Highway bridges and culverts . maybe placed close together, or inmany cases it will be sufficient to place them about 3 feet apart,center to center. The advantages of this type of foundation arethat it distributes the pressure and tends to prevent uneven settle-ment or tipping of the side waUs. The suitability of foundations for the more important structures€an be safely determined only by tests. This can be done bestby digging test pits wherever conditions will permit. In this way abetter idea can be gained of the actual material in the foundationthan by any other method. Where conditions do
Highway bridges and culverts . maybe placed close together, or inmany cases it will be sufficient to place them about 3 feet apart,center to center. The advantages of this type of foundation arethat it distributes the pressure and tends to prevent uneven settle-ment or tipping of the side waUs. The suitability of foundations for the more important structures€an be safely determined only by tests. This can be done bestby digging test pits wherever conditions will permit. In this way abetter idea can be gained of the actual material in the foundationthan by any other method. Where conditions do not permit test pits, an iron rod may bedriven to depths of from 10 to 20 feet, unless rock is encounteredbefore that depth is reached. This method, however, gives verylittle idea of the material through which the rod is driven. Asomewhat better way is to drive down 1-inch extra heavy ironpipe, which may be cut into 4-foot lengths and coupled together as Bui. 43, Office of Public Roads, U. S. Dept. of Agriculture. Plate FOUNDATIONS. driven. A driving cap should be provided and the driving shouldbe done with wooden mauls. Pipe has been driven in this mannerin the winter months to depths of about 30 feet or possibly pipe, after being driven, may be pulled out with a small chainand lever, so that a sample of the material through which the pipewas driven may be brought up inside it. This material can thenbe examined as the pipes are uncoupled and cleared out. Materialthat sticks in the pipe may be loosened by placing the 4-foot sectionof pipe in a small fire sufficient to generate steam from the moisturein the material, which, as it expands, forces the material out of thepipe. Great care should be exercised to have only sufficient fire togenerate the steam slowly, or otherwise the material may shootout of the ends of the pipe like a gun, or the pipes may burst or flyout of the fire with sufficient force to injure anyone standing near. .; / Y. -/-i. 77777777$: /;?/ T
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Keywords: ., bookauthorhoytchar, bookcentury1900, bookdecade1910, bookyear1912
