Sewer rehabilitation planning - priority and cost planning using GIS

Rehabilitation priority and cost planning are an important and integral part of urban drainage master planning in Switzerland. Although Entsorgung + Recycling Zürich (ERZ), the sewer-age utility of the city of Zürich, has considerable financial means available for the rehabilita-tion of its sewers, it has so far not established a continuous leading role in triggering rehabili-tation projects among the city’s utilities departments, which results in a suboptimal qualitative improvement of the sewer network. This was due to organisational as well as technical rea-sons. It was thus decided in late 2003 to develop a decision support tool for rehabilitation and cost planning, which visualises the most urgent rehabilitation needs. A lot of data necessary for rehabilitation and cost planning is readily available on different databases and servers, but was so far never linked to provide a semi-automatic tool that combined all the information. This paper describes the basics and the methods for the design of a rehabilitation- and cost-planning prototype.