Corrosion is the gradual destruction of material, usually metals, by chemical reaction with its environment. Given sufficient time, oxygen and moisture, any iron mass will eventually convert entirely to rust and disintegrate. The new Bay Bridge East Span is no different than any other bridge — corrosion is a culprit that tries to sneak aboard as soon as bridge construction begins. This is the third in a trilogy of reports on constructability challenges with the New East Span. Caltrans Spokesman Bart Ney calls it "The War on Corrosion."