Improved detectability of underground infrastructure - The stakeholders' perspective

While trenchless installation of utility infrastructure provides major improvement over trenches in terms of engineering sustainability (addressing particularly the social and environmental pillars in the 'three pillar' model), lack of detectability of existing buried utility infrastructure, by geophysical survey, can compromise the benefits if local excavation is needed to establish exact locations. More importantly, lack of complete knowledge on the location of existing utility infrastructure increases safety risks for personnel engaged in buried utility work. Location of buried utilities can be undertaken using a number of geophysical methods, but all are influenced in their efficacy and accuracy by the prevailing ground conditions and utility type. Success rates in location have fallen well short of the necessary 100% when used without recourse to local 'proving' excavations. To ensure that stakeholder requirements are incorporated into a major new UK study, entitled Mapping the Underworld (MTU), a questionnaire has been used to determine current and future accuracy requirements. The resulting data are facilitating assessment of geophysical location options against stakeholder needs, and providing a greater understanding of the bounds within which these requirements are achievable with current detection methods. This paper introduces MTU, outlines how MTU is assessing key location difficulties and relates them to questionnaire findings to establish future challenges to be met by geophysical survey methods. It concludes that full understanding of geophysical soil and utility characteristics is essential if detection of buried utilities is to meet stakeholder accuracy and detectability requirements, and recommends how this may be achieved practically.