The growing popularity of microtrenching for fiber optic installations has a direct correlation to our society’s thirst for data.
“The demand for bandwidth in urban areas is increasing dramatically,” says Jon Kuyers, engineering and product manager, Utility Products, Vermeer Corp. “We want instant data and large volumes of it quite quickly. The infrastructure that currently exists today, while decent, isn’t quite meeting what is currently occurring and the demand that is forecast.”
Consequently, more and more fiber optic lines are being installed. Since much of it is being placed in congested urban areas, contractors are turning to less disruptive, more cost-effective methods of installation.
One such method is microtrenching. “Microtrenching has become popular mostly for two reasons,” says Jason Proctor, heavy trencher product manager for the Ditch Witch organization. “In certain conditions, it is a more cost-effective method of installation. And it can be the only solution at times. Environmental limitations may prevent installation in the right-of-way or absence of right-of-way. It can be a bridge-gap between other forms of installation, such as directional drilling or plowing.”
A narrow focus
Unlike traditional trenching, which is primarily used in soil and may cut to 4 ft. deep and 4 to 8 in. wide, microtrenching, as the name implies, is used to cut a narrow, shallower trench, generally from about 3/4 to 2 in. wide and to a maximum depth of about 12 in., although some attachments can go as deep as 24 in.
“Originally, microtrenching involved a process where a narrow, 1- to 1 1/2-in. trench was cut in a street to a depth of only 2 in.,” recalls Gary Cochran, president, Coneqtec group of companies. “This utilized the actual base course of asphalt to support the cut and only cut through the top or wear course of the road.
“In many locations,” he continues, “a deeper cut is now being specified because the... shallow cut can be vulnerable during road surface repairs and other circumstances.”
“The intent is to trench deep enough to get underneath the solid upper layer, but shallow enough to stay above installation depths of existing utilities,” Proctor explains. “The target zone is 6 to 12 in. in depth and up to 1.5 in. in width.” However, depth and width will vary depending on the project requirements.
Microtrenching is primarily used to install fiber optic cable or conduit, though as Kuyers notes, “There could be potential for street lights or parking lot lighting.”
Most cuts are made in asphalt. However, the Ditch Witch MT12 microtrencher, which can be mounted to either a 45- or 62-hp utility tractor, has been used successfully in some concrete applications, Proctor points out.
The core elements of a microtrenching system include the carrier, a microtrencher attachment and a vacuum system to clean up spoil. A reel carrier option may also be available.
This configuration allows for increased equipment versatility and utilization. “You can take the attachment off quite quickly and configure [the tractor] with a different attachment if there is other work that could be accomplished,” says Kuyers.
Coneqtec-Universal offers two microtrenching attachments for use on skid steers. Both can be easily swapped out with other attachments as needed. “The value of these products... is that a 1 1/2-in.-wide microtrench can be cut by the first skid-steer attachment, and then exchanged with a second attachment on the same skid steer that mills to complete a ‘T’ cut (T-shaped repair),” says Cochran. “This provides a simple, one-machine solution for the microtrenching fiber-to-the-premises process.”
Fishel Company, based in Columbus, OH, is a 75-year-old utility contractor specializing in water, sewer, gas, telephone and fiber optic installations. With 20 offices in 11 states, “Team Fishel” employs more than 1,100 teammates.