New-York tribune., 1907-07-07
DEFLECTIoNs FROM THE LEVEL.

This section OF the double tube tunnel Is
completed, and q steel lined caisson is being put
In halfway UP the hill. be used ventilatins
shaft. When this is finished tho shore side of tina
tunnel will be completed and the soil disturbed for
the last time
After examining the shore section which Mr..
Noble explained was by far the worst bit Of work
In the entire construction the reporter travelled
out under the river along a section which is built
| through coarse sand that makes solid bearing
foundation. In this part there are few defects
Both tubes caulked IN this stretch. and ready
to receive the final lining OF cement the inside.
Entering airock where the atmospheric pres
sure was Increased to seventeen pounds 10 the
square inch. the reporter ushered into an
eight hundred-toot section which has been run
through fine sand and river silt Here and there
IS evidence OF difficulties encountered In the work
OF construction. The true tunnel level has been
departed from in several places, giving the align
ment wavy effect AT one point there Is down
ward DETECTION caused by the pitching OF the
shield of as much ten inches made greater by
fourteen inches by subsequent sagginG during con-
structon and after. Again the wavy line Is In evil
dence IN the alignment OF the tubes. showing de-
partures from the true level.
These dehections could have been obviated TO
great extent. Mr.. Noble explained had the con-
tractor added 10 his compressed air plant as fast
at Il was required Though repeatedly warned. he
failed TO do this. and the consequence was that
the tubes had not the required buoyancy during
construction TO enable the level 20 be maintained.
Here, again. lock Of experience was partly ths
cause OF the trouble. This is proved by the fact
hat to-day there IS just three times the capacity
in the compressed air plant that was considered
adequate when the work started. The cor
rection OF the wavelike defections IN the align
ment OF the tubes effected by taking lower
level line and removing the bottom plates OF the
sections and replacing them. that the floor of
both tubes. though lower than the true level. is
In a comparatively straight line. The wavy effects
In tho roof were left in order 10 give additional
head TO the eight inches originally provided
for above the tops OF the Though general
depression can be noticed IN the centre OF this
800 foot section of both tubes the floor level does
not appear TO be particularly out OF plumb. Walk
Ing through. one could not notice IT, and when the
tracks are In place IL will be even less noticeable
A gang OF 'sandhogs' was at work at intervals
OF about hfty feet along the section. sinking tho
pile foundations through the bottom of both tubes
There are be thirty pile traverses IN this sec
ton. fifteen in each tube. placed at irregular In
tervals OF about nifty feet apart at points where
the greatest sinking took place during and after
construction. In order TO put pile in place
section is cut OF the bottom OF the tube. Cast
iron cylinders % inches in diameter and feet in
length sunk In the soft soil under the tube.
top OF the other. until bedrock is reached. As
the cylinders sunk they filled with concrete
reinforced with heavy iron bars. The concrete is
allowed to settle and harden the piles being
driven. Tho two piles OF each traverse about
seven feet apart and between them Is a bed OF
inforced concrete. upon which the round bottom OF
the tubes rest that when completed both tubes
throughout the entire length will rest upon
crete bed supported by piles at either end which
reach down through the soft soil to bedrock. The
length OF the piles varies froDl ten 10 fifty feet