The laying of fiber optic cables for subways is a specialized and systematic project, involving key steps such as surveying and design, installation of cable trays, cable laying, and connection testing to ensure the stability of the subway communication system and train operation safety.
Main Steps and Methods:
1. Surveying and Design: Before laying, engineers conduct detailed surveys of the subway tunnels and stations to determine the optimal route, installation location, and required auxiliary materials (such as cable trays and clamps).
The design scheme considers electromagnetic compatibility (EMC) and fire protection requirements, selecting fiber optic cables with flame-retardant properties.
2. Installation of Support Systems: Cable trays, bridges, or clamps are installed along the tunnel walls or designated locations to support and secure the fiber optic cables. These support systems need to be robust and reliable to withstand vibrations and other environmental challenges from subway operation.
3. Cable Laying: Manual or Mechanical Traction: Using specialized laying equipment or traction devices, the entire reel of fiber optic cable is pulled from the starting point (usually the equipment room or junction box) along the predetermined cable tray path to the endpoint.
Avoiding Damage: Special care must be taken to protect the optical cable during operation, avoiding excessive bending, twisting, or external force damage. This typically requires the use of cable anti-knotting devices.
Sectional Construction: Due to the usually long length of subway lines, the optical cable will be laid in sections, spliced within each section.
4. Optical Cable Splicing and Connection: In designated junction boxes or equipment rooms, specialized equipment is used to splice or connect different sections of the optical cable to form a complete communication link.
5. Testing and Verification: After laying and splicing, professional instruments are used to comprehensively test the transmission performance of the optical cable (such as loss, bandwidth, etc.) to ensure that the signal transmission quality meets design standards.
6. Identification and Archiving: The laid optical cable is identified for easy maintenance and management in the future, and all construction and testing data is archived.
7. Challenges and Considerations: Operational Safety: Construction on existing lines can usually only be carried out at night after the subway has stopped operating. The work time is short, requiring high efficiency and strict safety regulations.
Complex Environment: The subway tunnel environment is complex, with factors such as vibration, electromagnetic interference, and humidity, requiring optical cables to have good environmental adaptability and anti-interference capabilities.
Specialized Equipment: Dedicated optical cable laying and testing equipment is required to ensure construction quality.
Through these professional and standardized processes, the subway can establish a stable, high-speed communication network to support the operation of critical services such as signal transmission, video surveillance, and passenger information systems.
Yulia Liu