This educational application supplements, but does not replace, the official AASHTO LRFD Bridge Design Specifications, applicable state DOT manuals, project specifications, and professional engineering judgment.
Failure Library
Real bridges. Real consequences.
Every AASHTO provision has a history — usually a costly one. These case studies ground the design equations in the mechanisms they prevent. Sources cited are NTSB, FHWA, and peer-reviewed forensic engineering literature. Loss of life is treated with respect; technical lessons are the focus.
Francis Scott Key Bridge (I-695, Baltimore, MD)
26 March 2024
Continuous steel through-truss with cantilevered main span
Cause: Container vessel Dali struck a non-redundant main-span pier, causing progressive collapse of the truss.
Design lesson: Vessel-collision energy on aging non-redundant piers can vastly exceed the 1977-era design envelope. Motivates re-evaluation under current AASHTO §3.14 (Vessel Collision) for major waterway crossings.
I-35W Mississippi River Bridge (Minneapolis, MN)
1 August 2007
Steel-deck-truss main span
Cause: Undersized gusset plates (U10) yielded under combined dead load, live load, and construction stockpiles.
Design lesson: Non-load-path-redundant connections require independent capacity checks — original design errors compounded by decades of added deck weight and inspection blind spots.
Silver Bridge (Point Pleasant, WV — Kanawha River)
15 December 1967
Eyebar-chain suspension
Cause: Stress corrosion cracking of a single non-redundant eyebar caused instantaneous collapse.
Design lesson: Non-redundant, fracture-critical members demand elevated inspection and material toughness. Codified in AASHTO fracture-control provisions.
Schoharie Creek Bridge (I-90, NY)
5 April 1987
Simple-span steel plate girders on RC piers
Cause: Local scour undermined a spread-footing pier during flood; pier tipped and the span dropped.
Design lesson: Scour is a foundation limit state — extreme-flood combinations must design foundations to Q_500 with countermeasures.
Tacoma Narrows Bridge (WA)
7 November 1940
Long-span suspension
Cause: Aeroelastic (torsional flutter) instability at moderate wind speed.
Design lesson: Wind is not just a static load. Long-span bridges require aeroelastic analysis and often wind-tunnel testing.
FIU Pedestrian Bridge (Miami, FL)
15 March 2018
Post-tensioned concrete truss (accelerated bridge construction)
Cause: Design errors at Node 11/12, plus retensioning under live traffic during construction, caused shear failure.
Design lesson: Construction-stage load paths differ from final ones. Peer review, error-checking culture, and stopping traffic during retensioning are non-negotiable.