An Energy Efficient Train Dispatch and Control Integrated Method in Urban Rail Transit

Regenerative braking technology has been widely used in metro train control. Improving the utilization of regenerative braking energy (RBE) can reduce the energy consumption of metro transit system. A novel train trajectory optimization method is proposed, in which control regimes coasting and maximum acceleration (CO-MA) are inserted according to the substation power flow. MA regime is inserted when the substation power is negative, which means there is REB can be used. CO regime is inserted to connect the trajectory and adjust the runtime. Improving the utilization of RBE according to the substation power flow makes the control optimization of trains independent, which can avoid the complex cooperation of multi-train control. A case study based on Guangzhou subway line is studied, and the results show that the proposed method can improve the utilization of RBE and reduce substation energy consumption efficiently.

Capacity configuration optimization of regenerative braking energy utilization system for electrified railways based on power sharing and energy storage

The delays of trains have serious impact on the efficiency of operation, and on the passenger satisfaction which reduces the quality of service. The quality of service needs to be enhanced and the energy saving is drawing more and more attentions. In this paper, the authors propose an energy-efficient adjustment approach to mitigate the delays of trains, and to decrease energy consumption, simultaneously. To reduce energy consumption, energy-efficient operation strategies are considered. The authors seek the best coasting point to decrease the tractive energy. And the authors optimize the overlapping time of accelerating phase and braking phase for contiguous trains to increase the utilization of regenerative braking energy. Finally, the simulation is presented to show the proposed approach. The authors illustrate that the current adjustment approach could result in unnecessary energy consumption. By contrast, the authors approach can observably mitigate the delays of trains, and provide better energy-efficient effect.

Urban rail transit (URT) develops rapidly in modern cities, and its energy efficiency attracts extensive attention. The utilization of regenerative energy (URE) is an important method for energy-efficient operation of URT. Regenerative braking is an energy recovery mechanism that slows down a moving train by converting its kinetic energy into electric energy. The electric energy can be utilized for other trains to accelerate in a cooperative way. To take full advantage of the regenerative energy, an energy calculation method which considers regenerative braking power to optimize the timetable is proposed in this paper. First, four operating modes of URE are defined and an integer programming model is formulated. Second, a branch and bound algorithm is designed to solve the optimal timetable in different scenarios. Third, the model is evaluated based on the operation data from the Yanfang Line, Beijing Metro, China. For peak hours, the results illustrate that the proposed method can significantly improve URE by 73.7% compared with the original timetable. Also, URE can be improved by 46.3% for off-peak hours. Finally, the comparison between the proposed method and the method based on the kinetic energy theorem is given. The simulation results illustrate that the proposed method could increase URE by 29.7% and 9.9% for peak and off-peak hours scenarios, respectively, in comparison with the method based on the kinetic energy theorem.

Rational planning for the underground space development in subway station areas, in coordinate with the urban rail transit development, has positive impacts on the sustainable development of cities. This paper induces the space syntax method for calculating the quantitative accessibility index of the urban rail transit and detects the coordination between urban underground space use intensity and rail transit system of the 7 selected subway lines in Tokyo. The results show that the station areas with higher accessibility index are the same sort with higher underground space use intensity. This means that the space syntax method is suitable and feasible for calculation of the quantitative accessibility index of subway lines. The higher the accessibility index is, the more underground space will be needed potentially in future. The areas with high accessibility of subway lines and low intensity of public underground space develop are the key districts under potential exploitation of underground space.

During the rapid development of urbanization, many huge cities are in the sensitive period that adjustment of urban spatial structure should be brought about with transport. Through dissecting Shanghai URT's development process, the interaction between URT and urban spatial structure is focused on in this paper. On the one hand, URT and urban spatial development form are mutual restricted; on the other hand, URT will promote the benign development of urban space, to form a layout of bead-shaped radial axis, and to avoid the negative overspread of a pie-type mode. For the oversize cities (such as Shanghai, Beijing, Guangzhou, etc) with strong economic power, after completing of URT' network layout in central areas, traditional mindset of transport planning should be changed, and the mode of TOD (Transit Oriented Development) should be adopt, thereby to achieve the object of coordinate development between a URT's network and a urban spatial structure in a city. Road area capita is lower in many major cities of our country, and service level of road is far below the traffic demand of motor vehicles. With a rapid growth of ownership of urban motor vehicles, traffic jams in Beijing, Shanghai, Guangzhou, Shenzhen, Wuhan and other major cities got worse. During 2010 in Beijing, the heavy congestions on Mid-Autumn Festival and National Day showed a warning sign that Beijing's road system serviceability couldn't afford the rush hour traffic demand. Therefore, developing of public transport, especially the URT (urban rail transit) system with features of mass transit, high speed and high efficiency, is the inevitable choice of solving major cities' traffic problems, and has showed a principal measure to form a perfect urban spatial structure with lower traffic congestion under the condition of limited urban land and transport resource. URT is safe, reliable, fast, and low-pollution. Due to the characteristics of high volume, fast and timely, it can provide the good accessibility of areas along the line and ensures people to travel further in as short as possible time. In other hand, it provides a strong transport support for the adjustment of the major cities' space layout and the expansion of urban built-up areas. Evolution of urban spatial form is the incorporated evolution of land and transport. Reference from the valuable experiences of development of urbanization

The construction and circulation of railways, especially urban rail transit, change the travel patterns of residents along the lines and provide convenience for residents in outer suburbs to enter the city center. At the same time, urban rail transit will likely have an impact on the social structure and types of residents in the area. This paper explores the urban gentrification caused by railways in mainland China, covering the old city renovation plan, demolition along the subway line, subway line terminus, and other perspectives. The findings show that with the development of urban rail transit, land prices in the area will increase and communities will become gentrified, which means possible crowding out of low-income citizens. This article intentionally explores the relationship between the subway and gentrification.

A synergistic energy-efficient planning approach for urban rail transit operations

As the scale of development continues to expand, carbon emissions of urban rail transit (URT) in China have gradually increased each year, posing certain pressure on the carbon emission reduction efforts in the URT industry. To evaluate the current status of low-carbon development in the URT industry, this paper first constructs an annual carbon emission accounting model for URT that considers both the construction and operation processes. Based on this model, the annual carbon emissions of URT in China from 2015 to 2023 are calculated. Furthermore, based on decoupling theory, the relationship between carbon emissions and industry development in URT is explored from both the construction and operation aspects. The results show that: (1) From 2015 to 2023, the total carbon emissions of URT in China increased significantly from 14.425 million tons to 24.7072 million tons. The proportion of carbon emissions from construction is higher during the study period, but the growth rate of carbon emissions from operation is faster. (2) The order of carbon emissions from URT in different regions from largest to smallest is: East > West > Central > Northeast. (3) During the study period, the carbon emissions from URT construction in China were weakly decoupled from the operational lines. (4) There was an expansive coupling relationship between carbon emissions from URT operation and passenger transport turnover in China. These findings can provide some guidance for the sustainable development of the URT industry.

To obtain an operation curve of a train with minimum energy-consumption and improve the utilization of regenerative braking energy without changing equipment and infrastructure, this paper proposes a new optimization method of energy-saving for a train based on an improved chicken swarm optimization algorithm after analyzing the calculation method of energy-consumption for a train and improving the chicken swarm optimization algorithm. On this basis, this paper establishes an optimization model of energy-saving for a train by taking minimum energy-consumption, accurate stopping and punctuality as optimization objectives, and solves the model with the improved chicken swarm optimization algorithm. Finally, a simulation analysis for the method proposed in this paper is performed by using MATLAB software with the running parameters of Nanning metro line 1 in China. The results of the simulation analysis show that the method proposed in this paper is effective in solving the optimization problem of train energy-saving.

With the increasing energy consumption in urban rail transit systems, energy-efficient train operation has been paid significant attention. Considering the application of regenerative braking technology, many studies focus on offline energy-saving train trajectory optimization, in which an accelerating regime is inserted into the train trajectory when there is regenerative braking energy (RBE) that can be utilized. However, in practical operation, train states are dynamic and scheduled trajectory might be useless. This paper proposes a real-time cooperative train control method based on Train-to-Train (T2T) communication technology. According to the train states transmitted through T2T communication, whether there is a train in braking regime is judged. Besides, an accelerating regime is inserted by changing train running modes when there is another train in the braking regime. A cooperative control algorithm is developed to achieve the energy-efficient cooperative control strategy. Besides, simulations based on a real-life metro line demonstrate that the proposed cooperative control method can reduce substation energy consumption and improve the utilization of RBE.

With the rapid development of urban rail transit, the traditional urban rail wireless network based on fixed infrastructure is not in a position to meet the increasingly complex communication demand. At the same time, Ad Hoc network, as a special wireless mobile network, is developing rapidly. Applying this self-organized networking architecture to the urban rail vehicle–ground communication network can overcome the problems existing in the traditional urban rail communication system. The routing protocols that can achieve low delay and highly reliable data transmission are important in the urban rail transit scenario. Therefore, combined with the wireless Ad Hoc network and the characteristics of the urban rail transit scenario, this paper proposes a dynamic addressing hybrid routing mechanism based on static configuration. Using an improved AODV routing discovery algorithm and then writing the routing table into the router in advance for static configuration not only reduces network overhead but also prolongs the network’s lifetime. It also saves the delay of routing discovery. Then, the cluster head node dynamically monitors the link status, dynamically finds the path when the link needs to be replaced, and selects different update paths according to different types of communication services. Finally, each algorithm’s network performance parameters, like the routing discovery overhead, residual link lifetime, packet delivery rate, throughput, and end-to-end delay, are analyzed and compared.

The sustainability appeal of urban rail transit

Rapid transit systems play a significant role in supporting rapid social and economic development in large cities all over the world. However, the systems consume a large amount of energy, which brings increasing environmental concerns. A number of energy-saving technologies have been studied on railways. However, few of the outcomes have been tested and evaluated in practice. This paper presents the development of a timetable optimization and trial test on a metro line to reach the full potential of the train regenerative braking system. To achieve this purpose, a timetable optimization algorithm has been developed, and a trial test of the optimal timetable has been arranged on a metro line for a whole day. In the test, all the trains running in the network were organized to operate in accordance with the optimal timetable. The trial test results indicate that by applying the optimal timetable, the regenerative braking energy utilization can be improved, thereby reducing the overall network energy usage.

AC heavy-haul trains produce a huge amount of regenerative braking energy when they run on long downhill sections. If this energy can be used by uphill trains in the same power supply section, a reduction in coal transportation cost and an improvement in power quality would result. To accurately predict the energy consumption and regenerative braking energy of heavy-haul trains on large long slopes, a single-particle model of train dynamics was used. According to the theory of railway longitudinal section simplification, the energy consumption and the regenerative braking energy model of a single train based on the train attributes, line conditions, and running speed was established. The model was applied and verified on the Shenshuo Railway. The results indicate that the percentage error of the proposed model is generally less than 10%. The model is a convenient and simple research alternative, with strong engineering feasibility. Based on this foundation, a model of train energy consumption was established under different interval lengths by considering the situation of regenerative braking energy in the multi-train operation mode. The model provides a theoretical foundation for future train diagram layout work with the goal of reducing the total train energy consumption.