The sun., 1919-06-29

have planned to link them
selves under the North River
by the greatest vehicular tunnel that
has yet been designed by civil engi-
neers. But good many competent
authorities question the practicability
Of the plans for the nonce agreed upon.
and some Of these experts urge de-
liberation and further study before
putting the scheme into execution.
One and all of these technical au-
thorities are in complete accord as to
the desirability Of the tunnel and the
need OF making 1t available at the
earliest possible moment, but. familiar
as they are with vast engineering I'M
dertakings, they plead that there are
aspects OF the contemplated great
single tube which are virtually novel
because of the diameter. the material
chosen for It's framework and the
physical conditions peculiar to the
bottom OF the North River.
Already New York State has obi
gated itself. as has New Jersey, to a
preliminary expenditure of 100000
pledged to a further outlay OF $1,000
900 for our share of the estimated
total cost Of the entire project. Every
body wants TO see the great work put
through, but no one wants to have
US make q false start II additional in
vestigation at a relatively modest
price will insure complete success and
satisfaction in the end.
Fehicular tunnels are no longer In
novations and there are two outstand-
ing examples abroad which have dem
onstrated the feasibility of engineer
ing structures of that sort, and up to
point the experience gained in driv-
ing those traffic tubes has its bearing
upon the local project. The two tun-
nels in question run beneath the
Thames. and in cutting the bores for
these tubes the shields burrowed their
way through a very firm waterbed
that measurably helped to make easier
some of the egineering aspects of the
tasks. This Is a point which will be
appreciated later when a comparison
is made with the mud that underlies
the sweep of the North River. Black
wall Tunnel extends beneath the
Thames six and a quarter miles be-
low London Bridge and was opened to
traffic twenty-six years ago. The Ro-
therhithe Tunnel. finished in 1908
dives under that historic waterway two
ana a quarter miles below London
Bridge.
The Blackwell Tunnel Is 6,200 feet
long, is lined with cast iron segments
faced with concrete, and has an outer
diameter OF 81 feet. 1t boasts one road
way 16 feet wide and a thanking
walk on each side a trif1e over
feet wide. The total cost of the under
taking was s6.833.160. The annual
traffic is about 500, 900 vehicles and
100000 passengers The Rotherhithe
Tunnel, which is broadly similar in
general getup to the Blackwell Tunnel
except that its external diameter IS
feet greater is 6,s26 feet long. and the
walks on each side OF the 16 foot drlve-
way are a little less than 8 feet wide
This traffic artery is the largest sub
aqueous tunnel now extaRt, and the
total outlay involved was $s,720, 900
The yearly movement within that tube
Is, In round figures, 100000 vehicles
and S,500,00o passengers.
This Tunnel biggest.
According to the plans which Gen
George w. Goethals has approved
for the New York New Jersey vehic-
ulsr tunnel, the outside diameter OF
the tube is to be AZ feet. and the inter
nal diameter So feet, the concrete
blocks or segments. which are to
form the tunnel envelope. are to be
feet thick. Within the tube the de-
sign provides for two traffic levels-tht
~ foot dHveways allowing each fun
three lines Of vehicles-one level beinl
devoted TO the eastbound and the
ether to the westbound traffic. Space
Is available for pedestrians on each
side Of the upper roadway. However
inasmuch as the gap to be spanned
by the tunnel will be $3.50 feet from
portal 10 portal. 1t is not likely thai
pedestrians will constitute an out
standing feature OF the traffic. Or
the other hand. II Is estimated that til,
tunnel will be used the first year b!