Getting closer with GPS – National mapping agency, Ordnance Survey recently offered utility companies the chance to see how Global Positioning Systems (GPS) could benefit them at a special demonstration in London.
Among those attending were representatives from Thames Water, Southern Water, South East Water and BT.
They worked with surveyors to see how the advanced data collection technology could pinpoint a specific location within just a few centimetres, providing a valuable tool for managing and positioning assets. The benefits of this shovel-width accuracy are clear – with improved efficiencies in asset capture and maintenance, work can be carried out more effectively and costs can be reduced.
Ordnance Survey realises the business need for such precision. A civilian using GPS will normally accept an accuracy of around 10 metres. This can be increased through a technique called Differential GPS (DGPS), whereby extra information is sent to the user’s GPS receiver to cancel out most of the error sources. Traditionally, a user would establish their own GPS base station infrastructure to carry out this task, adding time and cost to the operation.
However, Ordnance Survey links together a network of 55 permanent GPS base stations covering most of England, to provide a ‘regional’ model of corrections for this entire area. The system works by sending raw GPS data from the network in real-time to Ordnance Survey head office in Southampton where the correction model is generated. The user dials into this server using a mobile phone, relaying their approximate position. The server then returns the GPS correction tailored to their location, enabling the more precise positioning expected from Real-Time Kinematic (RTK) GPS, a three-dimensional 1-2 cm location.
The demonstration showed how utility companies could apply this increased accuracy to their advantage. GPS advisor at Ordnance Survey, Paul Cruddace, explains.
“We used corrected GPS positions fed into a Pen-PC to show how utility assets could be positioned and relocated in a real-life scenario.
“To simulate a pipe or cable being laid, we used a live version of Ordnance Survey’s OS MasterMap and overlaid the location of the new asset. Hence its position was recorded directly onto the map.
“A second demonstration showed how existing assets could be relocated. Three metal washers were buried into the ground to represent the assets and their exact locations programmed into GPS receivers. The challenge was to find them again – using only GPS technology.
“By linking up to the server at Ordnance Survey head office in Southampton, it was possible to gain an accuracy of just a few centimetres. Needless to say, all the washers were retrieved quickly and easily.”
Ordnance Survey now has plans to double the number of base stations to a projected figure of more than 100 across the whole country, broadening the coverage of this service. The mapping agency is co-operating with organisations such as the Met Office, the Royal National Lifeboat Institution (RNLI) and several water utilities to place the stations on their facilities. Once the stations are in place, this will be the second largest network of its kind in the world.
Thames Water has already agreed to run a pilot in and around London, to include National Grid Transco, to better understand the benefits of using GPS in utility asset management.
“With the drive to improve the recording of assets, GPS is increasingly a technology that companies are thinking about,” says Paul Cruddace.
“Centimetre -level precision means fewer mistakes in finding your location, and less time wasted in the process. The collection method can offer greater accuracy and increased operational efficiency compared with the traditional methods of gathering information, and by improving the management of assets there is scope for improving cost efficiencies too. ”