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Four million holes are dug every year in the UK. Five billion pounds are lost through the economic effects of disruption and traffic hold ups, while hitting a utility pipe or cable can prove fatal for those working on the road. Adam Hart- Davies reports on a major research project which is trying to solve the problems.

He takes us underground from his ancient ice house at the bottom of his Devon garden to report on Mapping the Underworld, the £3.5m programme involving universities throughout Britain. The aim is to improve how we locate the increasingly confusing and complex array of pipes, cables and sewers beneath our streets, and assess their condition - as well as ultimately providing a better map of what is beneath our cities to improve planning both above and below ground.

At the moment it's often difficult to know where such utilities are - an estimated one in four of all holes are dug in the wrong place. Maps may not be accurate because original records of where the pipes and cables are located often use reference points on the surface which have long since gone.

Existing sensors may have problems finding what is underground because of soil or weather conditions, while modern materials such as plastic or fibre optics pose a challenge to existing technologies.

Adam Hart-Davies tries out the prototype of a multi-sensor cart where four different sensors operate together to produce an all-in-one solution, so if one technology doesn't work well in certain conditions and with particular materials, another one will.

It is not an easy undertaking for the research teams or, as it turns out, for Adam testing the multi-sensor cart.

Producer: Sara Parker

A Unique production for ´óÏó´«Ã½ Radio 4 first broadcast in May 2012.