Smart Tunnel Safety Monitoring: Fire, Structure, and Traffic Intelligence
The intelligent tunnel monitoring system is a PLC (Programmable Logic Controller)-centric intelligent tunnel traffic control system. Its hardware mainly consists of a control core, field equipment, data acquisition equipment, and lighting control equipment. The control core includes a main PLC control cabinet and regional PLC control cabinets. Field equipment includes red/cross and green/arrow lane signs, traffic lights, variable message signs, fans, water pumps, gates, surveillance video, emergency broadcasts, and emergency telephones. Data acquisition equipment includes COVI detectors, traffic flow detectors, and illuminance/brightness sensors. Lighting control equipment is used to control enhanced lighting, basic lighting, and emergency lighting.
The software platform is a cloud-based configuration software management system. The system uses a stable and reliable ring network technology bus and PLC redundancy design to connect all traffic electromechanical equipment and sensors into a network, enabling mutual linkage. In addition, the system also integrates fire alarm linkage and accident linkage functions. Overall, this system is a comprehensive smart tunnel solution integrating new technologies such as the Internet of Things, cloud computing, big data, and mobile internet.
The tunnel duplex monitoring system is a landmark project in modern urban construction. It has been successfully implemented in the Shanghai Yan’an East Road Tunnel duplex project, effectively alleviating traffic management difficulties in the Pudong Lujiazui and Puxi Bund areas, and maximizing the safety and functionality of the tunnel. The system has a response time of approximately 30-60 seconds, employing a two-level computer network with a dual-ring optical network at the lower level, resulting in a response time of less than 10 seconds. It includes nine subsystems: power, traffic, CCTV, toll collection, broadcasting, wireless communication, dispatch telephone, fire alarm, and analog display, all operating in a coordinated manner under the unified command of a central computer system. The system comprises power monitoring and data acquisition systems, traffic monitoring and data acquisition systems, dual-machine equipment, modular software design, and an MTBF (Mean Time Between Failures) exceeding 106 hours. Toll collection efficiency has increased by over 30%, operational capacity by 20%, and economic benefits have significantly improved.
1. System Composition
Tunnels are categorized by length as short, medium, and long tunnels. Medium and long tunnels (>250m and >1km) generally require more monitoring facilities and have more centralized monitoring points. Medium and long tunnels are equipped with monitoring systems according to national design standards to ensure traffic safety and smooth flow within the tunnel.
The tunnel’s subsystems mainly include: lighting systems, ventilation systems, traffic guidance systems, CCTV monitoring systems, fire alarm systems, fire control systems, emergency telephone systems, broadcasting systems, and LED display systems. The main control and monitoring hardware involved includes PLC controllers (monitoring ventilation, lighting, fire pumps, lane/traffic indicator lights, etc.), vehicle detectors, luminance/illuminance meters, wind speed/direction meters, carbon monoxide/visibility meters, fire alarm control panels, LED displays, emergency telephones, and CCTV systems.
From the perspective of computer data acquisition methods, they are mainly divided into: PLC real-time monitoring system, CCTV television monitoring system, emergency telephone/fire alarm/broadcast system, LED display system, and emergency plan system. As a computer configuration software platform, these five subsystems can be integrated into one platform. However, in the current situation, the interface between the host software and the PLC real-time monitoring system is the most mature. The communication interface methods of other subsystems have their own independent characteristics and require customized interface development. Actual data exchange is inevitable, which requires the configuration software platform to have good openness, compatibility, and scalability.
2. Solution
Key performance indicators for tunnel monitoring systems include support for a robust client/server architecture, ODBC fast interface, OLE interface access, SDK development kits, and web deployment. ForceControl monitoring and configuration software meets these indicators, demonstrating its significant functional characteristics in the tunnel industry and providing an effective solution for data communication and acquisition.
1) Data from all PLC devices can communicate individually with the host computer via Ethernet, or the main PLC can aggregate data from all PLCs and communicate individually with the host computer. The host computer uses a dedicated server to communicate with the PLC devices. This primarily showcases the features of configuration software: establishing IO device configurations and variable labels, mapping actual IO device channel values to variable labels. This allows real-time data collection from the field to the monitoring center. The configuration software then shares data on the server side. Once in operation, the network server runs in the background with minimal memory/CPU usage, continuously refreshing and storing historical data without requiring any external screens to be opened, while maintaining the running server system. Data flow is synchronized with the client via a local area network (LAN) to display data on the operator station’s simulated process screen. This allows different operator stations to customize different process screens, and the client offers graphical self-development capabilities. This client/server architecture ensures the stability of the entire system while reducing the conflict rate of cross-control.
2) ForceControl’s ODBCROUTER component is suitable for integrating data from traffic emergency response plan analysis systems. It stores real-time or historical data in time intervals or by rate of change into the relational database required by the plan system, primarily using analog values and fault alarm values. The wizard-driven setup process eliminates the need to write many SQL script statements, providing simple, convenient, and fast raw data for the emergency response plan analysis system.
3) OLE interface (DBCOM) access is suitable for most high-level programming environments (DELPHI, VB, VC++, .NET, etc.). By directly loading the DBCOMOCX control registered in the system, data in the local or remote ForceControl real-time database (DB) can be accessed. In the emergency response analysis system, most switch data does not need to be stored; therefore, direct access to DB variables for monitoring is highly efficient and reduces the cumbersome process of always using ODBC as the data channel. The combination of “ODBC + OLE interface” optimizes the data integration between the monitoring system and the emergency response analysis system.
4) LED display systems, vehicle inspection systems, emergency telephones, fire protection systems, and CCTV systems have their own software and communication protocols. Configuration software for these hardware drivers in the traffic tunnel industry is extremely limited. When implementing the entire monitoring system integration solution, the development of driver interfaces for these subsystems needs to be considered. The ForceControl SDK package establishes a unified standard for driver interface development, which can be customized by high-level language (VB/VC++) developers or by the ForceControl driver department, offering flexible hardware interface driver parsing.
3. Network communication architecture
The hardware communication structure and system integration scheme are all based on Ethernet communication. The host software directly accesses the vehicle detector and LEDs through a customized driver interface program. The logic programming and debugging of the PLC hardware are all downloaded or uploaded directly in the central control room. CCTV communicates with the host software through the matrix’s communication interface. Emergency telephones and fire protection systems can obtain data through API, ODBC and other data access methods. In this way, the client controls all the tunnel monitoring subsystems, and the system integration is quite perfect.
4. Typical application cases
1. Shaanxi Xiaokang Tunnel Expressway Monitoring System
The Xiaokang Expressway monitoring system is a typical example of a multi-mode hybrid monitoring system. The Wangjiatai Tunnel Group and Dazongpo Tunnel Group are typical examples of group-controlled tunnels, while the Baojiashan Extra-Long Tunnel is a typical example of a long tunnel.
The entire tunnel monitoring system not only realizes the basic functions of a monitoring system, such as traffic monitoring, environmental monitoring, and information dissemination, but also, based on actual road operation conditions, implements various contingency plans, including time-series, time-period, and layered/segmented control. Users can effectively ensure safe tunnel operation through flexible and diverse “one-click monitoring.” It achieves a three-level control mode combining road and tunnel, which is of great significance. The reporting module provides users with a “drill-down” function, allowing users to analyze tunnel-related data from multiple angles and dimensions, providing necessary reference and decision support for tunnel operation management.
2. Ningbo Bay Changxiling Tunnel Monitoring System
The Changxiling Tunnel consists of two tunnels, left and right. The right tunnel runs from Shanghai to Ningbo, with its entrance located in Changxi Village, Zhangqi Town, Cixi, and its exit in Nanlian Village, Jiangbei, and is 765 meters long. The left tunnel runs in the opposite direction and is 775 meters long. Each tunnel has a net width of 14.75 meters and a height of 7.5 meters, designed as a three-lane tunnel with a speed limit of 120 kilometers per hour. The Changxiling Tunnel is the first tunnel in the southern connection line project of the Hangzhou Bay Bridge.
3. Xiamen Xiang’an Subsea Tunnel Monitoring System
The Xiang’an Tunnel is the first large-section subsea tunnel in China and a crucial transportation infrastructure project for Xiamen. Starting from Wutong on Xiamen Island, it connects to Xianyue Road and the Ring Road on the island. The project is massive, with a total length of 8.695km, including a 6.05km subsea tunnel spanning approximately 4200m of sea. Its scale and difficulty make it a world-class subsea tunnel project. After its completion, the travel time between Xiamen Island and Xiang’an District will be reduced from 1.5 hours to 8 minutes, significantly promoting the development and construction of the West Coast Economic Zone of the Taiwan Strait.
The system mainly includes multiple functions such as multi-level tunnel control, linkage control, ventilation control, information collection, data statistical analysis, and report printing. It monitors real-time information such as carbon monoxide concentration and visibility (CO/VI) within the tunnel, and combines it with meteorological monitoring, road condition information, and fire alarms to construct an intelligent and powerful rail transit command system.
The underlying PLC uploads data to the monitoring center via Ethernet to the ForceControl IO server, realizing data network sharing and fully leveraging the stable communication and high transmission efficiency of the ForceControl monitoring configuration software.
The introduction of configuration software into traffic tunnel monitoring systems is an inevitable trend in traffic tunnel management. Currently, most tunnel systems have reserved data interfaces using configuration software, laying the foundation for management to implement comprehensive information management in the future. The information platform with ForceControl monitoring configuration software as its core will also play an important role.