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The ULTIMA Hybrid utilises the inherent benefits of the STAKKAbox™ ULTIMA Connect system, providing amplified Class D strength capabilities without compromising on ease of installation.

The STAKKAbox chamber system features ULTIMA beams specifically developed for large scale access pits 2 meters in length and above. Manufactured to a variety of sizes, the ULTIMA beams provide enhanced lateral strength with a maximum beam length of 2.2 meters.

Precast slab sections for the top and base complete the Hybrid assembly. The precast concrete encasement has been designed to replicate the modular structure of the ULTIMA, with each section interconnecting to lock in place. Alternatively, a full precast concrete encasement can be provided. Base slab can also be in-situ cast concrete to suit installation requirement as an alternative precast base slab.

Highly engineered; the entire ULTIMA Hybrid assembly acts as an exoskeleton withstanding the harshest of installation environments.

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  • Fast and easy to install
    STAKKAbox™ access pits are significantly faster to install than conventional alternatives, providing substantial cost reductions for the installer. The modular assembly solution incorporates the ULTIMA Connect pit system, engineered ULTIMA beams and an interconnecting precast concrete base slab and encasement for rapid installation.    
  • Amplified Strength Capabilities 
    The entire ULTIMA Hybrid assembly, including the ULTIMA beams, precast base slab and encasement, acts as an exoskeleton achieving Class D load capacity certified to AS 3996. No specialist bracing, backfilling or concrete surround are required.
  • Variability in size
    STAKKAbox™ ULTIMA Hybrid can be used to construct virtually any conceivable access pit clear opening. ULTIMA offers a huge range of pit dimensions thanks to the large number of standard sections and the variability offered by the ULTIMA Connect system. With the enhanced strength capabilities provided by the ULTIMA beams, the Hybrid can withstand the most demanding of environments.
  • Sectional & twin wall design
    ULTIMA Hybrid pits are built to required depth by adding 150mm sections. Due to the twin wall design, individual sections are lightweight, meaning they can be easily lifted manually on site. Each access pit possesses vertical and horizontal ribs, resulting in a product that is strong vertically and on the sidewall.
  • Smooth outer walls with lip to ‘key in’
    Gaps in the outer wall will negatively impact the effectiveness of compaction around the access pit. STAKKAbox™ pits have smooth outer walls and an outer lip which keys into the backfill. Each ULTIMA Connect ring section is supported by ULTIMA beams which ensure all pieces are flush and no movement occurs once assembled.
  • Flexibility in Construction
    ULTIMA Hybrid pit systems offer a wide variety of wall section lengths, enabling customisation of pit width, length and depth to suit installation requirements. Duct entries can be quickly and safely formed on site with standard hand or power tools.  

    ULTIMA provides a superior solution to conventional methods, such as in-situ concrete, providing a rapid and flexible build over existing infrastructure or benching. Fine top-level adjustment is possible by horizontally cutting the top section or using structural packers up to 20mm.
  • Flat pack
    STAKKAbox™ ULTIMA Hybrid systems can be sent to site in a ‘flat pack’ arrangement, allowing for flexibility in delivery and installation. A large pit system can be reduced to a number of pallets rather than occupying an entire truck, reducing total freight costs.

Significantly reduce costs of in-situ construction through time savings

STAKKAbox™ ULTIMA Hybrid can be utilised for large pit builds, providing a rapid installation solution for challenging and high demand infrastructure applications.

  • Installation times significantly reduced
    Access pits that are cast in-situ can take a week to fully complete. It takes time to erect shuttering, install the rebar, pour concrete and waiting for it to cure.  

    In comparison, ULTIMA pits can be completely installed in one day, including excavation, pit install and backfill. This has a direct impact on cost as UlLTIMA requires less labour and results in quick turnaround for underground network access projects.
  • Flexible during installation
    The ULTIMA Hybrid chamber system is adaptable to the unique requirements of each site. This means that using ordinary site tools, chambers can be retrofitted over existing networks, can be drilled for duct entries and can be cut horizontally to reduce height.
  • Safe to install
    STAKKAbox™ access pits can be safely assembled in the excavation. Each ULTIMA section is lightweight enabling a one-person lift and safe construction.
  • Safe to the public
    In-situ cast chambers require the pit excavation to remain open throughout construction. Thanks to the rapid installation capabilities of the STAKKAbox™, full construction of the ULTIMA Hybrid is completed within hours and therefore reduces safety risks to the public.
  • Flat pack delivery
    ULTIMA Hybrid components can be flat packed to make transport to site easier. This method of transportation allows the pit to be built in the excavation (see case study). Even the largest pit can be packed on a couple of pallets, excluding precast elements, reducing space needed on site and transport emissions.
  • Consistent build quality
    When casting access pits in concrete, there are many opportunities for the build quality to be compromised by miscalculation, mistakes or inexperience. Skilled box builders are not always available on site. With ULTIMA Hybrid, you can always be confident in a consistent pit build quality.
  • Long-term performance
    Due to the high chemical resistance of the GRP material, ULTIMA Hybrid pits have a longer installed life than concrete alternatives. The ULTIMA beams, precast concrete base slab and encasement, in addition to the ULTIMA chamber system acts as an exoskeleton resulting in long-term pit integrity.
  • Large range of sizes
    CUBIS can provide a wide number of clear opening dimensions due to the amount of corner and sidewall pieces available. Pit height can be adjusted in increments of 150mm. Engineered ULTIMA beams can be manufactured to a variety of lengths. To find out if we can meet the size you require, please contact us
  • Established means of construction
    Large ULTIMA Hybrid pits have been used on several high-profile infrastructure projects including the 2017-2020 Capital Metro Light Rail project in Canberra, ACT.

 STAKKAbox™ ULTIMA Hybrid is commonly used for the following applications:


  • Motorway Communications
  • Drainage


  • Telecommunications 
  • Drainage
  • Buried Cable Routes

Power & Energy

  • High Voltage power cable jointing pits
  • Low Voltage power cable link pits


  • Jointing cable pits


  • Valve pits
  • Telemetry pits

STAKKAbox™ ULTIMA Hybrid is suitable for installation in environments rated to Class D under AS 3996, in accordance with CUBIS' Installation Guidelines.

STAKKAbox™ ULTIMA Hybrid is manufactured from Glass Reinforced Polymer (GRP) composite.

Benefits of GRP:

  • High strength to weight ratio
    The material is significantly lighter than other conventional materials that can provide the same inherent strength.
  • High temperature range
    GRP is a thermoset material, meaning that it irreversibly cures when heated. As a result, GRP will not melt, drip or form molten droplets.
  • Fire retardancy
    ULTIMA won't catch fire and has low smoke properties. This means the product can be used in enclosed areas such as tunnels and underground transport.
  • High mechanical properties
    The material is non-conductive, has a low coefficient of expansion and is resistant to weathering. GRP possess high tensile and bending strengths combined with high stiffness. The material is superior in mechanical strength properties compared to those of commodity thermoplastics such as the Polypropylene and the Polyethylene family.
  • Chemical resistance
    GRP is chemically inert, which means it is not chemically reactive. Its high chemical resistant nature is essential for ensuring a long service life when buried underground. GRP is not affected by frost, acids, alkalis or diesel, all of which will affect the lifespan of concrete products.
  • Not susceptible to creep
    Creep is the tendency of a solid material to permanently deform under continuous or long-term loading or mechanical stresses. For access pits, this is related to the process where an unsupported or non-compacted sidewall could move over time due to loading from traffic. This makes ULTIMA pits ideal for a wide range of project installations.

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

Precast Concrete Floor

CUBIS manufacture all precast concrete products using 40Mpa strength concrete with full steel mesh and bar reinforcement. 


Insitu Concrete Base

The ULTIMA Hybrid pit system can be supplied without a floor if an in-situ concrete pour option is required for the base slab

Installation of an ULTIMA Hybrid pit

For more product videos, please visit the Video section

ULTIMA Connect clear opening sizes are created by combining the corner pieces. This can include one or more sidewall pieces to offer a greater number of sizes.

The corner pieces are referred to by the internal length on the long side. This dimension will be 80mm shorter than the stated length as this is made up in the short length of the ‘corner piece’.

Please contact the CUBIS Systems team to discuss your project requirements.

  • CLICK HERE to open our ULTIMA HYBRID – Capital Metro Light Rail (Stage 1), ACT case study
  • CLICK HERE to open our ULTIMA HYBRID – Brisbane Airport Corporation New Parallel Runway case study

Download resources for the ULTIMA Hybrid pit system:

Product Flyer

Installation Guide

ULTIMA Product Profile Brochure

Related Products

Related Case Studies

Brisbane Airport Corporation New Parallel Runway 1 BAC's New Parallel Runway

As part of BACs New Parallel Runway project, STAKKAbox™ ULTIMA Hybrid was selected for the build & installation of an isolation pit for a water valve.

Website image case study (2) CBD Electrical Services Relocation Project: NSW

Cubis Systems were approached to provide an underground network access solution for the relocation of vital electrical services.

CUBIS CutV1 (SD 540p).mp4.00 03 21 07.Still002 Capital Metro Light Rail (Stage 1)

The Canberra Light Rail Project, Capital Metro, marks the exciting transformation of the public transport system connecting Australia’s ACT.