26-FT SPAN ARCH CULVERT.—The culvert was 62 ft. long and 26-ft. span and was built of 1-8 and 1-10 concrete mixed by hand. The wages paid were: General foreman, 40 cts. per hour; foreman, 25 cts. per hour; carpenters, 22½ to 25 cts. per hour, and laborers, 15 cts. per hour. The cost of the concrete in place, exclusive of excavation but including wing walls and parapet, was as follows:
| Per cu. yd. | |
| 0.96 bbl. cement, at $1.60 | $1.535 |
| 1.03 tons coarse gravel, at $0.19 | 0.195 |
| 0.40 tons fine gravel, at $0.21 | 0.085 |
| 0.32 tons sand, at $0.36 | 0.115 |
| Tools, etc. | 0.078 |
| Lumber for forms and centers | 0.430 |
| Carpenter work on forms (23 cts. hr.) | 0.280 |
| Carpenter work platforms and buildings | 0.050 |
| Preparing site and cleaning up | 0.210 |
| Changing trestle | 0.085 |
| Handling materials | 0.037 |
| Mixing and laying, av. 15½ cts. per hr. | 1.440 |
| ——— | |
| Total per cu. yd | $4.540 |
There were 1,493 cu. yds. of concrete in the work. The excavation cost $463 and the total cost was $7,243.
COST OF RAILWAY CULVERT.—The culvert was for a single track railway and contained 113 cu. yds. of concrete and required 36 cu. yds. of excavation. The figures are given by C. C. Williams as follows:
12-FT. CULVERT, KALAMAZOO, MICH.—A portion 1,080 ft. long of a new channel built in 1902-3 for a small stream flowing through the city of Kalamazoo, Mich., was constructed as an arch culvert of the form shown by Fig. 172. The concrete section is reinforced on the lines indicated by a double layer of woven steel wire fabric. The concrete was approximately a 1 cement, 6 sand and gravel mixture.
Fig. 172.—Cross-Section of Culvert at Kalamazoo, Mich.
The centers were built in sections 12½ ft. long of the form and construction shown by Fig. 173, and a sufficient number was provided to lay twelve sections of invert and six sections of arch. The arch centers were arranged to be uncoupled at the crown; this with the hinges at the quarter points permitted the two halves to be separated and each half to be folded so that it could be carried from the rear of the work through the forms still in place and erected again for new work. When in place the center ribs rested on the side forms which set on the invert concrete and are braced apart by the hinged cross-strut. This cross-strut was the key that bound the whole structure together; the method of removing this key is indicated by Fig. 174. From his experience with these centers the engineer of the work, Mr. Geo. S. Pierson, remarks:
"In work of this kind it is very important to have the centering absolutely rigid so it will not spring when concrete is being tamped against it and thus weaken the cohesion of the concrete. It is also important to have the arrangement such that all the centering can be removed without straining or jarring the fresh concrete. The centers were generally removed in about three or four days after the concrete arch was in place."