprehensive overview of Chinese mainland's urban rail transit development in 2023. By the end of the year, 28 provinces and 59 cities had 338 urban rail transit lines in operation, spanning 11,232.65 km. Subway lines made up 76.10% of this length, with 8,547.67 km, followed by fully automatic operation (FAO) lines with 9.37% and 1,052.43 km. The network expanded by 884.55 km in 2023, with 53 new lines (or sections) opening, including 539.50 km of subway lines and 252.79 km of FAO lines. The new lines involved 7 different system types and 30 cities, 3 of which inaugurated their first urban rail transit systems. In 2023, Chinese mainland's urban rail transit network also set a new record of annual passenger volume, surpassing 80 million passenger trips per day on average.

The subway engineering department regularly operates track inspection vehicles to detect the state of the tracks, which is crucial for residents' safe travel. The operational path of track inspection vehicles mainly relies on expert judgment, which is not only a timeconsuming practice but is also ineffective. To address the shortcomings of the current lack of systematic planning for the operational paths of track inspection vehicles, this study, set against the backdrop of the urban rail transit network, constructs a largescale subway inspection vehicle routing optimization model named Urban Track Inspection Vehicle Routing Problem (UTIVRP), under the conditions of a complex network. Considering the characteristics of subway networks, a cultural genetic algorithm with a special encoding method is designed and validated using practical examples from the Beijing subway. The computational results indicate that under the conditions of meeting the established inspection requirements, the optimization solution can not only reduce the idle mileage of vehicles by 48.88%, but also decrease the maximum deviation rate of the network's inspection interval by 93.33%.

Field experiments and simulation analyses were conducted on a Kaifengsuspended monorail demonstration line to evaluate the service performance of rubbertire suspended vehicles and steel guideway bridges and provide appropriate criteria and operating and design parameters for this type of vehiclebridge system. A rubbertire suspended trainsteel and guideway bridge coupling analysis program was developed. The vehiclebridge coupling model was built according to the measured parameters, including the stiffness and damping of the pneumatic spring and travel wheels. The calculated and measured dynamic responses of the vehicle and bridge were compared. The dynamic performance of the vehiclebridge structure was evaluated based on the calculations and related specifications. The results show that 1) it is feasible to use the vehiclebridge coupling simulation method to investigate the structural vibration performance of a suspended monorail system; the simulation results were consistent with field measurement results; 2) the ratio of the vertical deflection to the span of the steel guideway girder was less than the limit given in the specifications and the vertical stiffness of the structure was reasonable; 3) the maximum vertical and lateral rotation angles between two adjacent beams at the beamends were 4.5‰ and 1.5‰, respectively; 4) the maximum dynamic factors of longitudinal and lateral stress of the steel guideway beam were 1.17 and 1.14, respectively, at a vehicle speed of 80 km/h; 5) the unloading factor of the wheel and lateral acceleration of the guideway bridge were larger than those of conventional railway systems; the limits of these two indices could be set higher than in the current railway specifications as the suspended trains were unlikely to derail.