Rigonomics: Steering Tools Continue To Lead HDD Revolution

By Jeff Griffin, Senior Editor | September 2010 Vol. 65 No. 9
A Horizontal Technologies probe is readied.

For horizontal directional drilling, the first “D” in the acronym HDD is the key to the success of this versatile trenchless technology -- without the directional capability, HDD could never have achieved the impact in utility construction that it has over the last 20-plus years.

Drilling equipment has advanced rapidly since the first compact HDD models developed specifically for utility work became commercially available in the late 1980s. But perhaps no component of the HDD system has changed as dramatically as the equipment to track a drill unit’s drill head and provide information to adjust the path of the pilot hole as it is drilled.

From walkover electronics to wireline and now gyro steering technology, HDD installations can be more accurate and capable of longer distances and greater depths to install larger diameter product.

Today’s walkover systems are more accurate than earlier models, and increased depth capabilities of newer products allows walkovers to be used instead of wireline systems for some installations.

Depending on job requirements, most utility projects with small- and medium-size drilling equipment (generally those with 5,000 to 90,000 pounds of pullback) use the basic steering technology of early drill units: the orientation of a slant-face drill head is monitored by a crew member with a hand-held, walkover receiver that provides information about the location and orientation of the drill head, and that information is used to make steering corrections.

Walkover improvements
The first tracking receivers were modified locators that provided audible signals when the face of the drilling head was in the 12 o’clock position or deviated from 12 o’clock. Crew members often marked each length of drill string to visually indicate when the face was at 12 o’clock.

“The accuracy of today’s walkover tracker equipment is superior to previous units,” said Mike Dvorak, electronics account manager at Ditch Witch. “Equipment improvements have made various applications easier because of improved accuracy, offset tracking and drill through abilities.”

Siggi Finnsson, Directional Control Inc. (DCI) sales and marketing manager, said the ease of use of today’s walkover equipment helps contractors train people faster.

“A focus for walkover systems is to improve productivity,” said Finnsson. “More operating frequencies have also been introduced to help deal with interference.”

Manufacturers continue to make improvements to enable walkover models to effectively make on-grade installations.