. Handbook of construction plant, its cost and efficiency. ted by bolts are set 6 ft. apart on the completed invertsand 2x4 in. lagging is laid on them to form the arch center. Therings are collapsed by removing the connecting bolts. Trench excavation was begun June 3 and at the time the workwas visited, July 8, 1,600 ft. had been excavated. This, however,is no indication of the speed of the excavator, for it is workedonly fast enough to keep some 15 ft. ahead of the invert two favorable days, 184 ft. and 170 ft. of sewer were built, TRENCHING MACHINES 641 but the average advance ha
. Handbook of construction plant, its cost and efficiency. ted by bolts are set 6 ft. apart on the completed invertsand 2x4 in. lagging is laid on them to form the arch center. Therings are collapsed by removing the connecting bolts. Trench excavation was begun June 3 and at the time the workwas visited, July 8, 1,600 ft. had been excavated. This, however,is no indication of the speed of the excavator, for it is workedonly fast enough to keep some 15 ft. ahead of the invert two favorable days, 184 ft. and 170 ft. of sewer were built, TRENCHING MACHINES 641 but the average advance has been much less. The contractorstated that the machine had not worked over half the time. An estimate of the cost of operating the excavator based partlyon assumed progress, is as follows: Engineer $ Fireman , Coal Oil and waste 50 Repairs Depreciation Interest at 5 per cent Total cost per working day $ The machine will use about three-quarters ton of coal per be conservative we have assumed one ton at $ The. Fig. 03. Excavating Trench ,for Sewers Seventy-Eight InchesWide and Twenty Feet Deep at Des Moines, Iowa. repairs were also estimated at $, which is considered depreciation is taken at 300 days work per year for tenyears, and although it is assumed that the owner of such amachine will be able to sell it at the end of that time, no allow-ance for salvage value is made here. Assuming that the brick sewer may follow the machine at arate of 170 ft. per day, the cost per foot of trench excavationis 10 cents, or 5 cents per cu. yd. If the contractor coulddouble the rate of brick construction he could then reduce the 642 HANDBOOK OF CONSTRUCTION PLANT excavation cost by one-half, as he states that the machine isused about 50 per cent of the time. Other items enter into theincrease in speed of brick sewer construction which mightincrease the cost of that part of the work more than the reduc-
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbuilding, bookyear191
