It's awfully easy to blame a deceased bridge designer for the collapse of the Interstate 35W bridge, but I'm not buying it.
It stood for 40 years, under increasingly heavy loads, and didn't collapse until it started to corrode.
This still seems like a maintenance issue because the Minnesota Department of Transportation (MnDOT) should have looked into the strength of the gusset plates once they knew they were corroding.
With the gusset plates corroding, you would assume they would do the calculations on how much thickness was need to support the load vs. how much thickness remained on the plate. Was this vital step missed?
ROBERT HAUPERT, ZIMMERMAN, MINN.
Are the gusset plates really to blame? I read the gusset plates were a half-inch too thin. Were they too thin for the loads the original design was expected to carry? The bridge lasted how many years?
I would argue added weight, construction equipment and of course corrosion caused the failure and the gusset plates were the weakest link. Maybe MnDOT should have recalculated the loads and the condition of the plates during the inspection process.
When I change a design, I verify that my changes do not have any harmful side-effects. Was that process done with the bridge, taking into account all the variables?