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I-35W Bridge
Collapse
Nancy Daubenberger
Presentation to AASHTO SCOBS
T-1
I-35W Bridge
University
of
Minnesota
Downtown
Minneapolis
http://maps.google.com/
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
Bridge Rating
• Inspected annually since 1993; before that, was inspected every two
years
• Superstructure rated “structurally deficient” in 1990
• This was due to:
– Corrosion where the paint had deteriorated
– Poor weld details in the steel truss members and floor beams
– Bearings that were not moving as they were designed to move
– Existing fatigue crack repairs to the approach span beams
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
Maintenance Work at Time of Collapse • Replace concrete overlay,
repair joints and lighting, and install guardrail
• Work completed on outside
two lanes each direction
• Scheduled completion date
- September 30, 2007
• Cost - $9 million
• Contractor employees and MnDOT inspectors on bridge at collapse
The Response
The First 24 Hours
MnDOT’s Immediate Response
• 6:05 p.m. - Numerous concurrent calls to State Patrol Dispatch (911) and from field employees to RTMC and Maintenance Dispatch
• 6:10 p.m. - District Emergency Operations Center activated and DEOC staff report to RTMC
• Immediate traffic control for ramp and freeway closures provided by FIRST units, maintenance units, and contractors in the vicinity
Mn/DOT’s Regional Transportation
Management Center (RTMC)
Statewide Incident Response
• 6:20 p.m. – State Emergency Operations Center and Joint Information Center activated.
• Unified command center set up on
collapse site. Authority in command
changed as incident progressed:
– Mpls. Fire Department in charge of rescue
– Hennepin County Sheriff in charge of recovery
(MnDOT assisted with some demolition)
– MnDOT assumed command after recovery was
completed
Emergency Service Response • MnDOT Metro district provides maintenance staff and equipment
•MnDOT structural engineers called to site
• Effective response due to communications, planning, equipment, training, and experience with incidents on the Metro area freeway system
Traffic Response • 6:20 p.m. - began converting temporary traffic control measures to
more long term traffic control standards.
• 20 changeable message signs activated
• MnDOT assisted state patrol and other enforcement personnel
• Instituted 24-hour staffed traffic control
• By 7 p.m. – Over 150 employees activated
• 11:00 p.m. - Detour maps for a.m. rush posted on MnDOT Web site
• Overnight – closed I-35W with temporary barricades and converted Hwy 280 to a freeway.
I-35W Detour Map
Public and Media Response
• 6:10 to 8 p.m. continuous MnDOT
traffic radio coverage
• Detour maps and info provided on Web
and 511 Traveler Information
• Media briefings, interviews
• Coordinated responses with other
agencies/governor’s office
http://www.511mn.org
http://www.dot.state.mn.us/i35wbridge/index.html
Security Response
• MnDOT safety officers
statewide called in
• Homeland Security & FBI
investigate criminal or terrorism
potential
• OSHA ensures safety
• Navy divers assist recovery
• U.S. Secret Service for
president visit
• No-fly zone activated
Internal Agency Response
• Employees knew what to do, when to go, who to report to
• Aug. 2 – Lt. Gov. e-mail to employees
• Aug. 2 – State employee assistance available
• Aug. 6 – Lt. Gov./Deputy thank employees
• Aug. 8 – Tips to employees on handling threats
• Critical incident stress debriefings provided
The Response
Local and National
• Aug. 2 - Governor Tim
Pawlenty declares a state
of emergency and
activates State
Emergency Operations
Center
Governor’s Response
U.S. DOT Response
• Aug. 2 – U.S. DOT Secretary tours site and announces
$5 million grant to help pay for early expenses
Executive Branch Response
• Aug. 3 - First Lady Laura
Bush visits the site, victims
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
President Bush participates in a
briefing with Minneapolis Mayor R.T.
Rybak and Gov. Tim Pawlenty
Congressional Response
• Congress authorizes $250 million in Emergency
Relief money to repair and restore highway facilities
to pre-disaster conditions
MnDOT Continued Response
• Investigation
• Inspections
• Traffic Recovery
• Bridge Demolition
• Bridge Replacement
• Media/Public
Responses
Continued Response
Investigation
The Search for a Cause
• Message - cause
may not be known
for 12-14 months
The Search for a Cause • National Transportation
Safety Board leads
investigation
• Forensic engineering firm
assisting investigation
• Consultant to review
inspection procedures
Construction Materials Staging
Construction equipment and
vehicles
Piles of aggregate
U10 west node
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
Continued Response
Inspection
• Aug. 2 - Governor directs MnDOT to inspect all bridges on the trunk highway system in priority order
• Aug. 6 – MnDOT completes inspection of five bridges with the same arch deck truss design as I-35W bridge
• Inspection continues of state bridges, structurally deficient and fracture critical bridges priority
• Aug. 10 – MnDOT requests that local agencies and private owners accelerate inspections of their bridges
• Dec. 1 - MnDOT’s goal to complete all state bridges inspections
Inspection
Continued Response
Traffic Recovery
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
Traffic Distribution After Collapse
Transit
• Metro Transit assigned 25 extra
buses, ridership jumps 25-50%
• Advised public to “buy bus
passes, stagger work hours,
carpool”
• Began studying additional
service enhancements
Park-and-Ride use jumps after
I-35W bridge collapse
Continued Response
Bridge Demolition
Bridge Demolition and Removal • Aug. 6 – demolition begins to aid
recovery, Carl Bolander & Sons
Co., awarded demolition contract
• Aug. 20 – recovery completed,
site turned over to Mn/DOT
• Sept. 6 - Navigation channel
opened to commercial traffic
Continued Response
Media/Web info
Media and Public Response
• Media interest worldwide
• Media briefings, interviews
• MnDOT directed to be
transparent in info provided
• AG’s office required retention
of all incident-related data
• 50+ data practices requests
• Dedicated I-35W Web site
includes all documents
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
Continued Response
Bridge Rebuild
Bridge Rebuild
• 189’ wide
• 10 lanes of traffic, five in each direction
• Designed to handle Bus Rapid Transit (BRT) and/or a
managed lane (like I-394 MnPASS)
• Designed to be LRT ready
Bridge Rebuild – Design Build • Aug. 4 – Design Build teams pre-qualified
• Aug. 14 – public involvement process begins
• Aug. 21 – layout submitted to Minneapolis
• Aug. 23 - RFP delivered to five design-build teams
• Aug. 23 – all but 3 environmental permits acquired
• Sept. 19 – project bid letting
• Nov. 15 - construction begins
• Sept. 2008 – bridge completed
Bridge Rebuild - Review Process
• Minneapolis Municipal Consent hearing Sept. 20
• Technical Review Committee reviewed proposed
design
• Visual Quality Advisory Committee met with Design-
Build teams
Bridge Rebuild-Stakeholder Involvement
• Six open houses
• Community group Meetings
• Presentations/listening sessions
• Meetings with local, state, federal officials
• E-mail alerts/ notifications
• Web site, online comment form
• Handouts at park-and-ride lots
Bridge Rebuild-Environmental Review
• Environmental reviews accelerated due to
cooperation among agencies
• Includes a thorough analysis of the full range of
potential environmental issues for all aspects of the
project
• Met NEPA requirements
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 & Infrastructure
• Economic factors create urgency to rebuild quickly
• Daily costs to motorists of additional travel time and
distance estimated at $400,000
• Reduction in state’s average net economic output is
an additional $113,000 per day
Bridge Rebuild - Economic Impacts
Conclusions
What Went Right?
Lessons Learned?
What Was Done Right • Employees willing to work, just showed up, returned from vacations
• Excellent employee response due to experience and training
• Good coordination with other Governor’s office/other agencies
• Good work relationship between MnDOT and contractor employees
• Other agencies/states called and emailed offering help
• Material suppliers speeded up delivery
• Permits, other documents approved quickly
• No MnDOT employees injured during response and traffic recovery
What Worked Right
• In-place incident management infrastructure
• Redundancy in RTMC camera/communications
systems meant no network breakdowns
• Improved emergency radio communications
• MnDOT Web site reduced number of requests
Issues with Investigation
• Media, communications between national/local
agencies
• Sharing field office
• Who had jurisdiction
• Turning over portions of bridge to MnDOT
Lessons Learned • Consultant onboard to facilitate table top incident review exercise
• Cell phone service was overloaded
• Confusion about DEOC and CO roles and responsibilities
• Improved system for media inquires and data practices requests
• Confusion regarding what investigation results are public information
• Use caution posting detailed contact info
• MnDOT employees can work out of the box, be flexible, work in strange locations and do what needs to get done!
QUESTIONS?
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