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FORTRESS (Product)
FORTRESS (Product)
FORTRESS (Photo) (1)

STAKKAbox™ Fortress is a range of modular and structural preformed access pits, suitable for use across all major industry sector projects (in accordance with CUBIS’ installation guidelines). 

The system provides contractors with a means of constructing access pits quickly and inexpensively, whilst offering improved build quality, reduced defects and enhanced site safety performance.

The Fortress system is moulded in HDPE and possesses excellent strength to weight properties. Each section is ribbed internally to improve loading performance.

Using the Fortress system, complete cable pits can be constructed from excavation to reinstatement in less than one hour.

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  • Fast and easy to install
    STAKKAbox™ pits are significantly faster to install than conventional alternatives, with complete installations typically taking up to one hour. This results in reduced costs for the installer. No specialist equipment or plant is required in order to install the access pits and there is no need for specialist pit builders. 
  • Sectional & twin wall design
    Pits are built to required depth by adding 150mm sections. Due to the twinwall design, individual sections are light meaning they can be manually lifted. Each access pit possesses vertical and horizontal ribs,  resulting in a product that is strong vertically and on the sidewall. Most installations do not require specialist backfills, reducing installation costs.
  • Flexible during installation
    Pits can be adapted to suit on-site conditions with standard tools
    • Overbuild over existing networks
    • Introduce duct entries for cable entry. 
  • Smooth outer walls with lip to ‘key in’
    Gaps in the outer wall will negatively impact the effectiveness of compaction around the pit. STAKKAbox™ pits have smooth outer walls and an outer lip which keys into the backfill.
  • Flat pack option
    Fortress can be supplied in 'flat pack' format to make shipping more efficient.

STAKKAbox™ Fortress is commonly used for the following applications:

Highways (outside UK)

  • Motorway Communications


Rail (outside UK)

  • Telecommunications


Power & Energy

  • Low Voltage power cable link pits



  • Jointing cable pits (Telstra, NBN, local networks)



  • Valve pits
  • Telemetry pits

STAKKAbox™ Fortress is manufactured in nitrogen-foamed High Density Polyethylene, of which up to 70% is recycled material

Benefits of HDPE:

  • Excellent chemical resistance to ethanol, acetone, diesel etc.
  • Unaffected by sulfate ground conditions.
  • Recyclable
  • Robust - no breakage waste
  • Completely impervious to water
  • Nitrogen injection creates cellular core (CFC free)
  • High strength to weight ratio
  • High stiffness to weight ratio
  • Easy to cut for duct entries

Pit Accessories

Access pits can be pre-fitted with the following accessories:

  • Duct Entry
  • Cable Management
  • Steps

For more information, please visit the access pit accessories page.

Base sections

Standard Base

Access pits can be supplied with a base section, manufactured in ABS or LDPE. These are securely fitted to a ring section or bottom of a pit to provide a clean easy finish to the floor of the access pit. There is no requirement to 'float' a floor on site and the floor prevents vegetation and silt from entering.

Fortress offers a wide range of pit sizes, please contact the Cubis Systems team to discuss your project requirements.

Available sizes

Clear Opening Profile External Depth
450mm x 450mm ABC121 550mm x 550mm 150mm
600mm x 450mm A 715mm x 550mm 150mm
600mm x 600mm A 715mm x 715mm 150mm
675mm x 675mm A 780mm x 780mm 150mm
915mm x 445mm A 1020mm x 550mm 150mm
900mm x 600mm A 1020mm x 715mm 150mm
900mm x 900mm A 1020mm x 1020mm 150mm
1220mm x 675mm A 1325mm x 780mm 150mm
1200mm x 1200mm A 1325mm x 1325mm 150mm
1310mm x 610mm B 1480mm x 901mm 150mm

Download resources for the Fortress pit system:

Product Flyer

Installation Guide

Fortress Range Brochure

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