===========================================+==========+==========+======
|Manhattan.|Weehawken.|Total.
-------------------------------------------+----------+----------+------
Cubic yards placed | 4,137 | 790 |4,927
-------------------------------------------+----------+----------+------
LABOR. |Average Cost per Cubic Yard.
-------------------------------------------+----------+----------+------
Surface transport | $0.35 | $1.19 | $0.48
Superintendent and general labor at point | | |
of work | 0.17 | 0.04 | 0.16
Laying and mixing | 2.58 | 3.20 | 2.60
Forms: erection and removal | 2.62 | 0.32 | 2.25
Tunnel transport | 1.19 | 1.12 | 1.18
-------------------------------------------+----------+----------+------
Total labor | $6.91 | $5.87 | $6.75
-------------------------------------------+----------+----------+------
MATERIAL.
-------------------------------------------+----------+----------+------
Brick | $6.56 | $6.56 | $6.56
Cement | 1.76 | 1.75 | 1.76
Sand | 0.20 | 0.28 | 0.22
Forms | 0.92 | 0.98 | 0.98
Overhead conductor pockets | 0.15 | 0.09 | 0.13
-------------------------------------------+----------+----------+------
Total material | $9.59 | $9.66 | $9.60
-------------------------------------------+----------+----------+------
Plant running | $0.55 | $0.30 | $0.51
Surface labor, repairs and maintenance | 0.36 | 1.30 | 0.51
Field office administration | 0.55 | 0.88 | 0.60
-------------------------------------------+----------+----------+------
Total field charges | $17.96 | $18.01 |$17.97
-------------------------------------------+----------+----------+------
Chief office administration | $0.60 | $0.66 | $0.61
Plant depreciation | 0.35 | 0.64 | 0.39
-------------------------------------------+----------+----------+------
Total average cost per cubic yard | $18.91 | $19.31 |$18.97
===========================================+==========+==========+======
In Table 16 the cost of grout is expressed in terms of barrels of cement
used, because in the schedule of prices attached to the contract, that
was the unit of payment for grout.
TABLE 16.--COST OF GROUT OVER ARCHES IN LAND TUNNELS.
Cost, in Dollars per Barrel of Cement Used.
======================================+===============+==========+======
| Manhattan. | |
|(Gy-East only.)|Weehawken.|Total.
--------------------------------------+---------------+----------+------
Barrels used | 3,000½ | 261½ |3,262
--------------------------------------+---------------+----------+------
Average Cost
per Barrel of Cement Used.
--------------------------------------+---------------+----------+------
Labor | $0.55 | $0.46 |$0.53
Material | 2.30 | 2.25 | 2.28
Field office administration | 0.08 | 0.06 | 0.08
Plant and supplies | 0.10 | 0.07 | 0.09
--------------------------------------+---------------+----------+------
Total field charges | $3.03 | $2.84 |$2.98
--------------------------------------+---------------+----------+------
Chief office and plant depreciation | 0.21 | 0.22 | 0.28
--------------------------------------+---------------+----------+------
Total average cost | $3.24 | $3.06 |$3.20
======================================+===============+==========+======
_Vitrified Earthenware Conduits for Electric Cables._--The general
drawings will show how the ducts were arranged, and that manholes were
provided at intervals. They were water-proofed, in the case of those
embedded in the bench, by the general water-proofing of the tunnels,
which was carried down to the level of the bottom of the banks of ducts;
and in the case of those below subgrade, by a special water-proofing of
felt and pitch wrapped around the ducts themselves.
The portion of wall in front of the ducts was bonded to that behind by
bonds, mostly of expanded metal, passing between the ducts. Examples of
the bonding will be seen in the drawings.
The joints between successive lengths of 4-way and 2-way ducts were
wrapped with two thicknesses of cotton duck, 6 in. wide, those of
single-way ducts were not wrapped, but plastered with cement mortar. The
ducts were laid on beds of mortar, and were made to break joints at top
and bottom and side to side with the adjacent ducts. They were laid with
a wooden mandrel; a square leather washer at the near end acted as a
cleanser when the mandrel was pulled through.
The specifications required the ducts to be laid at the same time as the
concrete and be carried up with it, but this was found to be a very
awkward operation, as the tamping of the concrete and the walking of
men disturbed the ducts, especially as the bonds lay across them. It was
resolved, therefore, to build the portion of the wall behind the ducts
first, with the bonds embedded in it at the proper heights and
projecting from it, then to lay up the banks of ducts against this wall,
bending the bonds down as they were reached, and finally, after all the
ducts were in, to lay the concrete in front of and over the top of the
ducts. Several detailed modifications of this general scheme were
followed at one time or another when necessary or advisable.
The laying of ducts below subgrade was not complicated by the presence
of bonds, the water-proofing caused the trouble here, as before
described.
The specifications called for a final rodding after completion. A group
of the apparatus used in this process is shown in Fig. 1, Plate XXXV;
the various parts are identified by the following key: