Condition assessment of water mains using fuzzy evidential reasoning

This paper describes a method of combining fuzzy inference and evidential reasoning to quantify the corrosion rate of buried metallic pipes, i.e., cast-iron and ductile-iron. The method relies on two bodies of evidence: the corrosivity of surrounding soil and the corrosion rate estimated from measured maximum pit depth. Fuzzy inference is used to deduce a corrosivity criterion, viz., corrosivity potential (CoP), for each body of evidence. The two CoPs are then fused using evidential reasoning to obtain a CoP that is expected to be more reliable than that obtained from any one individual body of evidence. This type of criterion can help utility managers make informed decisions on how to protect their pipes exposed to different soil conditions. The proposed reasoning framework is demonstrated through a case study based on soil properties and corrosion rate data.