BRIDGE INSPECTION House Transportation Finance November 12, 2008 Dan Dorgan State Bridge Engineer Duane Hill Assistant District Engineer Duluth
Dec 10, 2015
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
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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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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