. Economic Papers. mated and the culvert located to fit them. Thisis very important if a permanent culvert is to be used. It is folly tobuild a concrete culvert so short or in such a position that when the roadis improved the culvert must be rebuilt. Small culverts under long fills to take care of backwater can often beeliminated with economy by providing one opening sufficiently condition is met with frequently in the eastern part of the State. In the location of small bridges the following factors which ordinarilyenter into the selection of the site of larger structures may influe
. Economic Papers. mated and the culvert located to fit them. Thisis very important if a permanent culvert is to be used. It is folly tobuild a concrete culvert so short or in such a position that when the roadis improved the culvert must be rebuilt. Small culverts under long fills to take care of backwater can often beeliminated with economy by providing one opening sufficiently condition is met with frequently in the eastern part of the State. In the location of small bridges the following factors which ordinarilyenter into the selection of the site of larger structures may influence thelocation to some degree. A bridge should be located: (1) Where best foundations may be secured. (2) Where the stream is narrow and banks high, thus reducing thecost of construction. (3) Where the stream is straight above and below the bridge. It is possible, sometimes, to reduce the number of bridges required toaccommodate the same travel, as illustrated in Fig. 1, p. 11. COUNTRY ROADS IN NORTPI CAROLINA 1 I. Fig. 1.—Three bridges were eliminated by re-locating this road. SIZE OF OPENING. A culvert should be large enough to provide for all ordinary rainfallwhich may come upon the area it drains. It is not advisable on countryroads to make the size as great as wTould be required by the record break-ing rains which sometimes occur. The damage occasioned by a washoutonce in 15 or 20 years is not sufficient to offset the added cost in makingthe structure large enough to care for the additional water. ~No great refinement in the determination of the area of waterway ispossible or necessary. The convenience and economy of the use ofstandard sizes and designs makes the problem one of determining whichof several standard sizes will be more nearly satisfactory. For example,should a 24-inch pipe, which has an area of square feet, be toosmall, the next size, a 30-inch pipe, would be used, which has an area square feet, or 56 per cent greater than the 24-inch. The same
Size: 2015px × 1240px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookideconomicpape, bookyear1912
