I-35 W Bridge - National Society of Professional Engineers · PDF file•Aug 3 - First Lady...
Transcript of I-35 W Bridge - National Society of Professional Engineers · PDF file•Aug 3 - First Lady...
“From Tragedy to Triumph”
I-35W Bridge
Khani Sahebjam, PE
Vice President | HDR Engineering, Inc.
Former Deputy Commissioner/Chief Engineer | MnDOT
History
• Bridge background – Bridge completed 1967
– 1907 feet long • 3 span continuous truss
– Main span 456 feet
– ADT 141,000
– Sufficiency rating – 50.0
– Annually inspected • In depth fracture critical
– 500 hours annual average by MnDOT maintenance
– Scheduled replacement 2020-2025
I-35W Bridge - Looking North July, 1967
August 1, 2007
The Collapse
Collapse occurs at 6:05 pm
Wednesday, August 1, 2007
Over 100 vehicles on the
bridge at the time
13 fatalities, 140 injuries
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
MnDOT’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
Response the First 12 Hours
• Unified command center set up on collapse site. – Minneapolis Fire Department in charge of rescue
operation
– Hennepin County Sheriff in charge of recovery
August 1, 2007
First 12 Hours | continued
• 7:00 p.m. – More than 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 MnDOT web site • Overnight
– Expanded signing and barricades of closed I-35W
– Converted TH 280 to a freeway
August 2, 2008
• MnDOT Engineers assess stability of wreckage for recovery personnel
• MnDOT retains Wiss Janney Elstner and TranSystems / Lichtenstein for forensic investigation
Command Site
• Federal Agencies arrive at command site FEMA, FBI, Coast Guard, OSHA, OIG, FTA, NTSB, Rick Capka, and National FHWA staff
• NTSB leads investigation team
• MnDOT engineering team begins to organize for rapid replacement
Media Coverage
August 2, 2008
• Governor Conducts interviews throughout morning
• 2 p.m. news conference Governor announces – Emergency Statewide Bridge
Inspections beginning with underdeck trusses – Forensic Investigation Team
• Wiss Janney Elstner • Transystems
• MnDOT provides bridge background and responds to questions
• National and International News Organizations present • National Transportation Safety Board updates
NTSB Chairman Mark Rosenker
Responding to Media Requests
• Daily 2 pm news conference – Became only means to respond to
volume of requests – Format - statement, update on
specific issue, take questions – Length was 30 to 45 minutes – When it ended, held questions till
next day
• MnDOT goal was transparency – Document requests were
voluminous – Website posting of plans,
inspection reports, bridge studies – Dedicated I-35W website included
all documents
August 3 Press Conference
Media on Top of Nearby
Buildings
Responding to Media Requests
| continued
• MnDOT priority was local media requests
• Within days, some media began own investigations and speculation
• Correcting factual errors consumed time
Spectators and media on
adjacent 10th Avenue Bridge
Recovery of Victims
• 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, investigator,s and contractor
– Balanced desire to recover victims vs. need to preserve evidence
Navy Dive Team
Diver Perspective
Recovery of Victims | continued
• Aug. 20 – Navy Divers recover 13th victim, site turned over to MnDOT
• Sept. 6 - Navigation channel opened to commercial traffic
• Sept. 27 – Final steel removed from river
Removing Wreckage from Navigation
Channel
Executive Branch Response
• Aug 3 - First Lady Laura Bush visits the site and victim’s families
• Aug 4 - President Bush pledges to cut red tape that could delay recovery
• Aug 21 - President declares emergency under Robert T. Stafford Act authorizing funds for safety and recovery efforts
Traffic Restoration
• Work to convert Hwy 280 to a freeway including closing at-grade signalized intersections to cross traffic, upgrading ramp termini signal systems and lengthening frontage road
• Add lane each direction on I-94 from Hwy 280 to I-35W by overlaying and restriping shoulders
• Many temporary projects on other Metro alternate routes
Dead Load of Original 1967 Bridge
Compression
diagonal Tension
diagonal
Orange and red shading: exceeds yield stress
Stress
Yield
stress
0
Allowable
After 1977 and 1998 Modifications Orange and red shading: exceeds yield stress
Compression
diagonal
Tension
diagonal
Stress
Yield
stress
0
Allowable
Loads at Time of Accident
Compression
diagonal Tension
diagonal
Orange and red shading: exceeds yield stress
Stress
Yield
stress
0
Allowable
Accident Loads on 1-Inch-Thick Gusset
Plates
Compression
diagonal
Tension
diagonal
Stress
Yield
stress
0
Allowable
Bridge Rebuild Legislative/Congressional
Hearings
• Aug 15 – Hearings with Minnesota House and Senate Transportation Committee
• Sept 5 – MnDOT staff testified before the U.S. House of Representatives Committee on Transportation and Infrastructure
Timeline • August 1 – Bridge Collapses
• August 4 – Issue Request for Qualifications
• August 8 – Short Listed Teams
• August 23 – Request For Proposals Released
• September 14 – Technical Proposals Received & Technical Evaluation
Begins
• September 18 – Financial Proposals Received
• September 19 – Project Letting
• September 20 – City of Minneapolis Grants Municipal Consent
• October 8 - Project Award to Flatiron/Manson
• November 15 – Construction begins
Evaluation Criteria
• Quality (50 percent) – Experience and authority of key individuals
– Extent of quality control/quality assurance
– Safety
– Measures to evaluate performance in construction
• Aesthetics/Visual Quality (20 percent) – Visual enhancements to the structure
– Involvement of the public after letting
• Enhancements (15 percent) – Roadway enhancements
– Structural enhancements
• Public Outreach/Involvement (15 percent) – Impacts to the public
– Approach to communications
Best Value Selection Process
• Based on cost plus time divided by technical score
• Resulted in Flatiron/Manson being awarded the best value contract – 91.47 technical score – $233.8 million cost – 437 days to complete
Eco-friendly Concrete
• Inspired by ancient symbol for water
• A new self-cleaning and pollution eating concrete
• One on each end of bridge
Why Project was Successful
• Common goal by all
• Funding in place within days
• Well prepared
• Sound partnerships
• Streamlined processes
• Servant leadership
• Situational leadership
Outcomes
• Process changes – Inspections (Gusset plates) – Design procedures – Peer review of design for major bridges – Maintenance follow up – Placement of construction material on bridges
• NTSB reports gusset plate design flaw main cause of
collapse
• State established $38 million to compensate survivors and families of those who died
Current Status
• Building public trust and confidence in transportation system and MnDOT
• Litigation continues – State paid Plaintiffs
– Bridge Contractor settled with Plaintiffs
– Consultant ‘A’ settled with State
– Consultant ‘A’ settled with Plaintiffs
– Consultant ‘B’ settled recently with MnDOT
Washington State I-5 Skagit River Bridge
• No fatalities
• Fast recovery
• Truck hit
• Funding debate