Mole ploughing has been used as a trenchless technology for many years but has recently taken a major step forward from the fixed plough blade, commonly referred to as a “dead” blade to the present vibratory mole plough unit, commonly referred to as a “live” blade.
The original mole plough can be traced back to the late 1700s when a plough blade with a cartridge shaped mole was drawn through wetlands to form voids and thus assist the drainage of the groundwater. This method is still in use today for the regeneration of wetlands.
As the technique developed it was then used to form the void for the insertion of drainage pipes and later cable or duct, which was fed down the rear face of the plough blade.
The predominant use early in the 20th century was for the installation of drainage pipes with the slit left by the passage of the blade being filled with gravel to form a fin or slit drainage system.
With progress from horse drawn equipment to steam and then tractor mounted ploughs or towed ploughs the size of the plough and depth ploughed increased with a substantial requirement for increased power from the tractor unit to drag the plough through the ground.
The breakthrough came with the vibratory plough blade, and the fact that a live blade rather than a dead blade was passing through the ground the power requirements and the size of the power unit decreased remarkably.
This has led to compact very manoeuvrable power units working on rubber tyres that can work adjacent to or on the highway while ploughing in the verge without causing the damage inherent in the use of tracked machines.
As the installation of telecom cables are currently at 450mm, 600mm and 750mm deep the modern mole plough is ideally suited to service installation works.
Battersby Construction & Groundworks Ltd have been involved in Mole Ploughing for over 20 years. Initially with a wire towed plough, then advancing to a frame mounted plough used with a large agricultural tractor.
Up until about 5 year ago this practice and method were commonplace and 200km per annum+ were being carried out using this method.
The increasingly sophisticated requirements for moleplough technology, resulting from the NRSWA and in particular control of depth, compaction and trench positioning necessitated the advance from the frame-mounted plough to an advanced vibratory plough.
Battersby Construction & Groundworks Ltd researched the market in robust, compact high power tractor units to operate and deploy the vibratory plough and ancillary equipment.
The result was to use a 145bhp four-wheel drive and four wheel steer tractor unit with a high flow power take off unit to enable the vibrator on the plough and ancillary hydraulics to be adequately powered.
This power unit was provided with a quick-change hitch therefore allowing rapid inter-change-ability between the mole plough, trencher and a rock wheel.
The trenching technologies are synergistic with each other and in particular operational efficiency is gained by combining the deployment capability and capacity into the same tractor unit. Additional attachment on the units provide availability of a “Top Cutter” which can plane out surfacing materials, be it bitmac or concrete, to a depth of 300mm.
This combination of deployment technologies, in a highly automated tractor unit, allow savings on saw cutting and the breaking out of surface materials.
In addition, there is reduced environmental impact as the arisings from the “Top Cutter” are suitable for duct surround and trench backfill reducing the requirement for imported backfill materials.
Battersby Construction & Groundworks Ltd now have 6 various units in their fleet allowing them to tackle the toughest of ploughing conditions.
The vibratory plough has:
- an aggressive but controllable shaker speed and with large amplitude it provides ample soil fracturing force while minimising reinstatement
- horizontal and vertical float and the blade is steerable allowing maximum manoeuvrability in tight turns or around obstacles
- quick change hitch attachment to allow ploughing to be offset by 900mm allowing the machine to sit on the road while ploughing in the verge
- a base tractor unit which is a four wheel drive, crab steerable unit mounted on rubber tyres. This allows access to confined spaces, narrow sloping verges and other difficult terrain without tracking damage to surfaces.
The ploughs are used for direct burial of:
- armoured copper and fibre optic cables,
- pre-ducted copper and fibre optic cables.
Note 1: The cables can be in service at the time of installation and are ploughed without damage or loss of service.
Note 2: The normal depths achievable are 450mm and 600mm with cables or sub ducts up to 40mm diameter.
Note 3: At standard depths it is possible to lay multiple duct or cable configurations along with a warning tape.
Note 4: It is possible in good conditions to direct bury services up to 900mm with cables or duct up to 50mm in diameter.
Note 5: Greater depths, diameters and using up to 6 sub are possible dependant on suitable ground conditions.
Note 6: Battersby Construction & Groundworks Ltd have the capability of maintaining a laid depth of 600mm through rock or carriageway by utilising a specialist rock wheel attachment to the tractor unit. By using the rock wheel in cutting a carriageway it ensures that the reinstatement required is minimised. Only in the hardest of bedrock is it necessary to reduce cover where the service cable or duct will be protected by concrete.
- The Advantages of Moleplough Technology.
|FEATURE||RESULTS||TANGIBLE BENEFIT||INTANGIBLE BENEFIT|
|1. High output of the machine.||Reduced unit costs.||
|2. Leaves a tidy job||Reduced environmental impact of operations||Time saving in reinstating the ground disturbed||
|3. Ploughs the cable in at the same time as the excavation eliminating the need for ducting||
Reduced unit costs
|4. Various sizes of cable and sub-duct can be laid in a wide variety of locations||Increased flexibility for deployment||
|5. Cables can be ploughed in live||Reduced customer impact and time to deliver service||