Show SURFACE OF ROADS methods to be Emp employed foyed in construction st depends on conditions to bo be met FOUR SETS ARE summarized Lo location catlon design drainage grading Gra dingo etc are important each feature described separately and in full Ir parea by the united states department of 0 agriculture the proper method to employ in co constructing a sand clay rood road surface depends o oi 01 i iho to be met in general there distinct sets lof of conditions all of which may occur in the same locality or ayen even on different sections of the same road these are ares case 1 where the original roadbed d Is sandy and it Is desired to construct ole he surface by mixing admixing ad clay case 2 where the original roadbed Is composed of clay and it Is desired to construct the surface by ad mixing sand band case 8 3 where it Is desired to construct the surface of topsoil or other natural a tur I 1 sand 1 andalay dclay an clay mixture without ad m mixing 1 aln g a any n y of the roadbed material 1 case 4 where itis it Is desired to supply ithe the clay and sand separately and mix ithe the two materials together in place to form the surface 1 before discussing the different cases separately separate lythe the general ends which all can best bf it tie lie described separately for each of the four sets of conditions mentioned me above case J l to construct a sand clay j surface by ad mixing clay with band i from tile the roadbed first grade the roadbed in alio the manner already described for earth carth bed construction bu i keep the crown flat on the portion to bo be surfaced then spread clay over dyer that part of bf the roadway which tile tho s bur u r face le la to cover to such depth th that t cheh at alta Is mix edwith the sand of the roadbed a surface about eight inches thick after compacting will be obtained ta ined the loose depth of clay feces sury bury to secure it finished surface eight ta thick ick usually will vary from to six inches according to the amount of sand band the clay contains after the clay tins hns been spread plow up sand from beneath in sufficient quantity to make the not net proportion of cloy clay about 2 to tol 1 ordinarily tho the plow furrows should extend down into the sand from tour four to six inches depending on the compactness of the roadbed and the amount of sand originally present in the clay hut but it Is better to have too little than too much sand because it Is easier caster to add solid sand from the roadbed than to haut haul additional clay next harrow the surface with a disk harrow barrow repeat the operations of plowing find harrowing until the sand and clay are mixed thoroughly and uniformly then shape up the surface with it a grading machine or road drug drag and permit upon it after the first soaking rain plow and harrow the surface again until the surfacing material practically becomes mud after which shape up the surface and keep it in shape by repeated dragging until it has dried out and Is thoroughly compacted watch theroan the road carefully for several months after it wr flat or K nta nT 1 ilir i 1 tta TT 1 y 1 crew ca motion ready to receive the f he material V f at W sea fast for th depth I 1 r 44 4 ww 4 3 sho i r a oni he roa r for n W 3 71 ir arto 10 aiache H ns t tiit t 11 ll lil sl iw 1 1 cross as of bied roa road TYPICAL CROSS SECTIONS SECTION 3 SHOWING ME METHOD Y OD OF constructing 1 SAND SAID CLAY ROAD BY mixing SAND OR CLAY WIT WITH THE ROAD BED MATERIAL V Ws should hould be b at I 1 12 reef feet for f track rack road and Sg rally not less than S re t j for t track rack W js should hould be e not less than an n S not less than met 3 feet jf brrown li Hr crown rown v sri fram f ato to the foot for level arade rade to t I 1 to the tha foot for a grade of 54 5 L pi I 1 of the tha construction methods should MCI aim 16 to attali attain will be summarized briefly 1 the questions of location design drainage grading etc are if anything more important in the case of sand clay roads than in tho the case of erth earth roads 2 the amount of clay contained in a finished flais hed sand band clay road surface 1 should hould I be only slightly more mor ethan aban sufficient to fill 1111 the voids vold sin la the sand ordinarily about one part of clay to two parts of sand gives satisfactory results though the proper proportion for any particular case can be determined best by experiment 8 5 for average country road traelic and a stable roadbed the depth of a sand clay surface should be about eight inches after it Is compacted if clean sand aad pure clay were used to make the mixture the respective depths of the sand layer and the clay layer required would be approximately eight inches and fo four ur inches measured loose it Is customary to decrease the surface thickness from center to sides aides with a feather edge extending out over the shoulders but this practice makes it necessary for most of the traffic trade to td use the center of the thab la Is first constructed to correct den bf band or clay and to kep keep the surface in shape case Z 2 to construct a sandy bandy day clay road surface by ad mixing sand with clay from the roadbed the process la Is exactly similar to that described for case that sand band Is spread over the graded roadbed and clay la Is plowed up front from beneath to mix with it the depth to 0 which the sand should be spread ifor an eight inch finished surface usually varies from tour four to eight inches according to the amount of sand contained originally in the clay of the roadbed the depth to which the plow furrows should extend down into the th clay usually varies from about three indies inches to about five inches and depends on the sand content of the clay and the compactness of tile the roadbed it should be borne la in mind that in this case it Is better to hav hat e L a asur sur plus 0 sand than a surplus of fifty clay in the surface because the former Is more easily corrected case 8 figure 2 illustrates the two principal steps involved in constructing a sand day surface with topsoil or other natural sand band clay mixture the roadbed should be graded in the usual way except that the portion to W crom sect iott rudy to r ceya the surfacing ma j 1 l 1 I i i W rini 1 1 n attl IL a 10 inches 1 4 1 W tress cross section of completed road TYPICAL CROSS SECTIONS SHOWING METHOD OF A ROAD USING TOPSOIL OR arher MIXTURE W be b at least 10 fief feet for binale track i vad road andS generally not less that hart feet for double trac kW be not lesa lam than 14 reet feet and t an 9 feet ai H crown varies vanes from r f to 0 th the fol for trade arade to t I 1 to featt fop foe a adeoe adeo arade of az 5 Q road ad and heavy vehicles using the edge of the surface anre liable to break through the surfacing material 1 4 in constructing a sand clay surface f ace the two constituent materials should be thoroughly and intimately mixed d together in all cases in ank ing artificial mixtures therefore much plowing and harrowing burrowing are required 5 no matter what method Is followed in con constructing a sand clay y surface traffic usually must be depended lapo to puddle and compact the surfacing material and the road never I 1 should be considered complete until after it has been subjected to traffic tor for a considerable period during this period the surface should be kept in shupe by repeated dragging and it if ine essary additional sand or clay should be supplied at points which show weakness owing to these materials ter litIs not having been mixed in proper apro options ort ions other her features fea turca of the construction I 1 be surfaced should be trenched out with tile the grading machine to receive the ahe surfacing material the surfacing material should be spread to such 1 n depth that it 11 will 1 I be at least eight inches thicket thick thic kat at the center when compacted case 4 where it Is necessary to bring the sand and clay on the road separately and mix them in place the tha method employed should be a combination of the methods already do ascribed scribed bed that Is a trench should be formed wi with th the bie grading machine to receive alie bottom layer of material which maybe may be either theland the sand or tho the clay and the top layer should then be spread and tho the mixing done as described s in case 1 1 or case 2 the depths of the respect respective lve layers should be such as to secure a completed surface at least eight inches thick and the proportions should be toed axed in the manner already described in dis cussins the other cases |