The Washington times., 1904-12-25
DRIVING Tunnel
UNDER HUDSON
Making Rapid Progress on
Engineering Work.
BORING THROUGH THE MUD
Difficulties Sometimes Met in These
Great Undertakings Beneath
the Surface,

The rapid progress made in the con-
struction of the trolley tunnel under
the Hudson River at New York is ex-
citing the wonder and admiration of
engineers
The records of fast tunrel-drivfng
have not only been broken but left out
or sight And vet the chief feature of
the work is its extreme simp1icity--the
ease with whick u task formerly aban-
doned as all but impossible is being
pushed ahead at so great a speed. Says
Engineering News" in an editorial:
Everyone has heard of the person
who, for the purpose of escaping from
the observation of his fellowmen,
crawled into a hole and pulled the hole
IN 'arser him. That mythical feat is now
equaied by the achievement of a we'll
known New York engineer who is driv-
ing Il tunnel under the Hudson River
and actually pushing the hole ahead of
him
The work on the south tube for tho.
Hudson River tunnel represents
method -tunnef-driving which, we risk
little in saying, has never been carried
on or attempted before In the world
That it is successful is attessed by ths
rate at which the tunnel is being driven,
which far exceeds all records of fast
tunnel-driving ever made
The Hydraulic Shield.
What is being done is to push the hy-
draulic shield right into the soft mud,
which is forced to either side and
upward into the bed of the river The
tunnel is not thus being excavated at
all, but il is actually bored in the same
manner that an awl bores hole in wood
ln.,fl nf
mel in this manner, nearly all the diff
ficulties and dangers attendant upon
submarine tunneling are eliminated. The
worknen are projected by the iron
walled tunnel around them and the
shield in front.
So long as the shield can shove its
way ahead without encountering bould-
ers or other obstacle, necessitating the
opening of bulkhead doors and work in
front of the shield. the workmen are as
safe as if they were in the open air
Moreover. when the shield is pushed for
ward in this manner, there is actually
no tunneling work to be DONE Ali the
workmen have to do is TO place ring
after ring of the cast-iron lining as the
shield moves ahead Hydraulic power
makes the hole that is ordinarily dug by
pick and shovel and dynamite.
Softness of the Silt.
1t viii be evident. of course. that this
method Of workin@ is only made possible
by the exceeding softness of the SEMI
fluid silt underlying the Hudson River
and through which the tunnel is being
driven This semi-huid silt has defeated
every engineer who has hitherto at
tempted TO penetrate 1t by ordinary tun-
neling methods De Witt Ha skins spent
years Of time and q large slice of Trenor
W. Parks fortune in driving 1000 feet
OF the north tunnel. and the enterprise
was then abandoned by both engineers
and ca o:talists.
After lying idle for half dozen years
an English corporation undertook to
complete t with the famous firm of s.
Pearson & Son as the contractor. and
the distinguished Sir BENJAMIN Baker as
consulting engineer But the million
and a half of money which was raised
proved insufficient to complete even the
one river tunnel, and again the work
was abandoned, and lay untouched for
thirteen wears.