Evening star., 1928-03-25
CITIES PLAN TUNNEL ROADS
TO SOLVE AUTO CONGESTION
Underground Life Becoming More of
Reality as Traffic Increases-Many
New Projects Proposed

Underground life in buildings, tun-
nels and subterranean highways is be-
coming more of a reality than ever as
these digging projects multiply through
out the United States, while other ma
tions of the world are planning super
tunnels that will make the most modern
of those of today seem small in COM
parison. q careful survey reveals.
Confronted by the ever increasing
traffic problem created by the automo-
bile and aroused by prospects that this
will be much worse within the next two
to five years, many American cities and
States are boring giant tunnels under
bays. rivers. and mountains and plan
ming tiers OF streets in their main busi-
ness section, the cost of which viii ex-
ceed $i00, 100000.
The worldwide epidemic OF tunnel
building received its greatest single i'm
petus from the outstanding success Of
the Holland vehicular tunnel undcr the
Hudson River. and the fact that It
could be so eff1cientlv ventilated by me-
chanical means. Tests proved that air
conditioning made the air in the Hol-
land tunnel purer than that in the
open spaces of Fifth avenue, despite
the fact that thousands Of automobiles
pour out tons of the deadly carbon
monoxide gas into the tunnel every
hour.
See Manufactured Weather.
In the Fall of 1926 several nationally
known ventilating engineers declared
that advances achieved in the science
Of controlled air would make 1t pos
sible to economically manufacture ideal
weather conditions for underground ac-
tivities. The first big ventilating job
completed was that of the Liberty tun-
mel which was cut through q mountain
In Pittsburgh. but which had been pre-
ceded by exhaustive ventilating tests
conducted by the Bureau OF Mines in
cooperation with the Public Health
Service and the American Society Of
Heating and Ventilating Engineers
In addition to these tests. engineers in
the ventilating industry had constructed
miniature tunnels in their laboratories
10 determine exactly the amount OF air
motion and change required To remove
all carbon monoxide fumes. The bene-
fits OF all these experiments combined
with the actual experience of operating
the Liberty tunnel were applied 70 the
larger and more spectacular tubes under
the Hudson
OF all the tunneling and other sub
terranean projects now under way, the
most unusual In conception and method
OF building Is the giant underwater. ve-
hicular tube connecting Oakland. Calf
and Alameda under the Oakland inner
harbor. This tube. which viii be
opened next July and will have cost
$4,000 900. is 4400 feet long and has
an inside diameter of 81 feet, which Is
seven and a half feet larger than the
inside diameter Of the Hudson twin
tubes. II will contain two street car
tracks and will be capable OF handling
a traffic flow OF 1000 automobiles per
hour.
Construction Closely Watched.
The tube is the first precast tube
ever built In the world and It's con-
struction has been closely watched by
engineers. The tube was precast In
concrete and steel In IL segments each
205 feet long and weighing 5000 tons
apiece. After the Oakland and Ala
media approaches we're built, the tube
seginents were fioated into place and
SUNK As each segment sank into place,
IL was Joined To one already IN place
with q huge steel collar and concrete
Duikheads At ends of the segments we're
then knocked out and joints further
strengthened from the inside
10 ventilate these big tubes fresh
air VIII be drawn In at the portal build
ing at each end, StXteen~foot fans pro-
PEELED by 00horsepower motors will
SEND fresh air into ducts underlying
three-foot sidewalks on each side ol the
tube The interior air will be- released
from duets along curb crevice This
crevice Is covered with sheet metal and
may be adjusted TO control the amount
Of air To he released Vtiated air will
be drawn OF through ceiling louvres at