In March and April 2023, Brownline surveyed three HDD crossings in Innsbruck, Austria. With the Alps in the background, the Drillguide Gyro Steering Tool was used to cross the river Inn three times.
These HDDs were executed by contractor Marty Bauleistungen AG. The first two crossings had a length of 190 m / 623 ft and were designed parallel to each other, each with a light curvature. They started and ended with around 1.5 m / 5 ft of space in between. These two crossings would serve to install power cables and optic fibre cables to improve the connections between the north and south riverbanks.
After the two parallel crossings were completed, a third crossing was launched from the same entry site. This one was used to install a water pipeline. The exit point was on a different street, so the 153 m / 502 ft bore line curved 37° left.
Gravel and stones
The soil consisted of mostly gravel and stones, which made drilling difficult. Using the downhole positional measurements from the Gyro Steering Tool, the pilot drills were steered precisely along the planned line under the riverbed. As a result of this accuracy, the punch-outs also happened exactly at the planned exit points.
The Pressure-While-Drilling (PWD) module allowed the engineers to monitor downhole pressures while drilling. This helped to avoid mud breakouts under the river and under the city streets.
By trusting in the Drillguide GST, the water, power, and internet connections were installed safely, accurately, and efficiently.