Horizontal Directional Drilling - Tunnels

A controlled drilled trajectory to install pipes, ducts, or structural elements with minimal surface disruption

Horizontal Directional Drilling (HDD) is a non-intrusive trenchless method used to install underground utilities beneath existing infrastructure, waterways, or urban environments. In tunneling contexts, HDD plays a key role in pilot bore construction, utility diversions, and geotechnical investigations, all without disrupting surface activities. VSL, through its specialist entity Intrafor, provides high-precision HDD services for tunnel-related works in challenging geological and urban conditions.

Applications of HDD in tunneling projects

Horizontal Directional Drilling (HDD) provides a versatile, minimally invasive solution for creating precise underground paths that support safe and efficient tunnel construction.

HDD allows utility installations and pilot holes without open-cut excavation, ideal for dense urban or sensitive environments.

Capable of navigating mixed ground conditions, from soft soil to fractured rock.

Advanced steering systems ensure accurate alignment over long distances.

HDD enables precise pilot bores and site investigations, reducing TBM risk during launch and breakthrough phases.

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VSL’s Horizontal Directional Drilling services

VSL delivers fully engineered Horizontal Directional Drilling (HDD) solutions, enabling precise, trenchless installations and pilot works that support complex tunneling projects.

Pre-project analysis and design

Each HDD project starts with a tailored assessment based on alignment geometry, subsurface conditions, and logistical constraints. VSL’s engineering teams conduct:
• Detailed feasibility studies
• Trajectory optimization
• Risk analysis for soil behavior, settlement, and existing structures

Trenchless drilling operations

Drilling operations are managed in three phases:
1. Pilot bore drilling: guided along a predefined trajectory
2. Reaming: enlarging the borehole progressively
3. Pullback: installing casing, utilities, or instrumentation
These operations can span horizontal distances of over 500 meters with minimal surface disruption

Utility, instrumentation & casing installation

Applications include:
• Tunnel drainage systems
• Dewatering wells and instrumentation pipes
• High-voltage ducts or communication lines
• Ground stabilization elements (e.g., jet grouting pipes, steel casings)

Why Choose VSL for Horizontal Directional Drilling?

  • Specialized expertise

    Through Intrafor, VSL brings decades of experience in geotechnical and HDD operations.

  • Turnkey execution

    Full-service offering from design to drilling and installation, minimizing coordination risk.

  • Urban and complex environments

    Proven track record in densely populated areas, near critical infrastructure.

  • Equipment range

    HDD rigs tailored to site constraints, with solutions for vertical, inclined, and curved alignments.

FAQs about Horizontal Directional Drilling

These are some of the most common questions we receive. Got another one? Reach out to us!

Pipelines of over 4km in length have been installed with HDD. Advances in drilling technology and operational practices continue to extend feasible distances.

Yes, HDD is specifically suited for urban areas due to its minimal surface footprint and non-disruptive nature.

VSL installs steel casings, dewatering pipes, monitoring instruments, and service conduits, tailored to the project’s requirements.

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Planning a tunneling project requiring trenchless access or instrumentation?

Contact VSL today to consult with our HDD experts and design the right solution for your environment.