ARMCO was instrumental in working with Department of Transportation to show the corrosion resistance and strength it possesses are very beneficial to bridges, extending the longevity of the bridge.
Primarily used for pin and hanger type construction, it has also been used for slide plates on older style construction and repairs.
Pin and hanger construction has been used in Michigan, Indiana, Illinois, and Missouri.
By Federal Highway Administration - Link
The pin and hanger are usually NITRONIC 60. Self mated the material requires no lubrication and does not require painting, further reducing maintenance over the life.
As a critical assembly, NITRONIC 60 must be ultrasonically tested as well as Charpy V-Notch tested to ensure impact resistance and toughness.
CVN results are typically taken at sub zero temperatures, basically a cryogenic level - in order to get a valid test result. The material does not produce a result at room temperature.
Slide plates help the bridge absorb the expansion and contraction of the structure during summer and winter months.