18-ft. Arch Culvert.—Mr. H. M. Jones is authority for the following data: An 18-ft. full-centered arch culvert was built by contract, near Paris, Tenn. The culvert was built under a trestle 65 ft. high, before filling in the trestle. The railway company built a pile foundation to support a concrete foundation 2 ft. thick, and a concrete paving 20 ins. thick. The contractors then built the culvert which has a barrel 140 ft. long. No expansion joints were provided, which was a mistake for cracks have developed about 50 ft. apart. The contractors were given a large quantity of quarry spalls which they crushed in part by hand, much of it being too large for the concrete. The stone was shipped in drop-bottom cars and dumped into bins built on the ground under the trestle. The sand was shipped in ordinary coal cars, and dumped or shoveled into bins. The mixing boards were placed on the surface of the ground, and wheelbarrow runways were built up as the work progressed. The cost of the 1,900 cu. yds. of concrete in the culverts was as follows per cu. yd.:
| 1.01 bbls. Portland cement | $2.26 |
| 0.56 cu. yds. of sand, at 60 cts. | .32 |
| Loading and breaking stone | .25 |
| Lumber, centers, cement house and hardware | .64 |
| Hauling materials | .04 |
| Mixing and placing concrete | 1.17 |
| Carpenter work | .19 |
| Foreman (100 days at $2.50) | .13 |
| Superintendent (100 days at $5.50) | .29 |
| ——— | |
| Total per cu. yd. | $5.29 |
It will be seen that only 19 cu. yds. of concrete were placed per day with a gang that appears to have numbered about 21 laborers, who were negroes receiving about $1.10 per day. This was the first work of its kind that the contractors had done. It will be noticed that the cost of 42 cts. per cu. yd. for superintendence and foremanship was unnecessarily high.
Six Arch Culverts 5 ft. to 16 ft. Span.—All these arches were built under existing trestles, and in all cases, except No. 2, bins were built on the ground under the trestle and the materials were dumped from cars into the bins, loaded and delivered from the bins in wheelbarrows to the mixing boards, and from the mixing boards carried in wheelbarrows to place. Negro laborers were used in all cases, except No. 5, and were paid 90 cts. a day and their board, which cost an additional 20 cts.; they worked under white foremen who received $2.50 to $3 a day and board. In culvert No. 5, white laborers, at $1.25 without board, were used. There were two carpenters at $2 a day and one foreman at $2.50 on this gang, making the average wage $1.47 each for all engaged. The men were all green hands, in consequence of which the labor on the forms in particular was excessively high. The high rate of daily wages on culverts Nos. 1 and 3 was due to the use of some carpenters along with the laborers in mixing concrete. The high cost of mixing concrete on culvert No. 2 was due to the rehandling of the materials which were not dumped into bins but onto the concrete floor of the culvert and then wheeled out and stacked to one side. The cost of excavating and back-filling at the site of each culvert is not included in the table, but it ranged from 70 cts. to $2 per cu. yd. of concrete.
Cost of Six Concrete Culverts on the N., C. & St. L. Ry. & St. L. Ry.
| No. of culvert | 1 | 2 | 3 | 4 | 5 | 6 |
| Span of culvert | 5 ft. | 7.66 ft. | 10 ft. | 12 ft. | 12 ft. | 16 ft. |
| Cu. yds. of concrete. | 210 | 199 | 354 | 292 | 406 | 986 |
| Ratio of cement to stone | 1:5.5 | 1:6.5 | 1:5.8 | 1:5.8 | 1:6.1 | 1:6.5 |
| Increase of concrete over stone | 16.0% | 9.9% | 6.3% | 12.3% | 8.3% | 5.3% |
| Bbls. cement per cu. yd. | 1.02 | 0.90 | 1.06 | 1.01 | 1.00 | 1.09 |
| Cu. yds. sand per cu. yd. | 0.43 | 0.49 | 0.44 | 0.46 | 0.46 | 0.47 |
| Cu. yds. stone per cu. yd. | 0.86 | 0.90 | 0.95 | 0.89 | 0.94 | 0.94 |
| Total day labor (inc. foremen and supt.) | 702 | 607 | 784 | 726 | 768 | 1,994 |
| Av. wages per day (inc. foremen and supt.) | $1.61 | $1.33 | $1.59 | $1.19 | $1.47 | $1.46 |
| Cost per cu. yd.— | ||||||
| Cement | 2.18 | 1.94 | 2.27 | 1.82 | 2.11 | 2.01 |
| Sand | 0.17 | 0.20 | 0.18 | 0.18 | 0.19 | 0.14 |
| Stone | 0.52 | 0.52 | 0.47 | 0.54 | 0.47 | 0.58 |
| Lumber | 0.88 | 0.43 | 0.48 | 0.43 | 0.31 | 0.57 |
| Unload, materials | 0.23 | 0.17 | 0.18 | 0.18 | 0.16 | |
| Building forms | 1.07 | 0.33 | 0.62 | 0.47 | 0.72 | 0.41 |
| Mixing & placing | 1.59 | 1.74 | 1.69 | 1.35 | 1.23 | 1.26 |
| ——— | ——— | ——— | ——— | —— | —— | |
| Total per cu. yd. | $6.64 | $5.33 | $5.89 | $4.97 | $5.19 | $4.97 |
14-ft. 9-in. Arch Culvert.—Mr. W. H. Whorley gives the following methods and cost of constructing a 12-ft. full centered arch culvert 204 ft. long. The culvert was built in three sections, separated by vertical transverse joints to provide for expansion; the end sections were each 61 ft. long and the center section was 70 ft. long. Fig. 170 is a cross-section at the center; for the end sections the height is 14 ft. 9 ins., the crown thickness is 1 ft. 9 ins., and the side walls at their bases are 5 ft. thick. The concrete was a 1-3-6 mixture, using slag aggregate for part of the work and stone aggregate for a part. The culvert was built underneath a trestle which was afterwards filled in.
Mixing and Handling Concrete.—The height of the track above the valley permitted the mixing plant to be so laid out that all material was moved by gravity from the cars in which it was shipped until finally placed in the culvert. Sand and aggregate were received in drop bottom cars and were unloaded into bins in the trestle. These bins had hopper bottoms with chutes leading to a wheeling platform, which was placed between two trestle bents and extended over a mixer placed outside the trestle. The cement house was erected alongside the trestle at the wheeling platform level and a chute from an unloading platform at track level to the opposite end of the house enabled the bags to be handled directly from the car to the chute and thence run by gravity to the cement house. Sand and aggregate were chuted from the bins into wheelbarrows, wheeled about 23 ft., and dumped into a hopper over the mixer. Water was pumped by a gasoline engine from a well just below the trestle to a tank on the trestle, whence it was fed to the mixer by a flexible connection, a valve so regulating the flow that the necessary amount was delivered in the time required to mix a batch.
Fig. 170.—Section of Arch Culvert, N., C. & St. L. R. R.