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Road Location Elements

straight, line, roads, feet, length, plane and considered

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ROAD LOCATION ELEMENTS INVOLVED.In general the determination of the best location for a road requires a study of the topographical fea tures of the region through which the road is to pass, and also an investigation of the nature and extent of the traffic to be provided for. Viewed as a question of economics, the best location is that for which the sum of the interest on the cost of construction and of the annual cost of maintaining the road and of conducting trans portation over it, is a minimum. The location of a wagon road is not, however, entirely a question of economics, since the location should be made with reference to the convenience and comfort, and perhaps also to the pleasure, of those who use it; and is fre quently more of a social or political question than one of economics. Only the economic features of location will be considered here, and they only briefly.

However, in locating a new wagon road, it is well to remember that the location will probably serve for many generations, and perhaps for all time, as the growing importance of the surrounding country and the location of buildings and of division lines of the land with reference to the road make it increasingly more difficult and expensive to change the location. Thus the location of a road is the field where costly errors and permanent blunders may creep in and forever fasten themselves upon the road and its users; and, worst of all, these errors become more costly as the use of the road increases.

In most parts of the United States, the roads are in the main already located, and the necessity for the location of new ones does not often arise; and hence as a rule, the only application of the principles of economic location will be in the re-location of com paratively short stretches of roads. The original location may have been fit and proper when the region was new and undeveloped, but the increase in the amount and the change in the character of the traffic may justify a very considerable change. There are many roads that could be materially improved by a careful re-location.

The principles to be observed and the methods to be em ployed in making the location of a wagon road are substantially the same as those used in the location of a railroad. The method of

examining the country and of making surveys will not be considered here, as such subjects are elaborately presented in treatises on rail road location.

The fundamental principles applicable in locating a new road or in improving an old one will be briefly considered; but no hard and fast rules can be laid down, for each road must be designed for the place it is to occupy and the service it is to render. In the loca tion of any road there will always be an opportunity to exercise keen insight and good judgment.

The subject will be considered under the four heads: distance, grades, curves, width, and placing the line.

Distance.

Other things being equal, the shorter the road the better, since any unnecessary length causes a constant threefold waste: (1) the interest on the cost of constructing the extra length; (2) the ever-recurring cost of repairing it; and (3) the time and labor employed in traveling over it. However, the advantage of straightness, i. e., of shortness, is usually greatly estimated. The difference in length between an absolutely straight line and one deflecting a little to one side is not very great. For example, in Fig. 3, if A B=B C= 1,000 feet, and BD-10 feet, the line A B C is only one tenth of a foot longer than the line ADC.* If AB—BC-1 mile, and BD = 300 feet, the line ABC is only 17 feet longer than AD C. "If a road tween two places ten miles apart were made to curve so that the eye could nowhere see more than a quarter of a mile of it at once, its length would exceed that of a perfectly straight road between the same points by only about one hundred and fifty yards." * One of the most common defects of ordinary country roads is that distance has been saved by a disregard of the desirability of easy gradients. The curving road around a hill may often be no longer than the straight one over it; for the latter is straight only with reference to the horizontal plane, but curved as to the vertical plane, while the former is curved as to the horizontal plane, but straight as to the vertical plane. Both lines curve, and the one passing over the hill is called straight only because its vertical curvature is less apparent to the eye.

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