Ground penetrating radar systems in the UK have until now had only limited scope and questionable reliability. Alan Sparks reports on how new technology is delving into new depths.
Striking underground services is a constant threat for utility companies and their contractors.
The effectiveness of ground penetrating radar (GPR) systems in locating them has always been limited. Existing equipment works to a common level of radiation, which produces limited results down to a restricted depth. However a new technology, known as RIS2K/MF could be about to give the technique a new lease of life.
Developed by Italian firm IDS and available from Utilx, it uses a higher level of radiation over a wider bandwidth.
Last month surveying specialist Detectaplant carried out the first trial of a new utility detection radar in the south London borough of Lewisham, with impressive results.
'This is the first time I have been excited about any equipment in the industry for a number of years, ' says Detectaplant director Paul Salisbury. 'This will enhance our ability to plan accurately for installation of pipes and cables.'
On the Thames Water-Morrison project the equipment was tested on two sections of a 700m survey: a 100m section of straight road and a 45m section which included a major road crossing.
Now full scale excavation is under way, and Utilx managing director Colin Tickle is confident that promising initial reports will go on to prove the system has been 'exceptionally accurate'.
The breakthrough has been in finding a way to deal effectively with the large quantity of data this method generates.
The radar comes equipped with an array of multi-frequency, co-polar and cross-polar antennas, which allow a high-resolution survey of the shallower depths while still achieving the desired depth range. In a further step forward, a separate antenna also enables an accurate measure of the ground type to be made.
All this information is selectively filtered before it is converted into an interactive 3D CAD drawing.
'The real advancement comes from the new found ability to deal accurately with the information in 3D, ' explains product promoter Steve Orchard of business development consultant Charador.
Indeed, the efficiency with which the system is able to sift through the detailed information is such that IDS has developed it further to create a train mounted system which can accurately survey track ballast while travelling at speeds up to 80km/h.
The information collected is converted into an easily digestible form where the client can immediately see specific soft spots and potential problems along the track.
Neither package comes cheap. The RIS-2K/MF system for utilities costs up to £70,000.
But Tickle is adamant that it will still represent value for money.
'Although costing about twice as much as its competitors, the system is far more reliable, presenting generous cost savings by avoiding trial pit excavation and costly reinstatement, ' says Tickle.
INFOPLUS Colin@utilx.co.uk http: //georadar. ids-spa. it