Quantifying uncertainty in visual inspection data

John Bennetts, G Webb, S Denton, Paul Vardanega, N Loudon

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

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Visual inspection is the most common form of condition monitoring used by bridge owners. Information derived from visual inspection data is commonly used to indicate the performance of bridge stocks and inform bridge management decisions. However, several studies have highlighted that the inherently subjective nature of the methods used to record this data can result in uncertainty, due to differences between different inspectors’ perceptions of the severity and extent of defects. It is important for asset managers to understand the nature of this uncertainty and the implications for decision making. This paper reports the results of a study which compared scoring of bridge defects by pairs of independent inspectors across 200 bridge structures on England’s strategic road network. A sample of 200 structures was selected to be representative of Highways England’s stock with regard to, inter alia, age, condition and structural form. Routine Principal Inspections for these sample structures, undertaken every six years by the relevant maintaining agents, were also attended by inspectors from WSP Ltd, with defects scored independently by each inspector. The results of these comparisons were used to derive an empirical profile of the uncertainty in different individual defect severity and extent scores. Statistical methods were then used to derive empirical probability density functions for the values of bridge and stock level condition metrics according to the widely adopted Bridge Condition Indicator system. The reported results highlight trends in the reliability of individual defect scores and the impact of uncertainty on commonly used performance metrics.
Original languageEnglish
Title of host publicationMaintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges
Subtitle of host publicationProceedings of the Ninth International Conference on Bridge Maintenance, Safety and Management (IABMAS 2018), 9-13 July 2018, Melbourne, Australia
EditorsNigel Powers, Dan Frangopol, Riadh Al-Mahaidi, Colin Caprani
PublisherCRC Press
Number of pages8
ISBN (Print)9781138730458
Publication statusPublished - 19 Jun 2018
Event9th International Conference on Bridge Maintenance, Safety and Management - Melbourne, Australia
Duration: 9 Jul 201813 Jul 2018

Publication series

NameBridge Maintenance, Safety and Management
PublisherCRC Press


Conference9th International Conference on Bridge Maintenance, Safety and Management


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