BY JAMES H. BRACE, FRANCIS MASON, AND S. H. WOODARD, MEMBERS, AM. SOC.
C. E.
This paper will be limited to a consideration of the construction of the
tunnels, the broader questions of design, etc., having already been
considered in papers by Brig.-Gen. Charles W. Raymond, M. Am. Soc. C.
E., and Alfred Noble, Past-President, Am. Soc. C. E.
The location of the section of the work to be considered here is shown
on Plate XIII of Mr. Noble's paper. There are two permanent shafts on
each side of the East River and four single cast-iron tube tunnels, each
about 6,000 ft. long, and consisting of 3,900 ft. between shafts under
the river, and 2,000 ft. in Long Island City, mostly under the depot and
passenger yard of the Long Island Railroad. This tube-tunnel work was
naturally a single job. The contract for its construction was let to S.
Pearson and Son, Incorporated, ground being broken on May 17th, 1904.
Five years later, to a day, the work was finished and received its final
inspection for acceptance by the Railroad Company.
The contract was of the profit-sharing type, and required an audit, by
the Railroad Company, of the contractor's books, and a careful system of
cost-keeping by the Company's engineers, so that it is possible to
include in the following some of the unit costs of the work. These are
given in two parts: The first is called the unit labor cost, and is the
cost of the labor in the tunnel directly chargeable to the thing
considered. It does not include the labor of operating the plant, nor
watchmen, yardmen, pipemen, and electricians. The second is called "top
charges," a common term, but meaning different things to different
contractors and engineers. Here, it is made to include the cost of the
contractor's staff and roving laborers, such as pipemen, electricians,
and yardmen, the cost of the plant and its operation, and all
miscellaneous expenses, but does not include any contractor's profit,
nor cost of materials entering permanent work.
The contractor's plant is to be described in a paper by Henry Japp,[B]
M. Am. Soc. C. E., and will not be dealt with here.
The contractors carried on their work from three different sites. From
permanent shafts, located near the river in Manhattan, four shields were
driven eastward to about the middle of the river; and, from two similar
shafts at the river front in Long Island City, four shields were driven
westward to meet those from Manhattan. From a temporary shaft, near East
Avenue, Long Island City, the land section of about 2,000 ft. was driven
to the river shafts.
[Footnote A: Presented at the meeting of December 15th, 1909.]
[Footnote B: _Transactions_, Am. Soc. C. E., Vol. LXIX. p. 1.]