The sun. [volume] (New York [N.Y.]) 1833-1916, 1907-05-29

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Steel Cylinders Filled With Cement and
Put Down In Sections Through Open.
inEs In the Bottom OF the Tubes.
Before trains begin running through the
East River tunnel from the Battery to Jorale-
mon street. Brooklyn. tho two big cast iron
tubes constituting the tunnel will rest on
piles driven through ifty feet OF mud and
sand to a solid foundation. This trestle
work was not In the original plans Of the
tunnel. but the need Of Il has caused no little
worry on the part OF the engineers. and has
made a disagreement between the engineers
for the city and for the tunnel company.
The driving OF these piles has been going
on for weeks at both end OF the tunnel.
Chief Engineer Rice OF the Rapid Transit
! Commission talked readily enc&gh about
the work yesterday. but Chief Engineer
George g.. Pegram OF the Rapid Transit
Subway Construction Company. which bad
the original contract for the Brooklyn
tunnel. sublet 1t to the New York Tunnel
Company and then had to take hold again
when the New York Tunnel Company got
into financial trouble. wouldn't discuss II.
It was believed at first that the soft
sand through which the tubes have been
bored would be q suitable support for
them when heavy rains are sent through
them. Later some Of the engineers felt
that the sand. which In places 10 littls moro
solid than ~quicksand. would not prevent
the tubes from buokling when subjected
to the weight Of crowded trains. At only
a few places do the tubes rest on solid
rock, and for more than 1000 feet on the
Brooklyn side there lie a long stretch Of
sand where it was believed that the tubes
would surely sag IL unsupported.
Chief Engineer Pegram decided long ago
that the tunnel ought to nave supports.
Chief Engineer Rice didn't agree with him,
and insisted that the original plan Of having
the tubes supported only by the sand and
gravel bed Of the river was sufficient. Then
Mr.. Pegram directed his engineers to make
a few tests to see how difficult IL would be TO
drive the piles after the tubes we're In place.
The engineers took out two or three seg-
ments at the bottom Of one Of the cast iron
tubes and made a wash boring to get at
conditions below the tunnel. The soft
material washed out 90 readily that MIR.
Pegram was confirmed in his fears. Then
a fifty foot steel tube pile was driven almost
to bed rock without much trouble. The
piles weren't sent clear to bed rock because
it was felt that the rock foundation would
give too much rigidity.
Then the engineers planned the driving
Of piles throughout the entire tunnel. The
work was begun on the Brooklyn side of
the rock peak which juts up about 1900
feet from the Brooklyn water line. and
was extended In both directions.
Driving the piles isn't as difficult as it
seems to a layman: The piles are steel
cylinders twenty inches. in diameter which
are put down in sections five feet long.
When the opening is made in the bottom
pile, a FIVE foot cylinder pointed sharp
at the lower end, is set upright in the tunnel
tube and then washed down into the sane
and gravel. AS fast as one Of these sections
is worked downward by washing out the
sand beneath 1t it is filed with concrete
section OF cylinder and washed further
into the sand. New lengths Of cylinder
filled with concrete are added until there
ie a Fifty foot pile Of steel and cement under
not only more easily installed than a solid
steel cylinder would be. but IL has much
greater supporting. power and durability
and Is not affected by moisture. The piles
are placed in pairs about fifty feet apart.
There has been much criticism OF b delay
Of the tunnel work not only from the city
authorities but from various commercial
and business organizations; but Chief En-
gineer Rioe declared yesterday that the
installation Of the piles had nothing TO do
with it. He said that the difficulty Of find
ing a place for the Joralemon street shaft
Of the tunnel has been the main trouble.
So many protests have been made against
the airshaft and ventilating plant along
Joralemon street that the tunnel contractors
nave had to select four different sites and
may be compelled to give up the one finally
selected.
Mr.. Rice said that he still didn't consider
the piles necessary, although he had become
convinced that 1t would be a good idea to
nave them. eff they do no more they will
give the people greater confidence in the
tunnel ne said. Although 1 don't be-
lieve there was ever any danger OF the
tunnel sagging. il is absolutely impossible
now. They don't cost much money, the
work is easy to do and we might az we'll put
them in while we are waiting FOR the Jorale-
mon street shaft
The chief engineer said that the work OF
installing piles would 60 on until the Jorale-
mon street shaft is ready, but that the OPP
Grafton Of trains wouldn't be delayed'H the
piles hadn't been completed. He hoped to
have the tunnel in operation as far as the
Borough Hall station by August or Septem-
Der.
when the Brooklyn tunnel is completed"
he said. 1t will be the safest tunnel in the
world. Its form OF construction renders IL
ideally capable of resisting any strain put
lpon II"