A spring steel device clamped to the underside of the rail base so that it rests tightly against the side of a crosstie. It prevents the rail from creeping longitudinally due to the forces of train braking, acceleration, and thermal expansion. Keeping the rail locked in place prevents track buckling and preserves the correct spacing of the ties.
Heard on the job
The track gang is out driving rail anchors to stop the ribbon rail from creeping down the grade.