Russ Lanoie of Conway, N.H., writes: "Washboard is a direct function of traffic, especially fast moving traffic, usually on a dry road, regardless of whether it is upgrade or flat. Providing as hard and compact a surface as possible will help eliminate washboard. Good gravel with considerable fines helps to hold moisture. Calcium chloride increases the road's ability to retain moisture in dry seasons helping to consolidate it to help prevent washboard and other problems."