Gusset plates are not glamorous, but like the two-dollar O-ring seals on the space shuttle Challenger, you take them for granted at your peril. When NASA was still a gleam in John Kennedy’s eye, Eisenhower’s Interstate Defence Highway system was pushing its concrete capillaries across America. In 1967 Minnesota completed its contribution to Interstate 35 West (I-35W) with an eight-lane bridge across the river Mississippi in the heart of Minneapolis.
For 40 years it eased the city’s spectacular growth, and it was bumper-to-bumper with rush hour traffic at 18.05 on a hot summer’s evening when stalled drivers heard a screeching cacophony of groans and explosive snapping sounds.
The roadway reared up beneath them, twisting in midair – catapulting the helpless concertina of cars like smashed dominoes into the pillar of dust and debris roiling up from the gaping hole in front. Ribbons of highway hung by a single steel thread, tilted down and sideways into the fast-flowing Mississippi. Chunks of road dropped 35 m (110 ft) perfectly flat to the river banks, like concrete salvers still bearing cars and trucks with their stunned and shaken occupants. But where the three central spans – 330 m (988 ft) of I-35W’s 615 m (1,907 ft) total – crumpled in a mockery of their former geometric confidence, the ugly detritus of steel tresses was woven with human rag dolls, and trickled blood.
The collapse was Minnesota’s worst-ever man-made disaster. It inspired heroism and provoked a blizzard of lawsuits. A 15-month enquiry found that at the very bottom of the well of minor mishaps that had accumulated coincidentally into a disaster were 24 (out of many) gusset plates of the wrong size. They had not been spotted in the original review process, and had therefore been incorporated into I-35W’s design and original construction.
When: August 1 2007
Where: Minneapolis, Minnesota, USA
Death toll: 13 dead and 145 Injured.
You should know: Surprisingly few people were hurt, it seems a pity that with providence on the survivors’ side for once, teams of lawyers are still pursuing class actions in the hope of squeezing someone – anyone – for a few bucks. Even though I-35W was a disastrous accident, lawyers are bent on finding someone to blame.