This article covers the six phases of the fiber optic construction process that is used to build OSP communications networks. While the article focuses on OSP construction and repair in Colorado, the process is broadly applicable globally (though other locales may have differences).
Fiber OSP networks power our communications networks through long haul, middle mile, and FTTX deployments. These networks enable many different industries and use cases, but the construction process is roughly similar.
Phase 1: Planning and Design of a Colorado Fiber Optic Telecom Network
Needs assessment for a new OSP fiber network
Fiber network planning starts with the identification of a requirement to connect two or more places. As a network operator or telecom identifies the purpose of the fiber network, the general construction requirements begin to become clear. The network operator must identify what and where the network is to connect. Additionally, the needed bandwidth and number of lines must be determined in order to scope network capacity.
Needs assessments and initial network planning are an integral part of the BEAD process. To learn more about how BEAD will impact Colorado, check out our post on the subject.
Engineering a fiber network during pre-construction
As planning transitions from conceptual to tactical, fiber network engineers must design a network that can accomplish the stated goals. This process will begin to take a general route and make it precise. Fiber engineers use GIS programs to plan fiber routes through existing ROWs and around obstacles. Assessment of the geography will also determine what type of installation will be required (e.g., aerial, plowed, or drilled).
Either during engineering or before engineering, the network owner will bid the work to a fiber contractor (such as Trace Fiber) for their construction estimate. Once a contractor is selected, the network owner will work with the fiber project manager to coordinate construction.
Permitting and site walks to prepare for fiber construction
Once the fiber network has been engineered, the construction contractor must apply for right of way (ROW) construction permits through the city or municipality. This approval process can be lengthy and is designed to deconflict new construction with existing utilities.
Fiber engineers may need to adjust construction plans as city engineers identify any potential issues. Additionally, the construction contractor will also need to supply traffic safety plans to ensure a safe worksite during the construction phase.
Additionally, network owners and construction PMs will conduct one or more site visits to refine plans around the most challenging parts of the project. These site visits are essential to building a plan that works for all parties.
Phase 2: Site Preparation for Fiber Construction
The site preparation phase begins when construction permits are approved by the relevant municipality. In some cases, the preparation of the fiber site may be dependent on other construction activities. This dependency could include road building, debris removal, or other utilities. Once the dependency has been satisfied, the fiber construction team can move forward with fiber optic site preparation.
Locating and marking existing utility lines
Before any digging can begin, fiber crews need to know exactly where existing utility lines are located underground. This locating process is conducted through services like 811 Locate. Utility locators utilize trace lines to locate and mark relevant lines. These underground utilities may include natural gas, sewers, water lines, and other communications lines.
The locate crew will mark the location of the existing utilities with spray paint and marking flags. These tools are designed to provide fiber crews with visual representations of lines that should be marked on their engineering drawings. Visual queues are only designed to last 30-90 days before dissipating.
Additionally, fiber drill crews may also utilize a technique called pot holing to verify that there aren’t any utilities in the intended drill path. Pot holing is the digging or hydrovac-ing of small holes to verify the clearance of an intended drill route.
Deploying and staging fiber construction crew & equipment
Once underground utility marking is complete, the fiber contractor will deploy its crews to the worksite. This crew will consist of multiple trucks, trailers, a hydrovac, directional drill, and traffic safety equipment. Additionally, the contractor will also need to deploy reels of fiber conduit (the big orange reels). While these logistics are easy near Denver, additional preparation may be needed to facilitate deployment to more remote locations (such as Southwestern Colorado).
Phase 3: Fiber Network Infrastructure Construction
For OSP networks, the construction phase is when the ‘real’ work begins. During the construction phase, all of the necessary components are installed in the utility right of way. These components may include:
- Conduit
- Fiber optic cable
- Handholds
- Network gear (e.g., splitters)
During the construction phase, construction crews will bring specialized equipment to the worksite. The exact type of construction equipment will depend on the type of fiber installation that is most appropriate for the environment. The purpose of the construction phase is to install the infrastructure necessary to protect the fiber optic cables.
Conduit is a hard outer plastic shell that protects the fiber optic cables from the elements and minor impacts. Most modern fiber conduit is made of HDPE plastic and is delivered to the construction site on large reels. These reels carry hundreds of feet of conduit that will be deployed to protect the new network. Some specialized conduit may have microducts installed inside it, enabling the conduit to carry multiple services or different networks.
There are two main types of conduit installation:
Aerial conduit installation (or self supporting fiber)
In areas with existing above ground utilities, aerial fiber installation may be a good option. This type of fiber installation can generally be installed faster and cheaper than underground, due to the decreased manning and equipment requirements.
For aerial conduit installations, crews will use bucket trucks to attach fiber cables and their associated conduit to the utility poles. These lines will be physically separated from other aerial utilities (such as electrical or coax cable) but will utilize the aerial right of way.
In Colorado, aerial installations are most common in locations where soil conditions make underground installation prohibitively expensive.
Underground conduit installation in Colorado
Underground network installations are either buried or installed in a drilled hole under the ground. Underground fiber installations are common as they are generally protected by the earth and the outer shell of the conduit.
In Colorado (as in most places), underground fiber networks are installed in utility rights of way (ROW). These ROWs house most utilities (electric, gas, water/sewer), so installers must be very careful to not disturb existing services.
Underground fiber installation is generally accomplished with one of two key technologies:
- Horizontal directional drilling (HDD, also known as boring) – horizontal drilling is the primary means for installing conduit to support underground fiber networks. This technology is able to drill through various ground types to create a passage for the conduit. Amazingly, the drills are steerable, meaning that they can avoid existing obstacles or trace turns in the ROW. This directional drilling for fiber optics is the most common method of deploying fiber OSPs in urban and suburban environments in Colorado.
- Plowing – Plowing is a rapid means of placing conduit into the ground in areas where there are few other utilities. While quick and inexpensive, plowing has the disadvantage of disturbing large areas of top soil and being unable to cross barriers (e.g., sidewalks).
Other key activities during fiber network construction
While the installation of the fiber conduit is the focus of the construction phase, other key activities must also occur to build the OSP network. Civil construction crews must perform the installation of handholds and other infrastructure. Fiber handholds are connection boxes where portions of the network will be joined in the following phase.
For underground networks, the OSP’s fiber handholds must be installed by digging them into the earth. These light civil construction crews follow the engineering to determine where the handholds will be installed. Then the crews excavate a hole to install the fiber handhold. For smaller residential handholds, this work might be done with shovels, but for larger concrete emplacements, the crews will use hydro-vacs and excavators.
Additionally, civil crews will also be involved with any other tasks related to the network’s construction. These tasks could include other light earth moving requirements or remediation of damaged ground or concrete. In come cases, specialty equipment (e.g., cranes) or crews (large cement jobs) may occur to meet the engineering requirements.
Throughout this phase, the construction company will be leveraging personnel and equipment in the utility right of way. These rights of way are generally next to and often cross roads and highways. To ensure the safety of the crews, the contractor will also setup and continually adjust traffic control measures. These traffic control measures could consist of flaggers, cones, barricades, or light traffic signs. The construction crews must work hand-in-hand with the traffic safety team as the work progresses geographically.
Phase 4: Fiber Installation, Splicing, and Termination for New Networks
Installing fiber into conduit
Once the conduit has been deployed underground or onto utility poles, the actual fiber optic cable can then be installed. Fiber optic cables are small glass filed cables that carry data at the speed of light. These cables are the actual transmission means for the OSP network. Fiber optic cables come in many configurations to support a variety of use cases. During the design phase of the project, network engineers will spec the right type of cable for the situation.
To install the fiber optic cable, crews will utilize one or more ducts (or micro-ducts) to isolate the cable inside the conduit from the installed handhold. This fiber installation can be accomplished by manually pulling fiber through the conduit or by utilizing compressed air to “blow the fiber.” Either method will result in newly installed fiber between two handholds.
Crews will work in a stepwise fashion to install the delicate fiber optic cable from handhold to handhold. These junction locations allow fiber from two or more directions to come together in a secure box.
Fiber splicing for OSP networks in Colorado
Once the fiber has been installed in the conduit, it must be fusion spliced together. This is akin to connecting electrical wires, but requires very clean connections to maintain signal integrity.
Since the inner core of the fiber optic cable is made of clear glass, these pieces of glass must be joined through a process called fusion splicing. Fiber fusion splicing is a delicate procedure where a fiber technician must utilize specialized equipment to perform the join. While the operation is performed in the field, fiber installers utilize specialty fiber vans or fiber trailers. These enclosed and climate-controlled spaces allow fiber splicing in a clean environment.
Fiber technicians utilize fusion splicers to actually join the fiber strands. This splicing equipment allows multiple individual strands to be spliced at the same time. Some common makers of splicing equipment include Sumitomo, UCL Swift, and Fujikura.
Termination of OSP fiber networks
As the fiber splicers gradually connect all the legs of the network, connections can be established between OSP nodes. Fiber technicians will connect the ends of the newly installed fiber optic cables to networking gear at each end of the new network segment.
These connections are generally made with factory installed terminations to ensure the highest signal quality at the termination locations. As network legs are established, fiber technicians can begin testing the network for signal quality, continuity, and loss.
As the fiber termination process comes to a close, the network will be ready for handover to the network owner for final testing.
Phase 5: Final Testing and OSP Network Activation
Once the entire OSP network has been physically installed and connected, the close out and activation stage can begin. While much of the work to this point has been performed by a single telecom contractor (like Trace Fiber Services) or a multitude of contractors, this phase hands off to the OSP network owner.
Since the network is now in place between two nodes, the network owner can begin running fiber optic tests & diagnostics to verify performance. This generally starts with an OTDR (Optical Time-Domain Reflectometer) to determine any issues with signal loss. It may then move on to other proprietary or specific tests for the network type. Any issues that are identified will be sent back to the contractor to remediate.
Additionally, in the closeout process, the network constructor will update drawings with “as-builts” to show where the fiber optic cables actually exist. This is critical for both the network owner as well as local authorities. In the future, 811 Locates will need to determine where these network cables exist to prevent accidental damage.
Once all of these steps have been completed, the network can begin operational use for its intended purpose. In some cases, individual fiber strands may be left as “dark fiber,” which means they are ready but not yet in use.
Phase 6: Maintenance and Repair of Colorado Fiber Networks
Now that the fiber optic OSP network has been installed and activated, maintenance is critical to keeping the network operational.
Network performance monitoring equipment constantly watches the OSP network to detect any transmission issues. If a significant issue is detected, network techs will try to diagnose the problem from their NOC (Network Operations Center). If the issue is determined to be a physical damage, a contractor may be dispatched to diagnose and repair the issue.
Emergency repairs for Colorado fiber network damages
While all reasonable precautions are taken to prevent damage to underground fiber networks, they can still be damaged from natural disasters or human construction accidents. When fiber damage does occur, network operators need a contractor who can restore service quickly.
Emergency fiber repair differs from planned construction in two key ways:
1) The emergency fiber repair team needs to work expeditiously, utilizing tools and techniques from all of the construction phases in a single evening.
2) The broken portion of the network must be unearthed to begin the repair process (instead of just drilling new cable).
During a network damage, emergency repair crews may deploy to the worksite with some combination of a mini-excavator, a drill, picks & shovels, a crane, and a fiber splice van. The team will work with permitting offices, CDOT, and 811 Locate to ensure they aren’t causing additional damage during the process. Additionally, the team will coordinate with the fiber network’s NOC.
Relocation and adjustment of underground fiber networks
Unfortunately, emergency damage isn’t the only threat to underground fiber network operation. Road expansion, changes in zoning, or routine upgrades may all require a contractor to service the network infrastructure. In these cases, fiber crews will need to relocate or upgrade portions of the fiber network to meet local requirements.
During the upgrade or relocation of a fiber network, the contractor will need to work through many of the construction phases, but also be mindful of the network’s current usage. In these cases, a new network leg will likely be built while the old fiber is still operational. This practice minimizes expensive downtime to switch over to the new fiber.
Need help with building or relocating your underground fiber network in Colorado?
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