Rail End Mismatch Inspection

Both Transport Canada and the FRA require railway joint locations to be inspected in order to measure vertical and horizontal rail end mismatch. Rail end mismatch increases the risk of derailment and can lead to accelerated rates of damage to track infrastructure. As little as 3mm of vertical or horizontal mismatch is considered defective for Class 4 and above tracks.

Horizontal rail end mismatch (gauge mismatch) increases the chance of the wheel flange “picking” the exposed edge of the rail end and causing the wheel to climb and potentially derail.

Vertical rail end mismatch (tread mismatch) creates higher dynamic wheel-rail forces which lead to accelerated wear and, if not corrected, can lead to early failure of track components. The resultant dynamic forces increase as the vehicle speed increases, the vertical mismatch increases, and the ramp length decreases.

Railway track joints can be inspected on-the-fly during a standard geometry inspection or as part of a dedicated joint linearity inspection track geometry trolley reporting includes a picture of the joint, key track geometry parameters (gauge, cant, surface and alignment) across the joint surface as well as precise vertical mismatch and horizontal mismatch to a fraction of a millimeter.