| 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.
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.