The Future of Road-making in America

by Archer Butler Hulbert

In addition to being well covered and drained, the surface should be kept as smooth as possible; that is, free from ruts, wheel tracks, holes, or hollows. If any of these exist, instead of being thrown to the side the water is held back and is either evaporated by the sun or absorbed by the material of which the road is constructed. In the latter case the material loses its solidity, softens and yields to the impact of the horses' feet and the wheels of vehicles, and, like the water poured upon a grindstone, so the water poured on a road surface which is not properly drained assists the grinding action of the wheels in rutting or completely destroying the surface. When water is allowed to stand on a road the holes and ruts rapidly increase in number and size; wagon after wagon sinks deeper and deeper, until the road finally becomes utterly bad, and sometimes impassable, as frequently found in many parts of the country during the winter season.

Road drainage is just as essential to a good road as farm drainage is to a good farm. In fact, the two go hand in hand, and the better the one the better the other, and vice versa. There are thousands of miles of public roads in the United States which are practically impassable during some portion of the year on account of bad drainage, while for the same reason thousands of acres of the richest meadow and swamp lands lie idle from year in to year out.

The wearing surface of a road must be in effect a roof; that is, the section in the middle should be the highest part and the traveled roadway should be made as impervious to water as possible, so that it will flow freely and quickly into the gutters or ditches alongside. The best shape for the cross section of a road has been found to be either a flat ellipse or one made up of two plane surfaces sloping uniformly from the middle to the sides and joined in the center by a small, circular curve. Either of these sections may be used, provided it is not too flat in the middle for good drainage or too steep at the gutters for safety. The steepness of the slope from the center to the sides should depend upon the nature of the surface, being greater or less according to its roughness or smoothness. This slope ought to be greatest on earth roads, perhaps as much in some cases as one foot in twenty feet after the surface has been thoroughly rolled or compacted by traffic. This varies from about one in twenty to one in thirty on a macadam road, to one in forty or one in sixty on the various classes of pavements, and for asphalt sometimes as low as one in eighty.

Where the road is constructed on a grade or hill the slope from the center to the sides should be slightly steeper than that on the level road. The best cross section for roads on grades is the one made up from two plane surfaces sloping uniformly from the center to the sides. This is done so as to avoid the danger of overturning near the side ditches, which would necessarily be increased if the elliptical form were used. The slope from the center to the sides must be steep enough to lead the water into the side ditches instead of allowing it to run down the middle of the road. Every wheel track on an inclined roadway becomes a channel for carrying down the water, and unless the curvature is sufficient these tracks are quickly deepened into water courses which cut into and sometimes destroy the best improved road.

In order to prevent the washing out of earth roads on hills it sometimes becomes necessary to construct water breaks; that is, broad shallow ditches arranged so as to catch the surface water and carry it each way into the side ditches. Such ditches retard traffic to a certain extent, and often result in overturning vehicles; consequently they should never be used until all other means have failed to cause the water to flow into the side channels; neither should they be allowed to cross the entire width of the road diagonally, but should be constructed in the shape of the letter V. This arrangement permits teams following the middle of the road to cross the ditch squarely and thus avoid the danger of overturning. These ditches should not be deeper than is absolutely necessary to throw the water off the surface, and the part in the center should be the shallowest.

Unfortunately farmers and road masters have a fixed idea that one way to prevent hills, long and short, from washing is to heap upon them quantities of those original tumular obstructions known indifferently as "thank-you-ma'ams," "breaks," or "hummocks," and the number they can squeeze in upon a single hill is positively astonishing. Quoting Mr. Isaac B. Potter:

"Side ditches are necessary because the thousands of tons of water which fall upon every mile of country road each year, in the form of rain or snow, should be carried away to some neighboring creek or other water channel as fast as the rain falls and the snow melts, so as to prevent its forming mud and destroying the surface of the road. When the ground is frozen and a heavy rain or sudden thaw occurs, the side ditch is the only means of getting rid of the surface water; for no matter how sandy or porous the soil may be, when filled with frost it is practically water-tight, and the water which falls or forms on the surface must either remain there or be carried away by surface ditches at the sides of the road.

"A side ditch should have a gradually falling and even grade at the bottom, and broad, flaring sides to prevent the caving in of its banks. It can be easily cleared of snow, weeds, and rubbish; the water will run into it easily from each side, and it is not dangerous to wagons and foot travelers. It is therefore a much better ditch than the kind of ditch very often dug by erosion along the country roadside."

Where the road is built on a grade some provision should be made to prevent the wash of the gutters into great, deep gullies. This can be done by paving the bottom and sides of the gutters with brick, river rocks, or field stone. In order to make the flow in such side ditches as small as possible it is advisable to construct outlets into the adjacent fields or to lay underground pipes or tile drains with openings into the ditches at frequent intervals.

The size of side ditches should depend upon the character of the soil and the amount of water they are expected to carry. If possible they should be located three feet from the edge of the traveled roadway, so that if the latter is fourteen feet wide there will be twenty feet of clear space between ditches.