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Tunnels built in the U.S. from the time of the earliest, 137-m Auburn Tunnel (1818-1821), and the Lebanon Tunnel (1824-1826) are noted, and comments are made on the tools used in tunneling. By 1850, 48 tunnels were completed for both canals and railroads. All these tunnels were in rock, hard and soft, and all required drilling and blasting. Until 1865 all drilling was done by hand and was called double jacking. The drilling and balsting technique is briefly described. During the period before 1850, the American method of tunneling was developed. In this method, tunnels were driven heading and bench, the bench being about 2.4 m wide. An important development during this period was the American System of timbering, which consisted of a five-piece arch erected on the heading on a wall plate if the ground needed support. The pneumatic drill was used in 1875 and, with some improvements was used until about 1945. All mucking was by hand; either a short D-handled shovel was used or one with a long handle known as a muck stick. A drill jumbo used on the Pennsylvania Turnpike is described which carried 8 drills mounted on hydraulically controlled booms.

p. 2-6

1977-9

Transportation Research News

Figures (2) ; Photos (9)

Drills; History; Mucking; Presplitting (Blasting); Rock drilling; Timbering; Tunneling; Tunnels

Bridges and other structures; Construction; Highways; History

TRIS, TRB

Mar 29 1978 12:00AM

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