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tunnelling

Ventilation Design for Tunnel Construction

The Air is Clean

Comprehensive Ventilation Systems for Tunnel Dust Control​

Protecting Workers. Meeting Regulations. Enhancing Performance.

Effective ventilation is essential in tunnel construction to control dust and safeguard worker health. With stricter regulations and growing awareness of occupational hazards, advanced ventilation systems are no longer optional—they’re critical.

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Why It Matters

Respirable Crystalline Silica (RCS)
Generated during excavation and drilling, RCS is a major health risk. Prolonged or high-level exposure can lead to:

  • Silicosis

  • Lung cancer

  • COPD

Acute symptoms can develop quickly in high-concentration environments.

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Regulatory Compliance

Workplace exposure limits for RCS have tightened globally, now set at 0.05 mg/m³ over an 8-hour TWA—matching asbestos standards. Compliance requires robust dust control strategies.

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Dust Control in Tunnel Construction

Underground environments demand a multi-layered approach:

  • Dust collectors and scrubbers

  • Face ventilation via ducting or brattice wings

  • Sequenced construction to optimize airflow

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Tailored Ventilation Design

Each tunnel project is unique. Our solutions consider:

  • Geology and climate

  • Tunnel size and construction method

  • Site access and logistics

  • Budget and project goals

  • Maintenance needs

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Common Tunnel Ventilation Models

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Tailored Systems for Effective Dust and Airflow Management

Grydale offers expertise in designing ventilation systems suited to various tunnel construction scenarios. Below are the most commonly used models:

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Forced Ventilation System

The most widely used method in tunnel construction, forced ventilation pushes fresh air into the tunnel via ducting. Air travels from the out-bye to the in-bye end, collecting contaminants along the way.

Best for: General tunnel applications
Considerations: Contaminants concentrate near the out-bye exit

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Overlap Ventilation System

This system combines forced airflow with a dust scrubber positioned near the ventilation outlet, creating dual airflow paths. Negative pressure helps pull air through the tunnel.

Best for: Long road or rail tunnels, especially at the roadheader face
Limitations: Less effective in short or confined drives
Key Requirement: Precise airflow balancing to prevent dust escape

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Extract Ventilation System

Air is drawn through the tunnel and exhausted via ducting to a scrubber, which cleans the air before release. Scrubbers can be placed in station boxes or shafts, with airflow regulated by louvres.

Best for: Short tunnels or permanent ventilation setups
Advantages:

  • Continuous clean air renewal

  • Contaminants confined to ductwork

  • Reduced exposure at the tunnel face

  • Lower noise levels

  • Efficient dust treatment before atmospheric release

Grydale dust scrubbers feature adjustable airflow, helping reduce operational costs while maintaining high performance.

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Grydale North America Ventilation Design Services Spot-Extraction

Grydale Ventilation Design Services

Engineered Solutions for Tunnel Air Quality and Compliance

Grydale’s engineering team delivers tailored ventilation designs for tunnel construction projects across North America. Our solutions ensure optimal air quality, regulatory compliance, and operational efficiency.

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Design Focus Areas

  • Airflow optimization

  • Dust and diesel particulate control

  • Energy efficiency

  • Noise reduction

  • Environmental monitoring recommendations

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Our Design Process

  • Comparative analysis of ventilation options

  • Recommendation of best-fit solution

  • Data collection for system specifications

  • Detailed design documentation for all phases:

    • TBM breakthrough

    • Stations, portals, and interconnections

    • Excavation shafts and cross passages

    • M&E fit-outs

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Documentation includes equipment specs, usage guidelines, and ventilation requirements for managing site contaminants. We also provide ongoing engineering support and plan updates as site conditions evolve.

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Advanced Design Tools

  • Ventsim™ DESIGN 5 – Ventilation simulation

  • Autodesk CFD – 3D airflow modeling

  • Autodesk Inventor – Mechanical and structural design

  • Verification – Model reviews and structural calculations

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Air Volume Calculations

Ventilation capacity is determined by:

  • Required airflow

  • Diesel equipment type and power (kW)

  • Number of personnel

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These factors guide the design of effective dust extraction and ventilation systems.

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Grydale North America Tunnelling Ventilation and Underground Construction Services

Tunnel & Underground Construction Services

We specialize in comprehensive solutions for underground infrastructure projects, including:

  • Dust Control & Source Extraction

  • Tunnel Ventilation Design

  • Main Tunnel Construction

  • Underground Station & Cavern Excavation

  • Cross Passage Development

Grydale North America- Talk to our Expert Team

Talk to Our Expert Team

Need guidance on implementing effective spot extraction solutions or tunnel ventilation design? Contact Grydale’s expert team to explore how we can support your project. We specialize in delivering practical, immediate solutions for dust control, backed by decades of industry experience

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