Application of Lean philosophy to routine inspection of bridges

Abstract

It takes significant time, money, labor, and equipment to run a routine bridge inspection program. This work examines the application of Lean philosophy, originating from manufacturing, as a means to assess and suggest improvements regarding the efficiency of bridge inspections. Lean aims to maximize time on activities that add value to the final product and significantly reduce losses identified as waste. The bridge inspection process was first considered as a process flow and broken down into stages. Bridge inspection stages were defined in sequential order as: the review of documents in preparation for inspection; mobilization of equipment and personnel to the site; inspection time including the time spent on visual assessment, measurement, note taking, and photographing bridge elements; demobilization; and report writing. Data was collected by shadowing each stage of the inspection of 26 bridges. The bridges were of various types, sizes, and conditions. Three different inspection team leaders and four associate inspectors were shadowed, comprising six team combinations. In order to apply Lean philosophy to bridge inspection, a time log of all activities by stage was created and the activities were classified based on their value to the final product (an owner-approved bridge inspection report) by identifying value added, required non-value added, and non-value added activities. Findings from this research suggest that the mobilization/demobilization, inspection and report writing stages each claimed approximately one-third of the total routine inspection duration. Report writing time further increased to half of the total duration when inspectors’ self-reported time on these activities was included. Furthermore, only 42% of total time spent on routine inspection of bridges was found to add value to the final output, an owner approved bridge inspection report. Different types of challenges observed during the shadowed bridge inspections informed recommendations that are provided as suggestions for possible improvements in the efficiency of bridge inspection.