Assessing the wider impacts of sub-surface utility infrastructure streetworks using the analytic hierarchy process

Sub-Surface utility infrastructure plays a crucial role in modern cities and as such, must ensure that it is sustainable so helping urban environments both to be resilient and prosper in the future. A key component of urban infrastructure projects is streetworks operations, which include: placement, installation, upgrading and renewal of utility infrastructure, all of which are expensive. To minimise the costs and associated wider impacts of utility streetworks, alternative engineering practices to the conventional open-cut trenching methods can be used, including various trenchless technologies and different types of underground utility tunnels and conduits. However, in urban areas open-cut trenching remains the most widely adopted solution for utility placement and maintenance by practitioners and the 'more of the same' approach is becoming increasingly unacceptable. This paper discusses wider impacts (and costs) of utility placement and their evaluation through the Analytic Hierarchy Process (AHP) technique for two different alternative engineering methods on a real case study scenario in the Netherlands. This provided the solid evidence allowing this work to demonstrate that although industry stakeholders still put more emphasis on short-term, direct economic costs when making decisions to choose the engineering solution for underground utility projects, an assessment of both short-term and wider long-term impacts of utility streetworks methods provides a much better performance indication for trenchless technologies and multi-utility tunnels as future proofed alternatives.