The diamond at Thomaston is a High Speed / Low Speed type. On the NS side, the rails are normal, there are no breaks in the rail and is considered the high speed side. On the CKIN side, the flanges of the cars ride up and over the NS rails. In this picture, you can see the gap under the wheel of the hopper. This design is popular where high speed railroads cross slow speed railroads. Maintenance costs are much, much cheaper on this setup.