Chapter VIII.

~WALLS IN TRENCH.~--In canal excavation, in subway work in cities, and the like, it is often necessary to dig trenches and build retaining walls in them before excavating the core of earth between the walls. The following examples of such work are taken from personal records: _Example I._--A Smith mixer was used, the concrete being delivered where wanted by a Lambert cableway of 400 ft. span. The broken stone and sand were delivered near the work in hopper-bottom cars which were dumped through a trestle onto a plank floor. Men loaded the material into one-horse dump carts which hauled it 900 ft. to the mixer platform. This platform was 24×24 ft. square, and 5 ft. high, with a planked approach 40 ft. long and contained 7,300 ft. B. M. The stone and sand were dumped at the mouth of the mixer and shoveled in by 4 men. Eight men, working in pairs, loaded the broken stone into the carts, and 2 men loaded the sand. Each cart was loaded with about 70 shovelfuls of stone on top of which 35 shovelfuls of sand were thrown. It took 3 to 5 minutes to load on the stone and 1 minute to load the sand. The carts traveled very slowly, about 150 ft. a minute--in fact, all the men on the job, including the cart drivers, were slow. After mixing, the concrete was dumped into iron buckets holding 14 cu. ft. water measure, making about ½ cu. yd. in a batch. The buckets were hooked on to the cableway and conveyed where wanted in the wall. Steam for running the mixer was taken from the same boiler that supplied the cableway engine. The average output of this plant was 100 cu. yds. of concrete per 10-hour day, although on many days the output was 125 cu. yds., or 250 batches. The cost of mixing and placing was as follows, on a basis of 100 cu. yds. per day: Per day. Per cu. yd. 8 men loading stone into carts $12.00 $ .12 2 men loading sand into carts 3.00 .03 1 cart hauling cement 3.00 .03 8 carts hauling stone and sand 24.00 .24 4 men loading mixer 6.00 .06 1 man dumping mixer 1.50 .01 2 men handling buckets at mixer 3.00 .03 6 men dumping buckets and ramming 9.00 .09 12 men making forms at $2.50 30.00 .30 1 cable engineman 3.00 .03 1 fireman 2.00 .02 1 foreman 6.00 .06 1 waterboy 1.00 .01 1 ton coal for cableway and mixer 4.00 .04 ------- ----- Total $107.50 $1.07 In addition to this cost of $1.07 per cu. yd. there was the cost of moving the whole plant for every 350 ft. of wall. This required 2 days, at a cost of $100, and as there were about 1,000 cu. yds. of concrete in 350 ft. of wall 16 ft. high, the cost of moving the plant was 10 cts. per cu. yd. of concrete, bringing the total cost of mixing and placing up to $1.17 per cu. yd. As above stated, the whole gang was slow. The labor cost of making the forms was high, for such simple and heavy work, costing $10 per M. of lumber placed each day. The forms were 2-in. sheeting plank held by 4×6-in. upright studs 2½ ft. apart, which were braced against the sides of the trench. The face of the forms was dressed lumber and all cracks were carefully puttied and sandpapered. The above costs relate only to the massive part of the wall and not the cost of putting in the facing mortar, which was excessively high. The face mortar was 2 ins. thick, and about 3½ cu. yds. of it were placed each day with a force of 8 men! Two of these men mixed the mortar, 2 men wheeled it in barrows to the wall, 2 men lowered it in buckets, and 2 men put it in place on the face of the wall. If we distribute this labor cost on the face mortar over the 100 cu. yds. of concrete laid each day, we have another 12 cts. per cu. yd.; but a better way is to regard this work as a separate item, and estimate it as square feet of facing work. In that case these 8 men did 500 sq. ft. of facing work per day at a cost of nearly 2½ cts. per sq. ft. for labor. _Example II._--The building of a wall similar to the one just described was done by another gang as follows: The stone and sand were delivered in flat cars provided with side boards. In a stone car 5 men were kept busy shoveling stone into iron dump buckets having a capacity of 20 cu. ft. water measure. Each bucket was filled about two-thirds full of stone, then it was picked up by a derrick and swung over to the next car which contained sand, where two men filled the remaining third of the bucket with sand. The bucket was then lifted and swung by the derrick over to the platform of the mixer where it was dumped and its contents shoveled by four men into the mixer, cement being added by these men. The mixer was dumped by two men, loading iron buckets holding about ½ cu. yd. of concrete each, which was the size of each batch. A second derrick picked up the concrete bucket and swung it over to a platform where it was dumped by one man; then ten men loaded the concrete into wheelbarrows and wheeled it along a runway to the wall. One man assisted each barrow in dumping into a hopper on the top of a sheet-iron pipe which delivered the concrete. The two derricks were stiff-leg derricks with 40-ft. booms, provided with bull-wheels, and operated by double cylinder (7×10-in.) engines of 18-HP. each. About 1 ton of coal was burned daily under the boiler supplying steam to these two hoisting engines. The output of this plant was 200 batches or 100 cu. yds. of concrete per 10-hr. day, when materials were promptly supplied by the railroad; but delays in delivering cars ran the average output down to 80 cu. yds. per day. On the basis of 100 cu. yds. daily output, the cost of mixing and placing the concrete was as follows: Per day. Per cu. yd. 5 men loading stone $ 7.50 $.07½ 2 men loading sand 3.00 .03 4 men charging mixer 6.00 .06 2 men loading concrete into buckets 3.00 .03 1 man dumping concrete from buckets .50 .01½ 10 men loading and wheeling concrete .00 .15 1 man dumping wheelbarrows 1.50 .01½ 3 men spreading and ramming 4.50 .04½ 2 enginemen 5.00 .05 1 fireman 2.00 .02 1 waterboy 1.00 .01 1 foreman 6.00 .06 10 men making forms 25.00 .25 1 ton coal 4.00 .04 Total 85.00 $.85 In addition there were 8 men engaged in mixing and placing the 2-in. facing of mortar as stated above. ~CHICAGO DRAINAGE CANAL.~--The method and cost of constructing some 20,000 ft. of concrete wall by contract in building the Chicago Drainage Canal is compiled from records kept by Mr. James W. Beardsley. The work was done on two separate sections, Section 14 and Section 15. In both cases a 1-1½-4 natural cement concrete was used with a 3-in. facing and a 3-in. coping of 1-3 Portland cement mortar. _Section 14._--The average height of the wall was 10 ft., and the thickness at base was one-half the height. The stone for the concrete was obtained from the spoil bank of the canal, loaded into wheelbarrows and wheeled about 100 ft. to the crusher; some was hauled in wagons. An Austin jaw crusher was used, and it discharged the stone into bins from which it was fed into a Sooysmith mixer. The crusher and the mixer were mounted on a flat car. Bucket elevators were used to raise the stone, sand and cement from their bins to the mixer; the buckets were made of such size as to give the proper proportions of ingredients, as they all traveled at the same speed. Only two laborers were required to look after the elevators. The sand and cement were hauled by teams and dumped into the receiving bins. There were 23,568 cu. yds. on Section 14 and the cost was as follows: Typical Wages per Cost per General force: force. 10 hrs. cu. yd. Superintendent 1.0 $5.00 $0.026 Blacksmith 1.1 2.75 0.016 Timekeeper 0.5 2.50 0.007 Watchman 0.6 2.00 0.007 Waterboys 3.9 1.00 0.022 Wall force: Foreman 0.9 2.50 0.013 Laborers 8.6 1.50 0.073 Tampers 2.3 1.75 0.022 Mixer force: Foreman 1.2 2.50 0.017 Enginemen 1.8 2.50 0.025 Laborers 6.7 1.50 0.057 Pump runner 1.0 2.00 0.010 Mixing machines 1.7 1.25 0.012 Timber force: Foreman 0.6 2.50 0.008 Carpenters 4.7 2.50 0.057 Laborers 1.2 1.50 0.010 Helpers 5.3 2.50 0.075 Hauling force: Laborers 2.6 1.75 0.026 Teams 6.3 3.25 0.116 Crushing force: Foreman 0.5 2.50 0.007 Engineman 1.7 2.50 0.023 Laborers 3.5 1.50 0.032 Austin crushers 1.7 1.20 0.011 Loading stone: Foreman 1.7 2.50 0.023 Laborers 32.9 1.50 0.280 ------ Total for crushing, mixing and placing $0.975 The daily costs charged to the mixers and crushers include the cost of coal, at $2 a ton, and the cost of oil. The gang "loading stone" apparently did a good deal of sledging of large stones, and they also wheeled a large part of it in barrows to the crusher. The plant cost $9,600, distributed as follows: 2 jaw crushers $3,000 2 mixers 3,000 Track 1,260 Lumber 500 Pipe 840 Sheds 400 Pumps 600 ----- Total $9,600 If this first cost of the plant were distributed over the 23,568 cu. yds. of concrete it would amount to 41 cts. per cu. yd. The cost of the concrete was as follows: Per cu. yd. Utica cement, at $0.65 per bbl. $0.863 Portland cement, at $2.25 per bbl. 0.305 Sand, at $1.35 per cu. yd. 0.465 Stone and labor, as above given 0.975 ------ Total $2.608 First cost of plant $0.407 _Section 15._--The conditions on this section were much the same as on Section 14, just described, except that the limestone was quarried from the bed of the canal, and was crushed in a stationary crusher, No. 7 Gates. The stone was hauled 1,000 ft. to the crusher on cars drawn by a cable from a hoisting engine. The output of this crusher averaged 210 cu. yds. per day of 10 hrs. The crushed stone was hauled in dump cars, drawn by a locomotive, to the mixers. Spiral screw mixers mounted on flat cars were used, and they delivered the concrete to belt conveyors which delivered the concrete into the forms. The forms on Section 15 (and on Section 14 as well) consisted of upright posts set 8 ft. apart and 9 ins. in front of the wall, held at the toe by iron dowels driven into holes in the rock, and held to the rear posts by tie rods. The plank sheeting was made up in panels 2 ft. wide and 16 ft. long, and was held up temporarily by loose rings which passed around the posts which were gripped by the friction of the rings. These panels were brought to proper line and held in place by wooden wedges. After the concrete had set 24 hrs. the wedges were struck, the panels removed and scraped clean ready to be used again. The cost of quarrying and crushing the stone, and mixing the concrete on Section 15 was as follows: Typical Wages per Cost per General force-- force. 10 hrs. cu. yd. Superintendent 1.0 $5.00 $0.024 Blacksmith 0.9 2.75 0.011 Teams 1.7 3.00 0.025 Waterboy 4.5 1.00 0.022 Wall force-- Foreman 1.1 2.50 0.010 Laborers 14.4 1.50 0.105 Tampers 0.1 1.75 0.001 Mixer force-- Foreman 2.1 2.50 0.026 Enginemen 2.1 2.50 0.022 Laborers 23.1 1.50 0.180 Mixing machines 2.1 1.25 0.022 Timber force-- Carpenters 0.8 3.00 0.013 Laborers 0.7 1.50 0.005 Helpers 10.2 2.50 0.125 Hauling force-- Foreman 0.7 2.50 0.009 Enginemen 1.4 2.50 0.019 Fireman 0.4 1.75 0.003 Brakeman 2.2 2.00 0.018 Teams 0.4 3.25 0.007 Laborers 1.5 1.50 0.010 Locomotives 1.4 2.25 0.015 Crushing force-- Foreman 1.0 2.50 0.014 Enginemen 1.0 2.50 0.014 Laborers 11.1 1.50 0.081 Firemen 1.0 1.75 0.008 Gyratory crusher 1.0 2.25 0.011 Quarry force-- Foreman 1.2 2.50 0.012 Laborers 19.0 1.50 0.140 Drillers 1.8 2.00 0.017 Drill helpers 1.8 1.50 0.013 Machine drills 1.8 1.25 0.011 ------ $0.993 The first cost of the plant for this work on Section 15 was $25,420, distributed as follows: 1 crusher, No. 7 Gates $12,000 Use of locomotive 2,200 Car and track 5,300 3 mixers 3,000 Lumber 1,200 Pipe 720 Small tools 1,000 ------- Total $25,420 This $25,420 distributed over the 44,811 cu. yds. of concrete amounts to 57 cts. per cu. yd. It will be noted that 2 mixers were kept busy. Their average output was 100 cu. yds. each per day, which is the same as for the mixers on Section 14. The total cost of concrete on Section 15 was as follows: Per cu. yd. Labor quarrying, crushing and mixing $0.991 Explosives 0.083 Utica cement, at $0.60 per bbl. 0.930 Portland cement, at $2.25 per bbl. 0.180 Sand, at $1.35 per cu. yd. 0.476 ------ Total $2,660 First cost of plant $0.567 It is not strictly correct to charge the full first cost of the plant to the work as it possessed considerable salvage value at the end. _Comparison._--For the purpose of comparing Sections 14 and 15 the following summary is given of the cost per cubic yard of concrete: Sec. 14. Sec. 15. General force $0.078 $0.082 Wall force 0.108 0.116 Mixing force 0.121 0.250 Timbering force 0.150 0.140 Hauling force 0.142 0.081 Crushing force 0.073 0.128 Quarry force 0.303 0.275 Cement, natural 0.863 0.930 Cement, Portland 0.305 0.180 Sand 0.465 0.476 Plant (full cost) 0.407 0.567 ------ ------- Total $3.015 $3.225 It should be remembered that on Section 14 there was no drilling and blasting of the rock, but that the "quarry force" not only loaded but hauled the stone to the crusher. The cost of mixing on Section 15 is higher than on Section 14 because the materials were dumped on platforms and shoveled into the mixer, instead of being discharged from bins into the mixer as on Section 14. [Illustration: Fig. 108.--Cross Section of Retaining Wall. New York Central Terminal Work.] [Illustration: Fig. 109.--Portable Concrete Mixing Tower, N. Y. Central Terminal Work.] ~GRAND CENTRAL TERMINAL, NEW YORK, N. Y.~--In building a retaining wall of the cross-section, shown in Fig. 108, a traveling tower moving on tracks parallel to the wall contained the concrete mixing plant. The construction of the tower is shown in Fig. 109. The tower had two platforms, one at the top carrying two 10-cu. yd. bins for sand and stone and the other directly below carrying 40 cu. ft. (4 cu. ft. cement, 12 cu. ft. sand and 24 cu. ft. stone) Ransome mixer driven by a 30 H.P. motor and a Lidgerwood motor hoist. The elevator tower carried two 40-cu. ft. Ransome dumping buckets traveling in guides and dumping automatically into the bins. These buckets were operated by the Lidgerwood motor hoist on the mixer platform. Sand and broken stone on flat cars were brought alongside the tower. The sand was shoveled direct from the car into the sand bucket, but the broken stone was shoveled into wheelbarrows which were wheeled over a light bridging from car to bucket and dumped. Wheelbarrows were used for handling the stone chiefly because the capacity of the plant was so great that enough men could not be worked in the limited space around the bucket to keep up the supply by shoveling. The wheelbarrow work added materially to the cost. Cement was carried from the cars to the sand bucket, hoisted and stored on the mixer platform which provided storage room for 100 bags. A 1-3-6 mixture was used; the sand and stone were chuted directly from the bins to the charging hopper and the cement was charged by hand. The mixed concrete was delivered to two 1 cu. yd. dump cars running on a 2-ft. gage track laid in sections on the cross pieces connecting the uprights of the forms. The track had no switches, so that one car had to wait for the other. Four men were required to push each car and two more men assisted in dumping the car and kept the track clear. The wall was built in sections 51 ft. long, each containing 250 cu. yds. One of these sections was filled in 8 hours with ease and by a little hustling a section was filled in 6¾ hours, which is at the rate of 37 cu. yds. of concrete per hour. Working 8 hours per day the cost of mixing, transporting and placing concrete with this mixing plant, with wages for common labor of $1.50 per day, was as follows: Total. Per cu. yd. 2 men carrying cement $ 3.00 $0.012 6 men shoveling sand 9.00 0.036 17 men shoveling stone 25.00 0.100 11 men wheeling stone 16.00 0.064 2 men at stone and sand bins 3.00 0.012 2 men opening cement bags 3.00 0.012 1 man dumping hopper 1.50 0.006 1 man dumping mixer 1.50 0.006 1 man cleaning chute, mixer, etc. 1.50 0.006 1 motorman or engineer 3.00 0.012 ------- ------- Total labor mixing $66.50 $0.266 8 men pushing 2 cars 12.00 0.048 2 men cleaning track, etc. 3.00 0.012 7 men spading concrete 10.50 0.042 ------- ------- Total labor transporting, placing $ 25.50 $0.102 1 foreman 5.00 0.020 Electricity estimated 7.00 0.028 ------- ------- Total general $ 12.00 $0.048 Grand total $104.00 $0.416 It will be noted that the cost of shoveling and wheeling the broken stone amounts to 16.4 cts. per cu. yd., or nearly 40 per cent. of the total cost of mixing and placing. The cost of spading the concrete is also high for a sloppy mixture, but is probably accounted for by the fact that the concrete had to be spaded so as to have 2 or 3 ins. of clear mortar next the forms. The forms used in constructing the wall are shown by Figs. 110 and 111. They were made in panels 51 ft. long and a locomotive crane was used to shift the panels. This crane worked handling forms only a small part of the time, but a form gang of 10 carpenters was kept busy all of the time moving and reassembling. Assuming the work of the crane to amount to $5 per day and the wages of the carpenter gang to amount to $25, we get a cost of 12 cts. per cubic yard of concrete for shifting forms. It should be noted carefully that the costs given for this work do not include cost of materials, interest on plant, superintendence and other items. [Illustration: Fig. 110.--End View of Forms for Retaining Wall, New York Central Terminal Work.] ~WALL FOR RAILWAY YARD.~--For building a retaining wall 7 ft. high, forms were made and placed by a carpenter and helper at $8 per M., wages being 35 cts. and 20 cts. an hour, respectively. Concrete materials were dumped from wagons alongside the mixing board. Ramming was unusually thorough. Foreman expense was high, due to small number in gang; 2 cu. yds. were laid per hour by the gang. [Illustration: Fig. 111.--Corner Detail of Retaining Wall Forms, New York Central Terminal Work.] Per day. Per cu. yd. 7 mixers, 15 cts. per hour $10.50 $0.53 2 rammers, 15 cts. per hour 3.00 0.15 1 foreman 30 cts. per hr., 1 waterboy 5 cts. 3.50 0.17 ------- ------ Total labor $17.00 $0.85 The total cost was as follows per cubic yard: Per cu. yd. 0.8 bbls. Portland cement, at $2 $1.60 Sand 0.30 Gravel 0.70 Labor mixing and placing 0.85 Lumber for forms, at $16 per M. 0.56 Labor on forms, at $8 per M. 0.28 ------ Total, per cubic yard $4.29 The sheathing plank for the forms was 2-in. hemlock. ~CONCRETE FOOTING FOR RUBBLE MASONRY RETAINING WALL.~--In constructing a footing for a retaining wall at Grand Rapids, Mich., a 1-2½-5 natural cement concrete was used. It was found that 1 cu. yd. of concrete was equivalent to 29.8 cu. ft. of material composed of 3.6 cu. ft. or 1.1 bbls. of cement, 8.4 cu. ft. or 2.7 bbls. of sand and 17.8 cu. ft. or 5.5 bbl. of broken stone. The labor cost of 15.5 cu. yds. of concrete was as follows: Item. Total. Per cu. yd. Foreman, 14 hours at 40 cts. $ 5.60 $0.3613 Foreman, 20 hours at 22.5 cts. 4.50 0.2903 Laborers, 49 hours at 12.5 cts. 6.11 0.3942 Mason, 2 hours at 35 cts. 0.70 0.0451 ------ -------- Total labor $16.91 $1.0909 All material was furnished by the railway company, the contractor furnishing labor only; his contract price for this was $1 per cu. yd. ~TRACK ELEVATION, ALLEGHENY, PA.~--The wall was 6,100 ft. long and 75 per cent. was on curves. The first wall built had a top width of 2½ ft. and a bottom width of 0.4 the height with the back on a smooth batter. Later the back was stepped and last the wall was proportioned as follows: Calling the height from top of foundation to under coping, then width of base was 0.45 (h + 3), the top measuring 2½ ft. The back was arranged in steps 24 ins., 30 ins. and 36 ins. high, and the thickness of wall at each step was, calling h equal to height of step from base, 0.45 (h + 3). Several forms of expansion joints were tried. The first was tarred paper extending through the wall every 50 ft.; the second was ½-in. boards running through the wall every 50 ft.; the third was ½-in. board extending 2 ft. into the wall, with a ¼-in. cove at the angles, every 25 ft. The third construction gave perfect satisfaction. A 1-2-5 natural cement and a 1-3-6 Portland cement concrete mixed fairly wet were used. The concrete was laid in 8-in. courses and faced with a 1-2 mortar. The forms were 2-in. white pine faced and jack planed on the edges; upon removal of the forms board marks and other defects were removed and a wash of neat cement was applied. One contractor used hand mixing. The sand and gravel were measured in wheelbarrows and wheeled onto the platform; the sand and cement were spread in thin layers, one over the other, and thoroughly mixed dry; the gravel was then spread over the mixture, the whole was shoveled into barrows or the pit again shoveled into place and rammed. The other contractor used a cubical mixer. A charging box holding 1¼ cu. yds. and graduated to show the correct proportions of sand and gravel was filled by shoveling; cement was placed on top and the box hoisted and dumped into the mixer. A barrel holding the correct amount of water was emptied into the mixer which was turned 10 or 15 times and discharged into cars. The costs of mixing by hand and by machine were as follows: Hand mixing. Total. Per cu. yd. ½ foreman at $3 $ 1.50 $0.025 3 men wheeling barrows at $1.50 4.50 0.075 10 men wheeling materials at $1.50 15.00 0.250 3 men mixing sand and gravel at $1.50 4.50 0.075 6 men mixing concrete at $1.50 9.00 0.150 1 man sprinkling at $1.50 1.50 0.025 ------ ------ Total $36.00 $0.600 The output of the hand mixing gang was 60 cu. yds. per day. Machine mixing. Total. Per cu. yd. 1 foreman at $3.50 $ 3.50 $0.035 1 stationary engineer at $3 3.00 0.030 ½ foreman at $1.75 0.87 0.009 15 men loading charging bucket at $1.50 22.50 0.225 2 men dumping charging bucket at $1.75 3.50 0.035 2 tagmen at $2, ½ time 2.00 0.020 1 man at trap at $2, ½ time 1.00 0.010 ------ ------ Total $36.37 $0.364 The output of the cubical mixer was 100 cu. yds. per day. The costs of placing concrete in the forms above the foundation by hand below 12 ft., and by cars and derricks any height, were as follows: By hand (barrows) below 12 ft. Total. Per cu. yd. 4 men loading concrete at $1.50 $ 6.00 $0.100 1 foreman ½ time at $3 1.50 0.025 10 men wheeling at $1.50 15.00 0.250 1 man scraping barrows at $1.50 1.50 0.025 2 men placing concrete at $1.50 3.00 0.050 1 man placing mortar face at $1.50 1.50 0.025 2 men mixing and carrying mortar at $1.50 3.00 0.050 ------ ------ Total $31.50 $0.525 By cars and derricks-- 1 horse and driver at $3 $ 3.00 $0.030 2 men dumping concrete ½ time at $1.50 1.50 0.015 1 fireman ½ time at $1.75 0.88 0.009 3 tagmen at $1.50 4.50 0.045 8 men placing and ramming conc. at $1.50 12.00 0.120 2 men mixing mortar at $1.50 3.00 0.030 2 men placing mortar at $1.50 3.00 0.030 2 men carrying mortar at $1.50 3.00 0.030 1 foreman at $3 3.00 0.030 1 stationary engineer at $3 3.00 0.030 2 men attending hook at $1.50 3.00 0.030 ------ ------ Total $39.88 $0.399 The costs of placing concrete in the foundations were as follows: By hand-- Total. Per cu. yd. 1 foreman ½ time at $3 $ 1.50 $0.025 4 men shoveling concrete at $1.50 6.00 0.100 1 man placing concrete at $1.50 1.50 0.025 1 man ramming concrete at $1.50 1.50 0.025 ------ ------ Total $10.50 $0.175 By machine-- 1 horse and driver at $3 $ 3.00 $0.030 3 men pushing and unloading car at $1.50 4.50 0.045 5 men placing and ramming at $1.50 7.50 0.075 1 foreman at $3 3.00 0.030 2 men dumping mixer at $1.50 3.00 0.030 ------ ------ Total $21.00 $0.210 ~COST OF RETAINING WALL.~--The following figures of the cost of a concrete retaining wall are given by C. C. Williams: Cost of Material. Unit Kind and amount of material-- Price. Cost. Stone, 441 tons $ .70 $308.70 Sand, 182.5 yds. .55 100.37 Cement, 536 bbls. .85 453.60 ------- Total $862.67 Lumber ¾ value $205.33 Wheelbarrows, ¾ value, 6 at $3.50 15.75 ------- Total $221.08 Excavation-- Labor, 4,002 hours at 15 cts. $600.30 Carts, 800 hours at 12½ cts. 100.00 Foreman, 460 hours at 35 cts. 171.00 Waterboy, 240 hours at 10 cts. 24.00 ------- Total $895.30 Concrete-- Labor, 2,398 hours at 15 cts. $359.70 Foreman, 224 hours at 35 cts. 77.40 ------- Total $437.10 Handling material-- Unloading cars, 380 hours at 15 cts. $ 57.00 Foreman, 40 hours at 35 cts. 14.00 ------- Total $ 71.00 Forms-- Carpenters, 997 hours at 22½ cts. $224.33 Work to support bridge-- Carpenters, 542 hours at 22½ cts. $121.95 Labor, 458 hours at 15 cts. 68.70 ------- Total $190.65 Superintendence and office-- Superintendent, 30 hours at 50 cts. $15.00 Office 20.00 -------- Total $35.00 -------- Grand total $2,937.13 Proportional costs-- Cost Per Per Cent. Yard of of Total Item. Cost. Concrete. Cost. Concrete materials $ 862.67 $2.02 46.7 Laying concrete 437.10 1.03 23.4 Lumber 205.33 .48 11.3 Building forms 224.33 .53 12.3 Handling material 71.00 .17 03.8 Wheelbarrows 15.75 .04 01.0 Supt., etc. 35.00 .07 01.5 --------- ----- ------ Total $1,851.18 $4.34 100.00 Work on bridge 190.65 Excavation 895.30 --------- $2,937.13