Evening star. [volume] (Washington, D.C.) 1854-1972, 1956-11-25

@--N~--N~@N-
to be the only Office where sec.
retarieS can ask to go home
early because of Seasickness.
During the spray-splatterec
harbor tour, two guides ex.
planned what was going on. They
were William Jordan. an engi
neer with the Maryland State
Roads Commission, and Free
Chaimson, an inspector with
Singstad g. Baillie, the engineer.
ing firm which designed the tun
mel. Mr.. Chaimson, a 26-year.
old Washington native, lives a
434l First street NE. and com.
mutes to the project every day.
He explained that the frs
step in the actual construction
was the preparation of the q
tube sections. Three shipyard'
did the work. Each section i
made of two 300-foot-long stee
tubes laid side by side and con-
nected by steel ribs.
The end of each tube is sealed
with a sheet steel diaphragm
braced with m assive stee
I-beams on the inside. Aftel
launching. each section is toweC
TO a "shape-up dock" near the
tunnel site.
Like Icing q Cake
There the interior is covered
with concrete to a thickness oil
20 inches ga inches in the tubes
which will lie beneath the Deep
est water0 The roadway is not
laid on the bottom of the tube
but on a deck built above the
bottom.
AS the concreting proceeds, the
tube sections float lower and
lower in the water. The outside
Of each section is protected by q
thin layer of pneumatic con-
crete shattered on like cake icing
The bottom is coated before the
launching and the coating is
carried up the sides of the shell
as it sinks lower.
When the sections are just
barely floating, they are towec
into position above the. trench
dug in the bottom Of the harbor
They weigh about 10000 tons BY
then. They are moved under the
supporting framework Of thu
twin lowering barges and NOR,
concrete is poured into pockets
between the two tubes, causing
the section to sink.
Surveyors transits are sighted
on poles fastened to the tubei
and projecting above the watel
to align the sections exactly
Divers under the water direct thu
placing Of the tubes against thu
ends of the tubes already il
place. When the position is jus
right. they slip steel pins int
the locking Tugs.
Then steel collars are clampet
over the junction, more concretl
is poured underwater to com
plete the seal and hold the tub
in place and 10 feet Of mud ant
clay is dredged into the trencl
on top of the tubes. Norma
sitting will fill the trench tn
rest OF the way.
Half Of Sections Placed
There are 81 sections Of tubinl
altogether. The eleventh one wa
sunk into place last Wednesday
The remaining 10 are all afioa
in various stages of concretine
They will be sunk at about tw,
week intervals. until the last
in place about next June.
The steel diaphragms are Gu
out after the tubes are in placl
and covered. The IL tubes al
ready in place extend out undeI
the harbor from the southern
shore. but only the FIRST foui
have been cut open.
That's where the inspection
party went, TO the end Of thu
fourth tube-l 200 feet into thu
water and 20 feet down. TIL,
slopes down on q 2ia pei
cent grade for that distance
Afr that. the grade eases to 4:
per cent before starting thu
gradual rise toward the othel
shore. u
At its lowest point. the road
way viii be 90 feet below the
Of the water.
The Anal iuncture Of tubes
win be made AZ q shaIlower
depth near the northern shore
The engineers have allowed two