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|Manhattan.| Weehawken.| Total.
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Square feet covered | 47,042 | 13,964 | 60,736
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Average cost per square foot.
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Labor | $0.07 | $0.07 | $0.07
Material | 0.12 | 0.09 | 0.11
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Total field charges | $0.19 | $0.16 | $0.18
Chief office and plant depreciation | 0.01 | 0.03 | 0.02
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Total average cost | $0.20 | $0.19 | $0.20
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_Brickwork in Arches._--Owing to the heavy timbering, the brickwork at
Manhattan was interfered with to a considerable extent, and the gang was
always kept at work at two or more places. The work was carried up to a
point where it was necessary to back-fill, or prop or cut away
encroaching timbers, and then the men were moved to another place while
this was being done.
The centers were set up in sets of seven, spaced 4 ft. apart. Two
14-ft. lengths of 3 by 4-in. yellow pine lagging were used with each set
of ribs, with 24 by 8-in. block lagging in the crown.
All centers were set ¼ in. high, to allow for settlement, except in
the 24-ft. 6-in. span, in which they were set ½ in. high. This proved
ample, the average settlement of the ribs being 0.01 ft. and of the
masonry, 0.003 ft. In the 24-ft. 6-in. span the ribs were strengthened
with 6 by 6-in. blocking and 12 by 12-in. posts to subgrade. Great
trouble was here encountered with encroaching timbering, due to the
settlement of the wide flat span. Grout pipes were built in, as
previously mentioned.
Each mason laid an average of 0.535 cu. yd. of brickwork per hour, or
4.28 cu. yd. per day. The number of bricks laid per mason per hour was
218, or 1,744 per day.
The bricks were of the best quality of vitrified paving brick, and were
obtained from the Jamestown Brick Company, of Jamestown, N. Y. The
average size was 8¾ by 3-15/16 by 2-7/16 in.; the average number per
cubic yard of masonry was 408, the arches being from 19 ft. to 24 ft. 6
in. in span and from 22 to 27 in. thick. The joints were 3/16 in. at the
face and averaged 9/16 in. through the arch.
The proportions for mortar were 1 of cement and 2½ of sand. One cubic
yard of masonry was composed of 73.5% brick and 26.5% mortar. The volume
of the ingredients in a four-bag batch was 12.12 cu. ft., and the
resulting mixture was 9.54 cu. ft. The number of barrels of cement was
0.915 per cu. yd. of masonry, and about 17.7% of the mortar made was
wasted. The average force employed was:
_Laying._
1 Foreman @ $8.00 per day
4 Layers " 6.00 " "
8 Tenders " 2.00 " "
2 Mixers " 2.00 " "
_Forms._
1 Foreman @ $4.50 per day
4 Carpenters " 3.50 " "
5 Helpers " 2.25 " "
_Transport._
¼ Hoist engineer @ $3.00 per day
¼ Signalman " 2.00 " "
4 Laborers " 2.00 " "
For materials, the following prices prevailed:
Cement, $2.00 per bbl.,
Sand, $0.90 to $1.00 per cu. yd.,
Brick, $16.00 per thousand, delivered at yard,
Centers, $26.00 each,
Lagging, $45.00 per 1,000 ft. B. M.
The cost of the brickwork is given in Table 15.