Verification tool for sewer database quality

Often the quality of information in sewer databases is questionable due to e.g. poor documentation and subsidence of sewers. As a result, decisions on sewer rehabilitation have to be made with unreliable or incorrect information. This paper presents an automatic validation tool for sewer database quality. This tool evaluates recency, reliability, accuracy, consistency and completeness of information in a sewer database. The evaluation of database quality consists of a combination of logical queries, which are implemented as automatic control algorithms. Information on database quality is useful for reducing uncertainty in decision-making on sewer inspection and rehabilitation. The verification tool has been applied to the database of several management authorities. The results show that the methodology provides useful information for decision-making. Interpretation of the results, however, depends on the management authority due to e.g. differences in standard specifications for sewers. In addition, checks of recency of information are difficult because information on revisions is not accessible or even unavailable.