National Academies Press: OpenBook

Guidelines to Improve the Quality of Element-Level Bridge Inspection Data (2019)

Chapter: 4. Conclusions and Suggested Future Work

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Page 39
Suggested Citation:"4. Conclusions and Suggested Future Work." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines to Improve the Quality of Element-Level Bridge Inspection Data. Washington, DC: The National Academies Press. doi: 10.17226/25397.
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Page 39
Page 40
Suggested Citation:"4. Conclusions and Suggested Future Work." National Academies of Sciences, Engineering, and Medicine. 2019. Guidelines to Improve the Quality of Element-Level Bridge Inspection Data. Washington, DC: The National Academies Press. doi: 10.17226/25397.
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Page 40

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39 4 CONCLUSIONS AND SUGGESTED FUTURE WORK 4.1 Conclusions The primary product of this research was a visual guide intended to improve the quality of element-level inspection data. This visual guide was incorporated into the MBEI during the course of the research. The revised version of the MBEI was approved by AASHTO in 2018. A guideline for improving the quality of element-level bridge inspections was also developed which includes recommendations for accuracy requirements and methods for improving the quality of element-level data. Methods for improving the quality of element-level data include performance testing of inspectors and inspector calibrations. Field exercises were conducted in the states of Michigan and Indiana using the visual guide. The results of the field exercises showed that there was variability in the damage quantities determined from element- level inspections. It was found that the variation was on the order of greater than 50% of the quantity being measured, based on statistical analysis of the data. It was found that the variation in the inspection data increased as the quantity of damage increased. The results from the field exercises also showed that there was inconsistency in the assignment of defect elements. Different inspectors tended to report different defect elements and different CSs for the same bridge element. It is noted that the field exercises included a limited number of participants and consequently the statistical analysis is based on a very small sample. Additional testing is needed to more fully characterize the quality of element-level inspection data. Based on feedback from the post-test questionnaire, more training and experience with the visual guide is needed to make the guide more effective for improving the quality of element-level data. Qualitatively, inspectors indicated that the guide was helpful and assisted in identifying the correct assignment of defect elements and CSs. Inspectors also indicated that the guide was relatively easy to use, but could be improved if it was reformatted to be more suitable for field use. It was also found that there was variability in the assignment of CS 4 for gusset plate elements in the Indiana field exercises. A truss bridge containing 72 gusset plates was inspected by 14 inspectors. It was found that 1/3 inspectors did not report any gusset plates in CS 4, while 2/3 inspectors did report gusset plate elements in CS 4. Among the inspectors that identified CS 4, the number of gusset plates identified in CS 4 also varied. This result is significant because assigning CS 4 indicates that a structural review is warranted for the condition observed by the inspector. Use of the visual guide was not found to improve the quality of element-level data based on the results of the field exercises. This may be attributed to a lack of familiarity with the visual guide during the conduct of the testing. The field exercises were the first opportunity for the inspectors to use the guide. Additional training and experience with the use of the visual guide is likely needed in order to be able to measure improvements in quality. A model for establishing accuracy requirements was developed during the course of the research. This model illustrates accuracy requirements using a statistical basis and considering the needs for decision- making and deterioration modeling. 4.2 Suggested Future Work The visual guide developed through this research does not include all of the defect elements that are in the MBEI. Development of visual standards for defects not currently included in the visual guide is suggested to provide a comprehensive manual that address all appropriate defects. Increased training could improve the quality of element-level inspection. This training should include the use of visual guides to identify defect elements and assign CSs consistently, as well as standard methods for estimating damage quantities. Inspector calibration exercises should be considered to improve the quality of element-level inspections and ensure the uniform understanding of inspection procedures and practices. Inspector calibration

40 exercises can help reduce the variation in inspection results from different inspectors. Calibration exercises can help ensure the proper application of procedures and practices for element-level inspection. As shown in data from the field exercises, improvements are needed to reduce the variation in identification of defects, assignment of CSs, and estimating quantities. Inspector calibration exercises, in which group of inspector compare results to a standard, would increase the uniform understanding of CS and quantity estimation. The exercises would also improve the consistency of defect element assignment. Finally, the field exercises conducted as part of the research indicated variation in the damage quantities reported from different inspectors examining the same bridge. However, the sample size was relatively small, consisting of only 24 inspectors from two states. Additional field exercises of this type are suggested to better quantify the quality of element-level inspection results. Because different agencies implement element-level inspections differently, the results are likely to be agency-dependent. A model for accuracy requirements was developed as part of the research. This model is based on statistical variations in the inspection results and decision-making thresholds which may be used for identifying future actions, such as maintenance or repair. This model was used to evaluate the impact of different accuracy requirements on deterioration modeling. The model developed as part of the research has not been tested in practical situations. The application of the model to actual bridges within existing bridge management systems is needed to further develop the approach. Additional research may be needed to further develop and implement these accuracy requirements.

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TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 259: Guidelines to Improve the Quality of Element-Level Bridge Inspection Data is intended to assist inspectors in identifying defects and assigning the appropriate condition state for bridge elements.

To ensure the safety and serviceability of bridges, the guidelines include accuracy requirements designed to help promote consistency in the collection of element-level data for bridges on the National Highway System.

The quality of element-level bridge inspection data is critical for effective bridge management and asset management practices. Therefore, the guidelines also include a methodology developed to verify the impact of different accuracy requirements on deterioration models.

The American Association of State Highway and Transportation Officials’ Manual for Bridge Element Inspection includes elements of the guidelines in NCHRP Web-Only Document 259.

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