A traveling step structure is mounted to a warehouse rack to allow convenient access to elevated shelves without blocking shelving corridors. A rack track is mounted to a rack between vertical rack members and a support track is fixed to the surface which supports the rack. The traveling step structure has a first frame mounted with followers to the rack track, and a second frame positioned outwardly from the first frame, and connected to the first frame for movement from a retracted position to an extended position. A plurality of steps extend between the first frame and the second frame and are pivotably mounted to both frames. When a user desires to access an elevated rack shelf, the second frame is pulled outwardly and downwardly to bring the steps into a horizontal position. A damper assembly is mounted between the first frame and a step to cushion extension.