Category Archives: Transportation History

Another Step Toward Safer Skies in Africa

By Dennis Jones, NTSB Managing Director

In my recent blog post, I talked about the NTSB’s visit to South Africa as part of the US Department of Transportation’s Safe Skies for Africa (SSFA) program. Last week, the NTSB team returned to Africa—this time, to the east African nation of Kenya—in continued support of the SSFA program, the aviation safety capacity-building initiative that includes collaboration between African countries and several US government agencies. In Kenya, as in South Africa, we once again shared investigative lessons learned with more than 150 air safety investigators, aviation trainers and operators, government officials, and safety advocates from Kenya and countries in the surrounding region.

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I was particularly excited about this trip because I first traveled to Kenya for accident investigation purposes 20 years ago, and later, based in the capital city of Nairobi, I worked to implement the NTSB’s SSFA program responsibilities. The goal of the SSFA program in Kenya was to help the country achieve FAA Category 1 status and pave the way for direct scheduled commercial air service between the United States and Kenya. The NTSB’s contribution toward this goal was to help Kenya’s accident investigation program meet international standards in accordance with the provisions of the International Civil Aviation Organization’s (ICAO’s) Annex 13. Our activities included working with the Air Accident Investigation Division of Kenya (AAID) to develop its program, which included on-the-job investigator training; establishing policy, procedures, and practices for the organization; and producing memoranda of understanding between AAID and other domestic government agencies. The NTSB partnered with ICAO as part of the SSFA program to conduct aircraft accident investigation workshops throughout Africa; the first such event was held in Nairobi in 2007.

It took some time but, thanks to Kenya’s painstaking and diligent efforts, and the assistance provided by the SSFA program, Kenya achieved an FAA Category 1 rating in February 2017. Consequently, US and Kenya air carriers can now, with the approval of their respective regulatory agencies, travel between the two countries. Kenya Airways, Kenya’s national carrier, will launch its inaugural flight to the United States, destined to JFK International Airport in New York, in October 2018.

Although Kenya’s government is focused on improving aviation safety, the country—and, more broadly, the continent—still faces challenges that the region’s stakeholders are dedicated to overcoming. General aviation (GA) safety issues have been formidable in the region, just as they are in the United States, and we sought to share some of our experience addressing this issue. Further, through the SSFA initiative, NTSB representatives have recognized other modal transportation safety issues and safety advocacy opportunities for future consideration as the agency formulates its international scope of activities.

After accompanying the NTSB team to South Africa last month, I was fully confident in its ability to conduct the workshop in Nairobi. The team was composed of professionals representative of the superb workforce at the NTSB, and they delivered powerful presentations sharing lessons learned.

Shamicka Fulson, a program manager in the Office of the Managing Director, coordinated the development of the workshops in South Africa and Kenya. She delivered opening remarks and provided an overview of the agency and the SSFA program to begin the workshop in Nairobi.

Clint Crookshanks, an aerospace engineer in the Office of Aviation Safety, facilitated a workshop related to identifying common aviation safety lexicon. He reviewed different accident case studies with the audience and discussed ways to interpret the generalized and vague definitions often found in aviation investigations, such as “substantial damage to aircraft,” or the distinction between an “accident” and an “incident.”

Luke Schiada, Deputy Chief of Aviation Safety for the Eastern Region, presented accident case studies that highlighted international cooperation. Luke told the audience that he believed “international cooperation is, in large part, about building relationships and trust.” He stressed the importance of interacting with and learning from the collective knowledge and experiences of participants in settings like the SSFA workshops. I can’t agree more; after all, we can’t improve within unless we are willing and able to learn from without. Even sharing enables learning and growth.

Dennis Hogenson, Deputy Regional Chief of Aviation Safety for the Western Pacific Region, focused on GA safety improvements. He pointed out that, like Africa, the United States is seeing a high incidence of GA crashes. He told his audience that, while airline accidents have become rare, GA accidents account for most aviation fatalities. In many of our GA accident investigations, we’ve discovered that pilots didn’t have the adequate knowledge, skills, or recurrent training to fly safely. Dennis encouraged his African counterparts to initiate more training and increase awareness of technology that can help prevent these tragedies; this is something we continue to strive to do in the United States via our Most Wanted List issue addressing loss-of-control in flight.

Nicholas Worrell, Chief of the Safety Advocacy Division in the Office of Safety Blog Image 2.jpgRecommendations and Communications, urged attendees—most of whom were investigators—to go beyond investigations to see real improvements in safety. The work doesn’t end with the report findings issued after the investigation; the work to improve safety just begins, he said. African safety organizations need to develop advocacy efforts and strategies to ensure their safety recommendations are implemented. Nick encouraged the audience to look to some of Kenya’s most notable leaders, like Jomo Kenyatta, political activist and Kenya’s first president, and Wangari Maathai, Nobel Peace Prize winner, both of whom saw a need for and executed effective advocacy to improve laws, policies, and practices.

The goal of our visit to Kenya was to continue fostering the development of a safer aviation transportation system in East Africa. It is integral to our mission at the NTSB to share globally what we have learned from 51 years of safety investigations. As the NTSB team supporting the SSFA program has shown, improving transportation safety is a collaborative process that doesn’t end at our borders.

NTSB Supports ‘Safe Skies for Africa’ Program

By Dennis Jones, NTSB Managing Director

Last week, as part of the U.S. Department of Transportation’s Safe Skies for Africa program, I led a team of NTSB investigators and communications specialists to South Africa to share lessons we’ve learned from our accident investigations. The Safe Skies for Africa program, created 20 years ago, aims to improve the safety and security of aviation on the continent. Our team shared some NTSB strategies with our international counterparts to help them achieve similar outcomes in their region.

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Managing Director, Dennis Jones, talks with attendees at the Safe Skies Symposium in Johannesburg, SA

From my perspective, the Safe Skies program is working. After spending about 20 years in Africa participating in accident investigations, conducting workshops, helping improve accident investigation programs, and training investigators, I’ve seen increased commercial air service between the United States and Africa (for example, there are now US commercial flights to Africa, which wasn’t the case earlier in my career), improved investigation quality, and a reduced rate of accidents involving commercial aircraft.

On this trip, the NTSB team shared a variety of lessons learned from different disciplines. Dennis Hogenson, Western Pacific Region Deputy Regional Chief for Aviation Safety, pointed out that, like Africa, the United States is seeing a high incidence of general aviation (GA) crashes. He told his audience that, while airline accidents have become rare, GA accidents account for most aviation fatalities in the United States. We investigate about 1,500 GA accidents each year; those involving loss of control in flight still result in more than 100 fatalities annually. In many of our GA accident investigations, we’ve discovered that pilots didn’t have the adequate knowledge, skills, or recurrent training to fly safely, particularly in questionable weather conditions, and their inability to appropriately recover from stalls often resulted in deadly accidents. Dennis encouraged his African counterparts to initiate more training and increase awareness of technology, such as angle-of-attack indicators, that can help prevent these tragedies.

Bill Bramble, a human factors investigator, outlined our investigation process and explained how we examine all factors—machine, human, and environment—to understand an accident and make recommendations to prevent it from happening again. Bill highlighted several accidents we investigated in which human factors played a role. But even when a probable cause statement focuses on factors not normally associated with human performance, it’s impossible to totally remove humans from the accident chain.

“Humans designed it, built it, operated it, maintained it, managed it, and regulated it. Human factors are always involved in complex system failures,” Bramble said.

To prevent accidents and improve the safety of air travel in Africa, it’s important that operating aircraft are airworthy, meaning that all structure, systems, and engines are intact and maintained in accordance with the regulations. To emphasize this point, NTSB aerospace engineer, Clint Crookshanks presented a series of case studies discussing airworthiness issues and offered guidance on ways to classify damage to aircraft.

Chihoon “Chich” Shin, an NTSB aerospace engineer, addressed helicopter safety. The number of helicopter operations (emergency medical services, tourist, and law enforcement support) in Africa is increasing, and so is the number of helicopter accidents. Chich presented case studies and highlighted some important safety issues from an engineering perspective.

“The metal doesn’t lie,” Shin said. He called for increased awareness of the safety issues affecting helicopter safety and encouraged action from key stakeholders, such as regulatory agencies and helicopter manufacturers and operators, to help reduce accidents and fatalities. He also touted the importance of crash-resistant recording devices to help investigators determine what happened in a crash and work to prevent it from happening again.

NTSB communications staff emphasized another side of our work in transportation safety. Stephanie Matonek, a transportation disaster assistance specialist, discussed the importance of planning for family assistance after an accident occurs.

“Having a family assistance plan in place, identifying your family assistance partners, and addressing the fundamental concerns for families and survivors that cross all cultures is not only a crucial step but the right thing to do,” she said.

Nicholas Worrell, Chief of the Office of Safety Advocacy, addressed messaging, encouraging attendees to go beyond investigations to teach their safety lessons effectively. He encouraged investigators to raise awareness of the safety issues they uncover to spur action on their recommendations.

Aviation is a global business. Our mission is to make transportation safer the world over by conducting independent accident investigations and advocating for safety improvements. With outreach activities like the one we just completed in Africa, we hope to make aviation safer, not only in Africa, but throughout the world. After all, transportation safety is a global challenge. When safety wins, we all win.

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NTSB Managing Director and staff with symposium attendees

The Age of Reason

By Chairman Robert L. Sumwalt

Some scholars play a critical role in founding a whole field of study: Sigmund Freud, in psychology. Noam Chomsky, in linguistics. Albert Einstein, in modern physics. In the field of safety, Dr. James Reason has played such a role. In this field, no single name is better known.

Dr. Reason turns 80 today, and if you’re reading this, it’s possible that you owe your life to his ideas.

NTSB reports have frequently cited Dr. Reason’s work, and I personally quote him liberally in my talks to industry and safety stakeholders.

His contributions to safety have been influential not only in transportation and workplace safety, but also in fields as varied as healthcare, nuclear power, and fraud prevention.

His books include Human Error; Organizational Accidents; Managing the Risks of Organizational Accidents; Organizational Accidents Revisited; The Human Contribution: Unsafe Acts, Accidents, and Heroic Recoveries; and A Life in Error: From Little Slips to Big Disasters.

He views safety as a system, and accidents as the result of any individual’s mistakes in combination with other failings in the system. People are fallible, but that doesn’t make accidents inevitable.

Focusing on a safer system, instead of only an individual’s mistakes, can help diminish individual error (for example, through better training and procedures). More importantly, studying the system reveals much more of “what went wrong” – and will go wrong again if not corrected, because other individuals will make mistakes.

Dr. Reason came up with a handy analogy for his view, called the “Swiss Cheese Model of Accident Causation.” (Just say “Swiss Cheese Model” to a safety or risk management professional, and they’ll probably nod knowingly.)

In this model, layers of protection against an accident, each of which has weaknesses, are visualized as slices of cheese riddled with holes. An accident occurs when the weaknesses, or holes, align.

 

Swiss Chese Model
Swiss cheese model by James Reason published in 2000. Source: https://openi.nlm.nih.gov/detailedresult.php?img=PMC1298298_1472-6963-5-71-1&req=4, open-access, CC Attribution 2.0 Generic

 

We’re all living in the Age of Reason. It’s a good age in which to live, one during which accidental deaths and injuries have been on the decline.

The continuous improvement of safety depends on safety professionals living with what Dr. Reason called a “chronic unease.” The paradox of safety is that the moment we think we’ve arrived, we introduce another hazard: complacency.

However, even in the chronically uneasy profession of safety, we find cause to celebrate every now and then. So, on that note, Happy 80th birthday to Professor Emeritus James Reason, on behalf of safety professionals everywhere—and on behalf of all those he’s saved, from every walk of life.

Refusing to Take “No” for an Answer

By Chairman Robert L. Sumwalt

On July 17, 1996, about 12 minutes after takeoff from John F. Kennedy International Airport, New York, Trans World Airlines (TWA) flight 800 (TWA-800), a Boeing 747-131, crashed in the Atlantic Ocean near East Moriches, New York. The accident killed all 230 people on board, and the airplane was destroyed. The NTSB’s investigation of this accident was the most extensive, complex, and costly air disaster investigation in US history, and was the subject of high public interest and front-page headlines for years.

On August 23, 2000, a little more than 4 years after the crash, the NTSB determined the probable cause to be an explosion of the center wing fuel tank (CWT), resulting from ignition of the flammable fuel/air mixture in the tank. Because multiple potential sources were identified, the singular source of ignition for the explosion could not be determined with certainty, but the likely source was a short circuit outside of the CWT that allowed excessive voltage to enter the vapor-laden fuel tank through the fuel-quantity–indicating system in the CWT.

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On December 13, 1996, while the investigation was still ongoing, the NTSB issued the first of three sets of safety recommendations to the FAA. We based these initial recommendations on early findings of the investigation to address the threat of a fuel tank exploding on an airliner. Two recommendations included the development of design or operational changes to prevent explosive fuel-air mixtures in the fuel tanks—including the development of nitrogen-inerting systems. A nitrogen-inerting system replaces the air in an empty fuel tank with nitrogen, creating an environment in which neither a fire nor an explosion can occur. A total revision to FAA regulations for wiring and maintenance, including those of fuel-quantity–indicating systems, also resulted from our findings in this accident investigation.

The FAA’s initial response to our inerting recommendations was to convene a group of industry experts, who found that the costs of implementing the recommendations was too high to be practical. We disagreed and urged the FAA to consider other options. The FAA tried again, tinkering around the edges of the problem, focusing on the wiring and electrical systems in aging aircraft. We welcomed these improvements but reiterated that the agency was ignoring the core issue—the hazard posed by potentially explosive aircraft fuel tanks. To its credit, the FAA chose to apply some “out of the box” thinking, and, together with Boeing, developed a system on the airplane to address the threat.

That innovative technology, called a molecular sieve, separates air into nitrogen and oxygen, the two primary gases. The oxygen is vented overboard while the nitrogen is used to inert the fuel tank. The FAA performed in-depth analysis of the technology, and Boeing produced several prototype systems for testing and evaluation. These tests showed the system to be effective, have minimal operational challenges, and to be reasonably priced. Boeing began installing these systems on some of the new airplanes it was producing.

On November 23, 2005, the FAA proposed a new regulation that required newly manufactured and in-service airliners to reduce the chances of a catastrophic fuel-tank explosion. A final rule was enacted by in 2008, and 100 percent compliance with the rule became mandatory on December 26th of 2017—21 years after the NTSB first recommended fuel-tank inerting to the FAA.

The enactment of the fuel-tank flammability rule is a major safety improvement, addressing a critical safety problem at the heart of many aviation accidents over 45 years. However, its enactment was clearly far from easy; it took the persistent advocacy of the NTSB and the efforts of FAA and Boeing staff unsatisfied with cursory cost-benefit analyses. It took the commitment of senior management at the FAA and DOT—including the Director of the Certification Service, Associate Administrator of Safety, the FAA Administrator, and the Secretary of Transportation—to implement this needed safety regulation.

The traveling public is safer today because these organizations, working together, refused to take “no” for an answer.

Recognizing Important Women Leaders at NTSB—From Yesterday and Today

By Chairman Robert Sumwalt

March is Women’s History Month, so it’s only appropriate to look at some of the American women who have helped influence and shape today’s transportation system, including those working at the NTSB today.

We have witnessed the extraordinary accomplishments of women like Bessica Raiche, the first female pilot in the United States to make a planned flight, and our very own Member Bella Dinh-Zarr, the first Asian American to become a Board Member at the NTSB. Member Dinh-Zarr has spent years advocating for and promoting safe and sustainable transportation. These women have reached great heights in their careers and are renowned nationwide for their successes.

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Shannon Bennett (left), Sharon Bryson and Dana Schulze

Yet, there are many more women—perhaps not as nationally known but just as important to the NTSB’s critical mission—that we would like to recognize. In celebration of Women’s History Month, we recently sat down with some of the exceptional women who have emerged from the NTSB’s ranks to become leaders in management and safety. They inspire staff every day to work hard to improve transportation safety, sharing NTSB safety messages and encouraging us all to remember our mission to save lives. They are role models for many at the agency—men and women. We asked them to share their thoughts on leadership with staff last week at a special briefing, and we think their lessons are beneficial to all, even those outside our organization. Here’s what they had to say.

Dana Schulze is the deputy director of the NTSB’s Aviation Safety (AS) Office. As second-in-command of AS, she oversees all aviation accident and incident investigations in the United States and those involving US products or operations overseas. More than 50 air safety investigators and supporting staff within AS report directly to her. She approves information AS releases and routinely briefs Congressional staff and industry stakeholders on behalf of our agency. She began her career in the aircraft manufacturing industry as a mechanical engineer and has experience developing, manufacturing, and conducting failure investigations involving aircraft systems. From there, she rose through the NTSB ranks to her current position. She attributes her success to a continuous learning approach and her interest in improving aviation safety. Because of her critical-thinking skills and ability to lead others, she quickly rose to a leadership position at the agency.

According to Schulze, she did not initially set out to join management, but when the opportunity was offered, she recognized that she could add value and be a good fit. She believes a leader should be able to inspire and motivate others. Through integrity, consistency, and transparency, a leader “can instill a balance of vision and practicality,” she says. She says she has been inspired by thought leaders such as Steven Covey. Transportation has long been a male-dominated industry, and Schulze encourages women to get involved with transportation-related STEM programs that interest them, even those outside their comfort zones.

Sharon Bryson is the NTSB’s deputy managing director. She joined the agency more than 20 years ago after a career providing services to military families at Dover Air Force Base. When she arrived at the NTSB, the agency had just been given the responsibility for family assistance by Congress. Bryson took a lead role in setting up the NTSB’s first family assistance program. This program, now called Transportation Disaster Assistance, is still in place today and has served thousands of families over the years. Later, after serving as director of the Office of Safety Recommendations and Communications, Bryson became the agency’s deputy managing director, a position that involves assisting the Managing Director with managing the day-to-day activities of the agency.

According to Bryson, having the opportunity to mentor others and share what she has learned about leadership is very important to her.  She strives daily to engage with staff members and actively highlights their individual abilities, with the goal of seeing them thrive. “A leader is supposed to support and guide,” she says. By recognizing the strengths and weaknesses of the people around her, she puts value in their diverse opinions; there is no room for judgement or negativity. “When all of these are combined, it creates an environment where people feel engaged and encouraged,” she says.

Shannon Bennett came to the NTSB’s Office of General Counsel in June 2010 before becoming an advisory and special assistant to Board Member Dinh-Zarr in June 2015. She comes from a long military history, having enlisted in 1993 as an Air Force ROTC cadet during college, then serving 11 years on active duty as a judge advocate. She continued to serve in the Air Force Reserve and was assigned as a judge advocate in the Office of The Judge Advocate General at the Pentagon. According to Bennett, when she separated from active duty in 2010, she wanted to find a job where, as in the Air Force, she felt that she was serving her country and making a difference in people’s lives. That’s how she wound up at NTSB.

Leadership is “the art of influencing and directing people to accomplish the mission,” Bennett says, quoting the Air Force Pamphlet on Leadership she received as an ROTC cadet. She tries to live by the adage “saw the log in front of you,” meaning, do your very best in every job that’s given to you no matter how big or small, rather than seek the glory of a job you don’t have. Mentoring is also very important to her, and she encourages all leaders to guide others.

As we celebrate Women’s History Month, let’s all take the time to look around us and celebrate the unique and powerful women in our own lives. We are so grateful to have Dana, Sharon, and Shannon as members of our “Women Dream Team,” as well as all the other female employees at the agency who work daily to improve transportation safety and inspire those around them.

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Thank You

SafetyCompassLogoBy Stephanie D. Shaw

We launched Safety Compass in March 2011 to provide you an inside-out view of the investigative and advocacy efforts we’re engaged in and the important safety issues we’re focused on. As we close out 2017, we want to say “thank you” to you, our readers. Thank you for your interest in the work we do and for sharing our safety messages and recommendations for improving transportation safety.

From teens and sleep to drones, autonomous vehicles to our investigative processes, we’ve given you an inside look at the NTSB and highlighted our comprehensive approach to improving transportation safety across all modes and for all people.

To wrap up the year, here’s a list of some of our most popular blogs of 2017:

Last month, we released data revealing that 2,030 more people died in transportation accidents in 2016 than in 2015. Of those fatalities, 95 percent occurred on the nation’s roadways. Many of those deaths were completely preventable! As we approach 2018, we call on each of you to help us reverse the trend of increasing transportation fatalities, especially on our roadways. Continue to read our blog, see the lessons we’ve learned through our investigations, and share the safety recommendations we’ve made to prevent transportation accidents and crashes, deaths, and injuries.

We encourage you to keep up not only with our blogs, but with other NTSB materials. Sign up to be on our Constant Contact list. Follow us on Facebook (@NTSBgov), Instagram (@NTSBgov), LinkedIn (@NTSB), and Twitter (@NTSB). And in case you missed it, we launched a podcast in 2017, too! Check out Behind-the-Scene @NTSB wherever you get your podcasts. If you’d like to suggest a blog topic, e-mail SafetyAdvocacy@ntsb.gov.

As 2017 comes to an end, we again extend our gratitude to you for working with us to improve transportation safety. We wish you safe travels this holiday season and in 2018.

The Silver Bridge Collapse: Don’t Blame the Mothman!

 

By Don Karol

Rumor has it that, just before the December 15, 1967, collapse of the US Highway 35 Bridge in Point Pleasant, West Virginia, a 7-foot-tall monster with large, piercing red eyes and huge, mothlike wings was seen lurking nearby, warning of the impending catastrophe. This “Mothman” was soon blamed for the tragedy in which 46 people died and 9 were injured. Of the 37 vehicles on the bridge at the time of the collapse, 31 fell with it, many plunging into the Ohio River. Fifty years after the collapse of what was then known as the Silver Bridge, paranormal speculation still swirls around the event, perpetuated by movies (like the Mothman Prophecies), legends, and myths. As a civil engineer, though, I put my trust in the laws of physics, materials science, and the findings of the NTSB investigation completed five decades ago, which proved without a doubt that the Mothman wasn’t to blame.

Silver Bridge, Point Pleasant, West Virginia
Section of Silver Bridge, Point Pleasant, West Virginia, that collapsed on December 15, 1967 (source: Herald-Dispatch)

The Silver Bridge collapse was the first significant highway accident investigation in NTSB history. Working with experts from the Federal Highway Administration, the states of West Virginia and Ohio, and leading engineering consulting firms, we determined conclusively that the cause of the collapse was an eyebar fracture in one of the bridge’s suspension chains. The fracture resulted from stress corrosion and corrosion fatigue that had developed over the bridge’s 40-year lifespan. Not surprisingly, no evidence was ever found connecting the Mothman to the failure.

This catastrophic event prompted national concern about the safety of bridges across the United States. President Lyndon B. Johnson ordered all US bridges to undergo safety inspections. Congressional hearings resulted in mandates requiring the US Department of Transportation to develop and implement National Bridge Inspection Standards. In December 1970, landmark legislation was enacted that established national requirements for bridge inspection and evaluation. One would think that these rigorous new inspection standards would take care of bridge failures forever. Unfortunately, during the past half century, that’s not been the case.

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A 100-foot-long section of the Interstate 95 bridge over the Mianus River in Greenwich, Connecticut, collapsed June 29, 1983 (source: Bob Child, Associated Press)

On June 28, 1983, a 100-foot-long section of Interstate 95 (Mianus River Bridge) collapsed near Greenwich, Connecticut. Two tractor-semitrailers and two passenger vehicles went down with it, resulting in three fatalities and three serious injuries. We determined that corrosion-induced forces led to lateral displacement of the suspension assembly, which went undetected by the state’s bridge inspection and maintenance programs and ultimately led to the collapse.

On April 5, 1987, tragedy struck again when two spans of the New York State Thruway (Interstate 90) fell about 80 feet into the rain-swollen Schoharie Creek. Four passenger cars and one tractor-semitrailer plunged into the creek, and 10 people were killed. We determined that the New York State Thruway Authority failed to maintain adequate support around the bridge piers, leading to severe erosion in the soil beneath the bridge footings. We also determined that the state’s bridge inspection program was inadequate. Not surprisingly, neither the Mothman nor the Loch Ness Monster was seen in advance of this collapse to forewarn of the impending catastrophe.

1987 bridge collapse near Amsterdam, New York
Divers search for victims in the Schoharie Creek after the New York State Thruway bridge collapsed near Amsterdam, New York, on April 5, 1987 (source: Fred McKinney, Times Union)

Other notable bridge failures we investigated in the late 1980s involved localized flooding and water scouring. One collapse occurred on April 1, 1989, near Covington, Tennessee, when two columns supporting three bridge spans collapsed, sending an 85‑foot section of the US Route 51 bridge 20 feet into the Hatchie River. Five vehicles fell with it, killing eight occupants. Again, our investigation identified deficiencies in the state authority’s bridge oversight. In response to our investigations of these events, additional requirements were developed for periodic underwater inspection of bridges.

Probably the most memorable bridge collapse we investigated occurred 10 years ago in Minneapolis, Minnesota, when a catastrophic failure occurred in the main span of the deck truss in the Interstate 35W highway bridge. As a result, 1,000 feet of the deck truss collapsed during rush hour, with about 456 feet of the main span falling into the river. A total of 111 vehicles were on the portion of the bridge that collapsed; 13 people died and 145 were injured. We determined that a design error in the gusset plates compromised the bridge’s load capacity, causing it to fail under substantial weight increases. Our investigation prompted the development of additional bridge quality assurance and improved bridge inspection requirements.

2007 bridge collapse in Minneapolis, Minnesota
Interstate 35W bridge over the Mississippi River collapsed in Minneapolis, Minnesota, on August 1, 2007 (source: Peter Matthews, Polaris)

On December 15, as we mark the 50th anniversary of the Silver Bridge collapse, let’s focus on the infrastructure improvements we need still need to make five decades later rather than try to place the blame on mythical creatures like the Mothman. Throughout the NTSB’s history, we have investigated catastrophic bridge collapses with one goal in mind: preventing future tragedies. Despite efforts to continually enhance the quality of bridge inspections, unforeseen disasters continue to occur, highlighting the need to thoroughly inspect and replace bridges before they collapse. Supernatural forces do not bring down bridges; neglect does.

 

Don Karol is a Senior Highway Accident Investigator and National Resource Specialist in the NTSB Office of Highway Safety.