Expansion joint systems are integrated, yet oen overlooked, components designed to accommodate repeated cycles of movement. Properly functioning bridge expansion joint systems accommodate these movements without imposing signicant secondary stresses on the superstructure. Sealed expansion joint systems also provide barriers preventing runo water and deicing chemicals from passing through the joint onto bearing and substructure elements below the bridge deck. Water and deicing chemicals have a detrimental impact on overall structural performance by accelerating degradation of bridge deck, bearing, and substructure elements. In extreme cases, this degradation has resulted in premature, catastrophic structural failure. In fullling their functions, expansion joints must provide a reasonably smooth ride for motorists.