Tile laterals, sub-mains and mains can be installed in a random pattern or in a parallel pattern. The random pattern is often used to tile only portions of a field where the parallel pattern is used to tile the entire field. A tile contractor will often bid a random pattern based on the length of tile line installed. If the whole field is to be tiled, a contractor will bid the project on a per acre basis. For a whole field tile system that is installed commercially, the costs can be $500 to over $900 per acre. Field costs are determined by the length of each lateral, spacing between laterals, length and diameter of submains and mains, topography, obstructions, and outlet conditions. Many farmers install their own tile and thus significantly reduce the cost of installation. More information can be found at University of Minnesota Extension.