The wedge plow or Bucker plow was first developed by railroad companies to clear snow in the American West. The wedge plow forces snow to the sides of the tracks and therefore requires a large amount of force due to the compression of snow. The wedge plow is still in use today in combination with the high-maintenance rotary snowplow. Function Three features are required for optimum performance: The plow has a smooth surface so snow will slide over the plow face rather than accumulating to be pushed along as an increasing mass. Wooden plows were carefully constructed of individually fitted boards and painted frequently to maintain a smooth surface. Steel plows can be sprayed with water in sub-freezing temperatures to form a smooth layer of ice on the plow surface. The plow has a horizontal wedge to lift snow above the level of snow accumulation beside the track. A cutting edge low above the rails usually employed a cast iron or steel leading edge for durability against ice and for weight to discourage the tendency of the wedge to climb over hard-packed snow causing derailment by lifting the wheels off the rails. Under most conditions, the tendency to climb was reduced by weight of snow on the upper side of the wedge, and by downward reaction force accompanying upward acceleration of lifted snow. However, this downward snow loading may be absent when a plow first strikes a snow drift or packed snow face where the plow train has previously stalled. Before making a running start against such conditions, prudent crews would dig into the lower edge of the drift or snow face creating a notch to receive and guide the leading edge of the horizontal wedge. The plow has a vertical wedge to push the snow horizontally away from the track. The vertical wedge may be less acute than the horizontal wedge, but often included a cast or sheet metal cutting edge on wooden plows. Pushing snow horizontally off the track may create an unbalanced horizontal force where asymmetrical snow accumulation is encountered. (such as snow drifting into one side of a cut) This unbalanced force may derail the plow. The leading edge of the horizontal wedge is typically forward of the vertical wedge so stabilizing downward snow loading precedes horizontal loads. Well-designed wedge plows work best at speeds which accelerate the snow first upward and transitioning to a horizontal