Page:The New International Encyclopædia 1st ed. v. 17.djvu/198

* ROAD. 178 BOAD. twcen tile county in wliiili the road is located and the abuttin}; propeily-owncrs. In case the latter petition for the iuiprovement, they pay 35 per cent, of the total cost; otherwise, only 15 per cent. In I'.IOO an act was passed requir- ing towns to keep tile State roads in repair, under the direction of the State Engineer. That official passes on all apjiUcations for State aid and is in charge of the work. To the close of 1900 New York had built oSVo miles of State road, and surveys and estimates for 404 miles were under way. The State Engineer is em- piiwcred to build telford, macadam, gravel, or other kinds of roads. Vermont appointed a State Highway Commis- sion of three members in 1S94, reappointed it in 1896, and in December, 1898, created the office of State Highway Commissioner. The com- mission of 1892-96 seems to have had no powers or duties save of investigation and advice, but it did some educational work and issued two re- ports. The Commissioner under the law of 1898 supervises the expenditure of the State road tax and is empowered to provide experts to give instruction in road-making. Other States than those named have made more or less extended inquiries relating to aid in road construction. The work is largely educational, since a vast expenditure would be required to macadamize all the roads of even the smaller States. The plan generally pursued is to improve either high- ways between important to^vns, or notoriously bad pieces of road. Often the two are combined. In mentioning educational work, the Road In- quiry Division of the United States Department of Agriculture should not be overlooked. For several years past much has been done at Wash- ington to collect and disseminate information relating to the benefits of good roads and how they may be best and most cheaply built and maintained. Numerous bulletins on the subject have been issued, and sample stretches of im- proved roads have been built in different sec- tions, notably in conjunction with the State agricultural experiment stations. The essentials of good roads are: (1) Proper location: (2) easy grades; (3) a smooth, hard, durable wearing surface. In the case of new roads there is little or no excuse for poor loca- tion, and no danger of it if the advice of a good road engineer is sought and followed. Ideal grades should not exceed a rise of 1 foot in 33 V3 of horizontal distance, which is known as a 3 per cent, grade. Telford allowed a rise of I in 30, and French engineers permit 1 in 20, but this is for smooth broken-stone roads. The only classes of wearing surface for im- proved roads considered in this article are gravel and macadam. (For wood, brick, and stone block and sheet and block asphalt, see P.we- MEXT.) Gravel, spread in layers and well rolled, makes a very good road surface, but one that is rather expensive to maintain. Gravel should be screened to free it from earth and to sort out for use the stones ranging from about % to IVi inches in diameter. The stones should be as angular as possible. A mixture of iron-bearing clay is desirable to bind the gravel together. Smooth beach or river gravel should be avoided, but some or all of it may be crushed and used where nothing else can he found. The lines be- tween the macadam and telford roads are not drawn so hard and fast as they once were. The tendency seems to be to use telford, or a founda- tion of large stone, where the ground is yielding or the traffic very heavy. The stones are placed by hand, as close together as may be. The pro- jections above the desired depth are broken off with hammers, after which two or more layers of broken stone are spread and rolled, each separately. Whatever the number of layers, the top one is composed of fine screenings, both to fill the interstices in the laj-er below and to give a smooth surface. The proper sizes for broken stone, and whether or not clay, loamy earth, sand, or some other material to fill the spaces between the stone and help to bind the stone together, should be used is a mooted ques- tion. There is much to be said in favor of having the fragments as homogeneous as pos- sible, both in size and hardness, and relying upon the roller so to pack the stone as to leave no voids. Such voids as would be thus left might well be filled as completely as possible with some material. There are obvious advan- tages in having this done bv the smaller sizes of broken stone. Some authorities strongly advo- cate fine gravel and sand for filling the inter- stices. Careful sprinkling of the upper la3'er of stone is essential, but if too much water is used it will penetrate to and soften the earth beneath, thus causing settlement in spots and an irregu- lar surface. The Massachusetts Highway Com- mission uses screens of V2, IV2, and 2I2 inches. Stones between 2V2 and IV2 inches in size are placed at the bottom; those between l^o and % inch come next ; and the screenings last. Each of the three layers is rolled separately and the last is sprinkled before it is rolled. The best material for broken-stone road surfaces in Amer- ica is generally considered to be basaltic or trap rock. Some limestones serve the purpose well. Carefully selected field stones, if of a kind that will break into angular pieces, often give good results. In general, any stone used for macadam or telford roads should be tough, fine-grained, and not readily acted upon by acids or the weather. Good drainage is an essential of all road and street construction. Water falling on the surface is removed by giving the road a proper inclina- tion, both longitudinally and transversely, and conveving it to natural watercourses. Culverts of masonry, vitrified clay, or iron pipe are em- ployed where open channels are impracticable, both to carry the water from the road sur- face and for natural watercourses beneath the roadway. Where roads pass through wet land, underdrains are necessary to keep the earth dry beneath the road surface. These, also, may be of stone or some kind of pipe, placed in the middle of the road, at the side, or running from the centre to one or both sides, according to local conditions. Maintenance of roads is no less important than their construction, but this fact is yet to be learned in most parts of America. Ameri- can engineers know how to build good roads, but can rarely secure the money necessary to maintain them, although money so spent is saved in the end. There are two methods of maintain- ing broken-stone roads — the constant and the intermittent road -repair system. In the former the roads are divided into sections, each in charge of one or more men. Broken stone is