No department of our work seems so easily handled, yet in no other one are so many errors made as in grading. It is difficult to suggest and impossible to offer set rules or specific principles because everything depends upon existing surroundings and peculiarities. Grading requires a natural conception of these conditions to produce good effects and results. The laying out and grading roads and the shaping of the ground lying between them constitute what we mean by grading. It will therefore be well to consider the various shapes of ground surface and offer a few suggestions. All natural surfaces may be divided into such as are convex, concave and flat, the latter horizontal or an even incline or slope. On level ground it is, of course, comparatively easy to layout the direction of the roads; we may consult our individual taste and inclination, but when that is established the difficulty begins how the best effects can be produced on the plane or flat surface. Nothing is more tasteless and monotonous than long stretches of level and flat surfaces, such as are the rage nowadays among landscape gardeners. No matter what may be the advantages for a rolling or undulating surface, these men insist on a nice "level," but only produce stiff lines and awkward grades. A dead level is not advisable, nor desirable, nor can it be made to look well and natural. To overcome this let the surface be somewhat convex or concave; occasionally introduce an easy depression, using the excavated material to form a gentle eminence or knoll beyond; even if necessary, raise or lower the road somewhat to get the effect. When we consider that in this operation the difference in cut and fill is double the depth of ground taken out we secure quite a diversity in surface with comparatively little labor.
On rising or broken ground, where convex and concave surfaces prevail it is more difficult to select the courses for roads; they should be arranged so as to convey the impressions that they are regulated by the shape of the ground and not the ground by them. Often a deep cut or heavy fill may be required to accomplish this, necessitating a considerable amount of labor, but above all a clear conception of the desired result is required. In the alteration of ground surface we must aim to produce unbroken, undulating, long sweeping .and easy lines from the edges of the road, and herein lies the difficulty, because it is impossible to mark such lines by means of tape measure or instrument; they can be conceived by experience. In making prominent eminences or knolls preliminary heights may be given by stakes for roughing out the desired surface, but the finishing contour, which gives the surface its final and lasting expression, can only be produced under constant watching and observation. Where natural elevations are found with intervening undulations, or when fine slopes are accidently revealed during the progress of work, they must be preserved, utilized and emphasized.
Burial sections need not and should not assume an arbitrary uniformity in grade, but should assume the character of gentle undulations. Occasionally individual elevations are desirable which will afford special opportunity for giving prominence to large and choice lots.
Grading or the shaping of ground surfaces and laying out roads are closely related to one another, in fact, somewhat depend upon each other; therefore a few words regarding the latter will seem appropriate. Grades for roads must be alternately ascending and descending, always accommodating themselves to the surface of the ground and thereby appearing natural. The margin of that portion of the section forming the edge of the road should be graded in such a manner so as to convey the impression that the turf had merely been removed. Attention has repeatedly been called to this important fact, and it cannot be emphasized too much, that those roads whose margins are tangent with the surface of the border produce the finest effects. In establishing longitudinal grades avoid perfectly level stretches and do not allow a rise of more than 1 in 20 if possible, in rare occasions must a steeper grade be employed; the various grades merging from one to another should be connected by easy lines, showing no abrupt angles at high or low points. For transverse grades engineers recommend that the convexity should be at least equal, if not greater, than the longitudinal grade, so as to throw the water into the gutters, thus preventing cutting and gulching of road surface. A road running along a hillside should incline toward the inner edge and the grade made sufficiently wide to admit of a road gutter to be formed toward the hill. This will catch the water from the hill and carry it to an outlet before it has a chance to get in the roadbed and will generally prevent serious cutting and washing out.
The operation of grading or moving ground is very expensive work therefore we should employ every precaution against unnecessary outlay, and study well how to economize and save time and labor. In the first place have a plan well developed and digested and carry in your imagination the result to be obtained. It is necessary to be able to see mentally the finished work before operations are begun. Arrange cuts so as to equal the fills as nearly as possible. Where more material is needed than the cut will yield it should be obtained from as near as possible. Be sure never to remove earth from a place that would have to be filled again in the future, nor place material from where it would have to be removed again; place the material once handled where it is wanted and where it is to remain. Handling ground twice or even more times in consequence of poorly planned work or from inexperience is what often makes grading much more expensive than need be under proper conditions, The only exception to this rule admissible is when, during progress of grading, it seems advisable to save good surface soil for covering bare and poorer places. Such soil should be in all cases preserved even if need be by double handling.
Whatever method is employed to move the ground let there be regularity and order so that no time counts against the improvement in hand. In work of large proportions and on extended scale the greater part of grading is done by plow, scraper and harrow, but to put on the finishing surface handwork alone, guided by an experienced eye will answer.
From the publication:
AACS - Proceedings of the 9th Annual Convention
September 18, 19 and 20, 1895