i-35 bridge collapse and responsesp.bridges.transportation.org/documents/i-35bridge... · •...

I-35W BridgeDan Dorgan & Kevin Western

Minnesota DOT

AASHTO Subcommittee onBridges and Structures

May 21, 2008

Omaha, Nebraska

2

I-35W Bridge Collapse• Bridge Background

• Bridge Collapse August 1, 2007

Emergency Response

Rescue Operations

Traffic Management

• August 2, 2007

Investigations Begin

Media Coverage

Federal Response

• Managing Demands of Media

• Recovery of Victims and Bridge Removal

• MnDOT Actions in Aftermath of August 1st

• Transportation Political Debate

•Observations Lessons Learned

3

II--35W Bridge35W Bridge

UniversityUniversityofof

MinnesotaMinnesota

DowntownDowntownMinneapolisMinneapolis

http://maps.google.com/

4

I-35W BridgeBridge Background

• Bridge Completed in 1967

• 1907 Feet Long

•3 span continuous truss

• Main span 456’

• 2 trusses

• 11 approach spans

• Continuous steel multi beam

• Continuous concrete slabs

• ADT 141,000

• 4 lanes each direction

• Structurally Deficient – SR 50.0

• Annually Inspected – In depthFracture Critical

• MnDOT 20 year plan called forReplacement 2020-25

July 1967

5

6

Two Studies of Fatigue Potential

• 2001 University of Minnesota –Fatigue Evaluation of the DeckTruss of Bridge 9340

• 2007 – URS – Fatigue Evaluationand Redundancy Analysis

• Multi Girder Approach Spans HadRequired Retrofits for FatigueCracks

7

Previous Bridge Modifications

• 1977 Concrete overlay

• 1998 Railing repair, drainage system, minordeck repair

• 1999 Painting Portion of Truss Spans

• 1999 Anti Icing System

• 2001 Curb & Slab repair

Average yearly MnDOT Maintenance Hours 500

8

Contract Maintenance Work at Time of Collapse

• Contract to replace concrete overlay,repair joints and lighting,and install guardrail

• Work completed:North bound – two inside lanesSouth bound – two outside lanes

• Scheduled completion datewas September 30, 2007

• Cost - $9 million

• Contractor employees and Mn/DOT inspectors on bridge at collapse

9

August 1, 2007The Collapse

Collapse occurs at 6:05 p.m.Wednesday, August 1, 2007

Over 100 vehicleson the bridge at thetime

13 fatalities140 injuries

10North End – I 35W Bridge – South End

11North End

12Pier 7 North End Main Span

13Main Span

14Pier 6 South End Main Span

15South Spans

16

Emergency Response• 6:05 p.m.

– Numerous concurrent calls to StatePatrol Dispatch (911) and from fieldemployees to RTMC andMaintenance Dispatch

– Motorists on bridge, constructionworkers, citizens in area assistinjured

– Emergency personnel from TwinCities and Western Wisconsinrespond

• 6:10 p.m.– District Emergency Operations

Center activatedMn/DOT’s Regional

Transportation ManagementCenter (RTMC)

• Immediate traffic control for ramp andfreeway closures provided by FIRST units,maintenance units, and contractors in thevicinity

17

18

19

20

21

22

Response the First 12 Hours• 6:20 p.m. – State

Emergency OperationsCenter.

• Unified command centerset up on collapse site.Authority in commandchanged as incidentprogressed:– Mpls. Fire Department in

charge of rescue– Hennepin County Sheriff in

charge of recovery (Mn/DOTassisted with somedemolition)

– Mn/DOT assumed commandafter recovery was completed

23

First 12 Hours – (continued)

6:20 p.m.– Started converting I-35W

temporary traffic control measuresto longer term traffic controlstandards with barriers and signs

– 20 changeable message signsactivated

– Mn/DOT Metro District providesmaintenance staff and equipmentfor security efforts

– 800 megahertz communicationsystem was critical for responders

24

First 12 Hours – (continued)• 7:00 p.m.

– Over 150 employees activated, mostjust returned without a call

– Mn/DOT structural engineers called tosite

• 10:00 p.m.– Governor and Mayor provide an

update to public. Number of victimsunknown.

– Rescue Operations Ended, RecoveryBegins

• 11:00 p.m.– Detour maps for a.m. rush posted on

Mn/DOT Web site

• Overnight– Expanded signing and barricades of

closed I-35W– Converted T.H. 280 to a freeway

25

I-35W Detour Map

26

August 2, 2008– Engineers assess stability of wreckagefor recovery personnel

– MnDOT contacts Wiss Janney Elstnerand TranSystems/Lichtenstein forinvestigation

– Recovery Operations Continue

– Federal Agencies Arrive at CommandSite FEMA, FBI, Coast Guard, OSHA,OIG, FTA, NTSB, Rick Capka andnational FHWA staff

–NTSB Leads Investigation Team

– Law enforcement and NTSB UpdateVictims Families

–Engineering Team begins to organize forrapid replacement

27

Media Coverage August 2nd

– Governor Conducts interviewsthroughout morning

– 2:00 pm Press Conference

Governor announces

• Emergency Statewide BridgeInspections beginning withunderdeck trusses

• Forensic Investigation Team

• Review of MnDOT InspectionProgram

FHWA – Tom Everett participates

MnDOT provides bridge background

and responds to questions

– National and International NewsOrganizations present

– National Transportation SafetyBoard Updates

NTSB Chairman Mark Rosenker

28

National Response

• Aug. 2 – Secretary Peters andFHWA Administrator Capka

• Aug. 3 - First Lady Laura Bushvisits the site, victims families

• Aug. 4 - President Bush pledgesto cut red tape that could delayrecovery

• Several site visits by SecretaryPeters and President Bush, andcontinuing presence by RickCapka

29

• Congress authorizes $250 million inEmergency Relief money to replace bridgeand restore highway facilities to pre-disaster conditions

• Total Federal Emergency Relief $373.5M

30

Managing Media Requests• Held Daily 2:00 pm Press Conference

• Became only means to manage volume ofrequests

• Format was Statement, Update on specificissue, Open to questions

• Length was held to a reasonable time – 30 to45 minutes

• When it ended, held questions till next day

• Governor and Commissioner directedMnDOT to be transparent• Document requests were overwhelming

• Website posting of plans, inspection reports,bridge studies

• Dedicated I-35W Website includes alldocuments

• Document Management System establishedto gather and store all bridge information

• Later removed inspectors names afterharassing phone calls to their homes

31

Managing Media Requests(continued)

• Our Priority was local mediarequests

• Within 24 hours mediabegan their owninvestigations andspeculation.

• Our time was consumedcorrecting misinformation

• After 3 weeks ended face toface interviews andresponded to writtenquestions.

32

U.S. Navy Dive Team

Recovery of Victims andBridge Removal

• Access to site controlled bypolice and fencing – 24/7

• Site protocol followed duringrecovery of victims

• Navy Divers from Norfolk, VAassist in recovery

33

Navy Divers Perspective

34

• Aug. 6 – Careful demolitionbegan to aid recovery, andNTSB investigation

• NTSB Investigation TeamSupervises Removal– All steel members marked and

indexed

– Members removed by torch –underwater cuts could take 1-4hours

– Extensive coordination requiredwith divers, sheriff, investigatorsand contractor

– Balanced desire to recovervictims’s vs. need to preserveevidence

35

Aug. 20 – Navy Diversrecover 13th victim, siteturned over to Mn/DOT

Sept. 6 - Navigation channelopened to commercial traffic

Sept. 27 – Final steelremoved from river

36

Structural Steel Laid OutOn River Flats

37

38

39

National Transportation Safety Board

• Investigation is in progress

• Completion expected in 2008

• Information has been posted on the NTSBwebsite at: www.ntsb.gov under “PressReleases” 2007 & 2008

40

Minnesota Actions Since August 1, 2007

Bridge Inspection

Aug. 2 - Governor directs MnDOT toinspect all bridges on the trunkhighway system in priority order

• Aug. 6 – MnDOT completes inspectionof four under deck truss bridges

• Inspection continued of all MnDOTbridges, with priority to structurallydeficient and fracture critical bridges

• By December 21, 2007• 3875 MnDOT bridges inspected• 840 Local Bridges• Supplemented MnDOT inspection

teams with PB Americas, MichaelBaker, HDR, Volkert, and STV

41

Bridge Inspection

• Governor Directs Mn/DOT to conduct an independent “Stem toStern” review of bridge inspection program– Mn/DOT retains PB Americas to conduct– 301 bridges inspected and used in Condition Rating Comparison

• Findings– Condition ratings for 282/301 bridges within 1 NBI rating– MnDOT Program Consistent with other States and complies with NBIS– Better documentation to track- inspection findings to follow up

maintenance actions– Clarify responsibilities between routine and fracture critical inspection

teams– Develop special inspection procedures for complex bridges

Minnesota Actions Since August 1, 2007(Continued)

42

Minnesota Actions Since August 1, 2007(Continued)

Gusset Plate Reviews forTrusses:

• 25 Mn/DOT Trusses

• 30 Local Bridges

• Includes bridge rating,gusset analysis, fieldverifications of condition

43

Truss Bridge Gusset Plate Checks Performed by Mn/DOT

• Rivets/bolts in shear and bearing

• Buckling at ends of diagonals

• Flexure at sections cut along length and height of gussetplate

• Tension at ends of all tension members

• Block shear at ends of all tension members

• Gusset Plate free edge unsupported length to thickness ratio

Minnesota Actions Since August 1, 2007

44

Minnesota Actions Since August 1, 2007(Continued)

Gusset Plate Findings:

• Unsupported edges not meeting coderequirements for edge stiffeners

• St. Cloud Bridge closed andreplacement accelerated

• Buckling requirements not satisfied onI535 in Duluth

• Bearing on rivets under review for onebridge

• Approximately 11 of 25 completed

• To date no plate thicknessesdeficiencies similar to I35W found

45

Revised Bridge Construction LoadSpecifications in response to FHWA August8, 2007 Advisory

• Unless otherwise allowed in plans, limits constructionto loadings similar to design liveload.

• Construction materials limited to 65000 lb per 1000square feet.

• Alternate loadings require submittal by contractor’sengineer and approval of Mn/DOT Project Engineer.

Minnesota Actions Since August 1, 2007(Continued)

46

Peer Review of Major Bridge Designs

• Spans over 250 feet or unique bridgetypes

• Independent design review by a separatedesign firm

Minnesota Actions Since August 1, 2007(Continued)

47

Transportation Funding Debate

• Previous MN Legislative Proposals in 2006 & 2007

• 2008 Transportation Bill & Veto Override– License Plate Fee increase– 5 cent Gas Tax Increase– $1.8 billion in bonding of which $600 M bridges– Up to 3.5 cent added gas tax for bond payments– By June 2018, replace all SD below 50, and FC bridges, unless reason

documented to remain in service– Approximately 130 bridges to be replaced

• Joint Legislative Committee to Investigate Collapse– Multiple Hearings Conducted

• Victims Fund Legislation

Minnesota Actions Since August 1, 2007(Continued)

48

Observations and Lessons Learned

• Our employees responded on August 1-2, returningwithout being called. They have tremendous strength.

• Stress debriefings were valuable tools to shareemotions.

• Watch for signs of employee struggles with mental andphysical health. Reassign to other duties as needed.

• Protect employee’s privacy; others won’t hesitate to callthem at home.

• Communicate with employees as often as possible,rather than the news be their source.

• It is important to have Governor and other leaders inforefront to help restore public confidence. Agencycredibility will take time to restore.

49

Observations and Lessons Learned(Continued)

• Existing partnerships/relationships with the FHWA, Minneapolis, andother agencies were key in responding to the tragedy.

• Dedicating a team solely to rapid replacement was needed. Othersdealt with collapse.

• Establish a Web Site to make information public versus respondingto individual data requests.

• Clarify within the organization what is public information and what isnot.

• Daily News conferences are manageable, individual interviews areoverwhelming.– Hold to a reasonable time.– When conference is over, address further questions the next

day.– Be factual and calm.– Avoid speculation– Use non-engineering terms when possible– Keep accusatory questions in perspective – lives have been lost.

50

Observations and Lessons Learned(Continued)

• Anticipate that cell phones will fail, an 800MHz system is key for emergencies.

• A redundant traffic management system isinvaluable.

• Understand politics will be part of it.

• Within tragedy is also the impetus toreview processes and improve, be open tothe opportunity.