The foundations are 4 ft. deep and 2½ ft. wide. The walls on top of the foundations are 7 ft. high, 18 ins. wide at the base, and battered up to 14 ins. at the top for wings and 12 ins. at top for walls. The floor is 22 ft. by 18 ft. and 1 ft. thick. The wheel guard is 12 ins. thick by 14 ins. wide and 32 ft. long. The itemized cost of this bridge, containing 73 cu. yds. of concrete, is as follows:
| Materials. | Total. | Per cu. yd. |
| 70 cu. yds. gravel at 70 cts | $ 49.00 | $0.6726 |
| 10 cu. yds. broken stone at 70 cts | 7.00 | 0.0959 |
| 75 bbls. cement at $2.20 | 165.00 | 2.2603 |
| 7,000 lbs. steel rails at 1.15 cts | 80.50 | 1.1027 |
| 1,000 lbs. junk rails at 0.6 cts | 6.00 | 0.0819 |
| 200 ft. B. M. lumber wasted at $29 | 5.80 | 0.0794 |
| 15 lbs. nails at 3 cts | 0.45 | 0.0061 |
| Labor and Supplies: | ||
| 2 days excavation at $14 | 28.00 | 0.3835 |
| ¾ day foundation at $14 | 10.00 | 0.1369 |
| 1½ days building forms at $14 | 21.00 | 0.2876 |
| 2 days filling forms at $14 | 28.00 | 0.3835 |
| Hauling lumber and tools | 8.00 | 0.1096 |
| Hauling cement and tools | 18.00 | 0.2465 |
| Taking off forms | 2.30 | 0.0315 |
| 1,000 lbs. coal at $4 per ton | 2.00 | 0.0274 |
| ——— | ——— | |
| Total cost | $431.05 | $5.9054 |
In round figures the cost per cubic yard of concrete in the finished bridge was $5.90. Summarizing we have the following cost per cubic yard of concrete in place:
| Item. | Per cu. yd. |
| Cement | $2.26 |
| Steel | 1.22 |
| Lumber | 0.22 |
| Gravel and stone | 0.76 |
| Labor | 1.41 |
| Coal | 0.03 |
| —— | |
| Total | $5.90 |
The average cost of concrete in place for all the work done in Greene County by day labor was $6.25 per cu. yd. In the job itemized above the bank caved in, causing an extra expense for removing the earth. The gravel used in this bridge was very good clean river gravel.
METHOD AND COST OF CONSTRUCTING TWO HIGHWAY GIRDER BRIDGES.—The following account of the methods and costs of constructing two slab and beam highway bridge decks on old masonry abutments is taken from records kept by Mr. Daniel J. Hauer. The first bridge was a single span 15 ft. long that replaced wooden stringers and floor that had become unsafe; the second was two short spans of a steel bridge that was too light for the traffic of the road, and it was torn down and moved elsewhere, by the county authorities. The work was done by contract, and in each case consisted of building the reinforced floor and girders on the old masonry walls that were in good condition. While the work was going on traffic was turned off the bridges, fords being used instead. Figure 154 shows a sketch of the cross-section of the floor and girders. In Example I the girders had a depth below the floor of 12 ins. and were of the same width. In Example II the girders were 14 ins. wide and had a depth below the floor of 18 ins. The floors on both bridges were 6 ins. thick. Kahn bars were used for reinforcement.
Fig. 154.—Cross-Section of Concrete Girder Bridge.
Example I.—This bridge was but little more than 5 ft. above the stream, which was shallow and not over 7 ft. wide, unless swollen by floods. The bottom for several hundred feet on either side of the bridge was covered with coarse sand and gravel, that had pebbles in it from the size of a goose egg down. This was taken from the stream by men with picks and shovels and hauled to the site of the work with wheelbarrows, and then screened so as to separate the gravel from the sand. As it was found that the sand was so coarse that it would take more cement than the specifications called for in a 1-2½-5 mixture, some much finer sand was bought and mixed with it. For the privilege of taking the sand from the stream $1 was paid the property owner. This was done to get a receipt and release from him, rather than as an attempt to pay royalty on the gravel and sand. This dollar is included in the cost of the labor in getting these materials.
The cost of materials per cubic yard for the bridge was as given below, the mixture being as stated above. The cement cost $1.40 per barrel, delivered at the bridge.