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Making Good Roads

Making Good Roads image
Parent Issue
Public Domain
OCR Text

At the bcginning of the present century the highwaya of England were so bad and the ratos for toll so heavy that public attention was attracted to the gituation. The investigations which follöwed led to the formulatiou of rules for the oonstrnction of roads which have rcsulted in the splendid highwaya for which Great Britain lias become famous. Macadam and Telford were the most prominent road engineers of that time, and the two different systems of roadbuilding which they advocated are still used, according to the requirernents ,of the locality where roads are to be built. In the United States most roads have natural beds, and the character of these beds is determined by thegeology of the región in which they lie. Henee the roadbeds consist of clay, sand, loam, gravel, etc. , or may occasionally be on the surf ace of the country rock. From this neoessary relation between soil and road it usually happens that the poorest roads are in the regions of poor farms, where property values and conscquently taxes are low and there is little money to spend on the roads. This is especially true in stony districts, for a stony soil is the most unmanageable material for a road. Of the natural roads those on clay soil are best in dry weather, those on .sand best m wet weather. Wlien vrt witn. a certain proportion of water fine sand becomes hard and elastie, as we see on the bcaches of our Atlantic coast froni Lond Island southward. Of the natnral soils, the best for road purposes are those variable mixtures of sand and clay called loams. Loam roads average better through the year than those of clay or sand. Á limestone gravel also makes a good road, as does a fine quartz gravel mixed with clay. From everyday experienee it is clear that natural roadbeds are not fit for heavy traffic w.hen under varying conditions of moisture. The experienee of over 2,000 years has shown conclusively that there axe frwo essential pomts to be airued at in the construction of a road: First, a hard, smootb, waterproof surface. Second, a thoroughly dry foundation. These principies were known to the Romans 300 B. C. and used in the construction of their best higkways. The surf ace of a good road must be of sufficient strength to resist thewearand tear of trafilo and smooth enough to prevent undne straiu andwear on vehicles. In eonnection with this the soil beneath must be made drv and kent dry. fore the subject of road drainage is as important as tb at of road metaling. The best road covering is composed of angular fragmente of sorae stone grinding on the surface into a dust which, when wet, will bind or in a measure cement the fragmcnts togetber, so tb at water will not penétrate. The angular form is essential to make the fragmcnts interlock. The sizes should be quite uniform, except that the surface layer may consist of fragmenta different in size from those in the bottom course. The total thickness of this metaling must be at least 6 inches on a natural soil foundation. The fragments should not exceed 2 inches iu diameter and should be rolled in two separate courses with a heavy steam roller until the surface is absolutely firru. This is the macadam system. Where the soil foundation is clay or for any reason difficult to drain the telford method is used. In this case a course of flat stones about six inches deep, set on edge and closely wedged together, is placed upon the soil, and the crushed stono is placed over this four inches thick and rolled solid. In good practice it is customary to roll the earth before the stone is laid upon it and then roll the stone foundation. The telford foundation forms a bridge which prevents the road from sinking in moist soil. In some places tile drains, one on each side of the road, are necessary. After the road is built it must be kept constantly in repair, and the neglcct of this principie is to a great extent responsible for the poor roads of the United States. The macadam and telford systems above described are necessary for roads designed for heavy traffic in all weathers, but roads for pleasure driving only do not need the same expensive preparation. Would Benefit Farmers. It is said that the farmers of Missouri would benefit by the employment of convicts ou road improvements to the amount of $12,000,000 annually. Oood Roatls Notes. Good roads are cheapest in the long nm, also in the short run. Ask for good roads, insist on getting them. A road should lie ílxed a little while beforo it nceds it rather than a long while after. If you don't see the good roads you want in your viciuity, ask for them. Good roads indícate corporate intelligence.


Old News
Ann Arbor Democrat