TABLE 15.—Cost of Brickwork.
| 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.