How is fiber optic conduit installed with directional boring?

Most new fiber optic lines run through conduit, a protective pipe buried in the ground. Directional boring is one of the most common ways to get that conduit under streets, driveways and yards without digging a long trench. Here is how the job usually goes, from plans to a finished route.

The process at a glance

1. Start with the plans

Every fiber job starts with the prints: where the route goes, where each handhole or box sits and how the run is broken into sections. The crew checks the route against the real site, looking at pavement, driveways, landscaping and anything else the bore must pass under.

2. Locate what is already there

Before anyone drills, the area is called in to 811 so utility owners can mark their lines. Texas law lists boring and drilling as excavation, and it requires the excavator to give notice before work begins. Telecom lines, including optical lines, are themselves classed as underground facilities under that same law. A fiber route often shares the ground with power, gas, water and other telecom lines, so the locate matters on every job. Our guide to calling 811 in Texas covers the timing.

3. Drill the pilot bore

The rig drills a small-diameter pilot hole along a steered path from the entry point to the exit point. A transmitter behind the drill head sends data up through the ground, and a crew member follows it with a walkover locator so the operator can steer around obstacles and hold depth. See what a walkover locator does.

4. Ream and pull back the conduit

If the conduit is larger than the pilot hole, a reamer widens the bore. The conduit is then attached behind it and pulled back through the hole. When pullback is done, the conduit runs underground and is exposed only at its two ends.

5. Set handholes and boxes

At each end of the run, and at pull points in between, a handhole or larger box is set. These access points are where crews will later pull the fiber, make splices and service the line. Getting their location and depth right is part of what the network owner pays for.

6. Pull or blow in the fiber

Fiber cable is light and has relatively low pulling-tension limits, which is one reason it goes into a protective duct instead of straight into the ground. Cable is placed in one of three ways:

• Pulled in with a pull line, sometimes with mechanical help.
• Blown in with equipment that moves the cable along on high-volume air.
• Pre-installed in duct by the manufacturer.

Large conduit can also be divided with innerduct, smaller duct inside the main pipe, so it can carry more than one cable. Keeping water away from the fiber is a major concern outdoors, which is another job the duct and the cable jacket do.

7. Restore the surface and record the route

When the conduit is in, the pits are closed and the surface is repaired: concrete, asphalt, soil or landscaping. Then the crew records where the conduit actually went. The locator’s bore log, the handhole locations and job site photos come together into an as-built record. See what an as-built is and why it matters.

What a contractor needs from a fiber boring crew

• A route that follows the prints, with any changes noted.
• Conduit at the depth the plans call for.
• Handholes and boxes where the plans put them.
• A clean, restored surface.
• An accurate record of the finished route.

UGA, based in El Paso, Texas, provides fiber and telecom conduit boring, including conduit placement, fiber pulls, handholes and boxes, with traffic control and permitting support and restoration. To talk about a route, request a bid.

This article is general information about the installation process. Depths, materials and steps are set by each project’s plans and the network owner’s requirements.