GPR (Ground Penetrating Radar) is a technology that has been used worldwide for more than 30 years. Its purpose is to identify and locate objects underground which could include pipework, cables, barrels and organic objects such as underlying roots from trees and plants.
The introduction of GPR has been a revelation in the arboricultural field as it has enabled far greater analysis of underlying problems with tree rot and root growth without the need for intrusive and potentially damaging excavation. A tree radar unit can identify a number of issues such as internal trunk decay and subsurface root mapping (morphology), meaning the arboriculturist can get a clearer picture the condition of a tree and the position and depth of the underlying roots without major disruption.
Mapping tree roots using GPR technology has several advantages over traditional, outdated methods such as:
The TreeRadar unit is a scanning cart with a 400MHz or 900MHz antenna slung beneath it, which emits a beam for every 1cm travelled, down to a depth prescribed by the operator (usually between 2 - 3m, which is the maximum depth). The radar reflection is recorded in a field computer and then analysed by the operator, using the latest software. Water and metal reflect, therefore the machine records live roots which contain moisture, and cannot detected dead dried out roots. For each scan line a 'virtual trench' is produced which shows all roots. The 400MHz radar detects roots with a diameter greater than 20mm (to a maximum depth of 3m), while the 900MHz radar detects roots with a diameter greater than 15mm (to a maximum depth of 2m). The machine cannot determine root diameter, due to the current lack of correlation between the amounts of live root tissue in a root compared to the thickness of a roots. For example a large root may only have a live central core.
Tree radar scans are completely compliant with BS5837 - the British Standard in relation to the design, demolition and construction where trees are affected.
The latest version published in 2012, applies to all trees that could be affected during every phase of a development project so understandably, schemes should comply with BS5387 when considering any development in the vicinity of trees, whether or not planning permission is required.
BS5387 determines when a tree survey should be carried out, what it should cover, measurements that must be taken and how trees should be categorised for quality and value. Tree radar technology offers a quick and practical solution to these criteria to make an informed judgement. It also classifies roots with a stem diameter of 25mm and above as major structural roots, coincidently fitting in with the results obtained from the 400MHz radar antennae.
In 2015, Lloyd Bore took delivery of their own tree radar unit, which is the latest specification model available on the market.
The great thing about our tree radar device is its size and portability. No larger than the average lawn mower and very light and easy to manoeuvre, the process can take place in virtually any situation where there’s good access without disturbing the surrounding habitats or environment. The process is very quick and straightforward, meaning data can be collected within minutes.
If you want to find out about this exciting new technology or need the help of our arboriculture team, please speak to Ian Lee who heads up the department. He will be delighted to explain the process and how the TreeRadar can help give incredibly accurate results about your trees, their general condition and what lies underneath at root level.
LloydBore are currently undertaking research in partnership with other operators, undertaking scans and then excavating the ground to measure the actual root diameters and comparing this to the reflection signatures. The intention is to use this data to evolve the analysis software, with the ultimate aim of enabling future versions of the software to analyse root diameter.