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Project KAREN UFB Cable Lay


Rock cutting, Project KAREN ultrafast broadband cable-lay.Trenchless Technology

Utilities are distributed using two general systems: Overhead and Underground. Water, Waste Water, Sewer, and Gas, have generally used the underground system. Telecoms, Cable TV, Power, and now UFB Fibre Optics are now usually specified for underground installation. This trend is due to the development of new materials and composite technology in cable construction as well as the obvious protection afforded from the elements, the improved aesthetics in the built environment, and improvements in remote detection of installed underground cables using scanning devices above ground.

Installation of underground utilities has been done either by traditional forms of trenching, such as excavation, rock-cutting, or by cutting into soil with a kind of ripper blade, attached to a tracked earthmoving vehicle (such as TruLine Civil’s 26 ton Volvo EC240), known as mole ploughing. Ripper mole ploughing of cable is accomplished by pulling the ripper blade with a cable laying section trailing behind, cutting through the ground using brute force. This method is more economical than opening a trench, installing the utility, removing spoil and restoring to original site condition.

Project K.A.R.E.N.

Project KAREN (Kiwi Advanced Research and Education Network) links all New Zealand's Tertiary and Crown Research Institutions via UFB from Auckland to Invercargill. New UFB (UltraFast Broadband) was deployed via fibre-optic cable the length of the country. TruLine laid in excess of 100km in discontinuous sections in the South Island;

  • from Whatamango Bay in the South Island, south to Picton,

  • from Timaru south through Makikihi on the Timaru–Pareaora section of SH1,

  • from Oamaru south along the Alma–Maheno Road section of SH1, and

  • the section down the Leith Valley Road into Dunedin.   

    Client: FX Networks
    Engineering Consultant: FX Networks
    Duration: April 2010–November 2010

    Project Overview

    TruLine Civil undertook laying in excess of 100 km of the fibre-optic ducting cable for this large project of national significance including several kilometres of continuous rock-saw trenching in the Marlborough Sounds, Port Underwood to Picton vicinity, and approximately 100 km of mole-ploughing between Oamaru and Dunedin, much of this on busy State Highway One.

    Rock-sawing, Port Underwood to PictonA 32 mm duct was laid continuously and both pressure tested and continuity tested to ensure the fibre-optic cable ducts were both clear of obstacles and free of any distortions to the ducting tubes. This proof-testing ensured that the subsequently laid fibre optic cable was installed successfully using the cable-jetting method.  

    Fibre-optic cable duct specifications;

    • Type: direct buried installation, aluminium foil moisture barrierRock-sawing, Project KAREN cable-lay.
    • Dimensions, overall: 50mm (rocksaw trenched) 32mm (moleploughed), Microducts: 5mm diameter
    • Capacity; 4-way

    Outsized Excavator Mounted Ripper Blade Mole-ploughing Methodology

    Outsize excavator mole-ploughing.Ripper blade mole-ploughing was undertaken using an excavator mounted plough on a 26 ton Volvo EC240. The advantage of this configuration of mole-plough is that it can be worked off-centre. For example we can plough inside a guardrail while the excavator is outside the guard rail on the road—in other words we can plough beyond the outside dimensions of the excavator, offset to one side, this is very handy for ploughing trenches behind guardrails, drains and other obstacles frequently encountered on the roadside. 

    Directional drilling passing cable under roads and sealed drivewaysHorizontal Directional Drilling and cable-pulling methods were used to pass the cable under sealed driveways and roads that intersect with the highway resulting in minimum disruption to existing infrastructure and minimising the cost of reinstatement.


    TruLine Civil believe in being a solutions provider or one-stop-shop and therefore undertook to install and test the continuous line of ducting ready for cable-lay using whatever methodology was required and best suited. This ranged from rock-saw to mole plough, horizontal directional drill to trenching via excavator and hydro-vac excavation.

    Hydrovac ensures that existing underground infrastructure remains intact. This usually involves using a water-blaster or occasionally a compressed air lance to dissolve the soil into a slurry of debris that can be sucked away using powerful suction from a wide vacuum pump. This leaves a nice neat trench with existing pipes and cables undamaged. The hyrovac method is used to both locate existing services and trench past leaving the existing services intact. Vacuum excavation is considered the best practice for safely finding and seeing existing underground utilities and it reduces by more than half the chance of damaging buried utilities. 

    This contract was completed on time and within budget, while the programme timeline was very tight it was achieved to a good level of client satisfaction.

    Project KAREN ICT Context

    Project KAREN (Kiwi Advanced Research and Education Network) was deployed by the installation of new UFB (UltraFast Broadband) fibre-optic cable from Auckland to Invercargill linking all New Zealand's Tertiary and Crown Research Institutions via UFB. KAREN represents a significant national investment in IT infrastructure and is hosted on NZ-based servers at Otago, Auckland and Canterbury Universities. It leverages many other national investments in IT infrastructure through deployment on the high-speed KAREN grid. The KAREN grid has been set up with an academic focus and will be used for research and education, as well as for proof-of-concept application deployments and testing.

    Contact us

    TruLine Civil is determined to incrementally improve the service we deliver our clients, and the quality and range of civil engineering services that we offer to owners and stakeholders who expect excellence.

    Excellence in Infrastructure.

    TruLine Civil.

    Interested in our services? You can contact us +64 (21) 228-5090 and ask for Geoff Powell or e-mail me at 

    Christchurch Address 

    Greywacke Road extension,
    New Zealand 


    Credits: Photos and case study documentation by Shaun G. Waugh

  • Click thumbnail for larger image

    Project KAREN UFB Cable Lay Rock-cutting, Port Underwood to Picton. Cable lay, Port Underwood to Picton.
    Outsize excavator mole ploughing, SH1 Makikihi. Cable-jointing, SH1, Makikihi. Outsize excavator mole ploughing, Leith Valley, Dunedin.

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