Selecting utilities placement techniques in urban underground engineering

Placement of utilities has not been generally accomplished in any sustainable technique resulting in a veritable maze in high density urban areas. As underground space scarcity grows in our cities due to the increasing demands for utility services, subsurface facilities such as utility tunnels are becoming more efficient in providing the required infrastructure. There is a growing public awareness of aesthetic considerations and impatience with street cuts and their associated costs, traffic interferences, noise and accidental utility cuts. Unfortunately the lack of data and the difficulty in quantifying the intangibles has made it impossible to arrive at a reasonably accurate figure of overall negative impact on the urban environment of street cuts. Due to this, current practices of traditional trenching depending only on cost indicators remain as first option in urban planning instead of more sustainable techniques, like utility tunnels. However, it is well known that intangible costs to the public and the utilities might make the utility tunnel concept to be economically feasible in the long run. This paper presents a methodology based on AHP and Delphi processes for the selection of utilities placement techniques in which the intangibles are also assessed to avoid short-sighted urban underground planning.