"The method used in moving these forms ahead for another day's work is probably one of the secrets of the low cost of this work, and it is one which we have never seen employed before. The bolt at A, Fig. 256, was taken out, and the tie brace B thrown up. We had hooks at the points C. A turnbuckle was thrown in, catching these hooks, and given several sharp turns, causing the entire form to spring downward and inwards, which gave it just enough clearance to be carried forward, without doing any more striking of forms than pulling the bolt at A. This method of pulling the forms worked absolutely satisfactorily, and never gave any trouble, and we were able to move the forms very late in the day and get them all set for next day's work, giving all the concrete practically 24 hours' set, as we always started concreting in the morning at the furthest end of the form set up and at the greatest distance from the old concrete possible in the 48 ft. length, as the furthest form had, of course, to be moved first, it being impossible to pass one form through the other.
"Six 16-ft. sections of these forms were built, and three were used each day on each end, as shown by the diagram MN, Fig. 256, which gives the day for the month for the completion of each of seven 48-ft. sections.
"A gang of men simply shifted on alternate days from end to end of the conduit, although several sections were in progress at one time; and of course, finally, when a junction was made between any division, say of 1,000 ft. to another 1,000 ft., one small form was left in at this junction inside of the conduit, and had to be taken down and taken out the entire length of the conduit.
"The centers for a 16-ft. length of this conduit cost complete for labor and material, $18.30, but they were used over and over again; and, after this conduit was completed, they were taken away for use at other points, so that the cost is hardly appreciable, and the only charge to centers that we made after the first cost of building the centers, was on account of moving them daily. Part of this conduit was built double (two 6-ft. conduits) and part single, the only difference being that, where the double conduit was built, two forms were placed side by side, and not so much was undertaken in one day.
"These conduits, when completed and dried out, rung exactly like a 60-in. cast-iron pipe, when any one walked through them or stamped on the bottom."
Mr. Woollard gives the following analysis of the cost per cubic yard of the concrete-steel conduit above described:
| Per cu. yd. | |
| 1.3 bbl. cement | $1.43 |
| 10 cu. ft. sand | 0.35 |
| 25 cu. ft. stone | 1.10 |
| 26 sq. ft. expanded metal, at 3 cts. | 0.78 |
| Loading and hauling materials 2,000 ft. to the mixing board (team at $4.50) | 0.50 |
| Labor mixing, placing, and ramming | 1.38 |
| Labor moving forms | 0.60 |
| —— | |
| Total | $6.14 |
Wages were 17½ cts. per hr. for laborers and 50 cts. per hr. for foremen. The concrete was 1-2-5, a barrel being assumed to be 3.8 cu. ft. The concrete was mixed by hand on platforms alongside the conduit. The cost of placing and ramming was high, on account of the expanded metal, the small space in which to tamp, and to the screeding cost. When forms were moved they were scraped and brushed with soft soap before being used again.
From Mr. Morris R. Sherrerd, Engineer and Superintendent, Department of Water, Newark, N. J., we have received the following data which differ slightly from those given by Mr. Woollard. The differences may be explained by the fact that the cost records were made at different times. Mr. Sherrerd states (Sept. 26, 1904,) that each batch contains 4 cu. ft. of cement, 8 cu. ft. of sand, and 20 cu. ft. of stone, making 22 cu. ft. of concrete in place. One bag of cement is assumed to hold 1 cu. ft. He adds that a 10-hour day's work for a gang is 63 lin. ft. of single 6-ft. conduit containing 47.4 cu. yds. of concrete and 1,260 sq. ft. of expanded metal. This is equivalent to ¾ cu. yd. of concrete per lin. ft. The total cost of material for one complete set of forms 64 ft. long was $160; and there were 7 of these sets required to keep two gangs of men busy, each gang building 63 lin. ft. of conduit a day. Since the total length of the conduit was 3,850 ft., the first cost of the material in the forms was 18 cts. per lin. ft.
Cost of Labor on 6-ft. Conduit: