Timber Hurdles are to be not less than 3 feet 6 inches from the top bar to the bottom bar. Hurdles are driven into the ground so that the bottom bar rests on the ground. The angle of the hurdle is such that the top bar is 37 inches above ground and the overlay from the top bar in the direction of racing is 20 inches beyond the bottom bar. Each flight of timber hurdles must be at least 30 feet in width.