Breaking through key technologies and entering the high-speed track through urban rail construction

Urban rail transit has a huge impact on promoting urban structural adjustment, urban layout integration, land development and utilization, as well as the sustainable development of cities and transportation. The picture shows the underground space complex of Wuhan Optics Valley Square planned and constructed by China Railway Fourth Engineering Group Corporation.

With the rapid development of rail transit in China, it has also penetrated into all aspects of urban economic construction. The construction of rail transit not only promotes the change of urban commercial structure and enhances the value of real estate along the line, but also drives the migration of industrial land to the suburbs, greatly improving the urban environment.

The planning and design of urban rail transit systems directly affect the basic layout and functional positioning of cities, and have a strong guiding effect on urban development. "When discussing this topic, independent analyst Xu Hong told reporters that urban rail transit has a huge impact on promoting urban structural adjustment, urban layout integration, land development and utilization, as well as the sustainable development of cities and transportation.

It is precisely because urban rail transit plays such an important role that builders must continue to make breakthroughs in core technology fields in order to make urban rail transit construction "fast and stable". Recently, reporters learned from China Railway Fourth Survey and Design Institute Group Co., Ltd. (hereinafter referred to as "China Railway Fourth Survey and Design Institute") that the institute, led by "smart urban rail", has created and formed eight innovative technologies, including TOD development, fully automatic operation, prefabricated intelligent construction, intelligent operation and comprehensive monitoring, and urban underground large space, leading urban rail construction into a high-speed development track.

Green development has become a new trend in urban rail construction

As of the end of 2022, the operating mileage of Wuhan Metro has reached 435 kilometers, ranking fifth in China and top ten in the world. However, as the subway network becomes increasingly complex, the narrow underground working space, high pollution emissions, extensive construction methods, and high labor demand have become challenges that constrain subway construction.

In August 2022, the scorching sun shone brightly. The construction site of the No. 2 air shaft in the Tangma section of the Qianchuan Line of Wuhan Metro is bustling with extended arm excavators, transport vehicles, and other vehicles shuttling back and forth, creating a bustling scene of construction.

During the operation of the No. 2 air shaft in the Tangma section, we adopted the prefabricated hollow steel pipe concrete support technology to successfully complete the construction work of the foundation pit, which is the first technology in the country. "Xu Junlin, Deputy Chief Engineer of the Fourth Iron and Steel Institute, introduced that after calculation, compared to traditional cast-in-place concrete support, the prefabricated technology can reduce carbon emissions by about 75%, significantly reducing the impact on the environment.

The reporter learned that in recent years, the country has vigorously promoted prefabricated building in civil construction on the ground, and the Fourth Railway Research Institute took the lead in trying to develop a complete set of technologies for assembly and superposition design and construction of underground stations in China. It is reported that in the face of the urgent need for industrial modernization, Tiesiyuan has used the BIM collaboration platform as a means to predict and optimize the construction process and technology. At the same time, laser technology has been introduced to build an intelligent lifting collision prevention warning system, achieving intelligent manufacturing throughout the entire process of design, production, construction, etc.

Xu Junlin said that this technology, combined with the research on the assembly integration scheme of architecture, decoration, pipeline, etc., aimed at standard design, modular collaboration, integration and informatization, and took the BIM collaboration platform as the means, introduced the three-dimensional dynamic simulation technology to simulate the whole process simulation of assembly and construction, and predicted and optimized the construction process and process; At the same time, laser technology is introduced during the construction process to build an intelligent lifting collision prevention warning system, achieving information exchange in design, production, construction, and other aspects, and comprehensively improving the intelligent construction technology of prefabricated underground stations.

We have developed a prefabricated pavement paving system, which can choose different types of paving according to different spans, solving the problems of cast-in-place concrete paving. We have also developed an integrated comprehensive support system, subway assembly slab track system, as well as prefabricated platform slabs, prefabricated stairs, prefabricated supports, prefabricated rail top air ducts, and other supporting equipment and machinery. At the same time, we have also developed prefabricated construction equipment and machinery, "said Xu Junlin.

According to the plan, the future prefabricated intelligent construction technology will also be promoted and adopted in multiple cities such as Wuhan Metro Line 3 Phase II Project, Wuxi Metro Line 5, Jinan Metro Line 8, and Shenzhen Metro Line 15.

In addition to promoting the prefabricated construction model to reduce costs and increase efficiency, and continuously promote green development, the builders of China Railway Fourth Design and Research Institute also continue to innovate in various stages of urban rail operation, focusing on creating a "green subway" throughout its entire lifecycle through energy management systems.

As is well known, one of the key guarantees for the operation of fully automatic urban rail trains and stations is electricity. With the formation of the rail transit network, the total electricity consumption has significantly increased, and reducing operational energy consumption and total electricity consumption is an urgent need to achieve sustainable development.

Therefore, taking advantage of the advantages of the Comprehensive Design Institute, China Railway Fourth Design Institute has been deeply cultivating and optimizing energy-saving strategies for many years. In collaboration with well-known universities and equipment manufacturing enterprises, it has developed the Urban Rail Transit Energy Intelligent Management System (UIEMS), becoming the first urban rail transit energy intelligent management system in China to achieve dynamic energy-saving control of major energy loads such as traction systems, HVAC systems, and lighting systems.

He Bin, Deputy Chief Engineer of the Electrification Institute of China Railway Fourth Engineering Group Corporation, introduced that the system is based on data monitoring and establishes a hierarchical energy consumption evaluation system for the three major energy consumption systems (traction, HVAC, and lighting) that occupy nearly 80% of the iron energy consumption area. This provides a quantifiable evaluation basis for energy consumption indicators and achieves dynamic optimization of energy consumption.

It is understood that the electrical energy sent by the power plant through the power transmission line is converted into the voltage suitable for the train and distributed to the contact rail location, which is called a traction substation. He Bin revealed that by using the urban rail energy intelligent management system, the previously independent traction substation system can be uniformly regulated, which can save about 5% of energy.

At the same time, the urban rail energy intelligent management system installs CO2 sensors and humidity temperature sensors in various public areas of the subway, sensing the temperature and density of the environment in real time. Combined with the station environment, it analyzes the adjustment needs and dynamically adjusts according to environmental changes, achieving "more people blow, less people blow", which can save about 8.8% of energy.

The urban rail energy intelligent management system is also equipped with illuminance sensors and human body sensing sensors to sense changes in illuminance and density of pedestrian flow. It comprehensively considers natural light and advertising lighting, and adjusts the lighting illuminance in real-time. Based on the situation of trains entering and exiting the station, lighting needs can be predicted in advance, and the light strip above the shielded door can be adjusted to turn on the incoming lights and turn off the outgoing lights. The intelligent lighting system can save energy by 1.8%, "said He Bin, After using the urban rail energy intelligent management system, the annual carbon dioxide emissions can be reduced by 2.44 million tons in the long term, which is equivalent to about 14000 trees planted each year.

Creating a better riding experience through technological innovation

With the development of cities and the increase in passenger flow, rail transit is facing increasing challenges. In order to achieve efficient, safe, and low consumption operations, fully automatic operation technology has emerged.

At the end of 2021, Wuhan Metro Line 5 was opened, and this Wanghongxian Road is the first subway line in Wuhan to adopt fully automatic driving. Sitting in the subway, you can directly see the scenery outside the window from the front and rear positions, as if riding on a time shuttle.

This is the first fully automated driving route in Wuhan, with an average daily passenger flow of 263800 people. Tiesiyuan has implemented 108 full scenario applications on Metro Line 5, and has proposed automatic coupling and decoupling scenarios for the first time in the country.

It is reported that 24 fully automated lines have been opened in 14 cities across the country, with a travel distance of 500 kilometers. Among them, 5 lines from China Railway Siyuan have achieved unmanned driving, and the "Metro Line 5" has become a popular online route for citizens and tourists to "check in".

"The key to ensuring the automatic operation, accurate parking, safety and stability of trains lies in the train operation control system. This is the 'central nervous system' of train operation." Liu Tao, deputy chief engineer of the Communication Signal Research Institute of the Fourth Railway Research Institute, introduced that as early as 2013, the Fourth Railway Research Institute established a fully automatic operation technology research team, which is an earlier research team tracking this technology in China.

After years of exploration, China Railway Fourth Research Institute has developed a series of fully automated operation technology specifications, defined 108 subway fully automated operation scenarios, and created 1085 technical requirements. After fully automatic operation technology, compared with traditional lines, the failure rate of Wuhan Metro Line 5 has decreased from 1.8 to 0.7 times per million train kilometers, the punctuality rate has increased from 99.89% to 99.99%, and the travel speed has increased from 35 kilometers per hour on ordinary lines to 37.55 kilometers per hour.

In terms of rail transit monitoring, the Fourth Railway Research Institute also took the lead in undertaking the national key research and development plan Research and Demonstration of Key Technologies for Comprehensive Monitoring of Urban Underground Infrastructure Operation, and built a comprehensive monitoring system for rail transit infrastructure operation based on Internet of Things, intelligence and safety.

Liu Tao introduced that the types of fully automatic operation design projects of China Railway Fourth Design Institute cover various systems such as subways, urban areas, straddle monorails, and suspended monorails. They have participated in the design of over 20 ongoing projects and have undertaken the first fully automatic operation project in multiple provinces and cities. They have become the most experienced team in FAO design in China.

It is worth noting that the construction of urban rail transit not only enhances people's travel experience. More and more urban rail stations have become central squares or city centers for citizens' leisure and consumption. By radiating outward from the center of the urban rail station and integrating planning and design of land, transportation, and other related factors, the contradiction between traffic congestion and insufficient land use during urban development can be coordinated. Ultimately, the urban rail station will achieve a "mixed use" that integrates work, commerce, culture, education, and housing.

Tiesiyuan is also well aware of this development trend. According to Liang Tian, Deputy Chief Engineer of China Railway Fourth Engineering Group Co., Ltd., the institute has accumulated eight TOD design technologies, including development planning along the track, urban design around the station, comprehensive development of station city integration, comprehensive development of field city integration, comprehensive transportation hub development, rail transit station development, underground space development, and TOD development of municipal tunnels.

As of 2022, China Railway Fourth Design Institute has undertaken more than 180 TOD design projects in more than 30 cities across the country, including 15 completed projects with an area of 3 million square meters; 53 projects under construction, 6.5 million square meters; More than 110 projects and 10 million square meters are planned.

Under this concept, the underground space complex of Wuhan Optics Valley Plaza, Hangzhou West Station, Hangzhou Qinwang Channel Project, comprehensive development of the upper cover of Hangzhou Wuchang Vehicle Base, Shenzhen Xili Hub, Suzhou Tian'edang Vehicle Depot Upper Cover Development, Huizhou North Station Comprehensive Transportation Hub Supporting Project, and Wuxi Xuelang Vehicle Depot Upper Cover Development are all exemplary works of the "TESIYUAN TOD Integration Plan".

Building subway stations like building blocks and remotely repairing subway tracks... Currently, urban rail transit design and operation and maintenance technology are becoming increasingly advanced. It is precisely through continuous breakthroughs and innovations in technology, as well as continuous roots in urban rail transit, that China Railway Fourth Design and Research Institute can focus on "comprehensive development, smart urban rail transit, green and low-carbon, safety and resilience", and forge an innovative path of high-quality development.