The fiber optic cable was changed from overhead to trench laying

Switching fiber optic cables from overhead to trench laying involves burying the cable underground in a conduit or protective trench to enhance protection, aesthetics, and long-term reliability.

Key Differences Between Overhead and Trench Laying

Overhead fiber optic cables are installed on poles and are generally cheaper and faster to deploy, but they are more exposed to environmental hazards such as storms, falling trees, or accidental damage from construction activities. In contrast, trench or buried installations provide better protection against physical damage, improve the visual aesthetics of the area, and are more suitable for urban environments where pole installation may be impractical .

Trench Installation Process

1. Route Planning and Surveying: Before trenching, a detailed survey is conducted to map existing underground utilities and avoid conflicts with gas, water, or electrical lines .
2. Trench Excavation: Trenches are typically dug 1–1.2 meters (3–4 feet) deep, with adjustments for frost or hard rock conditions. In hard rock, a minimum of 300mm (12 inches) backfill cover is required, often with a protective concrete slab .
3. Conduit Installation: Fiber cables are usually placed inside PVC or HDPE conduits, sometimes with innerducts to facilitate future cable pulls. Conduits protect the fiber from moisture, mechanical stress, and rodent damage .
4. Cable Laying and Protection: The fiber is pulled through the conduit, and the trench is backfilled with sand or other padding materials. Protective measures such as bricks or marker tapes are added to indicate the cable location and prevent accidental excavation .
5. Testing and Documentation: After installation, fibers are spliced, terminated, and tested for insertion loss and return loss. Detailed documentation ensures future maintenance and network expansion can be performed safely .

Advantages of Trench Laying

• Enhanced Protection: Buried cables are less susceptible to environmental damage and accidental cuts.
• Aesthetic Improvement: No poles or overhead lines are visible, which is preferable in urban or residential areas.
• Future-Proofing: Conduits allow for easier upgrades or additional fiber installations without repeated excavation .

Considerations

• Cost and Labor: Trench installation is more labor-intensive and expensive than overhead deployment.
• Construction Disruption: Excavation can disrupt roads, sidewalks, and existing infrastructure, requiring careful planning and permits .
• Depth and Protection: Proper burial depth and protective measures are critical to prevent damage from future digging or surface activity . Switching from overhead to trench laying is a strategic choice that prioritizes long-term reliability, safety, and urban integration, but it requires careful planning, adherence to standards, and proper protective measures to ensure the fiber network remains robust and maintainable .