Trenchless pipeline construction: The backbone of the energy transition

The amount of construction work for new cable and pipe infrastructure or work on existing grids as part of the energy transition in Germany is enormous: for example, several hundred kilometres of underground cables (electricity highways) are currently being installed to transport green electricity. At the same time, a pipeline-based hydrogen infrastructure needs to be built, which will be realised partly through new construction and partly through the conversion of existing gas pipelines. The so-called hydrogen core network alone will cover a length of around 9,400 kilometres. The district heating networks are also to be successively expanded as part of the heating transition. And the huge upgrade of the fibre optic infrastructure, which will be a necessary prerequisite for further digitalisation in Germany, should not be neglected either.

However, it is not just about building new pipes for energy supply and digitalisation: some of Germany's drinking water and wastewater networks are decades old and need to be renovated or replaced. In practice, this involves work on the existing network, which often takes place in confined spaces - as is the case in urban areas. Obstacles such as roads, rivers or railway lines also regularly have to be crossed, which is often not economically feasible using the classic open construction method.

For all these applications, whether new construction or renovation, trenchless pipeline construction (closed construction method) is a very attractive alternative to conventional pipeline construction (open construction method) and is regarded in practice on many construction sites as a pragmatic, economical and fast solution.

What is trenchless pipeline construction?

Also known as „NODIG“ („no dig“), this technique does not involve digging an open trench. Various technologies – such as horizontal drilling, soil rockets or pipe lining – are used to lay or rehabilitate supply infrastructure underground. In practice, various trenchless pipeline construction technologies are increasingly being combined with digital measurement methods.

What are the advantages of NODIG?

The closed construction method is not only environmentally friendly and conserves resources. It also minimises damage to roads, pavements or other surfaces, as there is no need for often costly restoration work. A further advantage lies in the reduction of construction noise, CO2 and pollutant emissions.  Construction projects can also be realised more quickly and economically compared to open construction methods.

Depending on the area of application, different NODIG technologies (laying techniques) are used on the construction site.  The most common methods include

Pipe lining („inliner method“) is a common method used for the trenchless renovation of underground drainage systems or for the renovation of pressurised pipelines for gas, water and district heating supplies. A flexible hose impregnated with a reactive resin system is inserted into the pipe or sewer, where it is cured on site to form a ‘socketless new pipe’.

The horizontal directional drilling (HDD) method is ideal for laying new cable ducts and pipelines at depths of up to 10 metres and over distances of up to 500 metres. The method is particularly suitable for underpassing railway lines, motorways, roads or watercourses.

In areas with limited space, such as house connections, small excavation pits or shafts, the mini-flush drilling system is often used, which is specially designed for shorter distances and tight conditions. Another innovative technology is the keyhole method: This keyhole technology minimises surface intervention.

The bursting method is a trenchless method for renewing old pipes in which a conically shaped bursting body destroys the existing pipe and displaces it into the surrounding soil. At the same time, a new pipe is pulled into the resulting cavity. This method is particularly suitable for renewing gas, water and wastewater pipes and also allows an increase in cross-section.

In the close-fit process, a new pipe with a small outer diameter is inserted into the old pipe and then mechanically or thermally adapted to the inner wall of the old pipe. This creates a close-fit contact and the new pipe takes over the function of the old one without it having to be removed.

Long pipe relining is a trenchless method for renovating damaged pressure pipes, which is primarily used for drinking water, waste water and gas pipes. In this process, a new pipe – usually made of PE-HD or steel – is welded on site in strings and pulled or pushed through the existing, cleaned pipe section. This creates an annular space between the old and new pipe, which is often filled with backfill material to secure it and transfer the load. The result is a statically self-supporting, as-new pipe.

Microtunneling is a trenchless, remote-controlled method for laying pipes and cables underground, in which a steerable drill head is guided precisely from a starting shaft to the target shaft. The tunnelling machine crushes the soil, which is transported hydraulically or mechanically via the pipe string to the starting pit. Hydraulic presses are used to push the pipes in sections directly behind the drill head into the newly created tunnel. The process is usually controlled and measured using modern laser technology, which ensures very precise routing with minimal disruption to the surface.

The jacking method (also known as the soil displacement method) is used for the trenchless construction of pipelines, particularly for shorter distances. Here, a pneumatic pile driver drives a steel pipe through the soil, which later serves as a casing for the media pipe. This displaces the soil and the pipe is laid in a single operation.

In 2025 and 2026, the Herrenknecht AG Power-Pipe® tunnelling machine will be used by Heitkamp Construction Swiss on various construction lots of the SuedLink extra-high-voltage direct current line:

• Lot 2: since May 2025, four parallel bores, total length 6,280 m, planned completion of construction by October 2025
• Lot 1: planned project start October 2025, drilling of eight drives, total length 7,540 m, planned construction time eight months
• Lot 6: planned project start: January 2026, drilling of 22,180 m through various geological formations

The trenchless two-phase process with the Power-Pipe® (AVNS350XB) combines elements of microtunnelling and horizontal directional drilling and is suitable for dense pipe runs and near-surface routes.

The AVNS350XB is a fully remote-controlled, high-precision tunnelling machine with a drilling diameter of 505 mm, which is suitable for distances of more than 1,000 m. It enables safe undercrossing of existing infrastructure such as pipelines, roads and waterways and allows drilling with very small distances of 1 to 2 metres, so that several lines can be laid simultaneously – a significant advantage in the construction of underground cable routes. Due to its smaller diameter, it can cover distances up to ten times longer than with traditional methods.

In this method, the machine is pushed into the ground with jacking pipes and pulled back after breaking through at the target point. A cable conduit is then pulled in, into which underground cables are then laid.

Digital tools are becoming increasingly important in drilling technology. They stand for more precise procedures and at the same time enable clean process documentation.

One recent development is the ORFEUS drill head ground penetrating radar from manufacturer Tracto-Technik. The new Grundodrill JCS130E HDD drill head is now ready for series production following practical tests by customers on various construction sites.

 Among other things, the drill head is said to be characterised by lower CO2 emissions. According to the manufacturer, in combination with the ORFEUS drill head radar, it should be possible in future to recognise obstacles at depth during drilling. A combinable, newly developed drill string should be able to transmit large amounts of data using internal data cables when using ORFEUS. This database could be used to develop new digital applications and assistance systems with a view to automating the drilling process in the future.

BIM (Building Information Modelling) could also play an increasingly important role in trenchless pipeline construction in the future - especially in HDD applications. BIM is an intelligent, 3D model-based method for the digital planning, execution and management of structures and also plays a key role in the digital transformation of pipeline construction. Particularly in sensitive areas of application where, for example, the focus is on nature conservation and strict specifications must be adhered to, professional as-built documentation and clean reporting are especially important.

A recent development in the German association landscape strengthens the topic of „trenchless pipeline construction“: On 1 July 2025, the members of the Rohrleitungssanierungsverband (RSV) and the German Society for Trenchless Technology (GSTT) voted in favour of merging to form the BGT - Bundesverband grabenlose Technologien (Federal Association of Trenchless Technologies) at general meetings. With around 200 members and the association's headquarters in Berlin, it is hoped that the association will be better recognised in politics and by the specialist public so that trenchless methods and their advantages can be used even more intensively in the construction and rehabilitation of pipe-based infrastructures in the future.

Learn more about this exciting topic at Wire & Tube, taking place April 13–17, 2026.