I35W Bridge A Transportation Agency s Emergency Response. Dan Dorgan State Bridge Engineer Minnesota Department of Transportation

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1 I35W Bridge A Transportation Agency s Emergency Response Dan Dorgan State Bridge Engineer Minnesota Department of Transportation February 15, 2010

2 I-35W Bridge Bridge Background Bridge Collapse August 1, 2007 August 2, 2007 Emergency Response Rescue Operations Traffic Management Investigation Begins Media Coverage Responding to Public and Media Recovery of Victims and Bridge Removal Mn/DOT Actions Following August 2007 NTSB Investigation Minnesota Legislature: Victims Fund and Transportation Funding Impact on Employees Observations - Lessons Learned

3 I-35W Bridge Downtown Minneapolis University of Minnesota

4 I-35W Bridge Bridge Background Bridge Completed in Feet Long 3 span continuous truss Main span approach spans ADT 141,000 Sufficiency Rating 50.0 Annually Inspected Mn/DOT 20 year plan called for Replacement/Renovation July 1967

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6 Two Previous Studies of the Bridge 2001 University of Minnesota Fatigue Evaluation of the Deck Truss of Bridge Fatigue Evaluation and Redundancy Analysis Multi Girder Approach Spans Had Required Retrofits for Cracks at Diaphragm Connection

7 Previous Bridge Modifications 1977 Concrete overlay 1998 Railing repair, drainage system, minor deck repair 1999 Painting Portion of Truss Spans 1999 Anti Icing System 2001 Curb & Slab repair Average yearly Mn/DOT Maintenance Hours 500

8 Contract Maintenance Work at Time of Collapse Contract to replace concrete overlay, and repair joints. Work completed: North bound two inside lanes South bound two outside lanes Scheduled completion date was September 30, 2007 Contractor employees and Mn/DOT inspectors on bridge at collapse

9 August 1, 2007 The Collapse Collapse occurs at 6:05 p.m. Wednesday, August 1, 2007 Over 100 vehicles on the bridge at the time 13 fatalities 140 injuries

10 North End I 35W Bridge South End

11 North End

12 Main Span

13 Pier 6 South End Main Span

14 South Spans

15 Emergency Response 6:05 p.m. Numerous calls to 911 Motorists on bridge, construction workers, citizens in area assist injured Emergency personnel from Twin Cities and Western Wisconsin respond 6:10 p.m. District Emergency Operations Center activated Mn/DOT s Regional Transportation Management Center (RTMC) Immediate traffic control for ramp and freeway closures provided by FIRST units, maintenance units, and contractors in the vicinity

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20 Response the First 12 Hours Unified command center set up on collapse site. Mpls. Fire Department in charge of rescue operation Hennepin County Sheriff in charge of recovery Rescue operations well coordinated by emergency responders. August 1, 2007

21 First 12 Hours (continued) 6:20 p.m. Maintenance started converting I- 35W temporary traffic control measures to longer term traffic control standards with barriers and signs 20 changeable message signs activated 800 megahertz communication system was critical for responders

22 First 12 Hours (continued) 7:00 p.m. Over 150 employees activated, most just returned without a call 10:00 p.m. Governor and Mayor provide an update to public. Number of victims unknown. Rescue Operations Ended, Recovery Begins 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

23 I-35W Detour Map

24 Key Decisions Early August 2 nd Division of Tasks Dedicate a team to bridge replacement Identify individuals that would address questions on the collapsed bridge Retain a forensic expert for the collapse investigation Previous planning for a bridge emergency replacement addressed typical interchange bridges, not a major river crossing.

25 August 2, 2008 Mn/DOT Engineers assess stability of wreckage for recovery personnel Mn/DOT retains Wiss Janney Elstner and TranSystems/Lichtenstein for forensic investigation Federal Agencies Arrive at Command Site FEMA, FBI, Coast Guard, OSHA, OIG, FTA, NTSB, Rick Capka and National FHWA staff NTSB Leads Investigation Team Law Enforcement and NTSB Update Victims Families Mn/DOT Engineering Team is organized for rapid replacement Command Site

26 Media Coverage August 2nd Governor Conducts interviews throughout morning 2:00 pm Press Conference Governor announces Emergency Statewide Bridge Inspections beginning with underdeck trusses Forensic Investigation Team Wiss Janney Elstner Transystems Independent Review of Mn/DOT Inspection Program FHWA Participates Mn/DOT provides bridge background and responds to questions National and International News Organizations present National Transportation Safety Board Begins Updates

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35 Responding to Public and Media Requests Held Daily 2:00 pm Press Conference Became only means to respond to volume of requests Format was Statement, Update on specific issue, Open to questions Length was held to a reasonable time 30 to 45 minutes When it ended, held questions till next day Approach to Press Conferences Share the information we possess Be factual and calm Avoid speculation. Ok to admit you don t know. It is Ok to stop and think before answering. Use non-engineering terms when possible Provide information that informs the public Keep accusatory questions in perspective lives have been lost 8/3/07 Press Conference

36 Responding to Public and Media Requests (Continued) Mn/DOT goal was to be transparent Document requests were voluminous Website posting of plans, inspection reports, bridge studies Dedicated I-35W Website included all documents Later needed to remove inspectors names after calls were made to their homes.

37 Responding to Public and Media Requests (Continued) Mn/DOT priority was local media requests Within days, some began their own investigations and speculation. Correcting factual errors consumed time Document Management System established to gather and store all bridge information Spectators and Media on Adjacent 10 th Avenue Bridge

38 National Response Aug. 2 Secretary Peters and FHWA Administrator Capka on site Aug. 4 - President Bush pledges to cut red tape that could delay recovery Several site visits by Secretary Peters and President Bush, and continuing presence by Rick Capka

39 Within days, Congress authorizes $250 million in Emergency Relief money to replace bridge and restore highway facilities to predisaster conditions Total Federal Emergency Relief $373.5M

40 Recovery of Victims Access to site controlled by police and fending 24/7 Aug. 6 Careful bridge demolition began to aid recovery, and NTSB investigation Navy Divers from Norfolk, VA assist in recovery NTSB Investigation Team Supervises Removal All steel members marked and indexed Members removed by torch underwater cuts could take 1-4 hours Extensive coordination required with divers, sheriff, investigators and contractor Site protocol followed during recovery of victims Navy Dive Team

41 Navy Divers Perspective

42 Assigned bridge engineers to assist NTSB not previously involved in bridge Aug. 20 Navy Divers recover 13th victim, site turned over to Mn/DOT Sept. 6 - Navigation channel opened to commercial traffic Sept. 27 Final steel removed from river Removing Wreckage from Navigation Channel

43 Structural Steel Laid Out On River Flats

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46 September 2007 November 2008 Anticipate and Act Identify what we should do Resulting from the investigation or internal process reviews Don t wait Take action Take opportunities to communicate what you are doing Encouraged and reassured our staff Keep them focused Understand rebuilding credibility is a journey

47 Minnesota Actions Following August 1, 2007 Bridge Inspection Aug. 2 - Governor directs MnDOT to inspect all bridges on the trunk highway system in priority order Inspection continued of all MnDOT bridges, with priority to fracture critical bridges and those rated structurally deficient By December 21, MnDOT bridges inspected 840 Local Bridges Supplemented MnDOT inspection teams with PB Americas, Michael Baker, HDR, Volkert, and STV

48 Minnesota Actions (Continued) Peer Review of Major Bridge Designs April 2008 Spans over 250 feet Unique bridge types Independent design review by a separate design firm Design Criteria and Assumptions Review of Design Constructability Review

49 Bridge Inspection Minnesota Actions (Continued) Governor Directs Mn/DOT to conduct an independent Stem to Stern review of bridge inspection program Mn/DOT retains PB Americas to conduct 301 bridges inspected and used in Condition Rating Comparison Findings June 2008 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

50 Minnesota Actions (Continued) Process Reviews of Internal Procedures Completed as a follow-up to PB study and Legislative Auditor Study Internal QC/QA Design Procedures are under review Inspection Consolidated documentation of QA/QC procedures for Routine and Fracture Critical Inspections Increased use of UT to assess corrosion Maintenance Revised procedures to document maintenance follow up to inspection findings

51 Gusset Plate Reviews and Inspections January 15, 2008 NTSB urges truss and gusset plate load ratings for bridges citing design error in I-35W Bridge. Mn/DOT developed a checking process for gusset plates in October-November 2007 No software or rating methods existed for checking truss gusset plates, few examples in references Mn/DOT began the analysis of several bridges in Fall 2007

52 January 15, 2008 Press Conference Mn/DOT conducted news conference following NTSB Press Conference on January 15 Informed the public we had already begun the design review of gusset plates on our truss bridges Committed to completing the process by July of 2008 Shared the purpose was to determine if original designs were correct Noted we had no reason to suspect a similar error this was precautionary

53 Truss Bridge Gusset Plate Checks Performed by Mn/DOT in 2008 Rivets/bolts in shear and bearing Buckling at ends of diagonals Flexure at sections cut along length and height of gusset plate Tension at ends of all tension members Block shear at ends of all tension members Gusset Plate free edge unsupported length to thickness ratio

54 Gusset Plate Rating Results By July 1, 2008: 25 trusses load rated to verify original design was correct By August 1, 2008: 25 bridge field inspections of gussets completed No design deficiencies similar to I-35W found Wabasha Bridge

55 Results of Reviews Typical Areas of Loss Gusset Plates Below: Deck Joints Drain Pipes Section Loss Areas: Interior Face Along Chord (Red) Interior Face Along Edges of Diagonals (Green) Interior Face Along Edges of Verticals (Blue) Exterior Face Along Top of Lateral Brace Gusset Plate Extensive use of ultrasonic devices to measure plate thickness Blatnik Bridge

56 Documentation of Losses Visual ( 1/8 ) & NDT ( 1/8 ) Quantify Depths Quantify Areas Identify Locations Include Contours

57 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 All necessary repairs were completed by July 2008 Blatnik Bridge

58 Press Conferences Held in Each City Impacted Local press conference on the day we restricted or closed a bridge. Commissioner, State Bridge Engineer, District Engineer, and Elected Officials Participated. Commissioner emphasized safety was our number one priority. Described what our inspectors had discovered. Why we needed to act. Stated we were acting conservatively out of an abundance of caution. Committed to repairing as soon as possible. Promised to update them on progress.

59 DESOTO BRIDGE St. Cloud Closed March 20, 2008-Replacement Accelerated

60 BLATNIK BRIDGE - Duluth Restricted May 6, Lane Each Direction Repairs Completed July 2008 Overlay weight and Previous Corrosion had reduced Safety Factors at 29 Locations $1.1 Million Repair Job

61 WINONA BRIDGE Closed Temporarily June 3, 2008 Repairs Completed July 2008

62 WINONA BRIDGE $108,000 total cost Corrosion had reduced Safety Factors at 15 locations

63 Minnesota Actions Revised Bridge Construction Load Specifications in response to FHWA August 8, 2007 Advisory April 2008 Unless otherwise allowed in plans, limits construction to loadings similar to design liveload. Construction materials limited to 65,000 lb per 1000 SF. Individual Stockpiles limited to 25,000 lb per 100 SF. Vehicles, materials, equipment limited to 200,000 lbs per span. Alternate loadings require submittal by contractor s engineer and approval of Mn/DOT Project Engineer.

64 Legislative/Congressional Hearings and Investigations Congressional Hearing September 2007 Several Minnesota Legislative Hearings Regarding Transportation Issues and the I35W Bridge Investigative Report to Joint Committee to Investigate the I35W Bridge Collapse May 2008 Office of the Legislative Auditor, State of Minnesota Evaluation Report: State Highways and Bridges February 2008

65 National Transportation Safety Board Investigation NTSB led the investigation with a team of professionals including metallurgists, engineers, and experienced investigators Investigation Docket has been posted on the NTSB website at: under Highway Accidents. Process was very disciplined progressing through fact finding, analysis, conclusions and recommendations. NTSB parties and contributors to the investigation included the FHWA, Wiss Janney, Elstner and Transystems, Mn/DOT, Jacobs Engineering, and PCI.

66 NTSB Investigation Results November 13-14, 2008 NTSB Public Hearing Collapse of I-35W Highway Bridge Minneapolis, Minnesota August 1, 2007 Page 152 Probable cause inadequate load capacity due to a design error by Sverdrup & Parcel and Associates, of the gusset plates at the U10 nodes, which failed under a combination of 1) Substantial increases in the weight of the bridge, which resulted from previous bridge modifications, and 2) The traffic and concentrated construction loads on the bridge on the day of collapse.

67 NTSB Investigation Results (Continued) Collapse of I-35W Highway Bridge Minneapolis, Minnesota August 1, 2007 Page 152 Contributing to the design error was the failure of Sverdrup & Parcel s quality control procedures to ensure that the appropriate main truss gusset plate calculations were performed for the I-35W bridge and the inadequate design review by Federal and State transportation officials. Contributing to the accident was the generally accepted practice among Federal and State transportation officials of giving inadequate attention to gusset plates during inspections for conditions of distortion, such as bowing, and of excluding gusset plates in load rating analyses.

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69 Mn/DOT Communication Following November 13-14, 2008 NTSB Hearing Commissioner responded to media following the hearing expressing thanks to the NTSB. Due to actions already taken, Mn/DOT was able to state action was complete or underway regarding all NTSB recommendations.

70 Minnesota 2008 Transportation Funding 2008 Transportation Bill License Plate Fee and 5 cent Gas Tax Increase $1.8 billion in bonding of which $600M bridges Up to 3.5 cent added gas tax for bond payments By June 2018, replace all bridges rated SD and below 50, and FC bridges, unless reason documented to remain in service Approximately 120 bridges to be replaced or repaired Victims Fund Legislation Existing statutory limits on liability inadequate $37 million in payments completed

71 Bridge Replacements Completed to Date 41 bridge projects are completed or underway. 13 major bridge projects planned over the next 8 years with 6 Mississippi River crossings.

72 Impacts on Employees and Organization Responded well on August 1. They returned without a call. Tremendous strength and perseverance shown. Stress debriefings were valuable tools to share emotions. We watched for signs of employee struggles with mental and physical health. Reassigned to other duties as needed. Communicate with employees as often as possible, rather than the news be their source. Provided reassurance. Important to have Governor and other leaders in forefront to help reassure the public. Media communication handled by Assistant Commissioner and Bridge Engineer to allow employees to focus on their job.

73 Observations and Lessons Learned Existing partnerships/relationships with the FHWA, Minneapolis, and other agencies were key in responding to the tragedy. Dedicating a team solely to rapid replacement was needed. Others dealt with collapse. Establish a Web Site to make information public versus responding to individual data requests. Daily News conferences are manageable, individual interviews are overwhelming.

74 Observations and Lessons Learned (Continued) A redundant traffic management system is invaluable. Understand politics will be part of it. Within tragedy is also the impetus to review processes and improve, be open to the opportunity.

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