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?