Guidelines to Improve the Quality of Element-Level Bridge Inspection Data (2019) / Chapter Skim
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E-1 APPENDIX E Field Exercise Results
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E-2 Contents E.1 FIELD EXERCISE OVERVIEW .......................................................................................... E-6 E.1.1 Field Exercise Plans ................................................................................................
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E-3 List of Figures Figure E-1. Image of a Snellen eye test chart.
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E-4 List of Tables Table E-1. Results from pretest questionnaire for Indiana field exercise.
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E-5 Table E-35. Inspection result for element 300 - Strip Seal for bridge M3 reported as a percentage of the total quantity.
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E-6 E.1 Field Exercise Overview This appendix describes the results of the field exercises completed as part of the research. The objectives of the field exercises were to evaluate the effectiveness of the guideline developed through the research, to assess potential changes to the Manual for Bridge Element Inspection (MBEI)
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E-7 E.1.1 Field Exercise Plans This portion of the report provides a brief overview of the execution of the field exercises. Complete details on the test bridges and protocols used during the field exercises are included in Appendix D, which documents the field exercise plans.
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E-8 participating in the study test relative to the overall population or other groups of inspectors participating in future (or past) studies.
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E-9 The participants were divided into two test groups: Test Group A (TGA) and Test Group B (TGB)
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E-10 Several questions on the pre-test questionnaire sought to gain insight into the typical methods that were used by inspectors to determine the quantities of damage in the field. The pre-test questionnaire sought to determine the methods that were used for estimating areas of damage for elements rated in sq ft (e.g.
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E-11 estimate and second by tallying lengths. Background that describes the motivation for these exercises is provided in the following section, as well as the results of the testing.
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E-12 efficiently. Second, not all surface areas of a member may be observable in the field.
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E-13 inspector are not bias by repeating the same estimates. Two estimating tasks were completed (S-BRITE 2 and S-BRITE 3)
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E-14 and the average (mean) value from both test groups combined was 8%, the error was calculated as - 4% and normalized error was calculated as 4/12 = 33%.
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E-15 Table E-4. Results of estimating areas on guide sheets.
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E-16 To characterize the scatter shown in Figure E-5, results were analyzed statistically to provide the mean (average) results for each of the two inspector groups, and the σ and COV are typically presented to summarize the test results efficiently and express the variation in the data.
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E-17 Figure E-6. Results from estimating the area of simulated damage on the webs of two plate girders.
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E-18 Table E-5. Results from S-BRITE Tasks 2 and 3 showing damage estimates and analysis results.
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E-19 The results from Tasks 4 and 5 are shown in Figure E-7, showing length estimates provided by the participants in TGA and TGB. These data show the length estimates for both tasks in terms of percentage.
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E-20 based on sq ft and presented as percentage is also shown for illustrative purposes. Both percentage estimation and tallying methods demonstrated a large overestimate as compared with the actual percentage based on sq ft, which is not surprising given the test arrangement.
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E-21 Table E-6. Results of S-BRITE Tasks 4 and 5 estimating damage by length (ft)
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E-22 Table E-7. Error analysis of the combined results from TGA and TGB for Tasks 2-5.
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E-23 E.2.4 Task S-BRITE6 Truss and Gusset Plate Elements This task consisted of inspection of the decommissioned steel truss erected at the S-BRITE center shown in Figure E-10. As shown in the figure, the single-span through-truss has corrosion damage and protective coating damage throughout the truss.
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E-24 Figure E-11. Examples of corrosion damage on the truss bridge showing gusset plate (A)
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E-25 It was more common for CS 4, where only one or two inspectors may have assigned CS 4. Consequently, mean values for CS 4 are not typically included in the tables; these data are addressed in the text.
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E-26 Neglecting this outlier, the COV for the total amount of damage for the combined groups would be reduced from 15% shown in Table E-8 to only 2%. These data illustrate that the quantities of damage assigned to CS 2 and CS 3 vary significantly in both groups TGA and TGB, but there is agreement in the total amount of damage in the truss (CS 2 + CS 3)
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E-27 TGB rated the protective coating system in the conventional manner of sq ft. Six of the seven inspectors in TGB provided an assessment of the protective coating, and each of these inspectors assigned quantities to CS 2, 3, and 4.
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E-28 review is a subjective assessment, such that one inspector might consider the level of damage requiring review while another might assign CS 3. These data indicated that for the combined group, the mean value was 39% with a COV of 56%.
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E-29 variation in inspection results, since the design characteristics and situational factors (e.g., access) are identical, and therefore, not a factor in any variation between inspection results between the two bridges.
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E-30 Figure E-14 illustrates the general conditions of test bridges I1 and I2. The figure shows an elevation view of the bridge where corrosion damage on the fascia beams can be observed (A)
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E-31 to normalize the results and assist in the analysis; obviously, the original test data was in the appropriate units for the given element. For example, corrosion damage in element 107 was reported in ft.
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E-32 Table E-12. Inspection results for Element 107-Open steel girder.
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E-33 These data indicate that there is variation in the interpretation of CS 4 and that not all participants are rating the coating element. It should be noted that the inspection sheet provided to the inspectors included a preprinted table for entering the values assigned for the coating (element 515)
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E-34 the resulting distribution of results was greater than, or less than, the results from using a sq ft assessment. It was found that the overall quantities assigned to the CS of 3 and 4 were significantly larger when the unit of linear ft was used as compared with units of sq ft, as shown in Table E-14.
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E-35 E.2.5.2.1 Element 12-Deck The expected outcome of the tasks was different estimates of CS and spatial estimates. In particular, the crack defects in the deck may be rated CS 2 or CS 3.
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E-36 concealed by a stay-in-place form, as indicated in Figure E-18. One member of TGB did not provide any results for the deck of I1.
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E-37 As shown in the table, the removal of this outlier significantly reduces the value of σ and the COV values, and improves the consistency in the mean results. With the outliers removed, the mean value for damage of the combined group drops from 15% to 7.7% for bridge I1, and from 13% to 10% for bridge I2.
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E-38 E.2.5.2.2 Element 510-Wearing Surface The riding surface of bridge I1 and I2 consisted of an overlay with cracking and areas of spalling and poor condition patches. The inspection of the wearing surface was completed from the shoulder of the roadway, while the bridge was open to traffic.
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E-39 All of the inspectors identified some portion of the wearing surface of bridge I1 as CS 3, and 8 out of 14 identified some portion of I2 as CS 3. Because of the role of material in poor condition (i.e., CS 3)
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E-40 that there was variability in the primary defect identified by the inspectors in different groups, but when all inspectors were combined into a single group, there was agreement that cracking was the primary defect affecting the deck. Table E-18.
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E-41 2310-Leakage. The condition of the compression seals at the ends of the bridge was fair to poor as shown in Figure E-22.
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E-42 Table E-20. Defects for compression seal identified by inspectors with CS 2, 3 or 4 for bridges I1 and I2.
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E-43 E.2.5.3.2 Element 210-Reinforced Concrete Pier Wall Bridges I1 and I2 included 87 ft of pier wall in generally good condition. For bridge I1, the control inspection assigned 1ft (~1%)
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E-44 Figure E-23. Photograph of two moveable bearings in bridge I1 showing corrosion damage.
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E-45 known what defect that inspector observed when assigning the CS 2. If three inspectors positively identified a defect, the quotient 3/5 is assigned.
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E-46 to increase. Results presented later in this report from Michigan, where experience in element-level inspection is greater, generally had less inconsistency in the assignment of defects.
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E-47 Table E-25. Condition ratings for bridges I1 and I2.
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E-48 one day." Likewise, answers to what did the inspectors liked least about the visual guide identified two concerns: 1) Four inspectors said that it was "large size" "bulky" and "lengthy" to "carry it around" and one of them mentioned that "we typically condensed inspection guides for ease of use in the field." 2)
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E-49 E.3.1 Pre-test Questionnaire A total of ten inspectors attended the inspection exercise with five inspectors in each day. The inspectors were randomly divided into two groups, TGA (the group who used the newly developed visual guide)
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E-50 if there appeared to be any effect from have a least one inspector that was not a qualified team leader. No effect could be found.
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E-51 Table E-27. Simulated area estimation as percentage of the total area of the sheet of paper.
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E-52 E.3.3.1.1 Element 109-Prestressed Girder For bridge M1 the control inspection rated element 109 for defect 1080-Delamination/Spall/Patched Area and assigned 1% of this element in to CS2 and 1% in to CS4. The control inspection analyzed that the spalling damage required review (CS 4)
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E-53 CS 4, such that for TGA and TGB only CS 2 and CS 3 quantities are included. The COV reported in this table indicate values are typically greater than 50%, with most being equal to or close to 100%.
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E-54 The results from the individual inspectors are shown in Figure E-25 for damage in the PS girder. This figure shows the individual CS 2 and CS 3 quantities for each of the 10 inspectors in TGA and TGB, and the combined quantity for CS 2 + CS 3.
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E-55 E.3.3.2 Task 2 Bridge M1 and M2 Substructure Elements This task consisted of inspection of element 205/207-Reinforced Concrete Column for bridges M1 and M2. In this task all inspectors were asked to assess the columns using unit of each; a later task asked the inspectors to rate the columns in ft.
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E-56 The data in Table E-29 shows that there was, when looking at the averaged values presented in the table, consistency in both TGA and TGB estimating about 50% of the columns were damaged in bridge M1; there was less consistency for bridge M2 where the mean value was 53% for TGA and 30% for TGB. There was some agreement between TGA and TGB in assigning CS 3 for bridge M1; TGA assigned 42% and TGB assigned 34% of the columns to CS3.
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E-57 It is useful to examine the individual inspection results to better understand the data presented in Table E-29. Table E-30 shows the CS assignments from each of the 10 inspectors in TGA and TGB.
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E-58 inspectors captured defect 1130, and one inspector assigned defect 1120 for this element. These data indicate that different defect elements were assigned among the two test groups.
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E-59 The time required to complete the assessment of the columns using the units of ft was reported by the inspectors as part of this task. The average time that inspectors reported to complete the assessment of the columns using unit of ft was 7 minutes per bridge.
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E-60 For Bridge M2, the control inspection rated the abutment with CS 2 damage by defect 1130-Cracking. Four out of five TGA members captured the same defect and CS assigned by the control inspection and one TGA member reported quantities without defect assignment.
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E-61 Table E-32. Inspection result for element 215 - RC Abutment and Element 234 - RC Pier Cap for bridge M1 and M2 reported as a percentage of the total quantity.
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E-62 Table E-33. Inspection result for element 313-Fixed Bearing and element 310 - Elastomeric Bearing for bridge M1 and M2 reported as percentage of the total quantity.
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E-63 Figure E-29. Bridge M3 span 5 deck surface showing delamination/Spalls/Patched Area defects.
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E-64 several inspectors that estimated less than 100 sq ft of total damage (CS 2 + CS 3) , and several inspectors that estimated more than 600 sq ft of damage.
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E-65 E.3.3.6 Bridge M3 Task 2 E.3.3.6.1 Element 300-Strip Seal, and Element 301-Pourable Joint Seal. This task consisted of inspection of element 300-Strip Seal, and element 301-Pourable Joint Seal.
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E-66 Figure E-31. Bridge M4 top of deck showing delamination/spalls/patched area on spans 4 and 6 All TGA members assigned defect 1080 for some portion of the deck.
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E-67 and 2307 sq ft (14%) damage in the deck.
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E-68 These values indicated that for the poured seal, where damage was less than 50%, the variation in results was much greater than for the strip seal where damage was close to 100%. Table E-37.
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E-69 Table E-39. Statistical results from NBI ratings of bridges in Michigan.
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E-70 some consistency in the reporting of defect elements in these data. For example, five members of TGA reported defect 1080 for bridge M2, and four members of TGB reported defect 1080 for bridge M2.
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E-71 Table E-41. Frequency table showing number of inspectors assigned defects for an element for bridge M1, M2, M3, and M4.
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E-72 Another question asked TGA members to rate the ease of use of the visual guide on a scale of 1 to 5, for 1 being difficult and 5 being easiest. Three inspectors rated the visual guide as 4 (Easier)
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E-73 time to complete the tasks was increased for TGA, the additional time required was not that significant. On average, TGA completed inspections in 54 minutes as compared to TGB completing the tasks in 50 minutes.
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E-74 Table E-43. COV values determined for TGA and TGB for the field exercises.
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E-75 The results from MI and IN were also analyzed to determine how the assignment of CS 3 related to the quantity of an element in CS 3. Figure E-35 shows the relationship between the numbers of inspectors reporting CS 3 and the mean value of the quantity assigned to CS 3.
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E-76 sparse to assess effectively; more data is needed for situations where the quantity of damage in CS 3 is greater than 10% is needed. One of the objectives of the field exercise was to compare the use of the visual guide with the traditional inspection approach.
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E-77 increased when using units of ft (98%) as compared with sq ft (72%)
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E-78 Using unit of length (ft) as compared to ea resulted in decreased quantities of damage and decreased variation between inspectors.
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E-79 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.
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