New-York tribune., 1911-11-29
SPECIAL ANNOUNCEMENTS.
EAST RIVER TUNNELS
How This Great Engineering
Feat Was Successfully
Accomplished.

The four East River tunnels ot the Penn
sylvania Railroad, on account of their large
diameter and the peculiar strata they
pierce, are generally considered the most
difficult subaqueouS tunnels so far con
structed. The construction OF this work
of nearly five miles Of % feet diameter
tubes required 10000 tons OF cast iron lin
ing. reinforced by two feet OF concrete, TO
hold out the quicksands and the river
above, and involved the largest subaque-
Gus tunnel contract ever placed.
The construction required about five
Years, and was accomplished by using COM
pressed air 10 hold back the river. The air
pressure required depends on the depth OF
water above the point considered, every
two feet OF water above the tunnel repre-
sents about one pound Of air pressure IN
the tunnel As the tunnels are Is feet N
diameter, the pressure necessary al the
bottom Of the tunnel was ten pounds greater
than that required at the &c
u the air. pressure was kept low enough
N prevent the river bed from being blown
off then the auicksand and water flowed
IN ~ the bottom, causing the tunnel 70 set
tie while II the pressure was kept high
enough 10 prevent settlement in the quick
ssnd. then the roof blew off. II was only
bv dumping 10000 cubic yards OF stifr
CLAW from scows to reinforce the river bed
,bst 2 pressure was maintained which kept
the bottom dry enough 10 prevent the tun-
mel sinking below grade.
The worknnen. or sand hogs" worked in
pre.sures up 10 forty pounds to the square
inch above atmosphere, and 42,VoWoW.
cubic feet Of air was compressed and forceo
into the tunnels. At times as much as
ADno cubic feet Of air minute escaped
from one tunnel alone, causing sufncien'
disturbance in the river above 10 defect
fe-ryboat from its course.
ror+v-tyro nationalities were represented
a. +hs twenty-five hundred men required To
osrrv out the work, which was prosecutor
6av and night continuously, in three-hour
shifts for the highest pressures.
Alfred Noble was the engineer In charge
for the railroad company. He is CONSIDERED
10 be the greatest living American engineer
His Judgment Is appealed 20 IN lmporlan'
,,ndertaklngs. as. for instance, the ran
srns canal. the greatest construction WORK
,n the world. which owes in no small meas
ure its present design 10 him.
lie Is loved and respected by all VINO
Lrou him. and takes all responsibility
abeD things 60 wrong, while giving creoi'
% his subordlnates when good work Is
done. ..o,
The contractors who staked their capitsl
on the correctness Of their bid and carfleu
ont The work successfully, are the Wen
known American firm OF :. Pearson q son
INC. which IS incorporated IN the STATE u
New York. and is At present ensaeeu 90
+be construction OF ten and d haf nlne'
of the New York state Barge Canal. lHe
+-,, a, : Pearson & Son is we'll known al
ovA- the world The latest or the grea'
,gorks they have undertaken INCLUDE the
National IIarbor, at Dover. England sno an.
,,e Tehuantepec Railroad, in Mexico, VIII
-h. bsrbors on the Atlantic and Facln'
,,des Of the isthmus. They operate thi'
rsnroad for the Mexican government ans ans
I, Is carrying Q large traffic, Lo"'"V t0'''