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Surveying theI-35W Bridge Collapse
Minnesota Society of Professional Surveyors57th Annual MeetingJanuary 28 - 30, 2009St. Cloud Civic CenterSt. Cloud, Minnesota
Where were you?
• Do you remember where you were onAugust 1, 2007 at 6:05 PM?
• I remember precisely!– My wife and I were seated at the 4th table
down on the left side in Famous Dave’srestaurant in Woodbury, MN and had justgotten our meals served.
– My cell phone rang, it was my son.
– The 35W bridge had collapsed!
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The CollapseOccurred at 6:05 p.m.
Wednesday, August 1, 2007
Over 100 vehicles on the bridgeat the time of the collapse.
13 fatalities105 injuries
I-35W BridgeI-35W Bridge
UniversityUniversityofof
MinnesotaMinnesota
DowntownDowntownMinneapolisMinneapolis
http://maps.google.com/
My daughter’sapartment
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U of M building
Army Corp of EngineersLock and dam
Railroad 10th Ave bridge
West River Rd
I-35W Bridge Construction - Looking North
July, 1965
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Concrete Slab
Floor Truss
Concrete Pier
Main Truss
Photos about 1 mo. before collapse
Looking South
Looking North
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An Unprecedented Event
I-35W Collapse Area
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Field offices
Safety gridmap
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SecurityBadges 1
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The President comes to town
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President of the United States of AmericaGeorge Bush, Governor Tim Pawlenty, &
Mayor R. T. Rybak
Aerial photos and LiDAR mappingMetro Surveys set ground control targets
Oblique photos Vertical photos & LiDAR
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FBI doing survey work
“Crazy” FBI surveyors!!
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FBI Laser Scanning
Cops everywhere and lots of themFBI surveying in background
Metro Surveys Static GPS in foreground
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Monitoring for possible bridge movement
Total station doing monitoring work
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Monitoringlocations
Monitoring continued in all weatherconditions
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This was why we were monitoring
Navy divers
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Morning coordination of day’s activities
Pre-CollapseHorizontal andVertical Control
Points
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FBI & StatePatrol Control
Points
They started onassumed datums
Establishing control with static GPS
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Section corner GPS work for R/W needs
Metro Surveys &FBI & State
Patrol ControlPoints
We felt all survey workshould be on samedatums. We GPS’d allFBI & State Patrolpoints and gave themXYZ values
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VRS stations usedfor establishingcontrol for the
bridge collapse site
HDS Laser Scanning
• “Scan the Bridge!”– First thought after the initial shock was the
need for Surveys to scan the wreckage
• New to MN/DOT– Delivered at end of January, 2007
– Used on various projects
– “Marketing” demos to MN/DOT personnel
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Scanning on south side of river
Scanning bysouth piers
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Working conditions
FBI
MN/DOT
Scanning by River Road
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Scanning from 10th Ave. bridge
Scanning from lock wall area
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Scanner on lock wall
Scanner at work on north side
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Two scanners on deck ofun-collapsed section
Both scanners in action
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Explaining the scanner to the Incident Commander
Total scanned area
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South side of river by locks
North side of river
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Wreckage with vehicles
Car perched on bent deck
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School bus
Section north of river
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Rail cars under bridge deck
Crushed rail cars
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Detail of scan – end of beam
Steel beams of bridge deckin river
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Steel over north piers
LASER SCAN OF COLLAPSED BRIDGE
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Bohemian Flats areaStaked location of trusses for forensic review
Traffic Restorationprojects
• Projectsconsidered forconstructionto re-routetraffic awayfrom 35Wbridge site
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Traffic Restoration projects
• Metro Surveysdid designsurveying and/orconstructionsurveying on 11different projects
Work on Traffic Restoration project
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2007 ConstructionProjects
• Normal constructionkept going
• Covered all jobswithout delays
• D3 crew assisted onUnWeave project
GPS’ing Minneapolis control monumentby Geodetics
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Metro Surveys& Geodetics
control points
Geodeticcontrol points
for building thenew bridge
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Thanks to Private Survey firms
• Haackanson/Anderson
• Sunde Land Surveying
• Comstock & Davis
Questions?
The Minnesota Department of Transportation’s authorization to present this power point
is in accordance with permission from the National Transportation Safety Board,
pursuant to 49 C.F.R. § 831.13.