Assembly Method of Tunnel Cable Tray Support

Tunnel cable tray supports are installed using adjustable consoles, threaded rods, or rock bolts, ensuring proper alignment, load distribution, and compliance with safety standards.

Overview of Tunnel Cable Tray Support

Cable trays in tunnels are designed to carry electrical, communication, and signaling cables safely while accommodating heavy loads, vibration, and long support spans. The support system must allow for continuous operation, easy maintenance, and precise alignment despite irregular tunnel surfaces or unaligned anchor points .

Support Types and Installation

1. Concrete Insert Rails and Central Supports
   • Used in cast section tunnels or culverts.
   • Consoles are mounted on concrete inserts to support the cable ladder centrally.
   • Height and lateral adjustments are possible, typically up to 60 mm in height and 20 mm sideways to compensate for misaligned anchors .
2. Rock Bolts and Threaded Rods
   • For tunnels with rock surfaces, cable trays can be fixed using rock bolts or threaded rods.
   • Adjustable brackets allow for alignment without repositioning the bolts, simplifying installation in irregular tunnels .
3. Accessories and Equipment
   • Expansion splices, radio wire holders, and lighting brackets are integrated into the support system.
   • Consoles can accommodate light fixtures by sliding them over the support, reducing installation time .

Assembly Steps

1. Planning and Layout
   • The system designer or engineer determines tray routing, support spacing, and load requirements based on tunnel geometry and cable types .
   • Typical support spacing for heavy loads ranges from 3 to 6 meters .
2. Mounting Supports
   • Install concrete inserts, threaded rods, or rock bolts at designated points.
   • Attach adjustable consoles or brackets to these anchors, ensuring proper height and lateral alignment.
3. Installing Cable Trays
   • Place the cable ladder or tray onto the supports.
   • Use expansion splices or connectors to join tray sections securely.
   • Ensure the construction height below the tray does not exceed 10 mm for compliance with tunnel standards .
4. Adjustment and Alignment
   • Fine-tune lateral and vertical positions using the adjustable brackets.
   • Verify that all trays are level and aligned to prevent stress on cables.
5. Securing Accessories
   • Attach lighting, detectors, signage, and radio cables using the integrated brackets.
   • Confirm that all components are firmly fixed and do not interfere with cable routing.

Safety and Compliance

• Only qualified personnel should perform installation, following local electrical codes and occupational safety regulations .
• Cable trays are mechanical support systems only and should not be used as walkways or lifting devices .
• Proper storage and handling of tray components prevent damage and ensure long-term reliability .

Key Considerations

• Use lightweight, corrosion-resistant materials such as GRP or perforated metal for tunnel environments .
• Ensure continuous operation of essential systems by maintaining proper tray support and alignment.
• Plan for future maintenance and cable additions by leaving adequate clearance and access points. By following these assembly methods, tunnel cable tray supports can be installed efficiently, safely, and in compliance with technical standards, ensuring reliable cable management in challenging underground environments.