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Remembering The Skagit River Bridge Collapse-A year later (May 23, 2013)

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Skagit County, WA: It’s been nearly a year since the Skagit River Bridge collapsed. On May 23rd, 2013 an oversize load struck the Skagit River bridge on Interstate 5,  between Mount Vernon and Burlington, Washington. The interstate is a major thoroughfare from Canada to Seattle. As the oversize load struck the bridge, the  bridge  collapsed into the Skagit River. I took with it innocent drivers who just happened to be in the wrong place at the wrong time.  I happened to be near the bridge with my wife and two kids  when it collapsed and was one of the first people on the scene alongside one of the first responding Burlington Police officers.  My wife was driving that day and we were headed to the mattress store near the bridge to buy a new mattress for our daughter. We never made it. When we turned the corner from Burlington Boulevard onto the road that goes under the bridge on the North Side of the river and she saw the bridge collapsed into the water she immediately stopped the vehicle in the middle of the roadway  and was in shock. A major fear of hers is going over bridges. She has always feared of one collapsing while driving over one.  As a former Firefighter/EMT, I immediately grabbed her cell phone, as my battery was dead and I  jumped out of our car and ran down the dike to get to the bridge to see if I could assist with any rescue efforts. If you’ve met me, you know I don’t run very often, but I sprinted right next to the officer to the bridge.  Our initial survey of the scene, showed a few vehicles in the water, one, which at the time appeared to be a large semi type vehicle and it was upside down, nearly completely submerged  with just the wheels showing. We weren’t sure at first if it was a bus or a semi or a motor home.  There was a truck and we could see at least one person in the truck. To the right of the truck was a small orange colored compact type car with the driver sitting on the roof.  The lights were still on and the windshield wipers continued to swipe from side to side. After a few brief moments to grasp the magnitude of the situation, not knowing what had brought the bridge down, and some scene assessment,  we were able to make voice contact with the driver of  the small car and realized the vehicle that we saw that was upside down and submerged was actually a travel trailer being towed by the pickup. The pickup driver was alert, and we were told he had a passenger who was injured, cold and wet. We didn’t know the extent of her  injuries. The subject we were able to talk to on the roof of the compact car, was wet and cold, partially in shock,  but otherwise appeared not to be injured. The response that followed was anything short of amazing. The Burlington police and Fire departments showed up on our side of the scene and The  Mount Vernon police and Fire department responded to the Mount Vernon side of the scene. Multiple Washington State Patrol troopers arrived. As these first responders were arriving, we were watching the travel trailer being essentially ripped apart by the force of the current of the river. Parts of the trailer were coming loose from the main structure and were floating down the river. We didn’t know how stable the bridge was or if the current was going to shift the bridge and drop the vehicles into the cold water.  Essentially we were on the side of the river, unable to help. Within moments, the Mount Vernon Fire department command rig arrived on the Burlington Side of the scene. When I saw, Mike Vos, exit the command rig, immediately I knew everything was going to run smoothly. I had known Mr. Vos  previously from my  Search and Rescue involvement and my time on the Fire Department. I know Mr. Vos trains extensively and he takes his job seriously.  Mr. Vos,  initiated command and requested an MCI status. The resources he requested one by one made it appear that he had already run an MCI bridge collapse. He knew exactly what he was going to need and he requested every resource  he needed in preparation of maybe going to need it before it was actually needed. EMS units arrived and staged. After a few minutes, the EMS rigs were moved to a safer spot in case something happened and the bridge was to shift or move. Scene safety was number one priority.  The  response was amazing to witness. The multi agency response was essentially  flawless and you could tell that all the first responders took their training serious. They were prepared for anything.  I was  witnessing something that most people have never witnessed in their life and most people never will witness. What followed was very precise and methodical searching downstream for victims by some units while others went above the scene and surveyed the scene looking down from the bridge. Some other units were gearing up for patient rescue, multiple other units were setting up rescue lines, and no one seemed panicked. They were all using their training in real life. From the distance we heard the sound of a chopper and we witnessed the Choppers from Snohomish County fly over the scene. They did a brief ariel search of the river and then landed in the parking lot next to the bridge.  The rescuers exited the choppers, put on their dive gear and made their way to the rivers edge to hop into the boats that were arriving.  During this time all the mutual  aid units that were requested started showing up and representatives from nearly every fire and EMS  agency in the county responded. Units from Snohomish County responded.  We witnessed the victims being rescued by boat and we were able to “live tweet” and post the incident as it happened on our personal Facebook Page.  Our photos of the incident  were shared thousands of times around the world and made the front page  of several major news agencies.  In the end, everyone was rescued, there were no fatalities, and not only did we witness history, we also witnessed the training, dedication and professionalism of our local first responders put into action. What followed the initial shock of the bridge collapse was the idea to start “Skagit Breaking” in case of another major incident and to keep local citizens informed of local happenings. Although we did not expect another major incident in Skagit County,  Skagit Breaking again became  a huge part of another major incident with the Oso Land slide. In essence, the Skagit River Bridge Collapse, brought you Skagit Breaking. We all know that  months of traffic backups followed as well as hundreds of thousands of dollars in lost business revenue for Skagit County and the tragic traffic accident  death of Trooper Sean O’Connell while directing detour traffic.  Here are some of the photos we took of the rescue and response on May 23rd, 2013.  A year later it seems as though this just happened yesterday. It goes to show that in a moment, your life can change. Story and Photo Brought to you by Chris Nelson

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I attended the Trooper Sean O’Connell Skagit River Bridge Dedication as well. Here are my photos from that:

 

 

 

Below is additional information on the I-5 Skagit River bridge Collapse from Wikipedia, the free online encyclopedia.

I-5 Skagit River Bridge collapse

From Wikipedia, the free encyclopedia
I-5 Skagit River Bridge
05-23-13 Skagit Bridge Collapse.jpg

Boats in the water and a helicopter overhead about an hour and a half after the bridge collapse.
Carries  I-5
Crosses Skagit River
Locale Mount Vernon, Washington
Maintained by Washington State Department of Transportation
ID number 0004794A0000000
Design Through-truss bridge
Material Steel
Total length 1,112 feet (339 m)
Width 72 feet (22 m)
Number of spans 4
Opened 1955
Daily traffic 70925
Collapsed May 23, 2013
Coordinates 48°26′43.8″N 122°20′28.1″WCoordinates48°26′43.8″N 122°20′28.1″W
References: [1]

The bridge before the collapse.

The bridge pre-collapse as seen from the roadbed, showing curved trusswork.

The I-5 Skagit River Bridge collapse occurred on May 23, 2013 at approximately 7:00 pm PDT, when one bridge span carrying Interstate 5 over the Skagit River collapsed into the river below. Three people in two different vehicles fell with the span; they were rescued by boat and did not sustain serious injury. The cause of the collapse was determined to be an oversize loadstriking several overhead support beams on the bridge, which led to an immediate collapse of the northernmost span.[2]

The through-truss bridge was built in 1955 and connects the Skagit County cities of Mount Vernon and Burlington. It had recently been evaluated as safe and though not structurally deficient, it was considered “functionally obsolete”, meaning it did not meet current design standards. The bridge’s design was “fracture critical”; i.e., it did not have redundant structural members to protect its structural integrity in the event of a failure of one of the bridge’s support members. The overhead support structure was known to have been struck by a truck as recently as October 2012. From an engineering standpoint, the bridge actually consists of four consecutive spans which are structurally independent. Only the deck and overhead superstructure of northernmost span collapsed into the river; the span south of the collapsed span also sustained damage from being struck by the same truck, though not severe enough to result in a collapse. Also, the piers below the deck were not damaged.

Because the bridge collapse severed a vital transportation link between VancouverBritish Columbia and Seattle, replacing the collapsed span became a high priority for the Washington state government. In June 2013 two temporary bridges were erected and placed on the collapsed span’s support columns while the permanent bridge was built. In September 2013 the permanent bridges were installed and work began to prevent similar failure of the remaining three spans.

 

 

Background[edit]

The bridge crosses between Mount Vernon and Burlington, in Washington State, about 60 miles (97 km) north of Seattle. It is part of the primary road transportation route between the metropolitan areas of Seattle and VancouverBritish Columbia. Before the collapse, approximately 71,000 vehicles crossed the bridge every day.[3]

The bridge was built in 1955, a year before the Interstate highway system was begun. The bridge carries 4 lanes of traffic, two lanes in each direction. The portions over the river are 4 consecutive spans, each 160 feet (49 m) long. The spans are built from triangulated steel girders, using a through-truss design where the roadway passes in an open tunnel between the left and right trusses and between the lower and upper truss work. The roadway has relatively limited vertical clearance for tall vehicles due to the upper truss members. The abutted spans share pier footings and appear to be one continuous bridge, but the 4 spans are actually independent.

The bridge was recently evaluated as safe and in good condition despite being 58 years old; it was not listed as structurally deficient. The bridge was classified as functionally obsolete, in this case because the bridge does not meet current design standards for lane widths and vertical clearance in new highway bridges.[1][4] This bridge was not a candidate for any significant upgrades or replacement and was being well maintained.

Through-truss design[edit]

This steel through-truss bridge has a “fracture-critical” design with non-redundant load-bearing beams and joints that are each essential to the whole structure staying intact. An initial failure (perhaps by cracking) of a single essential part can sometimes overload other parts and make them fail, which quickly triggers a chain reaction of even more failures and causes the entire bridge span to collapse. In 2007 the I-35W Mississippi River bridge in Minneapolis collapsed suddenly from slow cracking of a single undersized and over-stressed gusset plate. In steel these initial fractures begin small and take years to grow large enough to become dangerous. Following Minneapolis, such age-related disasters in fracture-critical bridges are now avoided by finding and repairing cracks in a required thorough inspection every two years. Eighteen thousand bridges in the United States are labelled fracture-critical (from their design) and require crack inspections.[5] The Skagit bridge was last inspected for cracks in August and November 2012 with only minor work needed.[6]

Besides fracturing, some bridges with critical non-redundant parts can also suddenly fail from buckling of compressive members, the opposite of tension and cracking. In through-truss bridges the critical compressive parts are the top-chord beams running horizontally along the top of the bridge, parallel to the roadway edges. They carry most of the weight of the bridge and traffic. The chords are normally kept aligned and held in place by vertical posts, diagonals, and sideways sway struts. Top chords will quickly fold if their joints somehow become misaligned. Buckling damage is cumulative, but mostly happens from collision damage or overstresses rather than from age and corrosion.[7]

The vertical clearance for vehicles is limited by the portals and sideways sway structs. These are relatively low in older bridges. In Washington State bridges, the sway struts are often curved downwards at the outer ends, with less clearance above the outer lanes and outer shoulders. Tall loads then need to use the inner lanes for maximal clearance. These bridges are vulnerable to impacts by overheight vehicles, and such impacts were common. There was a known strike on this bridge that occurred on October 22, 2012, and investigators found evidence of several other impacts in years past.[8] Bridge inspection reports dating back to 1979 frequently note damage caused by over-height vehicles, and an inspection report from late 2012 noted a three-inch gash in the steel.[9]

According to Charles Roeder, a professor of civil engineering at the University of Washington in Seattle, through-truss bridges were a common bridge design 50 years ago (there are 10,200 through-truss bridges in the US). But “If you take out some of the top framing, you set that bridge up for a stability failure.”[10] Before computers, bridge engineers analyzed truss forces by slide rule, with each calculation being time-consuming. Although the finite element method and plastic design theory, both capable of analyzing redundant structures, had recently been formulated and had seen occasional use, they required significantly more calculation than the simple calculation methods for statically determinate structures, which precluded the use of redundant structural members. A great number of bridges were being designed at that time, and there were insufficient design engineers available to design many bridges as indeterminate structures.[11]

Nowadays, through-truss and other fracture-critical designs are avoided in most new bridges for moderate-sized spans. Using three or more parallel main beams or trusses allows the structure to survive a single component failure.

Incident[edit]

Crews work at the scene of the collapse on the day following the accident.

The collapse was caused by a southbound semi-trailer truck from Canada hauling an oversize load to Vancouver, Washington, directly damaging sway struts and, indirectly, the compression chords in the overhead steel frame (trusswork) on the northernmost span of the bridge.[12] The vertical clearance from the roadway to the upper arched beam in the outer lane is 14 feet 7 inches (4.45 m), and all trucks with over-sized loads are expected to travel in the inside lane where the clearance is around 17 feet (5.2 m). The oversize trucker instead entered the bridge in the outer lane, while a second semi truck and a BMW were passing it in the inner lane.[13] The oversize trucker was traveling with a wide and 15 feet 9 inches (4.80 m) tall load, and after the collapse a “dented upper corner and a scrape along the upper side [were] visible on the ‘oversize load’ equipment casing being hauled on the truck.”[14] A pilot car was hired to ensure the load could pass safely. The pilot car never signalled the truck driver that there would be a problem crossing the Skagit bridge[15] and did not warn the trucker to use an inside lane.[16]

The oversize truck completed crossing the bridge while the first span immediately collapsed behind it. Both the driver of the oversized load and the pilot vehicle remained at the scene and cooperated with investigators.[17] The driver of the second passing truck has not been found.

There were no fatalities, but three people were transported to local hospitals[18] after being rescued from their cars. The cars remained on the flooded bridge deck after it fell into the river.[19][20]

The trucker, employed by Mullen Trucking, was hauling an over-dimensional load containing a housing for drilling equipment.[21] The company’s vice-president, Ed Sherbinski, said permits were issued from Washington State that included clearance for all bridge crossings on the route.[21] The truck had been led over the bridge by a pilot escort vehicle.[22][23] A spokesman for the Washington State Department of Transportation said there are no warning signs leading up to the bridge regarding its clearance height.[24] In Washington, only overcrossings of less than 14 feet (4.3 m) (the normal legal height limit) are required to have advance postings of height restrictions.[25]

The oversize truck also damaged a sway strut of the second span, but not enough to initiate a collapse. That span is being repaired, and all three remaining spans are returning to full use.

Investigation[edit]

An NTSB investigator examines the truck that struck the bridge.

This accident was investigated by the Washington State Patrol and the National Transportation Safety Board. NTSB’s Preliminary Report[26] attributes the collision to the tall-load truck being in the wrong, outside lane, and being crowded further into the shoulder by the passing truck. It attributes the bridge collapse to the collision taking out multiple sway braces, which destabilized the critical load-bearing (upper chord) members.

Aftermath[edit]

Gov. Inslee declared an economic “state of emergency” for three surrounding counties (Skagit CountySnohomish CountyWhatcom County) in order to cope with disruption to traffic and the local economy.[27] Traffic on I-5 was detoured around the scene of the collapse on an adjacent bridge upstream. State trooper Sean O’Connell died while directing traffic through the detour when his motorcycle hit a truck.[28] Shortly after the accident, three state lawmakers proposed a bill that would rename the repaired bridge after him.[29]

The collapsed span was temporarily replaced by a pair of 2-lane ACROW bridges rolled onto the existing bridge piers. It went into service on June 19.[30] Inspections on the temporary span near the end of July 2013 uncovered part of an “L” joint that holds the asphalt in place between the temporary bridge and permanent roadway came loose.[citation needed] The right lane of the bridge was closed for about two hours while crews welded the joint back into place and spread new asphalt.[citation needed]

A $6.87 million contract was awarded to contractor Max J. Kuney Construction of Spokane, to design and build a permanent replacement span.[31] It was built alongside the temporary span without interrupting traffic, and moved into place during an overnight closure on September 14–15, 2013.[32] Planned changes to the 3 remaining overhead spans should allow overheight vehicles to operate in the outer lanes.[33]

The collapse raised questions about how the state department of transportation regulates oversize vehicles. The State of Washington leaves it up to drivers to determine a safe route to their destination, unlike many other states that assign routes. The permit for Mullen trucking’s trip did not specifically note the Skagit River Bridge as a hazard on the route, even though the outer trusses were a full foot lower than the truck – this contrasts with an earlier permit to the same company that included numerous clearance warnings. State lawmakers are exploring making changes to the state’s oversize vehicle laws.[9]

Washington’s infrastructure[edit]

Prior to the bridge collapse the Seattle Section of the American Society of Civil Engineers (ASCE) issued the 2013 Report Card for the State of Washington infrastructure. The state’s bridges were given a grade of C− (an average score among states). There were 400 structurally deficient bridges in Washington. 36% of all bridges are older than 50 years. The oldest bridges were designed for an expected life of only 50 years; keeping them safe is increasingly difficult and expensive.[34] The advocacy group Transportation for America reports that only 5.10% of Washington’s bridges are structurally deficient, which is the sixth best in the country.[35]

See also[edit]

References[edit]

  1. Jump up to:a b Staff (2012). “NBI Structure Number: 0004794A0000000”National Bridge InventoryFederal Highway Administration. Retrieved May 23, 2013.
  2. Jump up^ “I-5 bridge collapses over Skagit River, no fatalities”. Seattle: KING-TV. Associated Press. May 23, 2013. Retrieved May 23, 2013.
  3. Jump up^ Ip, Stephanie (May 23, 2013). “I-5 bridge collapses into Skagit River in Washington; motorists reportedly in water”The Province (Vancouver, BC). Retrieved May 23, 2013.
  4. Jump up^ “WSDOT Structurally Deficient Bridges”Washington State Department of Transportation. September 1, 2011. Retrieved May 23, 2013.
  5. Jump up^ Jamieson, Alistair; Dedman, Bill (May 24, 2013). “‘Like a Hollywood movie’: Driver survives I-5 bridge collapse into Wash. river”US news on NBCNews.comNBC. Retrieved May 24, 2013.
  6. Jump up^ “Bridge Inspection Report”Washington State Department of Transportation. November 21, 2012.
  7. Jump up^ “Bridge Inspector’s Reference Manual”. USDOT Federal Highway Administration. October 2002.
  8. Jump up^ “Temporary Skagit River bridge may be open in weeks”King 5 television. May 26, 2013. Retrieved May 27, 2013.
  9. Jump up to:a b Mike Baker (June 20, 2013). “WSDOT knew trucks have clipped I-5 Skagit bridge for decades”Seattle Times. Retrieved June 20, 2013.
  10. Jump up^ Kris Maher (May 24, 2013), “Truss’s Design Is Dated, but Common”The Wall Street Journal
  11. Jump up^ “N.V.” (June 3, 2013), “Falling bridges — Difference Engine: A member too few”,Babbage blog (The Economist), retrieved 2013-11-04
  12. Jump up^ Becky Monk. What caused the Skagit River bridge to collapse? Puget Sound Business Journal, May 24, 2013. [1]
  13. Jump up^ “Detectives seek 2nd truck from bridge collapse”.
  14. Jump up^ Emily Heffter (May 24, 2013), “Bridge collapse: Oversize-load permits easy to get online”The Seattle Times
  15. Jump up^ “Oversized load blamed for Washington bridge collapse”CBC News. Retrieved 27 May 2013.
  16. Jump up^ “Couple who narrowly escaped I-5 bridge collapse tell incredible story”. May 31, 2013.
  17. Jump up^ “Washington bridge collapse caused by truck hitting span, authorities say”. foxnews.com. May 24, 2013. Retrieved May 24, 2013.
  18. Jump up^ Welch, William M. (May 24, 2013). “Bridge collapses in Wash. state; people in water”USA Today. Retrieved May 24, 2013.
  19. Jump up^ Hager, Mike; Lindsay, Bethany (May 23, 2013). “Three people pulled from Skagit River after I-5 bridge collapses in Washington; no fatalities reported”The Vancouver Sun. Retrieved May 23, 2013.
  20. Jump up^ Rafferty, Andrew; Kirschner, Justin (May 23, 2013). “Bridge collapses in Washington state – cars, people in water”NBC News. Retrieved May 23, 2013.
  21. Jump up to:a b Sinnema, Jodie; Associated Press (May 24, 2013), “Spruce Grove trucker implicated in bridge collapse in Washington state”Edmonton Journal, retrieved May 24, 2013
  22. Jump up^ Leavitt, Wendy; Straight, Brian (May 24, 2013). “Oversized load may be cause of I-5 bridge collapse in Washington State”FleetOwner.comPenton Media. Retrieved May 24, 2013.
  23. Jump up^ Martin, Kate (May 24, 2013). “Bridge could be out for months”GoSkagit.com. Skagit Publishing. Retrieved May 24, 2013.
  24. Jump up^ “Canadian trucking co. says it had Wash. permit to cross I-5 bridge that collapsed”.Associated Press. Retrieved May 24, 2013.[dead link]
  25. Jump up^ http://www.wsdot.wa.gov/NR/rdonlyres/337A7006-8808-4790-85EA-167C8AC39F2E/0/OverheightLoads.pdf
  26. Jump up^ NTSB (June 11, 2013). “Preliminary Report”.
  27. Jump up^ “Proclamation By The Governor, 13-04”Olympia, Washington: State of Washington Office of the Governor. May 24, 2013. Retrieved May 24, 2013.
  28. Jump up^ Christine Clarridge (June 6, 2013). “Fallen state trooper draped in praise”Seattle Times. Retrieved June 13, 2013.
  29. Jump up^ “As repairs continue, bill would rename bridge for fallen trooper”KOMO. June 3, 2013. Retrieved June 13, 2013.
  30. Jump up^ “Skagit River bridge now open to traffic”.
  31. Jump up^ “Spokane Construction Company Wins Bid To Replace Collapsed I-5 Bridge”.KNDU. June 18, 2013.
  32. Jump up^ “I-5 at Skagit River Bridge Span Replacement”. Retrieved September 15, 2013.
  33. Jump up^ “I-5 at Skagit River Bridge Vertical Clearance Upgrade”. Retrieved September 15, 2013.
  34. Jump up^ 2013 Report Card for Washington’s Infrastructure
  35. Jump up^ “The Fix We’re In For: The State of Our Bridges”. Retrieved May 30, 2013.

External links[edit]

About the Author

Chris Nelson
I'm a long time Skagit County Resident. I believe in doing the right thing and helping others when you can.

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