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OpEdNews Op Eds    H2'ed 9/7/22

The U.S. Bridge-Safety Cover-up - Bridge Collapses Kill People

Message Robert A. Leishear, PhD, PE, ASME Fellow

Unsafe conditions for our U.S. bridges are known, and a cover-up of bridge dangers threatens our lives.

Occasional reports in the press demonstrate a national lack of safety and lack of bridge-structural adequacy - 230,000 U.S. bridges need repair, 46,000 are structurally inadequate (2019, click here). To further endanger bridge performance, those responsible for ensuring bridge safety fight against new technology, and they attempt to conceal that new technology that will reduce bridge dangers. Those who influence the bridge industry even go to the extent of removing published technical information from the press to conceal facts that can prevent bridge collapse. Such a disservice to the engineering community and the pubic resulted in an inaccurate technical report for a near-disastrous Interstate 40 (I-40) bridge failure (Figure 1).

Refusal to address new technology prevents a clear understanding and implementation of appropriate bridge safety measures. Consider the cover-up of new technology first, and bridge failures and technical errors can then be discussed appropriately.

Figure 1: I-40 Bridge Cracked Partially Through a Major Structural Beam
Figure 1: I-40 Bridge Cracked Partially Through a Major Structural Beam
(Image by Arkansas Department of Transportation)
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Figure 1: I-40 Bridge Cracked Nearly Through a Major Structural Beam

Bridge Safety Improvements

In the 1970s, welded-steel bridge construction became prevalent, and new failure issues arose. For example, the 1982 Mianus Bridge collapse killed 3 people and injured 3 others (Figure 2). Even so, inspection and bridge design techniques markedly improved. However, several other major cracks in bridges have also been observed over the past 22 years (click here). The effects of grit blasting on these cracks were not investigated, where this grit blasting technology evolved at a later time.

Figure 2: 1982, Connecticut, Mianus River Bridge Collapse from Combined Corrosion and Fatigue
Figure 2: 1982, Connecticut, Mianus River Bridge Collapse from Combined Corrosion and Fatigue
(Image by Arkansas Department of Transportation)
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Figure 2: 1982, Connecticut, Mianus River Bridge Collapse from Combined Corrosion and Fatigue

New Technology

In a May, 2019 publication, grit blasting was announced to affect piping, bridges, and structures (Click Here). In October 2020. this new theory was shown to significantly decrease the strength of bridges when subjected to multiple loads from traffic (Structure Magazine, R. A. Leishear, click here).

This later article stated that:

"Overlooked as a design problem for decades, grit blasting is the standard process to improve coating adherence to steel surfaces. This process significantly degrades the strength of steel bridges, endangering safe design. In particular, engineers design a bridge, construction and welding are performed, and then construction is inspected and accepted. After acceptance of structural construction, painting staff grit blast steel surfaces and the fatigue limits from cyclic loading that were used in the design are inadvertently altered.

"These new fatigue limits provide lower estimates of the minimum failure stresses required to cause cracks experienced by a bridge due to repeated traffic loads from passing trucks, [where fatigue limits describe how many cycles are required to crack a bridge]. That is, grit blasting impacts high-speed shards of grit into steel to create a jagged steel surface that significantly reduces the fatigue failure limit, and consequently endangers previous and future [bridge] designs.

"Bridge designs - past, present, and future - are in jeopardy unless fatigue strength reductions due to grit blasting are evaluated for bridge safety. Yes, more research is needed and recommended, but the verdict is evident. Grit blasting reduces fatigue strengths of bridges, and this problem must be addressed to ensure bridge safety. The full effects on bridge safety are not yet known, and earlier accident investigations are also called into question since blasted surface finishes were not evaluated during previous investigations. Grit blasting fatigue is a new tool to troubleshoot bridge failures."

Leaders in multiple industries feed us garbage science, and the claims that grit blasting does not affect bridge safety falls directly into the category of garbage science.

Censorship of New Ideas

Structure Magazine censored "Coating Preparations Reduce the Strength of Bridges" by removing this article from their magazine when three members of the American Society of Civil Engineers objected to the content of this article. Per Merriam Webster, censorship is "censorial control exercised repressively censorship that has 'permitted a very limited dispersion of facts'." Three engineers from the American Society of Civil Engineers objected to this work, and the publication was dropped from the Structure magazine website. Such action certainly constitutes censorship.

Representing the American Institute of Steel Construction (AISC), Lloyd, Connor and Frank stated that "The October 2020 Structure article presents information and opinions on potential problems with the fatigue resistance of steel bridges prepared for coatings using grit blast cleaning methods. Some of the information in this article is misleading with unsubstantiated claims regarding the safety of existing and future steel bridges." When these three engineers first objected to my article, I was offered the opportunity to write a rebuttal in Structure Magazine, but that offer was later withdrawn, my article was withdrawn from the Structure Magazine internet, and the Lloyd, et al. article remains on the magazine website. Lloyd of the AISC refused to answer multiple emails that discussed this bridge safety concern. Refusing to accept such censorship, I republished my article through, and other websites have since republished my article as well.

Confronting Censorship and Unsafe Bridge Designs

To further stand against censorship and unsafe practices in the bridge industry, and disprove all claims opined by Lloyd, et al., I published a very detailed accounting of available experimental and theoretical data (Bridge Safety Dangers-Fatigue Cracks, Brittle Failures, and Grit Blasting, March, 2021, click here).

This article stated that:

"Fatigue failures in bridges have been extensively studied for decades, and experimental data was applied [by others] to create fatigue curves to be used for bridge designs, however, new research questions the validity of these curves with respect to safe bridge design...[T]here is a significant threat to bridge safety, while other authors believe that there is no safety threat at all.

"Bridge safety is questionable since bridge design requirements in the form of fatigue curves are [incorrect]. Available results clearly prove that bridge fatigue properties are [significantly] reduced by grit blasting, which in turn reduces the safety of design practices for bridges.

"Moreover, evolving facts prove that the inherent dangers in bridge design practices must be addressed and resolved. Specifically, bridge design curves account for repeated loads on bridges caused by traffic, and further research is mandatory to determine the safety errors inherent in these[fatigue] curves, which are shown to be inadequate by this innovative research, [where such errors may be as much as 57%]. A resistance to new ideas serves as an unacceptable reason to curtail technology that will improve bridge safety."

An Ongoing Government Cover-up of Bridge Dangers

"The Arkansas Department of Transportation (ARDOT) refused to provide [any] I-40 [reference] documents [or reports] to support this research to ensure safety of their citizens. The U.S. DOT Federal Highway Administration [FHWA] safeguards our bridges, but they [also] refuse to act [on this new information] to stop dangerous cracks in bridges (Preventable Disasters--The Fight for New Ideas, Never Give an Inch, June 2021, click here."

Specifically, I responded to ARDOT in May 2021 that "I find it difficult to understand when public officials stand in the way of advancing technology, which will promote the health and welfare of U.S. citizens. I have spent years performing volunteer research to this end. Although I cannot expect others to share the same compassion, I am disappointed that public safety is thwarted by others. With respect to the I-40 Bridge near-collapse [of a Mississippi River bridge that connects Tennessee to Arkansas], my interest is to prevent future accidents on this bridge and other bridges throughout the U.S. The I-40 Bridge crack could have killed many people. Yes, the law covers the denial of my [information] request, but law and ethics are not always the same." ARDOT did not respond.

Also, the FHWA did not respond to May 2021 emails, which included a draft of Bridge Safety Dangers-Fatigue Cracks, Brittle Failures, and Grit Blasting (click here). Titled, "FHWA Policies Kill People", those emails stated that:

"The attached paper cites the failure of the Secretary of Transportation to respond to this important safety concern about the I-40 bridge failure and the implications of this failure to bridge safety throughout the U.S. This paper has been published". [T]here [may be other future cracks] in the I-40 bridge. [I]mpending bridge [cracks] and other [bridge cracks] can be stopped. You have the opportunity to stop fatalities". "Comments are welcome".

With respect to the I-40 Bridge cracks, a draft of "Bridge Safety Danger--Fatigue Cracks, Brittle Failures, and Grit Blasting" was forwarded to the ARDOT in May 2021, during the I-40 Bridge investigation, and a response was not received. There is also no mention of grit blasting fatigue effects in a final I-40 investigation report.

Figure 3: I-40 Primary Crack Surface
Figure 3: I-40 Primary Crack Surface
(Image by Arkansas Department of Transportation)
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Figure 3: I-40 Primary Crack Surface

Figure 4: Initial Weld Crack
Figure 4: Initial Weld Crack
(Image by Arkansas Department of Transportation)
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Figure 4: Initial Weld Crack

I-40 Bridge Investigation Report for Fractures

Multiple fractures occurred in a 32-inch-high by 26-inch-wide beam of the I-40 Bridge over several years, and an extensive investigation was performed (I-40 Hernando deSoto Bridge, Fracture Investigation, Santuosso, et al., October 2021, Click Here). Although there is large amount of important information in this report, I disagree with one important report opinion.

The authors claimed that the first crack suddenly ripped through the 1-3/8-inch-thick side-plate steel prior to traffic loads near a repair weld, which was welded during initial fabrication. Their evidence to support this claim was that classic crack patterns were not observed on the crack surfaces, and that the direction of the crack was consistent with residual tensile stresses caused by hydrogen in the cracked weld.

I-40 Bridge Fatigue Cracks

From the drawings provided in their report, and the installation of the beam, the crack direction is perpendicular to the tensile stresses in the beam as well. That is, stresses from both the weight of the bridge and traffic were consistent with fatigue cracking of the weld, where in-service tensile stresses and any residual weld stresses tended to pull the weld apart.

In several decades of my troubleshooting experience with machinery and piping fatigue failures, specific fatigue-crack patterns occur only when the crack opens and closes in a single direction, as if opening at a hinge, which is typical of laboratory fatigue tests and some in-service cracks. When fatigue cracks open in three dimensions, the crack surfaces are damaged from abrasion between mating surfaces, and the crack patterns are damaged to leave a surface that looks like broken chalk (Figure 3).

Santuosso, et al., concluded that there was no evidence of fatigue-crack growth on the this initial primary crack, but they also noted that there was evidence of at least one previously arrested crack tip, which is, in fact, conclusive evidence of fatigue cycling on the weld surface. Given that fatigue evidence was provided in their report, I conclude that fatigue cracking occurred.

I-40 Bridge Fatigue Crack Formation and Grit Blasting

In light of this different interpretation of crack formation, grit blasting becomes a central concern, or driving force, for the series of cracks in the I-40 Bridge. The crack started at grit blasting defects, grew near the weld of Figure 4, and resulted in other cracks in the bridge.

Even so, Santosuosso, et al., noted that hydrogen embrittlement from welding was important to this fracture, and their case is convincing even though not experimentally proven. I therefore agree that hydrogen embrittlement near the weld was a probable secondary factor to the initial grit blasting-induced crack that ultimately started all of the other connected I-40 Bridge cracks.

Santosuosso, et al., did not mention grit blasting effects, and even though Structure Magazine and ARDOT thwarted the use of grit blasting research for bridge failure analysis, grit blasting-fatigue research was published before their accident investigation results were published. Whether or not Santosuosso, et al., were aware of new research is uncertain, but a literature review to become aware of new information was still a reasonable expectation.

Bridge Collapse Dangers

In short, grit blasting initiated beam cracks in the I-40 Bridge, and the potential for such cracks to collapse other bridges is unknown. Inadequate bridge failure investigations and inadequate bridge design information endangers the lives of people using our bridges. Granted, there are few major bridge catastrophes since inspections usually detect cracks before bridge failures, but the I-40 Bridge crack grew larger year by year. While inspections recorded the crack with photos, the cracks went unnoticed for several years, and that bridge was in danger.

I think that the biggest problem for this bridge danger is that all bridges are grit blasted prior to coating, or painting, and the potential scope of this industry-wide danger is overwhelming. Designs of in-service bridges may be inadequate, previous failure analyses may be incorrect, and current grit blasting practices may be unacceptable. The extent of bridge dangers is unknown.

I do not have an exact solution to stop grit blasting cracks in bridges, but combinations of sharp grit and rounded shot will improve fatigue performance, while providing some level of coating adherence. Further research is required, but such efforts are presently stifled by leaders in the bridge industry.

As long as grit blasting is ignored by the bridge industry, the danger will not be fixed - just blame bridge cracks on something else to avoid responsibility and avoid expensive actions to stop cracks. Bridge cracks endanger our lives, and such a danger should not be ignored, where ignoring myriad bridge cracks is the current approach to such cracks.

Addendum: The AISC Stands Against Technology That Prevents Bridge Failures

The American Institute of Steel Construction stands in the way of this new technology to prevent bridge cracks due to grit blasting. The AISC may claim that "For more than 100 years, the American Institute of Steel Construction has advanced the use of structural steel in buildings and bridges through the development of advanced technical specifications, research, and educational programs". However, AISC actions indicate otherwise.

As discussed here, the AISC influenced censorship of this bridge safety research in Structure Magazine, and the AISC still thwarts technology by refusing to address this important bridge safety danger. Specifically, the AISC, Structure Magazine, the ARDOT, the FHWA, and the contractors who wrote the I-40 Fracture Analysis Report refused to answer the following email.

"OpEd News Article: The U.S. Bridge-Safety Cover-up - Bridge Collapses Kill People

An article discussing the I-40, Mississippi River bridge fracture was released to the internet (Click Here). I strongly disagree with some of the results in an I-40 Hernando deSoto Bridge, Fracture Investigation, where a cover-up by industry leaders affected results. Grit blasting induced fatigue cracks, which in turn developed into major cracks in the bridge beams. Comments are welcome".

There is an opportunity here to make bridges safer, but those who have that authority act with indifference, i.e., per Merriam-Webster - unconcerned, incurious, aloof, detached, or disinterested. Although this article may be abrasive to AISC staff and accident investigators, my primary goal is to make bridges safer, and this goal should be an AISC goal as well. A comprehensive investigation of grit blasting effects and preventive actions for fatigue failures will prevent bridge cracks.

(Article changed on Sep 08, 2022 at 5:47 PM EDT)

(Article changed on Sep 09, 2022 at 3:32 AM EDT)

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Robert A. Leishear, PhD, PE, ASME Fellow Social Media Pages: Facebook page url on login Profile not filled in       Twitter page url on login Profile not filled in       Linkedin page url on login Profile not filled in       Instagram page url on login Profile not filled in

Robert A. Leishear, PhD, P.E., PMP, ASME Fellow, NACE Senior Corrosion Technologist, NACE Senior Internal Piping Corrosion Technologist, AMPP Certified Protective Coatings Inspector, NACE Cathodic Protection Tester, Structural Steel Worker, (more...)

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