@jacqueslees: Rail Anti-Creeper (Rail Anchor) When trains are running, longitudinal forces are frequently generated acting on the rails, causing the rails to move longitudinally, and sometimes even carrying the sleepers along with them. This longitudinal movement is called rail creep (creep). Creep generally occurs on the main (running) lines in the sections of double-track railways, in the loaded (heavy-haul) direction of single-track railways, on down gradients, and within the braking zones on approach to stations.