Mechanical laying process: mastering efficiency, precision, and sustainability in underground infrastructure

In the evolving landscape of infrastructure development, underground cable and pipe installation remains a critical, yet often overlooked, operation. While traditional excavator-led trenching has long dominated the field, the mechanical laying process is setting a new standard, combining speed, safety, and environmental responsibility.

Understanding this process is essential for engineers, contractors, and project managers seeking to deliver high-performance, future-proofed infrastructure.

Mechanical laying process: a technological evolution

Invented in the 1970s in France, the mechanical laying process emerged as a response to the inefficiencies and risks of manual trenching methods. Originally simple—a rock saw mounted on a tractor—the technology has since evolved into an integrated system comprising GPS-guided trenchers, reel carriers, cable wrapping machines, and highly specialized laying boxes.

At its core, mechanical laying allows the simultaneous trenching, laying, and initial backfilling of cables, ducts, or flexible pipes in a continuous, controlled operation. This contrasts sharply with traditional methods where each step is performed independently, requiring extensive human intervention, multiple machines, and substantial site disruption.

Key technical advantages of mechanical laying process versus traditional methods

The advantages of mechanical laying are profound—and measurable:

• Cost efficiency: By minimising machinery and manpower, mechanical laying can cut construction costs by up to 40%.

• Accelerated timelines: In soft soils, mechanical laying can achieve rates up to 2,500 meters per day—significantly outpacing conventional methods.

• Enhanced safety: Workers remain safely outside trenches, reducing the risk of injuries associated with manual cable placement.

• Unmatched precision: With adjustable rollers and GPS guidance, cables are laid exactly at specified depths and alignments, ensuring long-term reliability.

• Environmental responsibility: Fewer vehicles, reduced project duration, and minimal ground disturbance contribute to a lighter environmental footprint.

The process: five seamless steps to efficiency

1. Unrolling: Cables, ducts, or pipes are carefully unrolled via a reel carrier.

2. Wrapping: When multiple cables are needed, a wrapping machine binds them into a trefoil formation, preventing twists and reducing jointing.

3. Trenching: Advanced trenchers carve precise trenches, minimizing surface disruption.

4. Laying: Specialised laying boxes guide cables into the trench automatically.

5. Backfilling: Sand and soil are compacted above the laid cables, providing insulation and stability.

Each step is meticulously synchronized, achieving in hours what used to take days.

Proven success in NZ and Australia

Charlotte Pass, Australia: navigating extreme conditions

Replacing a 45-year-old backup power cable through the rocky, snowy terrain of Charlotte Pass required ingenuity and resilience. Thanks to mechanical laying technology, Marais Laying NZ completed the project ahead of schedule and within budget, preserving the fragile environment of the Kosciuszko National Park.

"The agility of the Marais team to adapt solutions on-site was remarkable. Their expertise turned complex conditions into a seamless operation."— Jed Cutter, Program Manager, Essential Energy

Harapaki Wind Farm, New Zealand: powering a nation’s future

At 1,000 meters above sea level, the Harapaki Wind Farm project posed significant logistical challenges. Over 220 kilometers of cabling were deployed with minimal disruption, thanks to mechanical laying techniques that allowed trenching, laying, and backfilling in tightly controlled time windows.

"Without mechanical laying, completing the trenching under active roadways would have been an operational nightmare."— Gareth Emeny, Site Manager, Marais Laying NZ

Harapaki Wind Farm will soon supply clean energy to 70,000 Kiwi homes, marking a major milestone in New Zealand’s sustainable future.

Looking ahead: mechanical laying as the new standard

In an industry where every minute counts and safety is paramount, the mechanical laying process offers unmatched advantages. Combining speed, safety, cost efficiency, and environmental care, it is poised to become the go-to method for future infrastructure projects across New Zealand and Australia.

When is mechanical laying the optimal solution?

Mechanical laying excels in the following contexts:

• Large-scale linear infrastructure (wind farms, solar farms, fibre optic networks)

• Projects requiring high precision (airports, smart cities, critical utilities)

• Environmentally sensitive areas (national parks, protected wetlands)

• Sites with tight construction timelines (road upgrades, industrial expansions)

However, it is less suited to highly urbanized environments with dense underground utility networks unless precise mapping and utility clearance are performed beforehand.

Towards a smarter way of building underground networks

Mechanical laying is not just an alternative—it represents a paradigm shift in how underground infrastructure is designed and delivered. By merging advanced technology, operational efficiency, worker safety, and environmental care, it responds perfectly to the growing demands for smarter, faster, and more responsible construction practices.

In a sector where margins for error are shrinking and performance expectations are rising, mastering the mechanical laying process is becoming an essential competency for modern infrastructure professionals.

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