1. A METHOD OF CLEANING RAILROAD TRACK, INCLUDING THE STEPS OF PROVIDING A ROTARY IMPELLER HAVING AN AXIAL EXTENT A FRACTION OF THE NORMAL DISTANCE BETWEEN THE RAILS, ROTATING THE IMPELLER AT A RELATIVELY HIGH R.P.M., POSITION ING THE IMPELLER BETWEEN THE RAILS SO THAT THE LOWER SWEEP OF THE IMPELLER WILL BE GENERALY AT THE SAME LEVEL AS THE TOPS OF THE TIES, DISPOSING THE AXIS OF THE IMPELLER GENERALLY PERPENDICULAR TO THE RAILS, TRAVERSING THE IMPELLER BACK AND FORTH BETWEEN THE RAILS IN A PATH GENERALLY PERPENDICUALR TO THE RAILS, AND WHILE THE IMPELLER IS BEING SO TRAVERSED, MOVING THE IMPELLER IN A DIRECTION GENERALLY PARALLEL TO THE RAILS AT A LINEAR RATE OF SPEED SUBSTANTIALLY LESS THAN THE TRAVERSING RATE OF SPEED.