Evening star., 1927-10-23

Continued from Sixth Page)
a certain amount of carbon monoXide,
one of the deadliest gases known.
Exactly how much Of this exhaust
was carbon monoXide gas was not
known. and so the Pittsburgh expert
ment station of the Bureau of Mines
was engaged to determine the amount
and composition of the gases dis
charged by an automobile engine. The
station is under the direction of A. c.
| Fieldner. one of the foremost gov
| ernment chemists in the country, and
more than 100 cars and trucks were
tested.
Safeguard Against MonOxide.
During the tests it was found that
several gases were discharged by gas
oline engines, but that carbon monox-
ide was the only one which deserved
serious consideration. 1t was also dis
covered that the amount of carbon
monoxide contained in the exhaust
gases varied from II of per cent up
to IA per cent. This gave the ventila-
ton experts the figures upon which
they could begin work.
| While these tests were going on in
Pittsburgh Prof. Yandell Henderson
of Yale was conducting a series of
| tests to determine just how much of
| this gas could be breathed safely.
| These tests We're made on students of
the institution. and after having tested
scores of students by various means
! and examined and analyZed specimens
of blood and eXhaled air, Prof. Hen.
derson came to the conclusion that
any man who remains in the Holland
| tunnel for an hour must breathe not
| r,nn fI,ar nrfO nf .tr1t, tIa
in 10000 parts of air. An increase to
s parts would produce a slight head.
ache, while parts would cause an eff.
| feet noticeable for some hours after.
| ward.
These experiments probably caused
a considerable saving in the expenses
of operating the tunnels, for had the
engineers, in the interest of safety,
set too high a standard of air purity,
it would have involved not only a
greater initial outlay for the purifying
apparatus, but would have entailed
additional running expenses.
Air Current Regulated. =
Tn order to keep the carbon monox.
ide down to the limit prescribed by
Prof. Henderson 1t was found that the
air current through the tunnel had to
be at the rate of gale Of ~ miles
an hour. Obviously, such a high wind
could not blow through the tube
where the vehicles passed. for aside
4 from the Inconvenience of such
draft, should car catch fire 1t would
not be long before the entire tunnel
would be a roaring holocaust.
The next step was to determine how
to maintain a windstorm of 72 miles
an hour and yet have 1t tanned in such
a way that motorists would not ex-
perience any danger or Inconvenience.
This was done by laying a duet be-
meath the roadway through which the
storm sweeps. From this duct
J ranches lead to what is termed the
expansion box, extending along the
curb of the roadway. Out of grilled
openings the air emerges in a gentle
breeze.
In the top of each tube, above the
roadway, is another duct, into which
the foul air and exhaust gases are
drawn through openings. This air is
sucked out by exhaust fans. A total
of 81 fans-42 blowers and AZ exhaust
ers-have been installed for purposes
Of creating the draft required, al.
though but 56 of them will be needed
at any one time. Enough are kept in
reserve so that should some of the
fans be crippled there will be others
that can be turned on. A total of
5000 horsepower is required to operate
the entire 81 fans.
Fans in Ventilation Shafts.
These fans are located in ventilation
shafts, of which there are two on each
side of the river. These structures
are about as tall as a 10-story build
ing. The fresh air is sucked in
through lowers or openings in the
walls, sent down into the tunnel while
the yitiated air is drawn forth from
the tubes and returned to the atmos-
phere by means of stacks on the roofs
of the ventilation buildings.
Complete control of the fans, as well
as the signal lights In the tunnel, is
located in an administration building,
where switchboard 20 feet long and
! ia feet high, curved like an arc, tells
by means of light flashes that all is
well or that something is wrong. In
the center OF this arc stands a man
who keeps his eye on the signal lights.
He can tell at a glance whether
any one of the "a fans is in opera.
ton or not, whether 1t Is running,
when 1t ought to be at rest, or
whether 1t In running at the required
speed. Other lights tell whether traf-
fic signals are in order as we'll as
the amount Of carbon monoxide in
the air. Another light will give the
warning when there is too much
water in the stump of the ventilating
duct, which Immediately calls forth
the order for starting the pumps.
But 1t Is nothing dangerous, merely
the seepage and the collected water
brought I'm by the automobiles.
Policemen Figure in Scheme.
At every interval of 4S0 feet is
stationed a policeman, who has tel.
ephone at his side. Should car
break down the policeman picks up
his phone and calls the emergency
truck. This truck is equipped with
doubleend drive, so that 1t can
run back and forth in the tunnel
without turning around. The Grip
pied vehicle then is hauled out of
the tunnel and traffic resumes Its
ordinary course.
Each tunnel is equipped with two
sets OF traffic lights. one for each
lane OF traffic. Each tube is one
| way thoroughfare. Every 240 feet
there il a traffic signal which orders
drivers to stop when il Is found ex.
pedient to send the traffic through
in waves rather than in steady
stream.
In order to combat fire. the most
extreme precautions have been taken.
Every 1875 feet there Is a closet with
fire extinguishers. These extinguish-
ers are Of the kind used by oil COM
panies to combat fires in their storage
fields. Boxes of sand also are placed
at frequent intervals.
In all respects, the Holland Tunnel
has been made as safe as modern