By Jonathan Amos
BBC News science reporter
The maze of pipes and cables that snake beneath the UK's streets are to be mapped in a £2.2m pilot project.
The underground: One wrong move and a whole street could be cut off
An intimate knowledge of this tubular underworld is expected to help reduce the number of holes that need to be dug by utilities, and cut traffic jams.
Nottingham and Leeds researchers will trial new 3D mapping technologies at half a dozen UK locations.
It is thought there are enough pipes and cables below ground in Britain to stretch to the Moon and back 10 times.
Some were laid more than 200 years ago and accurate information on their precise positions is often non-existent or sketchy at best.
Even modern records will be spread across numerous databases, making it very difficult sometimes for a contractor to know what a pneumatic drill might hit when it goes into the ground.
There are 30 to 40 incidents each year where workmen are seriously injured because they have accidentally sliced through electricity cables.
"When utilities and highways authorities are digging in the street, they often find things they didn't expect, or don't find the things they were looking for," explained Mike Farrimond, director of UK Water Industry Research Ltd, which is managing the mapping project.
"If we had detailed 3D maps of what was down there, we'd be much more efficient at finding and fixing leaks, and connecting people to services."
The schematic diagram above shows the typical level of complexity of pipes and cables that exists under one London street
Nationally, four million holes are dug each year at a cost of £1bn; indirect costs, such as road congestion, are estimated at £3-5bn
In the UK there are: 275,000km of gas pipes; 353,000km of sewer pipes; 396,000km of water pipes; 482,000km of electricity cables
A third of the pipes in London were laid more than 150 years ago; 20 cable firms have worked in London in the last five years
Camden High Street in London was dug up 144 times in one year; Glasgow's Great Western Road, 223 times
The project, known as Vista (Visualising integrated information on buried assets to reduce streetworks), is largely funded by the Department of Trade and Industry.
It will pull together the current records of pipes, cables and wires - be they held in digital form or on paper - and link them to new surveys undertaken at six trial locations.
The in situ observations will use ground-penetrating radar and other sensing technologies to find the precise depth and course of the local tubeworks - to within an accuracy of 5cm.
The project team hopes to come up with a mapping system that can be rolled out to other parts of the country.
Streetworkers would have a virtual map on their mobile devices
"You can't look at an Ordnance Survey map to find out what's under the ground," explained Tony Cohn, professor of automated reasoning at Leeds University.
"We will be producing an 'underlay' to the OS, to show you what's down there. We'll combine all the historical data from the utilities with the in-street data found with location-sensing technology. We want to merge this information dynamically and put it on some kind of handheld unit."
The project could result in mobile devices or displays in street diggers that would present streetworkers with a 3D picture of the pipe and cable layout in front of them. This would give workers the confidence to dig without the fear of accidentally cracking a water main or causing a major gas leak.
One of the major challenges facing the researchers will be in developing the centimetre-accurate, satellite-based location technology they will need to make their street observations.
The Global Position System (GPS) is far from reliable in high-rise urban areas or, indeed, in very leafy locations.
Utilities may encounter surprises when they go underground
"What we're doing is integrating GPS with other technologies, such as inertial navigation sensors and devices called pseudolites and locatalites (which are ground-based satellites, in effect); and survey equipment that measures angles and distances - to give us the accuracy we need," explained Dr Gethin Roberts from Nottingham University.
However, future streetworkers will not need such complicated location-finding equipment to make sense of their 3D maps. It is expected Europe's new sat-nav system, called Galileo, will greatly enhance the GPS performance once it comes on line towards the decade's end.
Although the Vista project is being led by Leeds in collaboration with Nottingham, there is support from 19 utility, transport and engineering organisations.
Vista links in with another project called Mapping the Underworld - funded by the Engineering and Physical Sciences Research Council (EPSRC), in collaboration with five other universities - which is researching improved sensor technologies to find pipes and new ways of tagging them so they never become lost.