CULEBRA CUT
Culebra Cut! Here the barrier of the continental divide resisted to
the utmost the attacks of the canal army; here disturbed and outraged
Nature conspired with gross mountain mass to make the defense stronger
and stronger; here was the mountain that must be moved. Here came the
French, jauntily confident, to dig a narrow channel that would let
their ships go through. The mountain was the victor. And then here
came the Americans, confident but not jaunty. They weighed that mass,
laid out the lines of a wider ditch, arranged complicated
transportation systems to take away the half hundred million cubic
yards of earth and rocks that they had measured. Nature came to the
aid of the beleaguered mountain. The volcanic rocks were piled
helter-skelter and when the ditch deepened the softer strata
underneath refused to bear the burden and the slides, slowly and like
glaciers, crept out into the ditch, burying shovels and sweeping aside
the railway tracks. Even the bottom of the canal bulged up under the
added stress of the heavier strata above.
Grim, now, but still confident, the attackers fought on. The mountain
was defeated.
Now stretches a man-made canyon across the backbone of the continent;
now lies a channel for ships through the barrier; now is found what
Columbus sought in vain--the gate through the west to the east. Men
call it Culebra Cut.
Nine miles long, its average depth is 120 feet. At places its sides
tower nearly 500 feet above its channel bottom, which is nowhere
narrower than 300 feet.
It is the greatest single trophy of the triumph of man over the
terrestrial arrangement of his world. Compared to it, the scooping out
of the sand levels of Suez seems but child's play--the tunnels of
Hoosac and Simplon but the sport of boys. It is majestic. It is awful.
It is the Canal.
When estimates for digging the canal were made, it was calculated that
53,000,000 cubic yards of material would have to be removed from the
cut, and that under the most favorable conditions it would require
eight and a half years to complete the work. But at that time no one
had the remotest idea of the actual difficulties that would beset the
canal builders; no one dreamed of the avalanches of material that
would slide into the cut.
One can in no way get a better idea of the meaning of the slides and
breaks in Culebra Cut than to refer to the accompanying figure. There
it will be seen that whereas it was originally planned that the top
width of the cut at one point should be 670 feet, it has grown wider,
because of slides and breaks, to as much as 1,800 feet at one place.
In all, some 25,000,000 cubic yards of material which should have
remained outside the canal prism slipped into it and had to be
removed by the steam shovels.
[Illustration: THE EFFECT OF SLIDES]
No less than 26 slides and breaks were encountered in the construction
of Culebra Cut, their total area being 225 acres. The largest covered
75, and another 47 acres. When the slides, which were more like
earthen glaciers than avalanches, began to flow into the big ditch,
sometimes steam shovels were buried, sometimes railroad tracks were
caught beneath the débris, and sometimes even the bottom of the cut
itself began to bulge and disarrange the entire transportation system,
at the same time interfering with the compressed air and water
supplies. But with all these trials and tribulations, the army that
was trying to conquer the eternal hills that had refused passage to
the ships of the world for so many centuries, kept up its courage and
renewed its attack. The result is that ships sail through Culebra and
that engineers everywhere have new records of efficiency to inspire
them.
These efficiency records are told in the cost-keeping reports based
upon one of the most careful and thorough cost-accounting systems ever
devised. This system was instituted for the purpose of keeping a check
upon all expenditures by reducing everything to a unit basis and then
comparing the cost of doing the same thing at different places. For
instance, if it were found that it cost more to excavate a cubic yard
of material at one place than at another, under identical conditions,
this fact was brought to the attention of the men responsible and an
intimation given that there seemed to be room for taking up a little
lost motion. The lost motion usually was recovered or else someone had
to be satisfied that conditions were not identical after all.
In no other part of the canal work do these cost-keeping reports tell
such a graphic story as in Culebra Cut. In spite of the fact that as
the cut became deeper it became narrower, and the slides and breaks
became more troublesome, to say nothing of the extra effort required
to get the excavated material out of the cut, every unit cost was
forced down notch by notch and year by year until the bottom in costs
was reached only a little before the actual bottom of the cut was
exposed to view.
For instance, in 1908 it cost 11-1/2 cents a yard to load material
with steam shovels, while in 1912 it cost less than 7 cents. In 1908
it cost more than 14 cents a yard for drilling and blasting; in 1912
it cost less than 12 cents. In 1908 it cost $18.54 to haul away a
hundred yards of spoil; in 1912 it required only $13.31 to perform the
same operation, although the average distance it had to be hauled had
increased 50 per cent. In 1908 it cost more than 13 cents a yard to
dump the material as compared with less than 5 cents in 1912. The
whole operation of excavating and removing the material, including
overhead charges and depreciation, fell from $1.03 a cubic yard in
1908 to less than 55 cents a yard in 1912. And that is why 232,000,000
cubic yards of material were removed for less than it was estimated
135,000,000 cubic yards would cost.
To remove the 105,000,000 cubic yards of earth from the backbone of
the Americas required about 6,000,000 pounds of high-grade dynamite
each year to break up the material, so that it might be successfully
attacked by the steam shovels. To prepare the holes for placing the
explosives required the services of 150 well drills, 230 tripod rock
drills, and a large corps of hand drillers. Altogether they drilled
nearly a thousand miles of holes annually. During every working day in
the year about 600 holes were fired. They had an average depth of
about 19 feet. In addition to this a hundred toe holes were fired each
day, and as many more "dobe" blasts placed on top of large boulders to
break them up into loadable sizes. So carefully was the dynamite
handled that during a period of three years, in which time some
19,000,000 pounds were exploded in Culebra Cut, only eight men were
killed.
[Illustration: STEAM SHOVELS MEETING AT BOTTOM OF CULEBRA CUT
L. K. ROURKE]
[Illustration: THE MAN-MADE CANYON AT CULEBRA]
The transportation of the spoil from Culebra Cut was a tremendous job.
A large percentage of it was hauled out in Lidgerwood flat cars.
Twenty-one cars made up the average Lidgerwood train. It required
about 140 locomotives to take care of the spoil, and the average day
saw nearly 3,700 cars loaded and hauled out of the cut. In a single
year 1,116,286 carloads of material were hauled out. There were 75
trains in constant operation, for each 2-1/2 miles of track in the
Central Division, which was approximately 32 miles long. A huge steam
shovel, taking up 5 yards of material at a mouthful, would load one of
these trains in less than an hour with some 400 yards of material.
Then the powerful locomotive attached to it, assisted by a helper
engine, would pull the train out of the cut, and then, unassisted,
would haul it to the dumping ground some 12 miles or more away.
[Illustration: AVERAGE SHAPE AND DIMENSIONS OF CULEBRA CUT]
Arriving near the scene of the dump, another engine, having in front
of it a huge horizontal steam windlass mounted on a flat car, was
hooked on the rear end of the train. Then the locomotive which had
brought the train to the dump was uncoupled and moved away, and in its
stead there was attached an empty flat car, on which there was a huge
plow. A long wire cable was stretched from the big windlass at the
other end of the train and attached to this plow. As the drum of the
windlass began to turn it gradually drew the plow forward over the 21
cars, plowing the material off as it went forward. The cars were
equipped with a high sideboard on one side and had none at all on the
other. A flat surface over which the plow could pass from car to car
was made by hinging a heavy piece of sheet steel to the front end of
each car and allowing it to cover the break between that car and the
next, thus affording a practically continuous car floor over 800 feet
long. The operation of unloading 400 yards of material with this plow
seldom required more than 10 minutes.
After the plow had finished its work it left a long string of spoil on
one side of the track which must be cleared away. So another plow,
pushed by an engine, attacked the spoil and forced it down the
embankment. This process of unloading and spreading the material was
kept up until the embankment became wide enough to permit the track to
be shifted over. Here another especially designed machine, the track
shifter, was brought into play. It was a sort of derrick mounted on a
flat car, and with it the track shifters were able to pick up a piece
of track and lift it over to the desired position. With this machine a
score of men could do the work that without it would have required a
gang of 600 men.
In addition to the Lidgerwood dirt trains there were a large number of
trains made up of steel dump cars which were dumped by compressed air,
and still other trains made up of small hand-dumped cars, and each
class found its own peculiar uses.
As has been said, the problem of digging the big ditch has been one of
the transportation of the spoil, and this has involved numerous
difficulties. In Culebra Cut no little difficulty was experienced in
keeping open enough tracks to afford the necessary room for dirt
trains. Slides came down and forced track after track out of
alignment, burying some of them beyond the hope of usable recovery;
often the very bottom of the cut itself heaved up under the stress of
the heavy weight of faulty strata on the sides of the mountain; and
sometimes the slides and breaks threatened entirely to shut up one end
of the cut.
In hauling away the spoil one improvement after another was made in
the interest of efficiency. It was found at first that the capacity of
a big Lidgerwood flat car was only about 16 cubic yards, and that with
a sideboard on only one side of the car, the load did not center well
on the car, thus placing an undue strain on the wheels on one side.
The transportation department, therefore, extended the bed of the car
further out over the wheels on the open side, and this served a triple
purpose--it permitted the steam shovels to load the cars so that the
load rested in the center, increased the capacity of each car by about
3 yards, and permitted the unloader plow to throw the spoil further
from the track, thus adding to the efficiency of the dumping
apparatus.
Frequent breaks in the trains were caused by worn couplers. These
accidents were almost entirely overcome by equipping each train with a
sort of "bridle" which prevented the separation of the cars in the
event of the parting of a defective coupler. In the operation of the
unloader plows it was found that the big cables frequently broke when
a plow would strike an obstruction on the car, and this caused no end
of annoyance and frequent delays. Then someone thought of putting
between the cable and the plow a link whose breaking point was lower
than that of the cable. After that when a plow struck an obstruction
the cable did not part--the link simply gave way, and another was
always at hand. On the big spreaders no less than 51 improvements were
made, each the answer of the engineers to some challenge from the
stubborn material with which they had to contend.
The major portion of the material excavated from the canal had to be
hauled out and dumped where it was of no further use. From the Central
Division alone, which includes Culebra Cut, upward of a hundred
million cubic yards of material was hauled away and dumped as useless.
At Tabernilla one dump contained nearly 17,000,000 cubic yards. A
great deal of spoil, however, was used to excellent advantage.
Wherever there was swampy ground contiguous to the permanent
settlements it was covered over with material from the cut and brought
up above the water level. Many hundreds of acres were thus converted
from malaria-breeding grounds into high and dry lands.
During the last stages of the work in Culebra Cut it was found that
some of the slides were so bad that they were breaking back of the
crest of the hills that border the cut. Therefore it was found to be
feasible to attack the problem by sluicing the material down the side
of the hills into the valley beyond. To this end a big hydraulic plant
which had been used on the Pacific end of the canal was brought up and
installed beyond the east bank of the cut. A reservoir of water was
impounded and tremendous pumps installed. They pumped a stream of
water 40 inches in diameter. This was gradually tapered down to a
number of 4-inch nozzles, and out of these spouted streams of water
with a pressure of 80 pounds to the square inch. These streams ate
away the dirt at a rapid rate.
The slides did not hold up the completion of the canal a minute, at
least to the point of usability. The day that the lock gates were
ready there was water enough in the canal to carry the entire American
navy from ocean to ocean. That day the big dredges from the Atlantic
and the Pacific were brought into the cut, and with them putting the
finishing touches on the slides at the bottom, and the hydraulic
excavators attacking them at the top, the problem of the slides was
solved.
Viewing Culebra Cut in retrospect, it proved an immensely less
difficult task than some prophesied, and a much more serious one than
others predicted. There were those who opposed the building of the
Panama Canal because of the belief that Culebra Cut could not be dug,
that Culebra Mountain was an effective barrier to human ambition.
Also, there were those who asserted that Gold Hill and Contractor's
Hill were in danger of sliding into the big ditch and that they were
mountains which neither the faith nor the pocketbooks of the Americans
could remove. Others saw the handwriting of Failure on the wall in
the heaving up of the bottom of the cut, interpreting this as a
movement from the very depths of the earth. Still others saw it in the
smoke that issued from fissures in the cut, which spoke to them of
volcanoes being unearthed and told them that the Babel of American
ambitions must totter to the ground. They did not know that these were
only little splotches of decomposing metals suddenly exposed to the
air, any more than their fellow pessimists knew that the heaving up of
the bottom of the cut was due to the pressure of the earth on the
adjacent banks.
To-day Culebra Mountain bows its lofty head to the genius of the
American engineer and to the courage of the canal army. Through its
vitals there runs a great artificial canyon nearly 9 miles long, 300
feet wide at its bottom, in places as much as a half mile wide at its
top and nearly 500 feet deep at the deepest point. Out of it there was
taken 105,000,000 cubic yards of material, and at places it cost as
much as $15,000,000 a mile to make the excavations. Through it now
extends a great ribbon of water broad enough to permit the largest
vessels afloat to pass one another under their own power, and deep
enough to carry a ship with a draft beyond anything in the minds of
naval constructors to-day. With towering hills lining it on either
side, with banks that are precipitous here and farflung there, with
great and deep recesses at one place and another telling of the
gigantic breaks and slides with which the men who built it had to
contend, going through Culebra Cut gives to the human heart a thrill
such as the sight of no other work of the human hand can give. Its
magnitude, its awe-inspiring aspect as one navigates the channel
between the two great hills which stand like sentinels above it, and
the memory of the thousands of tons of dynamite, the hundreds of
millions of money and the vast investment of brain and brawn required
in its digging, all conspire to make the wonder greater. It is the
mightiest deed the hand of man has done.