sentence: Double-decked ( or double-decker ) bridges have two levels , such as the George Washington Bridge , connecting New York City to Bergen County , New Jersey , USA , as the world 's busiest bridge , carrying 102 million vehicles annually ; truss work between the roadway levels provided stiffness to the roadways and reduced movement of the upper level when the lower level was installed three decades after the upper level .
question: how did something move _ _ _ ?
answers: reduced movement