Examples Op Reinforced-0on0rete Arch 017lverts 0 M

EXAMPLES OP REINFORCED-0ON0RETE ARCH 017LVERTS. 0. M. & St. P. Ry. Fig. 177 and 178, page 600, show the cross sections of two 8-foot reinforced-concrete semicircular arch culverts as built by the Chicago, Milwaukee and St. Paul Railway, and Fig.

179 shows the cross section of a three-centered arch culvert on the same road.* Fig. 177 was designed for a 16-ft. embankment, and Fig. 178 for a 32-ft. fill; and Fig. 179 also was designed for a 16-ft.

embankment. Fig 177 is supposed to give a bearing on the soil of 1.9 tons per sq. ft., and Fig. 178 and 179 are supposed to give 1.8 tons per sq. ft. The relative cost of the first two is shown in Table 88, page 605, and the center and forms used in constructing the third is shown in Fig. 180.

Illinois Central E. B. Fig. 181, page 602, shows the corn

plete drawings for a 16-ft. reinforced-concrete under-grade highway crossing built by the Illinois Central at Gilbertsville, Ky., which is representative of the practice of that road except that for a culvert proper the wings would usually be flared.* Notice that the inside face of the bench wall and of the wing are vertical, and compare with Fig. 175, page 599. On account of this structure's being in a city, false joints were marked on the arch ring, by nailing triangular strips on the inside of the concrete forms. Fig. 182, page 603,

shows the details of the cornice; and Fig. 183, page 603, shows the method of finishing all exposed edges. All exposed faces of the arch ring and parapet wall have a 1finch coat of facing mortar.

The structure shown in Fig. 181, page 602, contains 195 cu. yd. of concrete and 11,764 lb. of corrugated bars or 65 Ib. per cu. yd.

Fig. 184, page 604, shows a 20-ft. reinforced-concrete arch culvert as built by the Lake Shore and Michigan Southern Railway.t Notice that the side wall is plumb on the inside and that the face of the wing is battered, the portion of the wing projecting beyond the plane of the inside of the bench wall being cut away, as shown by the shaded portion abed.

This structure was built against the end of an old arch, the barrel of the new arch being 75 ft. 7 in. long. The structure con tains 943 cu. yd. of concrete in the arch ring and 132 in the wing walls, a total of 1,075 cu. yd.; and the arch ring contains 33,689 lb. of corrugated bars, and the footings 1,008 lb., a total of 34,697 lb. of steel. The arch ring contains 37 lb. of steel per cu. yd., and the foot ing 7 lb. The concrete was mixed 1 : 2i : 5, and required 5,590 sacks of cement, 495 cu. yd. of sand, and 990 cu. yd. of stone.