Scanning devices predict the location of underground pipes

A scheme to create 3D maps of underground infrastructure using an array of sensors has reached the technology prototype stage.

UK-based researchers have developed four scanning devices for predicting the location of buried pipes and cables as part of the £3.5m Mapping the Underworld project.

They hope that maps of electric, water, gas, telecoms and other underground infrastructure will reduce traffic delays by improving the speed and efficiency of roadwork operations.

Teams from Birmingham and Southampton universities have begun testing sensors that use sound waves, low-frequency electromagnetic waves and passive magnetic fields. Bath University has also completed a prototype for a ground-penetrating radar device.

Once trials are complete, the four sensors will be combined as a system that also uses official records and soil analysis from the British Geological Survey to produce 3D images of buried infrastructure.

These will be representations of where pipes and cables are probably located rather than a completely accurate map, said Chris Rogers, principal investigator and professor of geotechnical engineering at Birmingham University.

‘A three-dimensional map that gives the X-ray specs view is unlikely but something that gives a probability map of pipelines in the ground is achievable,’ he told The Engineer.

Academics from Leeds and Sheffield universities and a large number of industrial partners are involved in the project and the team is in talks with one commercial partner to create a national test facility.

Three of the sensor systems work by transmitting and receiving different waves (radio, low-frequency electromagnetic and sound) through the ground and calculating the pipes’ locations according to how the waves are disrupted.

The passive magnetic field detector uses an array of coils to measure how metallic objects affect the magnetic fields generated by electric cables and work out their location based on this disruption.

Low-frequency electromagnetic waves penetrate deep into the soil but the radar device’s waves are more easily attenuated. To compensate for this, the team uses transmitters and receivers above the surface and in pipes in the ground.

The vibro-acoustic system transmits transverse sound waves through the ground and along the pipes themselves, reading the vibrations as they return to the surface with a geophone detector or laser.

Combining the sensors’ data with official records would enable the team to have greater confidence in their results, said Rogers.

‘Even if you combine all the records from all the utility companies, the plan you get is incomplete and inaccurate but it gives some clue as to what’s there. So if we use that as an additional data stream, it gives us greater intelligence.’

Using geophysical information inferred from British Geological Survey data on ground composition would also make the sensor data better, as well as enabling the researchers to attune their techniques for the specific area they are working on.

The four-year project is funded by £3.5m from the EPSRC and grew out of an initial £1m scheme that looked at a range of technologies.

The team is also putting together a proposal for a third phase after the current research ends in 2012 that would develop technology to determine the condition of underground infrastructure and identify the location of problems such as leaks.