The Anderson intelligencer. [volume] (Anderson Court House, S.C.) 1860-1914, 1890-02-27
BILL ARP.
a Great Tunnel.

Six hundred men are now digging the
railroad tunnel under the St. Clair River
at Port Huron, in Michigan. at the rate
of fifteen feet each day. This means that
before the year is out one of the most
important pieces of civil engineering in
the country will be completed. More than
1900 feet Of The tunnel proper is now
resIdy for trains on the Michigan side and
900 on the Canadian. The remaining
1000 feet will be finished at a wonder.
fully rapid rate, considering the nature of
the work, if no accident interferes. It
has taken six months to do the work thus
far, but workmen are now more accus.
toned to the task and eau work with
greater facility in the use Of the mschin-
cry, so that the engineers in charge place
the completion ofthe work not later than
the end Of the year.
The tunnel itself is over 5000 feet
long. The approaches are equally long,
so that the entire length will be more
than two miles. Of this distance 2,310
feet are under the river, 1880 feet on the
Michigan land side, and 2,100 on the Ca.
madam. The grade is l foot in every 30,
except under the river bottom, where ii
is substantially level. It is an iron cy-
Under tunnel-lhe only one of the kind
in the country. There is neither brick
nor stone used in its construction. Meth
er are there any stays or suppor!s-simply
q mammoth iron tube built in sections
underground. It is designed for single
track.
Electric lights make it as light as day,
air engines keep the atmosphere as
healthy inside as above, and steam-pipes
hold the temperature at the proper point.
It is rs dry as q street in summer, and the
disagreeable features common to subaque-
GUS work are entirely absent. Work is
pushed from both ends.
The method of construction is simple.
A great cylinder, weighing more than 60
tons, 20 feet in diameter and II feet long,
is driven into the blue clay, which con-
stitutes the entire bottom of the river, by
the use of hydraulic power, with as much
ease as cakes Of soap can be carved out OF
general mass. Inside this cylinder,
which is called shield, twenty two men
are at work removing the dirt As fast
as the shield is pushed forward, which is
about two feet at a time, the clay thus
brought inside the shield is dug out to
the edge Of the great cylinder. Then the
hydraulic jacks are again started, and
slowly, but irresistibly the immense iron
tube moves another two feet into the sol.
id earth ahead Of il. Each jack has q
power of 5000 tons, and the combined
power behind the shield is more than
100000 tons.
Another ring of the iron lining is put
into place, and each foot tunnel is ready
for track laying as fast as the work pro.
crosses. There is no mason work, as
already stated, and when done the tunne
will practically be q continuous iron tube
20 feet in diameter and nearly 1000 fee
long.
The iron plates that form the lining
are of such curvature and length tina
any thirteen of them, with small key
piece, will make circle of 20 feet il
diameter. The edges and ends are turned
up, each piece being bolted by dozer
large bolts to its neighbor. Each one il
1S inches wide and weighs as near 1,OOt
pounds as the foundries can make them
Those for the Michigan side are made ii
Detroit, and those for the Canadian il
Hamilton, and thus the payment of dut.
is avoided. These great sheets are han
died with cranes and so readily that
complete circle is put up in about half al
hour. The lining is about 6 inches thick
so that there is no danger Of collapse from
pressure.
The ground through which the minera
has passed thus far has been uniforml,
stiff blue clay.
Dir. T. NJ. Murphy, who has charge 0
a portion of the work here, says this tun
mel will be the most economical one eve
built, if no unforeseen accidents happen
While employed on the Hudson Rive
tunnel be was satisfied if bis men mad
progress at the rate of thirty feet day
but here they have averaged over sixt
feet daily.
- The more man becomes wrapt u