SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/eng-tacoma-dynamic-wind

What central lesson did the first Tacoma Narrows Bridge failure teach designers?

Aeroelastic flutter let wind forces and deck motion feed each other, producing growing torsional oscillations.

Start playing free

  1. Its steel was too weak for traffic loads
  2. Aeroelastic flutter can amplify torsional motion ✔
  3. Wind matters only for tall towers

Why: Wind changed the deck's motion, and deck motion changed the aerodynamic forces. This feedback amplified torsional oscillation and pushed bridge engineers toward wind-tunnel testing, torsional stiffness, and damping.

Huh, didn't know that: On 7 November 1940, in winds near 42 mph, the deck switched from vertical waves to twisting, with the middle of the main span staying still.

The dad joke
The bridge engineer tested every angle, especially the aerodynamic ones.
Like this card?
Play the game

References

Answer: Aeroelastic flutter can amplify torsional motion. Wind changed the deck's motion, and deck motion changed the aerodynamic forces. This feedback amplified torsional oscillation and pushed bridge engineers toward wind-tunnel testing, torsional stiffness, and damping.

  1. Library of Congress Historic American Engineering Record: Tacoma Narrows Bridge tile.loc.gov/storage-services/master/pnp/habshaer/wa/wa0400/wa0453/data/wa0453data.pdf
    combined with the flutter and resonance already present in the deck produced the violent oscillations
    Checked 2026-10-10.

Think this answer is wrong? Tap "Challenge this answer" on the card in the game and tell us why.

Test yourself in the game

EngineeringHow many base units does the International System of Units (SI) have?EngineeringSince the SI redefinition voted in 2018, what defines the kilogram?EngineeringIn today's SI, how precisely is the value of the Planck constant known?

That's stuff everyone should know.