Hole Broken Through the South Tube of the New York and Jersey Tunnel Looking West
During the early work on the north tube of the uptown tunnels, a point was reached where the rock was sixteen feet above the bottom of the tunnel, and the overlying silt was in a semi-fluid state. Five barges of clay had been dumped in the river over this point to make a roof for the tunnel, but the fluid clay could not be controlled, and crept through the doors of the shield. After trying all known methods to get through, it was decided to bake this wet clay by means of intense heat. Two large barges of kerosene were sent into the tunnel, and an air pipe connected to them. Fine blow-pipes were also attached, and the fire from the blow-pipes was impinged on the exposed clay until it became caked sufficiently dry and hard to overcome slipping. It required eight hours of this baking to dry the clay hard, and, during this period, water had to be played continuously on the shield to avoid damage due to the high temperature. It is believed that this was the first time that soft material met with in tunneling under a river has been solidified by means of fire. Seven days after passing this troublesome point, the rock suddenly disappeared and the work proceeded without further trouble.
New York and New Jersey Tunnel Showing Signal and Car
Another unusual situation occurred in the south tunnel of the uptown tubes. When the shield had advanced 115 feet from the Jersey side, the night superintendent in charge of the tunnel work, in his anxiety to push the work, disobeyed instructions, and the tunnel got away from him and was flooded, and his men had a narrow escape with their lives. In order to regain the tunnel, several schemes were considered, including that of sending a dredge through to dredge out the bed of the river just in advance of the shield, a sufficient depth to enable a diver to go down and timber up the exterior opening of the doorway, where the silt and mud had come through and filled the tunnel. This plan had to be abandoned, as the river above was almost entirely occupied by shipping that could not be interrupted.
