Investigators say the soil composition and fluctuating water table probably caused the corrosion. The rest of the Leo Frigo (I-43) Bridge appears solid.
Engineers say the pilings for Pier 22 buckled last month, causing a portion of the bridge to sag two feet.
The bridge has been closed ever since and will remain closed until the DOT orchestrates the necessary repairs.
Experts examined the bridge's other support piers and say most are in the same condition as when installed 33 years ago. The bridge deck is also reported to be in good shape.