=======================================+==========+==========+==========
| | | Total
|Manhattan.|Weehawken.| yardage.
---------------------------------------+----------+----------+----------
Cubic yards placed |14,706½ | 3,723 |18,429½
---------------------------------------+----------+----------+----------
LABOR. | Average Cost per Cubic Yard.
---------------------------------------+----------+----------+----------
Surface transport | $0.31 | $1.43 | $0.54
Superintendence and general labor at | | |
point of work | 0.31 | 1.31 | 0.51
Mixing | 0.52 | 0.56 | 0.53
Laying | 1.38 | 1.45 | 1.39
Tunnel transport | 1.30 | 1.47 | 1.34
Cleaning | 0.21 | | 0.17
Forms: erecting and removal | 1.58 | 1.51 | 1.56
---------------------------------------+----------+----------+----------
Total labor | $5.61 | $7.73 | $6.04
---------------------------------------+----------+----------+----------
MATERIAL.
---------------------------------------+----------+----------+----------
Cement | $2.30 | $2.22 | $2.28
Sand | 0.34 | 0.40 | 0.36
Stone | 0.91 | 0.61 | 0.85
Lumber for forms | 0.47 | 0.45 | 0.47
Sundry tunnel supplies | 0.16 | 0.17 | 0.16
---------------------------------------+----------+----------+----------
Total materials | $4.18 | $3.85 | $4.12
---------------------------------------+----------+----------+----------
Plant running | $0.44 | $0.44 | $0.44
Surface labor, repairs and maintenance | 0.25 | 1.24 | 0.44
Field office administration | 0.50 | 1.72 | 0.75
---------------------------------------+----------+----------+----------
Total field charges | $10.98 | $14.98 | $11.79
---------------------------------------+----------+----------+----------
Plant depreciation | $0.62 | $1.57 | $0.81
Chief office administration | 0.24 | 0.31 | 0.25
---------------------------------------+----------+----------+----------
Total average cost per cubic yard | $11.84 | $16.86 | $12.85
---------------------------------------+----------+----------+----------
Cost of Miscellaneous Items in Concrete.
---------------------------------------+----------+----------+----------
|Manhattan.|Weehawken.| Average.
Cubic yards |14,706½ | 3,723 |18,429½
Amount, in dollars |$6,184.83 | $1,756.79|$7,941.62
Unit cost | 0.42 | 0.47| 0.43
=======================================+==========+==========+==========
The 24-ft. 6-in. tunnel adjoining the Terminal Station-West was
water-proofed by a surface-rendering method which, up to the present
time, has been satisfactory. Generally speaking, the arches of the Land
Tunnels, though not dripping with water, are the dampest parts of the
whole structure from Tenth Avenue to Weehawken, and it would seem as if
some form of water-proofing over these arches would have been a distinct
advantage.
There was no difficulty in applying the water-proofing on the
side-walls, after a little experience had been gained as to the best
methods. The specifications required the sand-wall to be covered with
alternate layers of coal-tar pitch and felt, seven layers of the former
and six layers of the latter, the felt to be of Hydrex brand or other
equally satisfactory to the engineer. The pitch was to be straight-run,
coal-tar pitch which would soften at 60° Fahr., and melt at 100° Fahr.,
being a grade in which distillate oils, distilled from it, should have a
specified gravity of 1.105. The pitch was to be mopped on the surface to
a uniform thickness of 1/16 in., and a covering of felt, previously
mopped with pitch, was to be applied immediately. The sheets were to lap
not less than 4 in. on cross-joints and 12 in. on longitudinal joints,
and had to adhere firmly to the pitch-covered surface. This layer was
then to be mopped, and another layer placed, and so on until all the
layers were in place. This water-proofing was to extend from the bottom
of the cable conduits to the springing of the brick arch. Where
sub-track conduits were used, these were to be surrounded with their own
water-proofing. The work was carried out as specified; the sand-walls
were not rendered, but were built smooth enough to apply the
water-proofing directly to them. They were dried with gasoline torches
before the application of the pitch, and in very wet sections grooves
were cut to lead the water away.
The first attempts were with the felt laid in horizontal strips. This
ended very disastrously, as the pitch could not sustain the weight of
the felt, and the whole arrangement slipped down the wall. The felt was
then laid vertically, being tacked to a piece of horizontal scantling at
the top of the sand-wall and also held by a row of planks braced
against it at about half its height. A layer of porous brick was laid as
a drain along the base of the water-proofing, covered by a single layer
of felt to prevent it from becoming choked with concrete.
The water-proofing of the sub-track conduits was troublesome, as the
numerous layers and the necessity for preserving the proper laps in both
directions between adjacent layers made the whole thing a kind of
Chinese puzzle. Various modifications, to suit local conditions, were
made from time to time. Conduits outside the general outline of the
tunnel are difficult to excavate, to lay, and to water-proof, and should
be avoided wherever possible.
The usual force in water-proofing consisted of a foreman, at $3.50 per
day, and nine laborers at $1.75 per day. These men not only laid the
water-proofing, but transported the materials, heated the pitch, and cut
up the rolls of felt. In general, two men transported material, one
tended the heater, and the other six worked in pairs, two preparing the
surface of the concrete sand-wall, two laying pitch, and two laying
felt.
The cost of the water-proofing operation was about as shown in Table 14.