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Show DRAINAGE FOR GOOD ROADS Essential Feature of an Improved Highway Another Requisite Is Firm Foundation. (.', l by t lie Cn'orl Ht;ito.s Depart -1 1 ! 1 1 fit V.i U:ulturf .) Aa I'sscnii.-il fi'iinin of nn improviM r;n Is ;i(liMjn;tIt! .Iniiriiijjjtr. Thorough duiinimi' U s iii'ri-ssiu'y tluit It i:t pi -At-t irjil! y !ni;n.'-ihl(! lo nminlaiii n s;it-Isfji.-inry ru;,,l unless it he k'wvh proper prop-er iitHMil.'ni;. AiioiIht priiiM; n;quire-im-nt wlicn-viT ;i"li;irl siirl';ir rn:id is tn In- i-oiisi ructcij is ;i linn mnl unyicTd u.; fntill'iii I iui). As tlu qiuilily of ttlH soil h;is iui iinporl.-inL lull iifiicu on tin f lopcr ntt'lliod of (Iniiiiii'i' ;irnl tin typi of f'i)ini(l;i l inn lo Ik; oniploynl, much I'iiri' junl sliiily must ho dovoted to tho njiiuri', typo, nnd ohiii'iictor of tho si lls in tin- sootion through ulik'h It is piopnscd to hiiild a road. The most important primary soils arc classified as gravel, sand, and clay, hut often many of the secondary or m;:. d soils, bemuse of their more r en-em en-em I oi-iMirreiiee In connection with ro.irt-li ill tiling operations, are equally Important. Such types as loam, marl, (jumbo, nnd hardpan are representative representa-tive of this order. In the design of n road the drainage structures are planned to take care tif water under throe general conditions rain that falls on a road surface or f,'rade; rain that falls on contiguous land and flows in accumulated volume toward tho road; and ground water from any Immediate source. To meet these conditions use is found for special spe-cial st r tic lu res, including longitudinal side ditches, usually parallel, or approximately ap-proximately parallel to the center lino; intercept ing ditches to accommodate water whose approach so close to the-roadway the-roadway as the side ditches Is likely to cause Injury; lateral ditches or culverts cul-verts to conduct accumulated water away from or under the road ; and suhdrains. In order to plan Intelligently Intel-ligently a system of drainage for any particular road, it is necessary to con- J fc VS-- ' H s . ..vVy.x ' V ...:-.-.-.v . ' ' Water Drains Readily From This Type , of Highway. slder not only the loc:i! character of the soil composing the roadbed, but also the topography of the adjacent land, the amount and rate of rainfall and the availability of materia! suitable suit-able for use in constructing drains. Surface drainage systems for roads consist of side ditches along the road, paved gutters (which are a development develop-ment of side ditches and replace them) open Intercepting ditches constructed to prevent water from reaching the road, and lateral or relief ditches to carry off the water which collects in the side ditches or in the intercepting ditches. Culverts and inclosed drains, which are constructed for the purpose of remixing storm water from the side ditch- s or gutters, are essentially a part nf the surface drainage system, and .". v not to be confused with suh-drain-; which serve an entirely different differ-ent purpose. AVhere the grade of a road Is so steep that the ordinary earth side ditches cannot be maintained satisfactorily satisfac-torily at a reasonable cost, or where earth side ditches would be Insanitary or appear unsightly, It Is customary to provide paved gutters for removing the surplus water. Prop inlets and catch basins are used to conduct water from side ditches ditch-es or gutters into underground drains or culverts. On country roads they are used most frequently on side hill locations loca-tions where the water collecting In the upper side ditch or gutter can be removed re-moved from the road at intervals by means of a culvert across to the lower low-er side. Drop Inlets usually are sufficient, suffi-cient, and catch basins seldom are used in country road work, except where It is especially desirable to prevent the silt and other foreign materia carried by the water, from getting into the underground drainage structure. |