====================+=====+====================================
Part. | No. | Material. | Weight, in pounds.
--------------------+-----+---------------+--------------------
Bore Segment No. 1 | 1 | Cast Steel | 3,004.0
Bore Segment No. 2 | 1 | " " | 2,628.0
Distance piece | 1 | " " | 423.5
Key | 1 | " " | 34.3
Plug | 1 | " " | 1,192.5
Yoke | 1 | " " | 57.3
Dogs | 2 | " " | 106.0
Slot cover | 1 | Rolled steel | 6.4
Plug cover | 1 | Cast iron | 162.0
Dog holders | 2 | Rolled steel | 6.4
--------------------+-----+---------------+--------------------
Complete weight of one pair, without bolts| 7,620.4
==========================================+====================
_Sump Segments._--In order to provide sumps to collect the drainage and
leakage water in the subaqueous tunnels, special "sump segments" were
installed in each tunnel at the lowest point--about Station 241 + 00.
The details of the design are shown in Fig. 14. The segment was built
into the tunnel invert as though it were an ordinary "_A_" segment. In
building the sump, three lining castings were bolted, one on top of the
other, and attached to the flat upper surface of the sump segment;
meanwhile, the bolts attaching the sump segment to the adjacent tunnel
plates were taken out and the plate and lining segments were forced
through the soft mud by hydraulic jacks, the three 6-in. holes in the
bottom of the sump segment being opened in order to minimize the
resistance. The sump when built appeared as shown in Fig. 14, the top
connection being made with a special casting, as shown.
The capacity of each sump is 500 gal., which is about the quantity of
water entering the whole length of each subaqueous tunnel in 24 hours.
_Cross-Passages._--When the contract was let, provision was made for
cross-passages between the tubular tunnels, in the form of special
castings to be built into the tunnel lining at intervals. However, the
idea was given up, and these castings were not made. Later, however,
after tunnel building had started, the question was raised again, and it
was thought that such cross-connections would be very useful to the
maintenance forces, that it might be possible to build them safely, and
that their subsequent construction would be made much easier if some
provision were made for them while the shields were being driven. It was
therefore arranged to build, at intervals of about 300 ft., two
consecutive rings in each tunnel, at the same station in each tunnel,
with their longitudinal flanges together, instead of breaking joint, as
was usually done. The keys of these rings were displaced twelve bolt
holes from their normal positions toward the other tunnel. This brought
the keys about 6 ft. above the bench, so that if they were removed,
together with the _B_ plates below them, an opening of about 5 by 7 ft.
would be left in a convenient position with regard to the bench.
[Illustration: DETAILS OF SUMPS IN SUBAQUEOUS TUNNELS AT STATION 241
FIG. 14.]
Nothing more was done until after the tunnels were driven. It was then
decided to limit the cross-passages between the tubular tunnels to the
landward side of the bulkhead walls. They were arranged as follows:
three on the New York side, at Stations 203 + 22, 206 + 80, and 209 +
80, and two on the New Jersey side, at Stations 255 + 46 and 260 + 14.
The cross-passages are square in cross-section.