Forensic Engineering Project tacoma narrows bridge.docx

Forensic Engineering Project tacoma narrows bridge

1. Forensic Engineering Project:
Tacoma Narrows Bridge (1940)
Haskell Jones
Student Number: 0673546-1
Mechanics of Materials
Dr. Justin Vander Werff
Course number: EGR-212
February 26, 2025

2. Figure 1. Tacoma Narrows Bridge. Failure of the Bridge. A Reprint of the original Reports. 002
Section B, Texas Engineering Experiment Station, 1944, oclc.org, Tacoma, Washington

4. Bibliography
Kawada, Tadaki. History of the Modern Suspension Bridge : Solving the Dilemma
between Economy and Stiffness. Edited by Richard Scott. Translated by Harukazu
Ohashi. Reston, Va.: American Society of Civil Engineers (ASCE Press), 2010.
-I think this resource will provide a good source for an intro of this paper. I
like that because this will be the source with the most reading, I will be able
to have a physical copy from the library. This will provide an overview of the
general subject and a brief intro into the specifics of the Tacoma Narrows
Bridge
“Simple Harmonic Motion.” 2014. In 50 Physics Ideas You Really Need to Know, by
Joanne Baker, 1st ed. Quercus.
https://search.credoreference.com/articles/Qm9va0FydGljbGU6Mzk1ODUyNg==?
aid=238521.
-This will make a good resource for explaining the generals of the physics of
how it collapsed to lay a baseline which I can build off of with specific
Tacoma data.
Mould, Steve. 2017. “A Better Description of Resonance.” YouTube Video. YouTube.
https://www.youtube.com/watch?v=dihQuwrf9yQ.
-This video will provide for a wonderful resource not only for myself to be
able to understand the previous source better but Steve Mould will also give
examples that make understanding the process of resonance easier in
general. I think this will give a good way to implement some amount of
layman’s terms into my analysis.
Gunns, Albert F. “The First Tacoma Narrows Bridge: A Brief History of Galloping
Gertie.” The Pacific Northwest Quarterly 72, no. 4 (1981): 162–69.
http://www.jstor.org/stable/40490791.

5. -Once I have established all the general understanding and fundamentals I
can elaborate into the initial intro of the bridge delving into the history and
potentially inspirations.
Petroski, Henry. “Engineering: Tacoma Narrows Bridges.” American Scientist 97, no.
2 (2009): 103–7. http://www.jstor.org/stable/27859292.
-Once the history is laid, I can now use this to get more into the actual
engineering design of the bridge. How it was meant to be designed and the
start to tie everything together into what made it ultimately fail.
Don Olson, Joseph Hook, Russell Doescher, Steven Wolf; The Tacoma Narrows
Bridge Collapse on Film and Video. Phys. Teach. 1 November 2015; 53 (8): 461–465.
https://doi.org/10.1119/1.4933145
-This resource has good diagrams and visuals of what happened, lending aid
to the rest of this paper all throughout.
British Pathé. 2013. “Tacoma Bridge Collapse: The Wobbliest Bridge in the World?
(1940) | British Pathé.” YouTube. https://www.youtube.com/watch?
v=XggxeuFDaDU.
-This is then a general good resource for me to be able to explain more of the
visuals of the actual collapse. Being able to see the disaster on film helps to
understand and let everything else fall into place
“Tacoma Narrows Bridge History - Bridge - Lessons from Failure.” Washington
State Department of Transportation. Accessed March 23, 2025.
https://wsdot.wa.gov/tnbhistory/bridges-failure.htm
-I like this source a lot because it presents all the points in very digestible
ways. Reading through this has helped me be a lot more confident in the
overall chain of events and general reasons.

6. Primary Information
Ai and Wikipedia research
I am an engineering student doing a project to understand how engineers
determined the causes of failure for the Tacoma Narrows Bridge that caused the
Bridge collapse in (1940). Can you please provide me information on how the
failure occurred
The collapse of the original Tacoma Narrows Bridge on November 7, 1940, was a
pivotal event in engineering history, driven by aerodynamic instability and design
flaws. Engineers determined the failure that occurred through a combination of
structural weaknesses, wind interactions, and aeroelastic flutter, as detailed below:
Structural Design Flaws
The bridge’s design prioritized slenderness and cost efficiency over aerodynamic
stability
Extreme flexibility: The deck was shallow (8 feet tall) relative to its 2,800-
foot span, creating a 1:350 depth-to-span ratio. This made it highly
susceptible to vertical and torsional motion
Solid plate girders: Unlike traditional open trusses, the bridge’s H-shaped
girders blocked wind flow, forcing air to move above and below the deck.
This caused flow separation and vortex shedding
Narrow roadway: At 39 feet wide, the bridge had an unprecedented 1:72
width-to-span ratio, reducing torsional rigidity
Aerodynamic Factors
Wind-induced oscillations escalated due to two key phenomena:
1.Kármán vortex shedding: Wind passing around the solid girders created
alternating vortices at a frequency proportional to wind speed f
s
=(U∗S)/D
2. Aeroelastic flutter: Moderate winds (~35–42 mph) excited a self-reinforcing
torsional oscillation. Unlike resonance, this instability grew unbounded due
to negative damping
Event Sequence Impact
Vertical "galloping" (July–Nov 1940)Mild oscillations (up to 5 feet) observed
during construction and use
Cable band slippage (Nov 7) Shifted motion to twisting mode (14
cycles/min), overloading cables
Torsional failure (~11:00 AM) Shifted motion to twisting mode (14
cycles/min), overloading cables

7. Investigation and Lessons Learned
Post-collapse studies by engineers like F.B. Farquharson and the Federal Works
Agency identified critical oversights
Wind tunnel testing: A 1:200 scale model revealed the bridge’s
susceptibility to flutter
Design revisions: Later bridges incorporated:
oOpen trusses for wind passage
oStiffening girders and dampers
oIncreased dead load for stability
The collapse debunked the initial resonance theory, emphasizing instead
aerodynamic instability and torsional flexibility
. This led to modern standards prioritizing wind-tunnel testing and aeroelastic
analysis in suspension bridge design
The failure underscored the importance of balancing aesthetics with aerodynamic
engineering, transforming suspension bridge design practices worldwide
[AI SOURCES]
1.https://www.thinkreliability.com/case_studies/tacoma-narrows-bridge-collapse/
2.https://wsdot.wa.gov/tnbhistory/bridges-failure.htm
3.https://www.thestructuralengineer.info/education/bridge-management/bridge-design/an-engineering-
point-of-view-for-the-tacoma-narrows-bridge-collapse
4.https://www.simscale.com/blog/tacoma-narrows-bridge-collapse/
5.https://www.ebsco.com/research-starters/history/tacoma-narrows-bridge-collapses
6.https://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)
7.https://endaq.com/pages/tacoma-narrows-bridge-failure
8.https://sheqnetwork.com/2024/11/27/the-tacoma-narrows-bridge-collapse-a-lesson-in-engineering-
accountability-and-how-contractor-software-can-help/

8. Can you elaborate further on how they figured how the fault occurred and what
they changed to make it work better the next go around
The investigation into the Tacoma Narrows Bridge collapse and subsequent
engineering improvements involved rigorous analysis and innovative design
changes. Here’s how engineers determined the cause and adapted future designs:
Investigation Methods
1.Wind Tunnel Testing
A 1:200 scale model was tested in wind tunnels, revealing the bridge’s
susceptibility to aeroelastic flutter (a self-reinforcing oscillation) rather
than simple resonance
This disproved the initial Kármán vortex shedding hypothesis.
Federal Works Agency Commission
A team including Othmar Ammann and Theodore von Kármán identified:
Excessive flexibility from the shallow, narrow deck (8 ft tall, 39 ft wide)
Torsional instability triggered by a slipped cable band, which unbalanced the main
cables and transferred stress to the thin girders
Negative damping: Wind energy fed into the bridge’s motion instead of
dissipating
Visual and Instrumental Data
Professor F.B. Farquharson’s footage of the collapse and strain measurements
confirmed the transition from vertical "galloping" to fatal torsional twisting at 14
cycles/minute
Key Design Changes in the 1950 Replacement
To address aerodynamic and structural flaws, engineers implemented:
Feature 1940 Bridge 1950 Bridge Purpose
Stiffening SystemSolid Plate GirdersOpen Trusses
(Wind-Permeable)
Reduced wind
resistance and
vortex shedding
Torsional Rigidity1:350 depth-to-
span
Deeper, wider
trusses
Increased stiffness
to resist twisting
Damping
Mechanisms
None Hydraulic shock
absorbers
Mitigated
oscillation
amplitudes
Cable Anchoring Weak cable bands
Reinforced bands
Prevented
slippage and
imbalance

9. Dead Load Lightweight Increased weight
(60% heavier)
Enhanced natural
damping
Long-Term Engineering Lessons
1.Aerodynamic Prioritization
Wind tunnel testing became mandatory for suspension bridges, focusing on
flutter resistance and dynamic stability
2.Material and Structural Advances
Open trusses replaced solid girders to allow wind passage
Orthotropic steel decks (as seen in the 2007 twin bridge) improved load
distribution and fatigue resistance.
3.Dynamic Modeling
Modern designs use computational fluid dynamics (CFD) and finite element
analysis (FEA) to simulate wind-structure interactions
The collapse transformed suspension bridge design, shifting focus from static
strength to dynamic aerodynamics. The 1950 replacement—and later bridges like
the 2007 Tacoma Narrows span—demonstrated the effectiveness of these
changes, remaining stable despite similar wind conditions
[AI SOURCES]
1.https://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)
2.https://www.thestructuralengineer.info/education/bridge-management/bridge-design/an-engineering-
point-of-view-for-the-tacoma-narrows-bridge-collapse
3.https://www.simscale.com/blog/tacoma-narrows-bridge-collapse/
4.https://endaq.com/pages/tacoma-narrows-bridge-failure
5.https://www.rjpn.org/jetnr/papers/JETNR2401005.pdf
6.https://wsdot.wa.gov/tnbhistory/bridges-failure.htm
7.https://www.wsdot.wa.gov/TNBHistory/bridges-aftermath.htm
8.https://www.thinkreliability.com/case_studies/tacoma-narrows-bridge-collapse/

10. 9.https://www.aisc.org/globalassets/nsba/conference-proceedings/2005/viola---2005-wsbs-final.pdf
Is there anything else you can give me as to historical similarities and other similar
bridges that either struggles from the same problems or were designed with this
bridge in mind to preemptively correct
The Tacoma Narrows Bridge collapse reshaped suspension bridge engineering,
revealing historical precedents and influencing future designs. Below are key
examples of bridges with similar aerodynamic challenges and those designed to
avoid them:
Historical Precedents (Pre-1940)
Several 19th-century bridges faced wind-related failures due to inadequate
aerodynamic understanding:
1.Brighton Chain Pier (1836): Collapsed from torsional oscillations during a
storm, foreshadowing Tacoma’s twisting failure
2.Niagara-Clifton Suspension Bridge (1889): Required extensive stiffening
due to vertical oscillations, later replaced by an arch design
3.Dryburgh Abbey Bridge (1818): Destroyed by vortex-induced vibrations, a
phenomenon later studied in Tacoma’s context
These cases were largely forgotten until J.K. Finch’s 1941 review highlighted their
relevance to the Tacoma failure
Post-Tacoma Bridges Incorporating Lessons Learned
Bridge Key Design
Improvements
Aerodynamic Strategy
Aerodynamic Strategy Streamlined box girderReduced drag and vortex
shedding
Akashi Kaikyō (1998) Triple-hinged stiffening
girder
Wind tunnel-tested for
flutter resistance
Great Belt (1998) Open truss with central
gap
Split deck to disrupt wind
flow
Millau Viaduct (2004) Aerodynamic, wing-
shaped deck
Minimized wind uplift via
CFD analysis
These designs prioritized stiffening trusses, wind-permeable structures, and
advanced testing to avoid Tacoma’s fate
Retrofitted Bridges

11. Golden Gate Bridge (1937): Added lateral bracing and vertical stiffeners in
the 1950s to dampen oscillations
Bronx-Whitestone Bridge (1939): Replaced solid plate girders with open
trusses post-Tacoma to reduce wind resistance
Tacoma Narrows (1950): Used deeper trusses (33 ft tall vs. 8 ft), 60% heavier
deck, and hydraulic dampers
Modern Approaches to Flutter Mitigation
1.Dynamic Dampers
oStonecutters Bridge (2009): Tuned mass dampers counteract
torsional motion
oMessina Strait Proposal: Active aerodynamic appendages adjust in
real time to wind.
2. Computational Modeling
CFD and FEA simulate wind interactions pre-construction, as seen in the
Øresund Bridge (2000)
3. Material Innovations
Carbon fiber-reinforced decks (e.g., Izmit Bay Bridge) reduce weight while
maintaining stiffness
The Tacoma collapse transformed bridge engineering from static strength
calculations to dynamic aerodynamics. Its legacy persists in mandatory wind
tunnel testing, open truss designs, and advanced flutter suppression systems
[AI SOURCES]
1.https://wsdot.wa.gov/tnbhistory/bridges-failure.htm
2.https://citeseerx.ist.psu.edu/document?
repid=rep1&type=pdf&doi=e55497834648dea18957f7e2cae2ca81b906d732
3.https://ascelibrary.org/doi/10.1061/(ASCE)0733-9445(1999)125:12(1367)
4.https://www.simscale.com/blog/tacoma-narrows-bridge-collapse/
5.https://www.asce.org/about-civil-engineering/history-and-heritage/historic-landmarks/tacoma-narrows-
bridges
6.https://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)

13. Key Information Comparison
Key Information from
Generative AI Wikipedia
What happened as the
failure unfolded over
time
The bridge started
“Galloping”, then the
cables started slipping,
and finally it started to
fail in torsion
The bridge started to
sway side to side, then it
started to break apart at
the center.
What are the identified
technical causes of
failure?
1:350 depth-to-span ratio
This made it highly
susceptible to vertical
and torsional motion
H-shaped girders
This blocked wind flow,
forcing air to move
above and below the
deck
1:72 width-to-span ratio
This reduced torsional
rigidity
The wind was unable to
pass through the girders
This caused a “never-
before-seen twisting
mode” whereby when the
left side of the roadway
went down, the right side
would rise, and vice
versa. This started
“aeroelastic fluttering”
What are the identified
human/system causes of
the failure?
Brighton Chain Pier
(1836)
Niagara-Clifton
Suspension Bridge
(1889)
Dryburgh Abbey Bridge
(1818)
These three bridges
came before the Tacoma
bridge and yet they didn’t
pay attention to the very
similar faults that arose
in them.
There was a huge
problem with the
financing of the bridge
primarily because the
tolls were not predicted
to pay the cost. They also
had massive stiffeners
planned but “eastern
consulting engineers”
petitioned for the bridge
to be built cheaper.
How did engineers (and
others) piece together
the evidence to figure out
what happened and why
The originally simply
hypothesized how it
collapsed but later did
wind tunnel testing on it
Wikipedia doesn’t have
nearly enough on how
they did the
investigating. They briefly

14. it happened? to fully analyze what
happened.
mention a wind tunnel
but primarily it delves
into the theories behind
the collapse.
What are impacts, policy
changes, and lessons
learned from the
incident?
Wind Tunnel Testing is
now mandatory, lattice
truces are now widely
used,
Wind tunnels were made
mandatory, they also
reverted to a much
stronger truss design
There weren’t any discrepancies however, the ai I feel had a more well rounded
selection of information and resources.

15. Figure 2. Cover of the brochure for the Official Opening of the Tacoma Narrows Bridge.
Thomas Neill Bridge Construction Photograph and Ephemera Collection, June 30,
1940, Washington.edu, Tacoma, Washington. Negative Number: UW21679
Figure 3. First Autos Cross Narrows Bridge, Seattle Times, July 2, 1940,
Washington.edu, Tacoma, Washington.
Figure 4. Opening day of the Tacoma Narrows Bridge, PH Coll 290.25, July 1, 1940,
Washington.edu, Tacoma, Washington, Negative Number: UW22310z

16. Figure 5. Film still of the Tacoma Narrows Bridge twisting, Farquharson, November 7,
1940, Washington.edu, Tacoma, Washington, Negative Number: UW21427
Figure 6. Tacoma Narrows Bridge midsection collapsing into the waters of the Tacoma
Narrows, Bashford and Thompson, November 7, 1940, Washington.edu, Tacoma,
Washington, Negative Number: UW21422

17. Figure 7. Underside of the roadway of the Tacoma Narrows Bridge during salvage
operations, Seattle Post Intelligencer, December 1940, Washington.edu, Tacoma,
Washington, Negative Number: PI-20799
Figure 8. Woman standing by the Washington Toll Bridge Authority and No
Trespassing" sign looking at the towers of the Tacoma Narrows Bridge, Seattle Post
Intelligencer, June 1943, Washington.edu, Tacoma, Washington, Negative Number
PI-20812

18. Failure Classification
I believe the primary and secondary classification of the cause of failure
according to McKaig’s list for this event are:
Lapses, or Carelessness
[A contractor or superintendent takes a chance, knowing he is taking it.]
As Wikipedia brought light to, originally there was proposed to be larger
stronger beams but Lean Moisseiff, the consultant engineer for the Golden Gate
Bridge, petitioned for it to be built cheaper. This also has aspects of ignorance as
well seeing as Lean Moisseiff did do tests and calculations predicting that a
slimmer design would work even though it clearly didn’t
Unusual Occurrences
[“extreme” storms]
I put extreme storms in quotes because they were more so moderate. It was
these somewhat higher than normal winds in combination with the previous
carelessness and ignorance that makes it worse. The winds were around 40 mph
which is not unheard of, but it is out of the ordinary.
I believe the primary and secondary classification of the cause of failure
according to Blockey’s list for this event are:
Limit States
[Overload AND Understrength]
Not only was the bridge somewhat overloaded with unexpected wind but
also it was understrength with lack of larger beams for stiffness and torsional
resistance.
Human-Based Errors
[Misunderstanding of Structural Behavior]
There are two factors I see here as an error. The misunderstanding of how
the wind would react to the bridge causing it to gallop and the lack of latticing in
the structure which didn’t allow the wind to flow through the structure.
Failure From a Christian Perspective
I believe that McKaig’s aligns more with how I believe Christians should look
at failure. While yes, the world does have its own fair share of deterioration and
challenges due to the fall, humans have been impacted to a much greater degree.

19. I think McKaig highlights human frailty and fallenness much better. I believe that
sin is the leading cause of failure and that comes in many forms, greed, laziness,
dishonesty, etc. While there are clearly other factors, I think that McKain manages
to get good coverage on the underlying human failures that lead to mechanical
errors. He does this while still allowing for the few possibilities of failure outside of
direct human fault.
Primary Information Compilation 2387
Introduction
November 7
th
, 1940, the Tacoma Narrows Bridge, built only 4 months prior,
collapsed. A culmination of greed, miscalculations, and simply human hubris that
resulted in the fall of the third largest suspension bridge of the age. The design of
the Tacoma Narrows Bridge had originally planned to incorporate 25-foot-tall
trusses to stiffen the roadway but was later petitioned and replaced 8-foot-tall
girders with no lattice. During the construction phase there were already
complaints about its vertical movement which earned the bridge the nickname
“Galloping Girtie”
The bridge opened on July 1
st
and remained operational until November 7
th

there began to be a sway in the bridge. Traffic slowly began to stop as the
oscillations became more severe until the point where the bridge was officially
closed due to the galloping and only one car left stranded on the bridge with a
reporter and his dog. The man was able to make it safely off the bridge on his
hands and knees but it wasn’t long after that the oscillations of the bridge began
to build to extents were the bridge was heard to be cracking, cables were slipping
and tearing and finally, the bridge ultimately failed and crashed into the narrows
bellow leaving the wreckage nearly unsalvageable apart from a few of the concrete
bases.
Methods
Even before the collapse of the bridge, and under normal wind conditions,
the Tacoma Narrows Bridge had some amount of sway to it. This led to the
Washington State Toll Bridge Authority hiring Frederick Farquharson, an
engineering professor at the University of Washington to conduct wind tunnel
experiments on the bridge and find a solution to its instability. The conclusion of
these tests was to either drill holes in the girders to allow for wind to pass through,
or to make the side profile more aerodynamic. The latter of these two options was
chosen but was not able to be implemented because the bridge collapsed only 5

20. days later. However, this wind tunnel practice was the way engineers and
researchers were able to deduce the theories behind the collapse.
Results
The bridge was designed originally to be deeper but one of the engineering
consultants, Lean Moisseiff, a man who was involved in the Golden Gate Bridge
and nearly every other major suspension bridge at the time advocated for a
change. Moisseiff was very set on the aesthetics of the bridge and so he petitioned
for the supports to be spread further apart, the 25-foot-tall trusses to be replaced
with 8-foot-tall solid girders and to make sure the bridge remained 2 lanes with
little to no room for sidewalks. While this did ensure an elegant bridge it also made
it one of the flimsiest ever constructed. Few suspension bridges had a length-to-
width ratio even as high as 47 and most only in the 30s, yet the Tacoma Narrows
bridge had a length-to-width ratio of 72. Not only this but the weight of the
Tacoma Narrows bridge was only 6,000lb/ft whereas comparable bridges were in
excess of 30,000lb/ft. All of these factors are pieced together to create an
incredibly light and exceedingly flexible bridge. Later in wind tunnel testing which
was requested by the insurance companies, it was found that the aerodynamics of
the solid girders were terrible, forcing the wind to go above and below the bridge
causing vortex effects to magnify the more it oscillated until it finally ripped itself
apart.
This failure of a bride did however cause more eyes to look in the direction
of wind tunnel testing prior to construction and it was made regulation that any
bridge must have mandatory wind tunnel trials before construction can
commence. This also brought light to the necessity of truss structures, latices to
allow for the wind to pass through bridges as opposed to around above and below
them. Bridges since the Tacoma Narrows have been constructed with this wind
path in mind.
Discussion
a.The primary cause of this catastrophe was Carelessness. While yes, a bridge
or any construction for that matter should be designed with some amount
of aesthetics in mind, this bridge clearly took it too far. Moisseiff did not take
the proper precautions when modifying the design to account for its original
strength.
The secondary cause of this catastrophe was Ignorance. I believe this
ignorance could have been solved with less carelessness however, it was
unknown how the solid girders would have affected the bridge as much as
they did. It was unknown how such a slender and shallow bridge would
respond to the wind that was inflicted upon it and the knowledge of the

21. importance in wind tunnel testing had not been realized. Although this
ignorance seems to stem from carelessness, I believe they are still separate
enough to keep as different factors.
b.The bridge should either not have been modified from its original design or,
at the very least, had more care put into the redesign. This care should also
have included wind tunnel testing prior to the genesis of construction.
c.The collapse of the Tacoma Narrows Bridge highlight not only mechanical
misunderstandings and missteps but it also exposes human corruption and frailty. As
Proverbs 16:18 says "Pride goes before destruction, a haughty spirit before a fall."
In your "Discussion," The desire to create a magnificent bridge of his own aesthetic
desire caused an oversight into the structural integrity of the overall design. This is in
contrast with what both James 4:17 says "If anyone, then, knows the good they ought to
do and doesn’t do it, it is sin for them." And Colossians 3:23 "Whatever you do, work at
it with all your heart, as working for the Lord, not for human masters." If this project had
been undertaken with an underlying understanding of integrity and human failing, more
precautions and more attention to detail would have taken place. To finish this off, I think
Proverbs 22:3 says it perfectly, "The prudent see danger and take refuge, but the simple
keep going and pay the penalty."
d.If I were in one of the engineers’ shoes I cannot tell if I would even have noticed an error
in the designs. It was a well-respected consultant that petitioned the design change and
I’m not sure I would have given it the much-needed humility to test it as extensively as it
needed. I do believe, however, that if I had been aware of the structural flaws that I would
have voiced my concerns and requested further clarification on the environment and
physics or not been able to sign off.
Kawada, Tadaki. History of the Modern Suspension Bridge : Solving the Dilemma
between Economy and Stiffness. Edited by Richard Scott. Translated by Harukazu
Ohashi. Reston, Va.: American Society of Civil Engineers (ASCE Press), 2010.
“Simple Harmonic Motion.” 2014. In 50 Physics Ideas You Really Need to Know, by
Joanne Baker, 1st ed. Quercus.
https://search.credoreference.com/articles/Qm9va0FydGljbGU6Mzk1ODUyNg==?
aid=238521.
Mould, Steve. 2017. “A Better Description of Resonance.” YouTube Video. YouTube.
https://www.youtube.com/watch?v=dihQuwrf9yQ.
Gunns, Albert F. “The First Tacoma Narrows Bridge: A Brief History of Galloping
Gertie.” The Pacific Northwest Quarterly 72, no. 4 (1981): 162–69.
http://www.jstor.org/stable/40490791.

22. Petroski, Henry. “Engineering: Tacoma Narrows Bridges.” American Scientist 97, no.
2 (2009): 103–7. http://www.jstor.org/stable/27859292.
Don Olson, Joseph Hook, Russell Doescher, Steven Wolf; The Tacoma Narrows
Bridge Collapse on Film and Video. Phys. Teach. 1 November 2015; 53 (8): 461–465.
https://doi.org/10.1119/1.4933145
British Pathé. 2013. “Tacoma Bridge Collapse: The Wobbliest Bridge in the World?
(1940) | British Pathé.” YouTube. https://www.youtube.com/watch?
v=XggxeuFDaDU.
“Tacoma Narrows Bridge History - Bridge - Lessons from Failure.” Washington
State Department of Transportation. Accessed March 23, 2025.
https://wsdot.wa.gov/tnbhistory/bridges-failure.htm