Retractable Tunnels

Structural Engineering

• Chassis: High-yield silver-anodised aluminium alloy (EN AW6060 T6 structural grade).
• Hardware: Stainless steel connection joints and specialised pantograph (scissor) systems for fluid mechanical retraction.
• Compaction Ratio: 5m modules retract down to approx. 35cm, allowing for a 90%+ clear site recovery footprint when closed.
• Wind Loading: Certified for structural stability up to 100 km/h (conditional upon compliant anti-lift tracks and lateral tensioning kits).
• Snow Load: Compliant rating at 0.10 kN/m² (EN13782 standards); fully compatible with internal heating loops for automated snow mitigation.

Membrane & Enclosure

• Fabric Technology: Serge Ferrari Precontraint 502 PES-PVC micro-yarn textiles with dual-sided protective synthetic coatings.
• Compliance: Certified BS 7837 Flame Retardant; heavily UV-stabilised, weather-proof, and anti-fungal treated.
• Maintenance: Segmented 1m independent roof panels running on continuous Keder strip profiles for rapid, localised panel replacement on site.
• Visibility: Optional integrated high-transparency PVC viewing strips and windows to optimise internal natural lighting.

Mobility & Site Adaptation

• Foundation-Free: Engineered for rapid installation on existing concrete hardstands, road-base, or bitumen without requiring permanent deep footings or council development approvals (DA).
• Wheel Configurations: Heavy-load nylon or all-terrain pneumatic wheel hubs (125mm to 200mm variants) to adapt to uneven industrial yards.
• Anti-Lift Ground Tracks: Optional precision floor guide rails to mechanically lock the wheels down against uplift vectors in high-wind regions.
• Modular Linking: Standardised industrial "Flashing" weather-seal kits to form air-tight, waterproof junctions against containers, site sheds, or buildings.

Dimensional Matrix

• Clear Span Widths: Scalable profiles starting from narrow 1.0m walkways up to massive 15.0m clear spans.
• Vertical Eave Clearances: Clear headroom options scaling from 1.8m up to 5.0m to clear oversized freight vehicles and plant machinery.
• Architectural Profiles: Available in Symmetric Curved Arch, Single-Pitch lean-to (wall-mounted), or Double-Pitch Asymmetrical alignments.

Ordering & Customisation

• Are off-the-shelf sizes immediately available? No. To guarantee strict compliance with local wind loads and ensure an exact layout match, every tunnel is custom-engineered and manufactured to order based on individual project configurations.
• What are the standard industrial frame finishes? The main pantograph linkages are high-grade silver-anodised aluminium. All integrated tensioning levers are powder-coated in a clean, corrosion-resistant RAL 9006 (White Aluminium) finish.
• What heavy-duty fabric colours can be ordered? We mandate premium Poly RS ADR 650 GSM fabric as our baseline standard. Colourways include industrial White, Grey, Champagne, Black, and Green. Specialised textiles like "Clear Crystal" high-visibility PVC and blackout membranes are available for light-sensitive operations.

Structural Capabilities & Dimensions

• What are the absolute maximum available dimensions? Clear-span widths extend up to 15m, and clear eave heights reach up to 5m. The total extended length is fully modular and infinitely scalable; there is no maximum limit to the length of a single run.
• What is the retraction ratio for storage space optimisation? Our scissor frames are built for high-density compression. A standard 10m site walkway compacts down to approximately 67cm when fully retracted, clearing up massive yard space for heavy machinery transitions.
• Can these tunnels navigate uneven or curved ground layout configurations? Yes. The modular frame linkages allow for controlled vertical sloping to follow natural terrain gradients and can be precision-engineered to track horizontal curves up to 90 degrees around structures.

Safety, Engineering & Compliance

• Are the fabric membranes fire-rated for United Kingdom compliance? Yes. All structural membranes carry fully certified United Kingdom fire-retardant standard endorsements under BS 7837, alongside international compliance benchmarks (NFPA 701 and UNI EN 13782:2015).
• What anchoring options are available for high-wind zones? Depending on your site constraints, the structures can be anchored using heavy-duty wall-fix brackets, mechanical concrete sleeve anchors, chemical earth stakes, or heavy modular concrete ballasts paired with high-tensile rated tie-down straps.

1. Site Operational Safety Protocols

• Mandatory Two-Person Deployment Rule: Manual expansion and compression operations must be executed in synchronisation by a minimum of two qualified site personnel to ensure balanced lateral tracking and prevent scissor frame binding.
• Pinch-Point Mechanical Awareness: Site staff must keep hands, PPE, and loose clothing completely clear of the aluminium scissor pantograph linkage paths during active retraction or deployment cycles to eliminate mechanical crush risks.
• Wheel Tracking Clearance Inspection: Prior to cycling the concertina structure, confirm that the ground tracking paths or concrete hardstands are completely clear of gravel, construction debris, or tooling to avoid sudden stop friction vectors.

2. Severe Weather & Environmental Safety Controls

• Wind Load Compliance Limits: The stated 100 km/h structural rating is strictly conditional upon the correct deployment of engineered anti-lift floor tracks, locked ground pins, or pre-stressed lateral tie-rods. Wind limits drop significantly if the structure is left unanchored during structural movements.
• Snow Load Management: In unheated temporary asset storage layouts, snow accumulation must be actively swept clear or monitored. For predicted major snow storm fronts, the PVC envelope should be fully retracted or internal space heaters turned on to mitigate load accumulation on the canopy framework.

3. Anchor Inspections & Structural Fire Controls

• Anchoring System Audits: Periodically audit all connection shackle pins, high-tensile steel cabling, turnbuckles, and chemical anchors to evaluate structural retention profiles over the asset lifecycle.
• Site Fire Separation Isolation: Only authorise original, factory-certified fireproof PVC replacement membrane segments. Ensure no high-heat electrical plant gear, fuel sources, or flammable raw construction stocks are positioned directly touching the architectural fabric line.
• Linkage Component Checks: Establish regular maintenance inspections of all pantograph locking pins, nylon wheel bearings, and track tracking mechanisms to maintain stable long-term operations.