Welcome to part four of my blog post on the construction and installation of the Fort Collins Connexion municipal broadband fiber network. In part three, we looked at the installation of service at my friend Collin’s house. In part four, we’re returning to my neighborhood and documenting the final construction steps before service goes live on my street.
January 30, 2020 – Splice Trucks in My Neighborhood
On Thursday, January 30, 2020, contractors for Connexion were splicing fiber cables together to connect the fibers distributed throughout the neighborhood back to the fiber distribution hub (FDH) for the area. One technician worked at the vault across the street while another technician worked at the vault directly in my cul-de-sac.
At the Splice Vault on Our Cul-De-Sac
A fiber cable runs from the vault across the street to the vault on my cul-de-sac. Inside the vault on my cul-de-sac are four pieces of conduit. One conduit contains the fiber cable from across the street. The other three smaller conduits are empty. The three empty lengths of conduit run to three flower pots distributed in front of about ten houses.
When someone orders service, a drop fiber is buried from the house to the flowerpot. The fiber is then pulled through the conduit in the flower pot up and into this vault. Inside the vault the drop fiber will be fusion spliced to the existing distribution fiber that runs through the larger conduit and across the street.
The splices are protected using a waterproof splice enclosure and a splice tray. The splice tray is shown in the photo above. The technician disassembled the splice enclosure and fed the fiber cable from across the street into the bottom of the splice enclosure. When houses subscribe to service, their drop fibers will be fed up into the bottom of the splice enclosure too.
This particular fiber cable was a 24-count, gel-filled cable. The technician removed the outer sheath of the fiber cable exposing the gel and 24 individual fibers. He used some isopropyl alcohol to remove the sticky gel from the fibers then placed the fibers into the races on the tray.
The 24 fibers were divided into a group of 18 and a group of 6. The 18 fibers were placed in the bottom of the tray (left side in photo). These fibers are not connected to the network and will not be used for service.
The remaining 6 fibers were placed in the top of the tray (right side in photo). These fibers will be spliced to the fibers that connect to the houses on our street. The space in the middle will hold and protect the individual splices when the time comes to install the drop fibers.
Remember that I wrote earlier that there are about 10 houses served by the conduit and flower pots out of this vault? There’s only six fibers allocated for connections to service though. Connexion is betting that not everyone will subscribe to service.
If more than six houses subscribe, technicians will have to reallocate and re-splice fibers from the splice vault all the way back to the fiber distribution hub to accommodate the extra houses. This is unlikely to happen.
After routing the fibers in to their raceways, the technician closed the splice enclosure and placed it into the vault as shown in the photo above. The splice enclosure is waterproof and will protect the exposed fibers and splices inside.
The orange wires in the vault are tracer cables used to locate the conduit and fiber underground. If you look closely, you can see that they’re tied to a ground rod in the side of the vault. The red tape on the fiber cable indicates that fiber cable runs toward the headend. Blue tape is used on fibers that run toward subscribers. Finally, the technician closed the vault.
At the Splice Vault Across the Street
Meanwhile across the street, a technician had the job to splice the six allocated fibers from the vault in the cul-de-sac into the 144-fiber cable running through this vault and through the neighborhood. The splicing is done inside the splice truck to provide a dry, clean, controlled work environment for the equipment, fiber, and operator.
Inside the vault are two fiber cables. The first cable has 144 fibers. It comes into the vault, some extra cable is coiled up, and then it leaves the vault. It is a continuous piece of cable. The second cable has 24 fibers. It begins at this vault and ends at the vault on my cul-de-sac. This is the situation shown in “Before Splicing” in the diagram above.
The technicians job is to carefully pluck out six fibers from the 144 fiber cable, cut them, and splice them to six fibers of the 24 fiber cable running to our cul-de-sac. The first step in the process is to pull the outer protective sheath off the 144 fiber cable and pull a section of it into the splice enclosure. The 144 fibers are carefully placed into raceways inside the splice enclosure. Unfortunately, I don’t have photo of this.
The 24 fiber cable is then stripped and pulled into the splice enclosure. The 24 fibers are run around raceways as well. After all the individual fibers are in their raceways, the technicians pulls 6 fibers from the 144 fiber cable and cuts them. He then uses a fusion splice machine to splice these 6 fibers to the 6 fibers allocated to our cul-de-sac. This leaves 6 fibers in the 144 fiber cable and 18 fibers in the 24 fiber cable headed towards everybody’s houses orphaned. This is depicted in the “After Splicing” section of the diagram above.
The fusion splicer automatically aligns the ends of the fibers then applies heat using an electric arc to fuse them into a single continuous piece of glass. A separate heater at the back of the machines shrinks heat shrink tubing to protect the splice.
When the splice truck drives off there will be continuous pieces of fiber from the vault for the drop fibers on our cul-de-sac to the fiber distribution hub (FDH) at the edge of the neighborhood. Inside the FDH, fibers from up to 32 homes are combined using a passive optical splitter into a feeder fiber.
The feeder fibers then run to an OLT at a fiber hut co-located at an electrical substation. From there, it’s redundant 100 Gbps fiber to core routers and to the Internet.
When the technician is done splicing the cables, the splice enclosure is sealed, the fiber is coiled up, and everything is placed in the underground vault. In theory the fiber on my street and in my cul-de-sac now connects all the way back to the electrical substation where the fiber hut containing the OLTs is located.
February 15, 2020 – A Bit More Splicing
I was riding my bike today and noticed another splice truck at the intersection of Overland and Skimmerhorn. I believe this is where the fiber from the electrical substation and fiber hut enters our neighborhood and where our fiber distribution hub is located.
This splice truck is a bit fancier than the previous splice truck. It has a window that’s just big enough for the splice enclosure to fit through. Inside that window is a smaller window that’s just big enough for the fiber cables to fit through. And inside that smaller window is a chunk of foam to keep the cold air outside the truck.
March 2, 2020 – Fiber Locates
Earlier this week someone painted hot pink lines along one of the fiber routes on my street then today a technician showed up to locate the existing conduit and fiber. It looks like they may have forgotten to run a length of conduit in the neighborhood. To see if they had or not, a technician located the existing fiber and conduit coming out of a splice vault across the street.
To locate the fiber, the technician opened the splice vault and disconnected the tracer wires from the ground rod inside the vault. He then connected the leads from a 3M Dynatel 2550 locator transmitter to the tracer wires and a temporary grounding rod placed next to the vault. In the photo above, the red wire and red clip connects to the orange tracer wires. The black wire and black clip connect to the temporary grounding rod which is mostly buried in the dirt and gravel.
The transmitter injects a radio signal on to the tracer wires. The radio signal can then be picked up using a radio receiver carried by the technician. The radio receiver has a highly directional antenna that can determine the precise location of the tracer wire underground and by extension, the location of the buried conduit it is inside. The locator radio receiver looks very similar to the beacon receiver for the Ditch Witch directional drilling equipment.
The technician starts at the fiber vault then works his way outward for each one of the conduits. He slow moves the receiver over the area where the conduti is located. Every time the radio receiver records a peak signal, he marks the ground with orange paint. In the world of utility locates, orange paint is used to mark communication cables. If you look closely at the photo, this technician does a lot of communications utility locates because his boots are orange.
March 3, 2020 – More Locates
Fort Collins Utilities showed up today and marked the location of the electrical and water lines in the vicinity of the vault across the street. This is the same location where the hot pink lines were painted and fiber locates where done earlier in the week. My guess is we’ll see some directional drilling work and some additional conduit put in the ground this week or the next.
On another note, they’ve finally installed bolts to secure the lids of the splice vaults.
March 4, 2020 – More Directional Boring
Yep, sure enough. Crews came back out on Wednesday and installed another piece of conduit on the north side of Michener Drive between Dixon Creek and Beaver Ct. With the new conduit, they’ll need to pull more fiber and redo some of the earlier splice work. In theory, construction in our neighborhood was finished on January 31, 2020. Given the current slow rate of subscriber additions and the number of neighborhoods in line for service ahead of us, I don’t think the additional work will delay when service is offered to our houses.
March 17, 2020 – A Splice Truck is Back
Today a technician in a splice truck showed up and spliced the new fiber in the new conduit into the network. There should now be two 144 strand cables and two 24 strand cables spliced together in the splice enclosure. I didn’t get close enough to confirm given the state of the world today.
March 19, 2020 – Snow and a Tent
Technicians came back again today to do more work on the fiber and splice enclosure in the vault across the street. This time they brought a small popup tent to let them work more easily in the cold, wet snow.
March 25, 2020 – City Inspectors and Asphalt Repairs
Today, city employees (not contractors) were driving around the neighborhood inspecting the fiber installation and doing their final quality control checks. This is the last step before the city accepts ownership of this portion of the network. The city employees also said this fiber is lit which means it is, in fact, connected all the way back to the OLT’s in the fiber hut at the substation.
Also this week, contractors were going around the neighborhood doing final repairs to the handholes crews had drilled in the road and sidewalks over the past few months. The photo above shows a completed repair to a handhole dug in the asphalt in front of my drive way.