. Bulletin - United States National Museum. Science. Figure 42.âSt. Clair Tunnel. View of front of shield showing method of excavation in firm strata. Incan- descent electric illumination was used. 1889-90. MHT modelâ1" scale. (Smithsonian photo 49260-D.) was finally completed in 1904, and is now in use as part of the Hudson and Manhattan rapid-transit system, never providing the sought-after rail link. A splendid document of the Haskin portion of the work is S. D. V. Burr's Tunneling Under the Hudson River published in 1885. It is based entirely upon firsthand material and contains drawi
. Bulletin - United States National Museum. Science. Figure 42.âSt. Clair Tunnel. View of front of shield showing method of excavation in firm strata. Incan- descent electric illumination was used. 1889-90. MHT modelâ1" scale. (Smithsonian photo 49260-D.) was finally completed in 1904, and is now in use as part of the Hudson and Manhattan rapid-transit system, never providing the sought-after rail link. A splendid document of the Haskin portion of the work is S. D. V. Burr's Tunneling Under the Hudson River published in 1885. It is based entirely upon firsthand material and contains drawings of most of the work, including the auxiliary apparatus. It is interesting to note that electric illumination (arc, not incandescent, lights) and telephones were used, unquestionably the first em- ployment of either in tunnel work. THE ST. CLAIR TUNNEL The final model of the soft-ground series reflects, as did the Hoosac Tunnel model for hard-rock tunneling, final emergence into the modern period. Although the St. (1,111 I uimel was completed over 70 years ago, it typifies in its method of construction, the basic procedures of subaqueous work in the present day. The Thames Tunnel of Brunei, and llaskin's efforts beneath the Hudson, had clearly shown that by themselves, both the shield and pneumatic systems of driving through fluid ground were defective in prac- tice for tunnels of large area. Note that the earliest successful works by each method had been of very small area, so that the influence of adverse conditions was greatly diminished. The first man to perceive and seize upon the bene- fits to be gained by combining the two systems was, most fittingly, Greathead. Although he had projected the technique earlier, in driving the underground City and South London Railway in 1886, he brought together for the first time the three fundamental ele- ments essential for the practical tunneling of soft, water-bearing ground : compressed-air support of the work during constructi
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