These ex-Clinchfield flatcars were converted into icebreaker cars in 1984 by the Seaboard Railroad, and they later made their way to CSX. To prevent impact damage to revenue railcars and lading, these cars featured large vertical steel frames to physically clear icicles from the inside of tunnels and low bridges. The phenomenon is more prevalent during spring and fall, when freeze/thaw cycles allow for the formation of large and damaging icicles.