The sun., 1919-06-29

VI ldlcT tOsStl Il water JdCkot
around It, and If this ever happened
a catastrophe might result, as the
tunnel lining, as usually built, would
not stand much tensile strain, espe-
Iially In q longitudinal direction. The
proposed concrete blocks advocated by
Gen. Goetnals would not be nearly as
strong as the lining OF the Pennsylva-
mia tunnel, which is composed OF
heavy cast iron supplemented by two
feet of concrete. Indeed it Is estt-
mated that the forty-two foot tunnel,
with n shell of concrete blocks,A will
be lighter than the fluid mass which
1t will displace, and therefore will tend
TO rise and invite rupture! In order
to give 1t structural weight enough
to Offset this the blocks would have
to be five feet thick-to Just that ex-
tent reducing the inside diameter and
the space available for the roadways
and other internal features.
Surely, it would be better to COM
struct tunnel which would always
be rigid and in a state of equilibrium,
and which would remain permanently
where put This can be done easily
by the open trench method. that is. by
dredging channel and driving an
ample number of foundation piles.
so that the tunnel could never sink
any lower and then make the tunnel
so heavy that 1t could never rise, and
so wide that II could never bend. II
could be built on the surface, like a
boat, with bottom, sides and roof OF
reinforced concrete. say G feet thick.
1t could be in lengths Of from $50 feet
; to 1000 feet, as circumstances dictated.
| and when ready these sections could
he towed Into position and readily
sunk on the sustaining piles. IN
Il am satisfied that the largest of
| these structural units could be SUBJ
merged in position within fifteen
minutes after shaving it properly
aligned at the surface, and therefore.
this operation need interfere no more
with river traffic than the docking or
departure OF a big passenger liner
| swinging across tho channel. Each
section would be launched within a
great open topped box or caisson
which would project high enough
above the water to furnish the needful
buoyancy in floating the concrete mass
from its place OF forming to its de-
signed position in the tunnel structure.
w
over the submerged piles, valves would
be opened in the buoyant framework
and the flooding water would carry the
whole mass to the river bottom.
Details of scheme.
at would be entirely practicable to
| provide an air chamber below each
section. If desired, SO as to permit ad-
/ MAJ Al
| Again, there are n number of we'll
known ways by which the sections
could bs linked together after sub
mergence. Personally, believe this
could best be done by means Of pneu-
matte ca!ssons, which would be lowered
right over the point OF junction. and
the cementing could be carried ont
deliberately and thoroughly
GAS others have remarked, the traffic
upon any narrow roadway must be
regulated with extreme care to avoid
ueup--a single vehicle breaking,
down or running wild may halt this
whole line. Similarly, confusion IS all
the more likely where the vehicles
move in three parallel lines at differ
ent speeds and horse drawn and self
propelling trucks. &C.. are travelling
side by side. In the case OF the pro-
posed forty-two foot tunnel there are
| two compartments, each having its
own roadway for traffic going in
prescribed direction. This, unfortu-
nately, Is bound 10 invite nlixup.
The plan offered by Mr.. Stuart
and myself differs radically. Each
section. no matter what its length, has
a width OF III feet and within this
! concrete rectangle are no fewer than
six Isolated driveways, each 25 feet
wide with lG feet of headroom. The
horse drawn traffic is kept quite apart
from the automotive vehicles. and
again, the latter are segregated agree
ably to their speeds. the slow moving
following passages that are distinct
| from those given over TO the faster
!, service. There are also two reason
ably wide footwalks. Half OF the tun-
nelways would be for eastbound and
the other for westbound movement,
There Is no doubt in our minds that
we could build our tunnel faster and
! possibly for even less money than the
price fixed for the design approved by
Gen. Goethals. Obviously. the distri-
tuition of our approaches would not
invite anything like the samo conges!
ton MS that imposed by a single 1s
foot tube"