A typical working gang is given herewith. Two such gangs were worked per shield per 24 hours, 10 hours per shift. All this work was done under normal air pressure.
| General: | ||||||
| ½ | Tunnel superintendent | @ | $200.00 | per | month | |
| 1 | Assistant tunnel superintendent | " | 5.00 | per | day | |
| 1 | General foreman | " | 5.00 | " | " | |
| ½ | Electrician | " | 3.50 | " | " | |
| ½ | Electrician's helper | " | 3.00 | " | " | |
| ½ | Pipefitter | " | 3.00 | " | " | |
| ½ | Pipefitter's helper | " | 2.75 | " | " | |
| Drilling: | ||||||
| 1 | Foreman | " | 5.00 | " | " | |
| 3 | Drillers | " | 4.00 | " | " | |
| 3 | Drillers' helpers | " | 3.00 | " | " | |
| 1 | Nipper | " | 2.50 | " | " | |
| ½ | Waterboy | " | 2.50 | " | " | |
| ½ | Powderboy | " | 2.75 | " | " | |
| Mucking: | ||||||
| 1 | Foreman | " | 3.50 | " | " | |
| 8 | Muckers | " | 2.75 | " | " | |
| Erecting Iron and Driving Shield: | ||||||
| 1 | Erector runner | " | 4.00 | " | " | |
| 3 | Iron workers | " | 3.00 | " | " | |
The duties of such a gang were as follows: The tunnel superintendent looked after both shifts of one shield. The assistant or "walking boss" had charge of all work in the tunnel on one shift. The general foreman had charge of the labor at the face. The electricians looked after repairs, extensions of the cables, and lamp renewals. The pipefitters worked in both tunnels repairing leaks in pipes between the power-house and the working faces, extending the pipe lines, and attending to shield repairs, and in the latter work the erector runner helped.
The drillers stuck to their own jobs, which were not subject to interruption as long as the bottom headings lasted. One waterboy and one powderboy served two tunnels. The muckers helped the iron men put up the rings of lining, as well as doing their own work. The iron men tightened bolts, whenever not actually building up iron. The list does not include the transportation gang, which will be described under its own heading.
The rate of progress attained was 4.2 ft. per day per shield where most of the excavation had been done before, and 2.1 ft. where none had been done before.
When the shields had got far enough away from the shield chamber, and before rock cover was lost, the first air-lock bulkhead walls were put in.
Air-Lock Bulkhead Walls.—The specifications required these walls and all their fittings to be strong enough to stand a pressure of 50 lb. per sq. in. Accordingly, all the walls were of concrete, 10 ft. in thickness, except the first two, which were 8 ft. in thickness, and grouted up tight.
There were three locks in each bulkhead wall capable of holding men, namely, the top or emergency lock which is set high in order to afford a safe means of getting away in case of a flood; this lock was used continuously for producing the lines and levels into the tunnels. It was very small and cramped for this purpose, and a larger one would have been better, both for lines and emergencies. This lock was directly connected with the overhead platform (also called for in the specifications) which ran the whole length of the tunnels. Side by side, on the level of the lower or working platform of the tunnel, were the man lock and the muck lock. In addition a number of pipes were built in to give access to the cables and for passing pipes, rails, etc., in and out.