BRIDGE INSPECTIONHouse Transportation FinanceNovember 12, 2008

Dan Dorgan

State Bridge Engineer

Duane Hill

Assistant District Engineer Duluth

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Focus Today

Brief overview of bridge inspection requirements

Actions taken in the last year in the bridge inspection area

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Bridge Inspection Requirements

See Appendix for information regarding: Governing Regulations for Inspections Bridge Inspection Frequency Bridge Inspector Qualifications

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Gusset Plate ReviewsJanuary 15, 2008 NTSB urges truss and gussetplate ratings for bridges citingdesign error in I-35W Bridge. No software or rating

methods existed for checking gusset plates

MnDOT began developing a checking process for gusset plates in October 2007

MnDOT had already begun the analysis of several bridges

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Gusset Plate Rating Results

By July 1, 2008: 25 trusses rated to

verify original design

By August 1, 2008: 25 bridge inspections

of gussets completed

No design deficiencies

similar to I-35W found

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Results of Reviews

• St. Cloud Bridge – closed and replacement accelerated

• Blatnik Bridge in Duluth – gusset stiffened to restore full safety factor

• Winona Bridge – reinforced gusset due to corrosion

• Hastings Bridge – unsupported edge stiffened to meet code requirements

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Fracture Critical Bridge Inspection PositionsOffice of Legislative Auditor inFebruary 2008 recommendsMnDOT provide additional fundsfor fracture critical inspections. MnDOT identifies 8 additional

inspection positions Bridge Office:

1 Inspection Engineer position filled

2 Inspector positions filled 3 Engineering positions in

process District 6, Rochester and Metro:

2 Inspection Engineer positions in process

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Governor’s Inspection Program

Governor ordered on August 2, 2007: In-depth inspection of all

state and local Fracture Critical Bridges

Routine inspection of all state and local structurally deficient bridges

Routine inspection of all other state highway bridges

Stem to Stern review of MnDOT’s Bridge Inspection Program

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Governor’s Inspection Program

By December 20, 2007T.H. System: 3,875 Routine and FC

Inspections Completed 270 by Consultants

Local System: 141 FC Inspections

Completed 43 by Consultants

843 Structurally Deficient Bridges

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17 Critical Findings Identified During Statewide Inspections

6 Bridges Closed Norman County Road 3 Mountain Lake Township Road in Cottonwood County Municipal Street 5 in Russell State Game Preserve Road 222 in Wabasha County Redwood Township Road 185 in Redwood County Municipal Street 18 in the City of Carver

6 Bridges with Load or Lane Restrictions 5 Bridges Repaired, Including 2 State Highway Bridges

T.H. 11 bridge over the Red River of the North in Kittson County was closed briefly until repairs were made on a beam that showed cracking

T.H. 10 near Little Falls was also closed briefly for repair after inspectors discovered damage to a beam, apparently caused when it was hit by a truck following the bridge’s previous inspection

PB Americas Inc. Process Review

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Findings

MnDOT is in compliance with NBIS in the areas of: Bridge inspection organization Qualifications of personnel Inspection frequency Inspection procedures Inventory Additionally, MnDOT inspector ratings were

consistent with Consultant inspector

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Recommendations Develop procedures to track maintenance action

items resulting from inspection findings Provide more inspection training to Program

Administrators Hire more fracture critical bridge inspectors Develop and document inspection procedures for

complex bridges Ensure that inspection data is entered into the

database within the newly required interval Clarify responsibilities among fracture critical

inspectors and agency owners Develop standardized narrative bridge inspection

reports

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Documenting Post-Inspection Bridge Maintenance

Office of Legislative Auditor recommended implementing standard procedures to document post-inspection bridge maintenance follow up.

A “Bridge Inspection/Maintenance Assessment Form” has been developed and distributed to Districts. Purpose is to document maintenance actions to be scheduled.

By December 2008, a standard “Bridge Maintenance Scheduling and Completion Spreadsheet” will be adopted to track completion of maintenance actions.

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Fracture Critical Inspection QA Process -7 Day Inspection Summary

7 Day Inspection Summary submitted by Inspection Team Leader provided to the Bridge Office gives a quick look at changes and significant findings within 7 days of the inspection: Significant Deficiency noted? New Load Rating recommended? Traffic or Safety Hazard present? Bridge Element Condition summary? Significant findings that may need further review in

the next 6 months? Purpose is to identify deficiencies that may require

immediate action before the In-Depth Report is written and reviewed

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Fracture Critical Inspection QA Process - In-depth Bridge Inspection Evaluation

Internal structural review by a Bridge Office Engineer of the In-Depth Inspection Report within 30 days of submitting a draft report Were critical findings resolved promptly? Are conclusions logically stated and correct? Is the structure functioning as designed? Should the load rating be re-evaluated?

Owner must acknowledge receipt of the report, and concurrence or disagreement with the evaluation and recommendations

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Routine Inspections – Longstanding QA Processes

All Inspection Reports reviewed and signed by the Program Administrator, who must be a Registered Engineer

Annual Audits conducted by MnDOT and FHWA for NBIS compliance 20 to 25 Counties/Cities/Districts (20% of state total)

audited by reviewing records provided to the Bridge Office Of the 20%, 8 to 12 Counties/Cities/Districts receive field

review each year to audit inspection procedures, qualifications of inspection staff, inspection files and documentation, and field inspection

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Audit Rotational Map2007 Agencies Include:

Rock Nobles

Pipestone Murray

Lincoln Lyon

Redwood Yellow Medicine

Renville Lac Qui Parle

Chippewa Kandiyohi

Swift Big Stone

Stevens Pope

District 4 District 8

2009

2008

2007

2006

2010

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Tracking Process for Inspection Completion

Began reporting quarterly in Sept, 2008: Number of inspections overdue by 1 and 3

months Number of inspections completed but not

entered into PONTIS database within the required 90 days

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Recurring Inspection TrainingTraining scheduled for 2009: Refresher training to be held at multiple

locations statewide to maintain inspector certifications – see Appendix for topics

FHWA Bridge Safety Classes to be held at MnDOT Training Center Bridge Safety Class 1 – “Engineering Concepts

for Bridge Inspectors” (1 week class) Bridge Safety Class 2 – “Safety Inspection of In-

Service Bridges” (2 week class) Fracture Critical Inspection Class – “Techniques

for Steel Bridges” (3.5 day class)

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Technical Memorandums

In February 2008, updated the following TechnicalMemorandums for the most current FHWArequirements: “Critical Deficiencies Found During Bridge

Inspections” – process to address, report and resolve

“Guidelines for Fracture Critical Inspections of Fracture Critical Bridges, Special Inspections for other Bridges, and Underwater Inspections” – procedures, frequency, inspector qualifications, Quality Assurance and reporting

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Inspection Equipment and Technology

Additional ultrasonic testing equipment purchased for expanded Fracture Critical staff

Contracting for Ground Penetrating Radar of selected bridge decks for delamination detection

Reviewing software and devices for use in electronic field data collection to aid bridge inspectors

Ordering additional snooper and trailer-mounted inspection platform for smaller bridges

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Removal of Potential Concrete Spalls from Bridge Decks Bridge crews have routinely removed loose

concrete from older structures Maryland Ave/I-35E incident of July 26, 2008 should

not have occurred Information, guidance and reminder to devote

resources for identifying and removing potential spalls was sent to Districts on 7/28, 8/4 and 10/23/08

Priorities for underdeck inspection and removal assigned according to deck condition

As of November 5, 2008, Districts report removing potential spalls from at least 16 bridges

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National Involvement and Leadership MnDOT has shared

with other states in numerous forums our experiences and learnings from the I-35W bridge

The process MnDOT developed to review the adequacy of gusset plates has been shared nationally and included in our manuals on the web

Participating in national research on gusset plate design and analysis

Participated in round table discussions of Bridge Inspection practices with Midwest States

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Bridge Monitoring Installations and Research

State of the art bridge monitoring systems installed in I-35W St. Anthony Bridge

A monitoring system is included in the Eastbound Wakota Bridge, currently under construction

Since the early 1990s, bridge monitoring systems have been used on at least 17 MnDOT bridges

University of Minnesota currently conducting research for MnDOT titled “Bridge Health Monitoring and Inspection – A Survey of Methods” to survey available technologies and assess their capabilities

MnDOT and the U of M are also developing a project to monitor an existing bridge

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Appendix

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Governing Regulations for Inspections

National Bridge Inspection Standards (NBIS) Requirements established

via Federal Rulemaking by the Federal Highway Administration

American Association of State Highway and Transportation Officials Manual for Condition

Evaluation of Bridges Minnesota State Statute

and Rules MnDOT Policies

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Bridge Inspection Frequency

Bridge Inspection Cycles – bridges are inspected once every 24 months per National Bridge Inventory System. In Minnesota, if the condition of the deck, superstructure or substructure is rated “4” or less, bridges are inspected annually.

Fracture critical bridges get an in-depth inspection at least once every 24 months.

Underwater bridge inspections are required every 60 months.

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Bridge Inspector Qualifications

MnDOT has 75 certified inspection “Team Leaders” that meet State and Federal requirements. Qualifications required for certification include: Professional Engineering license or 5 years of

experience performing inspections Successful completion of 3 week FHWA

approved inspector training Passing a proficiency field exam (MN

requirement) Attending refresher training to maintain

certification

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Bridge Safety Inspection Seminars – “Refresher Training”2008 Topics Railroad Bridge Inspections 2007 Statewide Bridge Inspection

Effort – Governor’s Mandate I-35W Bridge Collapse and

Investigation Critical Findings Process PONTIS Online Demo for

Inspection Date Entry Bridge Scour evaluation and

documentation Structural Inventory Reports

information and updating

2009 Topics (proposed) Fracture Critical Inspections I-35W Bridge Collapse and

Investigation Bridge Railings and Guardrail

inspection and coding instructions PONTIS Online Demo for

Inspection Date Entry Inspection note-taking and proper

documentation of findings Measuring section loss Load ratings Bridge Inspection Manual Updates

Gusset plate elements Scour and channel cross sections Hinge bearings

Work Zone Safety during Bridge Inspections