When a conduit is maxed out or “exhausted,” the ability to run a demarcation extension or to deliver additional (or new) fiber can become an expensive affair. When the pathway is full, the traditional option is to bore additional pathways for new conduit.

Facility easements must be obtained, which can take some time and require the best of negotiating skills with property and/or city officials. Even before the cost of core boring begins, engineering time is required to evaluate the whether the structural integrity of a floor would be compromised  in a  building. Add to this the cost of pipes, couplers and metals along with skilled manpower labor rates and, too often, environments that truly require additional bandwidth and connectivity can’t justify the return on the investment. The project is scrapped.

This is exactly what happened when an outside plant management (OSP) construction manager of a Fla.-based independent telephone company submitted a job request to AT&T and Verizon. The request involved the delivery of 12 single-mode fibers to a cell tower sitting atop a 14-story hotel. The goal was to provide backhaul services to relieve wireless congestion for each carrier’s traffic at this location.

The job request had been in limbo for quite some time because the traditional methods of cable placement in the fully occupied duct could not be performed. Attempts to pull/blow pulling-string ended up wrapping in and around existing cable. An engineering review estimated that the project would require seven or eight days of labor; the cost of placing new conduit, and for labor and materials, would be in excess of $15,000, due to core-boring requirements at each floor. Furthermore, even if the money had been appropriated, attempts to achieve facility easements had been shot down. The job had been considered “dead.”

A New Option

A form of ruggedized micro-duct combined with an innovative “pushable” fiber technology brought new life to the project. Using a push/pull placement method, the rigid construction and small footprint of 10-mm ruggedized microduct allowed for its placement into the exhausted duct. A total of 700 feet of duct was placed through 14 floors of the hotel, with multiple 90-degree turns, and deadbreak (ELB) junction-transitioning 1 1/4-ft. to 2-ft. duct was passed utilizing two pull locations. 

The first pull location involved a 90-degree turn through which 350 feet of microduct was passed. In addition, the small footprint of the microduct allowed for it to be easily transported to the top floor, allowing gravity to assist in the installation. (Note: The large reel sizes that are commonly deployed in order to get the maximum length without having to couple commonly present a  safety concern because they would require a couple of people to get a 2,000-ft. reel of traditional duct product and cable onto the rooftop. Depending on O.D. of the conduit being placed, the service elevator [f the building has one] may or may not be usable, given the size. This makes the transport of such a large and bulky item up stairwells a problem, even for the strongest team.)

The placement of the ruggedized microduct was completed within two hours; the 12 fibers were pushed into place in a total of 35 minutes. Total costs, including materials, was $3,000 – about 20 percent of the estimate for traditional methods.

Johnny Hill is COO at Clearfield Inc. Contact him at  jhill@clfd.net.

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