Case Study

Precision at Scale: Delivering the HS2 North Section Tunnel Drives

The North section of HS2 represents one of the most ambitious engineering feats in the UK’s modern infrastructure history. Central to this phase is the construction of twin-bore tunnels driven by massive 10-metre diameter Variable Density Herrenknecht TBMs.

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Client

HS2 (High-Speed Two)

Main Contractor

Balfour Beatty VINCI Joint Venture

Duration

July 2021 ongoing

Equipment

Twin Bore Variable Density Herrenknecht TBM

Tunnel Length

10 metre diameter – 1 mile long

Overview

Starting in July 2021, the Balfour Beatty VINCI (BBV) Joint Venture began the complex task of executing these 1-mile long drives. This project required more than just standard tunnelling; it demanded the operation of sophisticated Slurry Treatment Plants (STP) and the execution of Sprayed Concrete Lining (SCL) works. Since the project’s inception, Tunnelcraft has been a key strategic partner, ensuring that both the specialist plant and the tunnel faces were manned by elite, safety-conscious professionals.

The Challenge

The project faced a critical mobilisation window immediately following the global pandemic. The primary obstacles included:

Safety in High-Pressure Environments: Coordinating a massive workforce across TBM operations, SCL works (Sprayed Concrete Lining), and de-commissioning without compromising the stringent safety standards of HS2.

Rapid Workforce Expansion: The need to source and deploy over 200 competent personnel in a very short timeframe to ensure “Drive 1” stayed on schedule.

Complex Technical Requirements: Operating 10-metre Variable Density TBMs and Slurry Treatment Plants requires highly specific technical competencies compared to standard earth pressure machines.

The Solution

Tunnelcraft provided a robust, high-capacity labour solution that prioritised onsite leadership and technical excellence:

Efficient Large-Scale Mobilisation: Responded to tight timescales by quickly dispatching senior representatives to the site, allowing for the professional and efficient deployment of over 200 staff members.

Specialist SCL & Slurry Teams: Supplied niche operatives, including SCL Nozzlemen, Pump Operators, and Slurry Treatment Plant (STP) Supervisors, ensuring the specialized support infrastructure functioned at peak efficiency.

Comprehensive Mechanical & Electrical Support: Provided dedicated M&E Foremen and Fitters to maintain the integrity of the TBM and associated plant throughout the drive and the vital de-commissioning phase.

Commitment to Safety: Maintained a collaborative, “boots-on-the-ground” presence that resulted in both tunnel drives being completed with zero lost time injuries (LTI).

“The mobilisation of over 200 people soon after the pandemic was challenging but Tunnelcraft dispatched senior representatives to the site quickly… Timescales were tight but key competent staff were mobilised efficiently allowing Drive 1 to start as planned. Both tunnel drives were completed successfully without incident or lost time injury.” — Neil Johnson, Delivery Director Tunnels, BBV