Security System Application Trends in Traffic Construction

At present, China's urban rail transit is in a period of rapid development. From 1995 to June 2008, a total of 20 cities in 10 cities were put into operation in 12 years, and the operating mileage reached 730 km. According to incomplete statistics, the total planned length of the urban rail transit network in 15 cities including Beijing, Shanghai, Tianjin, Guangzhou, Shenzhen, Wuhan, Nanjing, Chongqing, Changchun, Harbin, Shenyang, Hangzhou, Xi’an, Chengdu and Suzhou amounts to 1,700 km. The total investment is 600 billion yuan. The 15 cities' network planning has been approved by the state from 2003 to 2007. With such a huge market for urban rail transit construction, what are the new applications and development trends in the security system? This article will be a tentative analysis and introduction.

Existing methods and systems for ensuring subway construction safety and on-site management mostly employ manual line inspections to indirectly understand the specific conditions of the construction and the conditions of the line intervals, and use this as a basis for construction scheduling and control. In fact, there are many factors that affect subway construction and site management. Except for the main factors of on-site construction and interval driving, such as lines, bridges and culverts, contact networks, natural environments, train conditions, construction personnel, crossings, access channels, and public security, etc. The status of the project is directly related to the safety of subway construction and site management.

Obviously, it is difficult for the original methods and techniques to carry out comprehensive and comprehensive supervision and supervision of the above factors. Security accidents caused by these factors often occur, construction workers are difficult to manage, and construction materials are stolen and lost. The use of video surveillance technology can provide comprehensive, detailed and intuitive supervision of all aspects of subway construction, so that the relevant personnel can timely understand the actual situation of the production site, especially in the event of an accident, the accident site information can be quickly transmitted to the relevant departments, To make it possible to comprehensively and accurately understand the actual situation and take timely and correct measures to ensure the safety and efficiency of subway construction.

Subway construction itself often has a monitoring system, which effectively monitors the deformation, settlement of buildings, pipelines, surface and road within 30m from both sides of the outer edge of the structure along the project. It integrates a large amount of monitoring information. (monitoring instrument data, monitoring data, basic geographic data, related thematic maps, basic image data, construction progress data, etc.), and a large number of calculation data (such as the crude difference test and the calculation of the data obtained from the outdoor observations and the calculation of the difference). The video surveillance system often exists as a module of the surveillance system, so it needs to solve the interface problem with the surveillance system.

Subway construction has the need for monitoring of line lengths and spreads, and as the construction surface continues to shift, monitoring video collection points also need to continue to move forward. Adopting digital video and wireless network transmission technology is a better solution. Tiandi Weiye Company With many years of experience in working with telecom operators, we have timely launched a 2.5G and 3G wireless network video site monitoring solution that solves the problems encountered during construction.

First, the multi-level networking structure of the security system is an inevitable trend of urban rail transit management. By the beginning of 2009, the operating routes in Beijing and Shanghai reached 220 km and 236 km, respectively. According to the 2008-2015 plan, Beijing will have 13 urban rail lines, more than 200 subway stations and 561 kilometers of operating distance. Shanghai will have 18 urban rail lines, more than 300 subway stations and 510 kilometers of operating distance. In addition, major cities have all launched their own large-scale urban rail transit network plan. According to the average of 40 video monitoring points for each subway station, 2 video monitoring points per car, and 1 video monitoring point every 200 meters along the tunnel, a large-scale urban rail transit security system will have tens of thousands of video surveillance. point. How to make a unified, flexible, and centralized management of this huge security system is called the giant challenge faced by urban rail operators, public security departments, and government management agencies.

Video surveillance for urban rail transit security systems usually consists of two parts: dedicated video and public security video. The dedicated video surveillance system provides visual information on train operations, disaster prevention and environmental control, and passenger guidance to the line control center dispatcher, station control staff, etc., enabling them to observe the train access station, passenger flow dynamics and related The operation of the equipment can achieve the purpose of effectively organizing and commanding passenger transportation work and directing rescue operations. At the same time, in view of the continuous occurrence of terrorist incidents on the subway worldwide, the public security department must also increase the public security video surveillance system in the subway for the public security department to maintain daily security. Handling sudden crimes. Now, with the development of video surveillance technology, the two parts are often unified on an integrated monitoring platform to reduce duplicate monitoring points and equipment construction. With the demand for networked operations, video surveillance systems as an important means of coordinated operation and command of networked operations and the necessary means for preventing terrorist incidents and handling emergencies, the establishment of a multi-level command and management system is the first problem that the system needs to face. .

According to the application requirements of the video system under networked operation, the newly-built subway video surveillance system should develop into a multi-level network including station-level monitoring, line-level monitoring, network-level monitoring, and municipal monitoring.

Station level monitoring: including local monitoring of stations, vehicles, depots, etc. Currently, it is mainly station monitoring. It is generally composed of cameras, video matrix (switching equipment), display equipment, etc. Each image signal is collected and processed by video processing. The video signal, one way video signal is transmitted to the remote line control center, and the other channel video signal is sent to this station video switching matrix for use by the station traffic command personnel and the public security staff on duty.

Line-level monitoring: Each station of each line will send image information through optical transmission equipment to the line control center, providing image display to traffic dispatchers, power dispatchers, disaster prevention dispatchers, dispatching directors, and police dispatch operators. And control. The general line control center has the ability to display multi-channel video information. The center has any option and camera control right for each channel.

Network-level center: The video signal of each line is transmitted to the subway network monitoring center and the public security monitoring center for use by the network-level command and dispatch personnel, and provides remote image routing and image control functions. As metro line monitoring centers in major cities currently use relatively centralized or decentralized settings, it is necessary to establish a corresponding network platform in order to establish a networked monitoring center.

City-level monitoring: According to the requirements of each city's traffic linkage command, the monitoring image of the subway needs to be transmitted in real time to relevant municipal emergency centers and other departments.

2. In-vehicle video surveillance will become an important part of the urban rail transit security system. The urban rail transit system will be a mobile and highly concentrated public place. Insecurity factors such as crowded people give criminals an opportunity to steal and rob. Such crimes occur from time to time, so it is necessary to strengthen the video surveillance of urban rail transit. Urban rail transit video surveillance includes two parts: station monitoring and train monitoring. At present, video surveillance systems are installed in urban rail transit stations in major cities in China. In general, cameras are installed in stations and station halls to achieve station monitoring; however, urban rail transit train monitoring has just started in China. In order to prevent the occurrence of urban rail transit emergencies, implement the scientific concept of development and the people-centered concept, ensure the safety of people's travel by vehicles, and actively develop the urban rail transit train video surveillance system, which is currently an urgent and important task of urban rail transit trains. There are two main goals to be achieved in the video surveillance system: First, real-time video surveillance of each compartment in the driver's cab is implemented to facilitate the driver to respond quickly to emergent situations in the compartment; and secondly, to realize the urban rail transit control center and The adjacent station's real-time monitoring of the running train cars enables the control center to understand the site situation at the first time and quickly make overall instructions and solutions. Therefore, the train video surveillance system will include monitoring and transmission within the vehicle, and the control center will monitor two parts.

The most important function to be implemented in the on-board part of the train video surveillance system is to transmit the video data acquired by the front-end equipment (cameras) of each car to the train driver's cabin in real time, displayed by the monitor and stored in the storage medium. The train is formed by connecting several cars. The electrical connection between the cars is achieved through a jumper cable connector (usually an aviation plug). The use of a connector actually creates a "breakpoint" in the transmission line, taking into account the loss caused by the "breakpoint" to the transmission and the limited space of the connector itself, the cable passing through the connector when building the communication and transmission system on the train. Must be as small as possible. Therefore, it is very important to choose the proper video transmission method in the vehicle part.

To realize the real-time monitoring of the running train cars in the urban rail transit control center, the real-time transmission of the video surveillance images in the train cars to the control center during the running must be realized through wireless transmission, and the vehicle wireless network must be constructed to realize the video. Image transmission.

There are many kinds of wireless transmission technologies, such as 3G mobile communication system, wireless local area network (WLAN), broadband wireless network (WIMAX), and so on. Through comprehensive comparison, selecting a high-speed wireless local area network (WLAN) is a relatively mature solution.

Each wireless bridge in the vehicle-to-ground wireless transmission platform is configured with a certain IP address, and the vehicle-mounted wireless bridge and the interval wireless bridge establish connection through wireless signals. There is an on-board wireless bridge in the driver's cabs at both ends of the train, one for the main and the other for the spare. The selection of wireless bridges depends on the characteristics of the manufacturer's products. It can be a front working mode or a rear mode. During the operation of the train, the on-board wireless bridge needs to establish contact with different terrestrial wireless bridges according to the strength of the signal, generating roaming and switching.