Greg Hollanders, Sr. Director of OSP Construction
With 20,000 route miles of fiber and counting, notably, 89% of the fiber that FiberLight operates is installed underground.
As global demand for high-capacity broadband surges, fiber optic networks are expanding at an unprecedented pace. While aerial deployment still has its place, underground fiber installation is increasingly favored for its reliability, protection, and long-term scalability. Ultimately, beneath our streets and sidewalks lies the true backbone of the digital economy–carefully planned, precisely engineered, and built to last.
Why Go Underground?
To begin with, underground fiber systems offer clear operational advantages. Cables are shielded from wind, ice, and accidental contact, drastically reducing maintenance and outage frequency. In dense urban or suburban areas, underground deployment also preserves visual aesthetics and minimizes pole congestion. Although initial construction costs are higher than aerial builds, the lifecycle cost per mile is often lower thanks to reduced weather-related damage and fewer service interruptions.
Planning and Design
Successful underground fiber installation begins well before any digging occurs. Engineers conduct detailed route surveys, GIS mapping, and utility locates to identify potential conflicts. Environmental considerations such as soil type, drainage, and existing infrastructure, guide decisions on whether to use open trenching, plowing, or horizontal directional drilling (HDD).
As a result, modern planning tools allow for micro-trenching in narrow corridors, maximizing efficiency and minimizing disruption. Conduit design, pull strength calculations, and bend radius tolerances are factored into every route to ensure long-term integrity and optimal fiber performance.
Underground Installation Techniques
The choice of methods depends on terrain, density, and existing utilities:
- Open Trenching: Traditional but effective in greenfield builds and rural areas.
- Plowing: Fast and efficient for shallow rural installations.
- Directional Boring (HDD): Ideal for road crossings, urban environments, or sensitive areas — allowing crews to install conduit without disturbing the surface.
- Micro-Trenching: Used in city streets and sidewalks, cutting narrow grooves just a few centimeters wide.
Once conduit is laid, fiber cables are blown, pulled, or jetted through the ducts using compressed air systems. Each segment undergoes fusion splicing, OTDR testing, and end-to-end verification to ensure loss levels meet design specifications.
Restoration and Verification
Post-installation, restoration crews return surfaces to their original condition, ranging from asphalt overlays to landscaping touch-ups. Network integrity testing confirms the system meets both optical performance and mechanical standards. Documentation and as-built mapping are essential for future maintenance and locates.
A Solid Future for Underground Fiber
As bandwidth demand continues to climb, underground fiber infrastructure provides the resilience and capacity required for next-generation technologies, from 5G backhaul to edge computing and smart city integration. While the process beneath the ground often goes unseen, it represents one of the most sophisticated and critical engineering efforts in modern telecommunications.