Guided Auger Boring
Pilot Tube Guided Auger Boring (PTGAB) is one of the most popular and cost-effective trenchless methods to accurately install steel casing for underground utilities, waterlines, and sanitary sewers. This method combines the pinpoint accuracy of the pilot tube installation to control line and grade with the excavation process of horizontal auger boring.
- Accuracy: Pilot tube guidance for auger boring equipment ensures line and grade accuracy prior to advancement of casing.
- Safety: PTGAB does not require removal of augers and personnel entry into the steel casing for line and grade control which can be extremely hazardous in small diameters.
- Geotechnical Confirmation: During the pilot tube installation, the contractor will have a good indication of the ground conditions including potential obstructions that can be mitigated prior to advancing the steel casing.
- Cost Benefits: End-users experience social and economic cost savings through reduced casing size, longer drive lengths, and greater productivity.
- The trenchless contractor sets the auger bore equipment up in the launch shaft with the same procedure as a standard Jack-and-Bore operation.
- An Akkerman 240A GBM system mounts directly onto the ABM track and the universal frame is adjusted to match the spring line dimension of the boring equipment.
- Pilot tubes are accurately installed from the launch shaft to the receiving shaft with tooling selected based on the ground conditions encountered.
- The Akkerman 240A GBM system is removed from the ABM track and moved to another project for continued productivity.
- The steel casing is connected to the installed pilot tubes. The connection between the pilot tubes and lead casing or auger is selected based on ground conditions and diameter of casing.
- The steel casing is thrust forward by the boring machine and is guided on the alignment by the installed pilot tubes. Excavated soil is removed by the augers to the launch shaft. Pilot tubes are sequentially removed in the reception shaft and placed into storage racks for later use.
For more information on the GAB method or to learn about our newest innovations in GAB, please contact our experienced sales representatives.
How to Choose Your Submethod
4-48 inches and larger with select tooling
Projects with displaceable N Value or SPT = < 50 Non‐displaceable N Value > 50 in homogeneous ground with appropriate tooling/equipment
Up to 600 feet
Minimum Shaft Size
10-ft. trench box length
The City of Oshkosh’s annual Capital Improvement Plan included concrete paving, utilities upgrades, an upgraded wastewater pump station, and appurtenant work. The utility upgrades included a crossing that passed under an active rail line in rock ground conditions, to increase the capacity of the sewer.