Trenchless construction (also known as "closed construction" or "No-Dig") refers to the installation of underground pipelines without continuously excavating the surface. Instead of an open trench, only a launch pit and a reception pit are required. In between, machines work underground. The result: less surface damage, shorter construction times, lower reinstatement costs and minimal disruption to residents and traffic.

The most common methods are earth rockets (soil displacement hammers), horizontal directional drilling (HDD/Mini-HDD), pipe jacking/microtunneling and pipe bursting. Stern Technic adds two new approaches to the mix: BOB, an autonomous fully electric drilling robot, and BUDDEL, a pneumatic pipe jacking system – both specifically optimised for small diameters (up to 50 mm) and short distances (up to 20 m).

An earth rocket is a pneumatically driven soil displacement hammer that is fired blindly into the ground – with no position tracking and no ability to correct course after launch. BOB, by contrast, navigates autonomously with real-time IMU tracking: you always know where the machine is, and BOB corrects its direction independently. BUDDEL operates semi-automatically with a controlled advance – also no blind drilling, but a controlled, reproducible boring process.

Typical applications include fibre optic house connections (FTTH), power cables for EV chargers and e-mobility, water and gas lines, district heating, telecommunications and irrigation systems. Trenchless installation is especially cost-effective for road crossings, residential areas with sensitive gardens or projects involving multiple house connections.

In most cases, yes – especially when you consider total costs. The pure drilling costs may be similar, but open-cut construction adds significant costs for surface reinstatement, traffic diversions, longer build times and resident compensation. Studies show savings of up to 70% in construction time and up to 80% in total costs compared to open-cut methods.