In constructing a gravel road the roadbed should first be brought to the proper grade. Ordinarily an excavation is then made to the depth of eight to ten inches, varying in width with the requirements of traffic. For a farm or farming community the width need not be greater than ten or twelve feet. A roadway which is too wide is not only useless, but the extra width is a positive damage. Any width beyond that needed for the traffic is not only a waste of money in constructing the road, but is the cause of a never-ending expense in maintaining it. The surface of the roadbed should preferably have a fall from the center to the sides the same as that to be given the finished road, and should, if possible, be thoroughly rolled and consolidated until perfectly smooth and firm.
A layer, not thicker than four inches, of good gravel, such as that recommended above, should then be spread evenly over the prepared roadbed. Such material is usually carried upon a road in wheelbarrows or dump carts, and then spread in even layers with rakes, but the latest and best device for this purpose is a spreading cart.
If a roller cannot be had, the road is thrown open to traffic until it becomes fairly well consolidated; but it is impossible properly to consolidate materials by the movement of vehicles over the road, and if this means is pursued constant watchfulness is necessary to prevent unequal wear and to keep the surface smooth and free from ruts. The work may be hastened and facilitated by the use of a horse roller or light steam roller; and of course far better results can be accomplished by this means. If the gravel be too dry to consolidate easily it should be kept moist by sprinkling. It should not, however, be made too wet, as any earthy or clayey matter in the gravel is liable to be dissolved.
As soon as the first layer has been properly consolidated, a second, third, and, if necessary, fourth layer, each three or four inches in thickness, is spread on and treated in the same manner, until the road is built up to the required thickness and cross section. The thickness in most cases need not be greater than ten or twelve inches, and the fall from the center to the sides ought not to be greater than one foot in twenty feet, or less than one in twenty-five.