Lessons from a Gusset Plate

You probably don't know what a gusset plate is. I sure didn't. But the little-known structural component offer a case study in the unlearned lessons of the I-35W bridge collapse. Gusset plates bind trusses and girders together. The complete report won't be out until the end of the year, but early findings [1] suggested that corroded gusset plates lead to the bridge's collapse. This isn't a new problem. The Minneapolis Star-Tribune reports [2]that 12 years ago an Ohio bridge buckled and nearly collapsed. The cause?

Investigators determined what was then a unique cause for the failure: Undersized and corroded gusset plates that were too thin to withstand an unusual load of construction vehicles and heavy equipment parked on the bridge that day.

The ever-useful Star Tribune reports [3] that officials just imposed heavy weight restrictions on a South Dakota bridge. The cause? You guessed it, corroded gusset plates. And last week, two lanes of (another) Minnesota bridge were shut down. Once again, corroded gusset plates.

We are lucky to have caught the problems. But luck runs out. A quarter [4]of our bridges are structurally deficient or functionally obsolete. According to the American Society of Civil Engineers [5], it will take 9.4 billion dollars a year for 20 years to fix our bridges.

But we shouldn't blame the gusset plates. Structural components rust and decay. The real blame belongs elsewhere. Permit a quick detour.

To limit state spending, some conservatives have argued, you have to cut off the money. Starve the beast and the beast can't do much. Ronald Reagan, in a presidential debate [6] way back in 1980, put it well:

"Well, if you've got a kid that's extravagant, you can lecture him all you want to about his extravagance. Or you can cut his allowance and achieve the same end much quicker."

Cut taxes and you can limit government expenditure. But it turns out that the state funded some important things. Bridges, for one. Now after all of these years of starvation, the signs are showing....

(If the whole gusset buisness is still confusing, the Minneapolis Star-Tribune has a good diagram . [7])

(For an in-depth investigation of the 'starve the beast' tactic, check this out [8][pdf])