guidelines to improve the quality of element-level bridge

Guidelines To Improve the Quality of Element-Level Bridge Inspection

DataGlenn Washer

University of [email protected]

June, 2017

This investigation was sponsored byTRB under the NCHRP Program. Datareported are work in progress. Thecontents of this presentation has notbeen reviewed by the project panel orNCHRP, nor do they constitute astandard, specification, or regulation.

mailto:[email protected]

Research Team • University of Missouri

– Glenn A. Washer, PhD., PI– Henry Brown, RE– Mohammed Hammed, GRA

• Jensen Engineering and Consulting LLC– Paul Jensen

• HDR – Brian Leshko

• Collins Engineering – Calvin Karper– Jeremy Koonce

• Purdue – Rob Connor, PhD

Agenda

• Review goals and objectives• Status• Overview of Progress• Future Work • Conclusion and Discussion

Goals and Objectives• Goal: Improve the quality of element-level

bridge inspection data • Objective

– Develop guidelines to improve the quality of element-level data collection for NHS bridges in reference to the AASHTO Manual for Bridge Element Inspection

• Improve consistency in data collection and assessment of bridge element conditions

• Establish accuracy levels for element conditions and applicable defect quantities to support bridge management system deterioration forecasting and evaluation

Status of Project

• Tasks 1 through 9 are complete– Interim Report I January 2016– Revised April 2016

• Interim Report 2 - April 2017• Future tasks of field exercises to assess

research products • Project is in the process of NCTE

Phase II Interim Report • Four main sections

– Interim Report• Suggested updates to the MBEI

– Guideline to Improve the Quality of Element-level Bridge Inspection Data

• Text • Visual Guide

– Field testing plan• Evaluate potential updates• Analyze quality of element-level inspection data

Visual Guide For Field Use• Why a visual guide?

– Research on VI shows that the use of visual guides to enhance text improves quality and reliability

– Provide uniformity in interpretation of text– Support inspectors in the field– Recommendation from 2007 scan on bridge

inspection quality assurance

Task 7 Develop Guidelines – Visual Guide

• Objective: Provide a tool for inspectors to improve the quality of element-level data collection

• Visual guide is a standalone document that contains two sections and two appendices– Section I – Visual Standard

• Defect-Based• For consistent rating in the field

– Section II – Spatial Estimation Diagrams & Tools– Appendix A – Element Examples– Appendix B – Defects CS4 Examples (?)

Visual Guide – Visual Standard• Contains the elements and defects

– Primarily steel and RC defects– Defines the CSs for 17 defect elements included in the study

• Visual Standard divided into 6 subsections– Reinforced Concrete – Prestressed Concrete– Steel– Steel Protective Coating– Movable Bearing– Joint

• Images were acquired from:– Field data collection – Existing manuals – Team members

Visual Guide – Section I Visual Standard

• Each subsection starts with the list of elements followed by the list of defects applicable to the elements

• A Visual Standard page content and layout


Defect Number and Name

Condition States descriptions

Boundary Images show CS in-between two CS’s

CS’s Images

• Scales are used to provide context – For cracks, comparator is used to indicate dimension

• Red rectangular shapes are used to identify the defect


• For reinforced concrete elements - crack defect, there are diagrams showing several different crack pattern densities


• For reinforced concrete elements - crack defect, there is a page contains figure showing crack width, its description, and some common things can be used to measure crack width


• Spatial diagrams available for area damage, cracks, and linear estimates

Visual Guide – Section II Spatial Estimation Diagrams

1 % Damage shown on bridge deck

Damage spread across the deck

Damage less spread across the deck

Damage concentrated in a single spot

• 10% area

Visual Guide – Appendix A Element Examples

• Element 12 - RC Deck, Defect 1190 – Abrasion/Wear

Visual Guide – Appendix A Element Examples

• Element 12 - RC Deck, Defect 1120 – Efflorescence/Rust Staining

Accuracy Guideline

Model for Accuracy / Tolerance Requirements (Guidelines)

• Current accuracy requirements are subjective

• Requirements could be improved through consideration of:– Inspection capability – Decision-making needs

• 10%, 20%, 30% – Future data needs – deterioration modeling

CS 3 Quantity (%) Action <10% Preservation

10% to 30% Maintenance repair / overlay >30% Rehabilitation/Repair

Inspection Capability • How much variation is there in inspection

results given the inspection process used – Routine inspection vs scoping or in-depth

• Access used • Documentation of quantities

– Area estimates vs tallying– Use of NDE technologies

• IR / Sounding +/- 5% • GPR, HCP +/- 20%

• Focus on routine insp.

Task 7 Effect of Accuracy on Deterioration Modeling

• Effect of various accuracy requirements on deterioration modeling was analyzed based on Markov models

Fast rate det. Slow rate det.

Rational Accuracy Requirement

• Quality Ratio (QR)– Range of values vs accurate inspection result– Consider the importance of the decision

Decision Threshold

Value

Accuracy Tolerance

Quality Ratio

Slow Fast 10% +/-2.5% 50% 40%

20% +/-2.5% 20% 29% +/-5% 45% 43%

30% +/-2.5% 12% 22% +/-5% 27% 33%

+/-10% 62% 56%

Field Trials

Task 8 Field Trials– Objectives• Compare the use of visual guide with traditional inspection

approach– Accuracy of inspection Accuracy of spatial estimates Correct assignment of condition states

As compared with a reference (the control inspection)Variation within group A and group BVariation between group A and group B

– Timeliness of inspection • Assess potential changes to the MBEI

– Use of different units – ft vs ea for columns, ft vs sq ft for steel protective coatings

– Reduced no. of defects and elements for seals

Task 8 Field Trial– Overview

• The experimental approach to field exercises is Control Bridge Model (CBM)– CBM is characterized by the use of small number of “control

bridges” to evaluate the quality of inspection results – Participants conduct routine inspection of the elements of CB

and complete a study-based bridge inspection report• The inspection results will be:

– Analyzed to assess the variation in results between different inspectors and the effect of using the visual guide

– Assess the procedures for inspection • Tallying areas vs spatial estimates

Potential Updates to the MBEI

Potential Updates

• Reorganized the manual– Repetition of defect descriptions could be

reduced– Organize by material

• e.g., Reinforced Concrete – Listing of all elements that are formed from RC– One listing of RC defects– Visual images of each defect

• Implemented in the visual guide

Potential Updates

• Units of measure for elements– Match parent element

• e.g., coatings in ft– Match shape of element

• e.g., columns (linear) in ft, abutments (planar) in sqft

– Tasks in field exercises included to assess SATO

Potential Updates• Concrete cracking

– Experimental element added for general cracking

• Larger cracks widths match previous BIRM descriptions

– Separate visual images for pattern cracking– Diagrams to illustrate CS for pattern cracking

Experimental Crack Defect

Potential Updates• Steel Protective Coating (515) CS

descriptions– Link to SSPC / decision making – Element created, not included in visual guide

Potential Updates

• Joints: Strip, pourable and compression joints seals (300, 301, 302)– Seven possible defects in current

MBEI– Combined into one joint element

• Damage and debris impaction included in guide

Potential Updates

• Settlement and scour defects– Structural conditions not related to materials

degradation – Could be a separate element or smart flag– No action at this time; committee

consideration

Future Tasks Phase III

• Task 10 Conduct Field Inspection exercises • Task 11 Revise Guidelines based on results of the field

exercises– Develop examples demonstrating the use of the

established accuracy levels and defect quantities• Task 12 Prepare Interim Report III

Remaining Tasks Phase IV• Task 13 Update proposed Guidelines after

consideration of review comments and propose modification to the AASHTO MBEI

• Task 14 Prepare final report that documents the entire research effort

• Target completion Spring 2018

Conclusion

• Visual guide is developed according to the approved Task 5– Study of sensitivity of deterioration modeling – Accuracy guideline developed

• Field inspection exercise plan are prepared – Test bridges selected – Logistical experimental plan prepared

• Interim report No. 2 prepared and submitted

Conclusion

• Field trials will provide key data – Quality of element-level data

• Key data for accuracy guidance

– Methods for improving the quality – Potential changes in units– Implementation of the developed guidelines

• New visual guide will provide a tool for inspectors– Improve the quality of element level data – Provide a model for a comprehensive visual guide

Questions / Comments /Discussion?

guidelines to improve the quality of element-level bridge

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