Responding to Bridge Hits in MnDOT’s Metro District

Sarah Sondag, PE | Bridge Inspection Engineer Mark Pribula, PE | Bridge Inspection Engineer

1,478 BridgesOver 27 Million SF of Bridge

Deck Area1,800 Overhead Signs900 Retaining Walls120 Miles of Noise Walls

Metro Structural Assets

District Split into Six Bridge Sub Areas

Forest Lake, Maplewood, Mendota, Eden Prairie, Plymouth, & Spring Lake Park

Each Sub Area Responsible for approximately:60 Interstate95 US & State Trunk Highway60 Municipal & County State-Aid

Crew size: 7 - 9 including Supervisor

Metro Bridge Personnel

Certified Bridge Inspection Team Leaders

Bridge Inspection Team LeaderCertified by MnDOT to conduct

inspections of in-service bridgesMust be present at the bridge

site at all times during a bridge inspection

Inspection Roles and Responsibilities

Program AdministratorCertified Professional Engineer

appointed to oversee the bridge inspection program

Review and approve all bridge inspection reports

Respond to inspection findingsReport critical findings to the

MnDOT Bridge Office

Inspection Roles and Responsibilities

Incident Defined as anything that could affect structural integrity

ResponseDispatching appropriate personnel and equipmentFirst call is to Bridge Maintenance Supervisor Certified Team Leader

Activating the appropriate communication linksDocumenting and reporting findingsDamage ReportCritical Deficiency Report (if needed)

Preparing and implementing any necessary repair actions

Incident Response Procedures

Incident Response Procedures

Documentation and Reporting Damage InspectionAssess structural damageReport:DateLocationEquipment RequirementsInspection Procedures,

Components, Findings and Recommendations

Incident Response Procedures

SIMS Damage Report

Documentation and Reporting Critical DeficiencyAsset condition is deemed critical as defined in the NBIS

Incident Response Procedures

Documentation and Reporting Critical Deficiency Reporting

Part I – InspectorLocation and Description of the Critical Deficiency

Part II - Program AdministratorAnticipated Plan for the Bridge

Part III & IV – MnDOT Bridge OfficeDescription of Final Action Taken

Incident Response Procedures

SIMS Critical Deficiency Report (Part I)

SIMS Critical Deficiency Report(Parts II & III)

Repair OptionsRepair by In-House Bridge

Maintenance Forces

Repair by ContractNegotiated ContractDesign-Bid-Build ContractState Contract (Retainer)Emergency Contract

Incident Response Procedures

Bridge Hit Response Examples

Bridge 9039 (W 86th St. over I-35W)

Structure Background Four Span Steel Continuous Multi-beam with Cover Plates Simple Span Approaches, Continuous Center SpanBuilt in 1957 & Refurbished in 1996

First Hit 01/19/2015

Low-boy carrying Back-hoe traveling Southbound right lane, impacted Beams 9, 2 & 1.

Rotated Beam 9 out of alignment over 28 – 34 FTHooked the beam’s bottom flange, causing a semi-

circular web tear at the vertical stiffener and propagation of an existing cover plate weld crack.

Third Hit 06/30/2015

Low-boy carrying back-hoe traveling Southbound right Lane impacted Beam 9

Rotated Beam 9 out of alignment over 28 – 34 FTBeam stool crushed and shear connectors lost

composite action

Low-boy carrying back-hoe traveling Southbound right lane

Back-hoe’s “knuckle” struck Beams 9, 8, 7, 2, & 1

Virtually identical location as 3rd hit, causing extensive impact damage

Fourth Hit 02/20/2016

Fourth Hit Cont.

Further rotated Beam 9 out of alignmentFull length deck “stool” failure along Beam 9 Shear stud connectors lost composite action

Fourth Hit Cont.

CenterPoint Energy 10" Natural Gas-line fractured above Pier 1

Pipeline capped that day and removed 3/03/16

Low-boy convey carrying storage tanks traveling Southbound Right Lane impacted Beam 1

Rotated Beam 1 out of alignment over 34 FT with vertical stiffener tearing

Beam stool crushed and shear connectors lost composite action

Fifth Hit 04/23/2017

Two BridgesBr. 9213 & 9039

Bridge 9213 (W 82nd St. over I-35W)

Structure Background

Four span steel multi-beam structure

Simple span approaches, continuous center span with welded cover plates

Built in 1957 & refurbished in 1995

Vertical Clearance 15.3'

Initial Response

Bridge 9039 (W 86th St.)Reported as a Critical Deficiency after the 4th hitClosed outside lanes above damaged fascia beamsClosed bridge after 5th hit

Contract in place to replace the bridge in July 2017

Bridge 9213 (W 82nd St.)Reported as a Critical Deficiency Closed eastbound lane above damaged fascia beam

Repair

Bridge 9213 Repair OptionsAdd repair to existing Bridge 9039 Replacement

ProjectJust outside of the project limits

Heat Straightening by State Contract

Beam replacement identified as best fix to restore full structural capacity

Replace Beam by Emergency AuthorizationNew beam or salvaged beam?

Repair

Emergency AuthorizationWorked with Contractor

on Bridge 9039 replacement contract to develop a rough work plan and estimate

Ordered a new steel beam due to schedule restraints for salvaging

Repair

Emergency AuthorizationRemoval Weekend closure (July 2017)

Beam PlacementNight closure (September 2017)

Deck PourNight closure (October 2017)

Over height roll-off container truck traveling Westbound Left Lane impacted Beam 1

Damage: girder fracture, spalling, delamination, stirrup bars & pre-stressing strands cut

Bridge 9733 I-35W over Lake St.

Semi-truck forced to avoid carBroke through guardrail & collided with

west pylon Semi-truck’s tractor caught on fire,

completely engulfed

Overhead Sign BridgeI-35W

QUESTIONS?

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