Based on the first successful application of new prefabricated technology in underground metro stations on line 2 of the Changchun Metro in China, a comprehensive analysis and discussion on research strategies for new prefabricated technology for large underground structures is provided. This paper introduces the application status of prefabricated technology in underground engineering worldwide, illustrates the different characteristics of prefabricated technology applied to ground buildings and underground structures, puts forward the key technologies, and compares the major technical, economic, and social benefits achieved. The successful application of prefabricated technology for underground structures in Changchun Metro demonstrates the feasibility and great advantages of the new prefabricated technology for underground engineering.

Intra-city mobility affects the well-being of city dwellers and the quality of urban life. A highly sophisticated and sustainable mass rapid transit system is key to facilitating such mobility. Metro Rail is one such successful system suitable for Indian conditions. A network of around 425 km is under operation and about 700 km is under fast track implementation in various cities (MoHUA in Annual report 2017–2018, Government of India, 2018). On the other hand, Metro Rail is an expensive form of urban transport, so any non-viability can leave the public transit agencies and the government in huge debt towards repaying the loans with which the system has been funded. In this context, achieving viability and long-term sustainability becomes mandatory for metro systems; such viability can be achieved by thorough performance assessment and benchmarking of the system in conventional and sustainable dimensions. Though institutionalization of benchmarking is practiced globally, few such efforts have been attempted in India. This study attempts to develop a mode-specific benchmarking framework for metro systems, structuring nine performance indicators (criteria) and 34 evaluators (sub-criteria) with a case study of Mumbai. Multi-criteria decision making techniques such as the analytic hierarchy process and direct weighting are engaged to incorporate a priority-based weighting system into the benchmarking framework. As the performance is benchmarked against set targets (absolute benchmarking), vagueness associated with the scaling/ranking is addressed through the fuzzy logic approach. Finally, the rate of performance of the Mumbai Metro Rail system is determined as 75% with acceptable results in the service, quality and societal sectors, though much improvement is needed in the sector of multimodal integration.

Inefficient transport systems impose extra travel time for travelers, cause dissatisfaction and reduce service levels. In this study, the demand-oriented train scheduling problem is addressed using a robust skip-stop method under uncertain arrival rates during peak hours. This paper presents alternative mathematical models, including a two-stage scenario-based stochastic programming model and two robust optimization models, to minimize the total travel time of passengers and their waiting time at stations. The modeling framework accounts for the design and implementation of robust skip-stop schedules with earliness and tardiness penalties. As a case study, each of the developed models is implemented on line No. 5 of the Tehran metro, and the results are compared. To validate the skip-stop schedules, the values of the stochastic solution and the expected value of perfect information are calculated. In addition, a sensitivity analysis is conducted to test the performance of the model under different scenarios. According to the obtained results, having perfect information can reduce up to 16% of the value of the weighted objective function. The proposed skip-stop method has been shown to save about 5% in total travel time and 49% in weighted objective function, which is a summation of travel times and waiting times as against regular all-stop service. The value of stochastic solutions is about 21% of the value of the weighted objective function, which shows that the stochastic model demonstrates better performance than the deterministic model.

Although demand responsive feeder bus operation is possible with human-driven vehicles, it has not been very popular and is mostly available as a special service because of its high operating costs due to intensive labor costs as well as requirement for advanced real-time information technology and complicated operation. However, once automated vehicles become available, small-sized flexible door-to-door feeder bus operation will become more realistic, so preparing for such automated flexible feeder services is necessary to take advantage of the rapid improvement of automated vehicle technology. Therefore, in this research, an algorithm for optimal flexible feeder bus routing, which considers relocation of buses for multiple stations and trains, was developed using a simulated annealing algorithm for future automated vehicle operation. An example was developed and tested to demonstrate the developed algorithm. The algorithm successfully handled relocation of buses when the optimal bus routings were not feasible using the buses available at certain stations. Furthermore, the developed algorithm limited the maximum degree of circuity for each passenger while minimizing the total cost, including total vehicle operating costs and total passenger in-vehicle travel time costs.

Monitoring of subgrade settlement in railway and highway helps to maintain traffic safety and reduce infrastructure losses. When an excess subgrade settlement is detected, maintenances of the unqualified subgrade will be processed in time, and early warning of constructions will be processed to prevent the occurrence of safety accident. In this article, a noncontact, real-time, and unattended system based on optical method is introduced to monitor the subgrade settlement remotely. Several high-power infrared LED targets are mounted on the subgrade and they will move as the subgrade subsides. The movements of the LED targets are detected by an optical detection device based on the principle of optical imaging. The displacement data is remotely transmitted to a server for analysis via GPRS. The remote monitoring system has been applied to the monitoring of subgrade settlement of Zhensheng highway in Guizhou province of China in 2014. This technology helped to detect the subgrade settlement that was caused by the construction of Beiyinpo railway tunnel. Four test points on road surface were monitored at a sampling rate every 20 minutes. The effectiveness of the system has been verified by the practical application.