. Automotive industries . SUBGRAOE TREATED WITH WATER GAS WALL OF CRUDE WATER GASTAR-EARTH MIX, Tilt SIDE DRAIN AND STONE SHOULDERS Fig. 18—Road sections showing different drainage schemes grained and more porous soils are free from suchtrouble. An attempt will be made by the Bureau of PublicRoads to grade all soils with respect to their bearingvalue. Subgrade failures have occurred in many partsof the country where drainage was employed, but in viewof the fact that in the cities very heavy traffic is suc-cessfully supported on light section pavements, the con-clusion is arrived at
. Automotive industries . SUBGRAOE TREATED WITH WATER GAS WALL OF CRUDE WATER GASTAR-EARTH MIX, Tilt SIDE DRAIN AND STONE SHOULDERS Fig. 18—Road sections showing different drainage schemes grained and more porous soils are free from suchtrouble. An attempt will be made by the Bureau of PublicRoads to grade all soils with respect to their bearingvalue. Subgrade failures have occurred in many partsof the country where drainage was employed, but in viewof the fact that in the cities very heavy traffic is suc-cessfully supported on light section pavements, the con-clusion is arrived at that the drainage of our roads inmany cases is not very effective during the wet season. The next step in the Bureau of Public Roads investiga-tion therefore was a series of tests on road drainagewhich was carried out at Arlington Farms, Va. The. Fig 19 il view of < m tructioti for road drainage U i( ideas underlying these tests are illustrated in Fig. Drainage The idea occurred to the officials in charge of thetests to try whether it was not possible to exclude waterfrom the subgrade by the use of water proofing mate-rials. This, of course, involves principles diametricallyopposite to those on which the present drainage systemis based, which only serves to carry away the waterafter it has saturated the subgrade and rendered itextremely soft. At 1 (Fig. 18) is shown an ordinary con-crete pavement on natural earth subgrade with drain-age ditches 2 4 ft. deep on both sides. At 2 this construc-tion is varied by providing at bothedges of the concrete pavementscreened gravel walls with a coveringof impervious material, the walls form-ing a sort of blind ditches of the samedepth as the drainage ditches withwhich they communicate through 3 the concrete slab is laid on a 3 gravel subbase from whicht
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectaeronautics, bookyear
