Show EARTH ROAD GRADE stability of embankments Is of great importance CAREFUL SCRUTINY IS URGED D td to prevent damage by shrinkage material used must be free from vegetable matter and uniformly com compacted packed prepared b by y the united states department of 0 agriculture one of th the c lost jost important considerations erat ions connected conflicted with the grading of an earth eaith road Is the stability of the embankments where a road Is situated in a cut and Is well drained it Is 19 not likely to be ba effected affected seriously by such agencies as shrinkage settlement and slipping eny one of which may injure or destroy a road situated on a poorly constructed embankment in grading a road therefore the methods employed in building the embankments are deserving of much more careful scrutiny than those thase employed in making to prevent a road over nn an embankment from being damaged by shrinkage I 1 or of the material forming the embankment ban kment the material must be free from vegetable matter and uniformly compacted as itis it Is deposited where the road surface Is to 0 o be of earth the embankment usually inny be compacted sufficiently to prevent injury from shrinkage by spreading the material in relatively thin horizontal layers and letting each layer be compacted by the grading teams as as the succeeding layer Is beling being spread layers of ordinary earth earm not more than 12 inches thick can be compacted fairly well in ili this way provided that the grading teams are made to travel over the entire surface of each layer and that the material Is spread uniformly where the road surface Is to be of some highly improved type each layer of the embankment ban han kment should be rolled thoroughly with it a power roller weighing not less than about ten tons settlement of embankments aside from that due to shrinkage may bb caused by the gradual flattening of the slopes slope sor or by lack of stability of the ground surface over which the embankment to Is constructed The question of ground surface stability usually does not arise as a grading problem except where an embankment Is being constructed ted over very marshy land it proper precautions are not observed the embank benr material may be absorbed gradually by the marsh until the entire roadbed has disappeared an occurrence which to la not infrequent where drainage of odthe the marsh is impracticable the lower portion of the embankment which would come in contact with the water should be formed ot of sony material that will cement together and distribute the weighton weight of lof the embankment over the entire bottom area some varieties of gru gravelly velly clay are excellent for this purpose where the marshy ratter Is very soft and deep it may be necessary to lay a wide foundation bed of logs or fa selnes upon which to fo construct the embank but such a toun foundation dation bed would 1 1 not norl bior aa emi aliv raa 1101 i I 1 ma 4 sur U do roughened sufficiently by plowing ir cf series of rather deep furrows about i two feet apart apar t old rock surfaces ordinarily dina rily are fairly rough to begin with but to prevent slipping it way may be feces sary in joithe some cases to blast steps into such surfaces before depositing embankment ban kment material no matter how the grading of ad an earth road may be accomplished it usually is economical to bring the road surface to its final shape by means of a grading machine in making excavations it is abt generally considered practicable to form the crown and side ditches with scrapers or hand tools alone and the cross section Is therefore frequently left approximately flat the grading machine Is then used I 1 1 1 in n the manner already described described to produce the required cross croas section after the road has been finished ith the grading machine it should bo be given frequent fit attention until the embankments have finished settling and the surface hns has become thoroughly compacted by the action of traffic usually a period of several months should elapse after a rood road la 13 graded before it Is considered complete and such settlements tind and irregularities as develop during this period should be corrected by the use of either a grading ma machine chilLe or a road drag construction costs aside frona from drainage structures the principal item of cost attached to fb the construction construct ioE of aft an earth road Is for thea he grading the cost of grading varies greatly according to the condition of the weather the nature of the material to tb be excavated tho the efficiency of lab labor ar I 1 teams and machinery etc C and seldom can be estimated in advance with any great degree of accuracy on this account average costs based on past experience peri perl enbe ence may inay be very misleading when applied jo to a particular project the first step in estimating the cost of grading a given road Is to ascertain the quantities 0 of work to be done after the quantities have been determined the cost may be estimated in either of two I 1 ways F first arst the organization tor for carrying ing on the work I 1 may be planned in detail and the estimate arrived at by considering the coltof cost of maintaining such buch an organization together with the rote rate at which irmay it may reasonably beeb be ex pecked to the work SP second c the cost per cubic yard for excavation excavation and the cost per ratio mile for shaping the roadway may be estimated tit at flat rates the first method esthe Is the most accurate though the latter Is the one employed roost most frequently |