Let’s assume that the trail has been marked with a single row of pin flags and the corridor has been cleared. Start by taking all the loose material lying on the ground (leaves, small branches, etc.) and raking it uphill. Keep this material uphill, as it will be used later in the process…
Stand below the pin flags and mark a spot, at your desired trail width, uphill from each flag. Next connect the dots by scratching a line from pin flag to pin flag and on the marks you made above each of the pin flags. You have just made a visual marker on the top and bottom of the tread. Don’t worry about the back cut yet; these marks are only for the tread.
Begin on the downhill edge and use a grubbing tool to loosen the organic material, decomposing leaves, duff and humus working your way down to the mineral soil. A good way to tell the difference: Organic material will burn, mineral soil will not. Remember there is no need to remove rocks and roots if you are building a technical trail.
Follow the grubbing tools with tools designed to broadcast the loosened soil; shovels, rakes, and McLeods are best for this job. Broadcasting is the process of distributing the excavated soil as far downhill and away from the tread as possible.
You may need to make multiple passes as you work toward the top edge of the tread, alternating between the grubbing and broadcasting tools. Remember to let the tool do the work for you. Once you’ve created a level surface for the tread, the trails profile should look like a park bench.
Excerpt taken from IMBA’s Trail Solutions, Guide to Building Sweet Singletrack, page 145
http://www.imba.com/resources/trail_building/trail_solutions.html
