Spoil was also used to claim nearly 500 acres of Pacific Ocean to create the Balboa townsite and the Fort Amador military reservation. Millions of cubic yards of material also had to be hauled out to big waste dumps in the jungle. In the largest of these, Tabernilla, 17,000,000 cubic yards of material were deposited. Balboa was the biggest dumpsite. Other big dumps were Gatun Dam, and Miraflores.
Gatun Dam, on the Atlantic, was, at the time of its construction, the largest earthen dam in the world and Gatun Lake the largest manmade body of water in the world. Today, Gatun Lake doesn t even make the top thirty list of such lakes. Two other dams were built on the Pacific side the Miraflores Spillway and, in the 1930s, Madden Dam farther up the Chagres River. With the building of Gatun Dam, the Chagres River valley between Gamboa and Gatun became Gatun Lake, with the Chagres flowing into it at Gamboa. The building of Gaillard Cut then extended the lake across the Continental Divide to Pedro Miguel Locks.
Earth slides in Culebra Cut were a constant concern for construction engineers. The first under the American effort occurred at Cucaracha on October 4, 1907 when some 500,000 cubic yards of material moved into the Cut following several days of unusually heavy rain. For ten days the slide moved an average of 14 feet every 24 hours. Cucaracha remains today a slide surveillance area.
A normal or gravity slide like Cucaracha, the largest of its kind at the Canal, occurs where a layer of porous material rests upon a sloping surface of harder material such as rock. Rainwater saturating the overlying porous material forms a slippery zone against the harder material below, causing the entire top layer, which can vary in thickness from 10 and 40 feet, to slide.
Geologists classify another type of slide as structural break or deformation slides. In these, factors such as unstable geological rock formations, slope steepness and height and the effects of blasting combine to form a slide. At the Canal, excavation removed lateral support from the high banks created in the deepest portions of Culebra Cut. Unable to sustain the weight above it, the slopes sheared and settled forcing the underlying layer of poor-quality rock and soft material to be crushed and forced laterally into the prism of the Canal, heaving up the Canal bottom.
The most formidable slides of this character occur during the dry season, and are in no way due to ground saturation by rainfall.
The two most serious structural break slides during the American construction period occurred on the east bank north of Gold Hill and on the west bank in front of Culebra village. The west bank slide covered a 75-acre area requiring the removal of some 10,000,000 cubic yards of material, and a number of village buildings had to be removed or demolished. The 50-acre Gold Hill slide on the east bank required removal of some 7,000,000 cubic yards of material.
Canal engineers were completely unprepared for and confounded by this unexpected slide activity. In 1906, the minority report of the International Board of Consulting Engineers placed total Culebra Cut excavation for a lock canal at 53,800,000 cubic yards; the minority report estimated the amount necessary for a 40-foot-deep sea level canal at 110,000,000 cubic yards. In 1908 the canal commission revised the Cut excavation estimate to about 78,000,000 cubic yards; in 1910 to 84,000,000; in 1911 to 89,000,000; in 1912 to nearly 94,000,000; and in 1913 to about 100,000,000. The increased Cut excavation required was due partially to an increased bottom width from 200 to 300 feet, an increase of about 13,000 cubic yards, but the slides were the main reason.
The one-year record high for construction-era excavation was set in 1908, with more than 37,000,000 cubic yards of spoil taken from the Cut. This was also the year in which Lieutenant Frederick Mears began directing the relocation of the Panama Railroad line to higher ground ahead of inundation of the existing tracks by the filling of Gatun Lake. Building the 40 miles of new track was completed May 25, 1912, at a cost of nearly $9,000,000.
WORK FORCE
The following chart shows the maximum force employed during each year of construction work
Date Work Force
May, 1904 1,000 (Approx.)
Nov., 1904 3,500
Nov., 1905 17,000
Dec., 1906 23,901
Oct., 1907 31,967
Apr., 1908 33,170
Oct., 1909 35,495
Mar., 1910 38,676
Dec., 1911 37,826
June, 1912 38,174
Aug., 1913 39,962
June, 1914 33,270
The following table shows the total number of contract laborers brought to the Isthmus throughout the work. It does not include the number of workers recruited from the United States.
Country 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913
Spain 1,174 5,293 1,831
Cuba 500
Italy 909 1,032
Greece 1,101
France 19
Armenia 14
Total Europeans 2,616 7,426 1,831
Fortune Island 361
Barbados 404 3,019 6,510 3,242 2,592 3,605 528
Guadeloupe 2,039 14
Martinique 2,733 585 2,224
Jamaica 47
Trinidad 1,079 205 143
Curacao 23
St. Kitts 933 9
St. Lucia 55
St. Vincent 296
Grenada 93
British Guiana 332
Total West Indies 404 5,799 9,491 7,505 2,592 3,605 205 942 528
Costa Rica 244
Colombia 1,077 416
Panama 334 10 13
Not classified 69
Grand Total 404 7,454 12,602 14,944 4,423 3,605 205 942 528
Providing food for more than 40,000 employees and their families in a country with little food production capability and few stores was a tremendous task at the beginning. With the goal in mind of maintaining a healthy and contented work force, the Isthmian Canal Commission imported food on the Panama Railroad steamers. They also started farms to grow fruits and vegetables, even plants and flowers, as well as farms to produce milk and eggs.
It was a difficult task in the beginning, but every effort was made to ensure adequate living standards, in accordance with standards of the time, for canal workers. Ice and cold storage warehouses were constructed, and a bakery and ice cream plant were set up. The Panama Railroad had refrigerated cars to provide distribution to settlements along the line of the canal.
Hotels or restaurants were established for the American bachelors. A number of mess halls were built for the European laborers where meals were furnished at 40 cents per day. Kitchens were built for the West Indian laborers. Rations were furnished and cooked in these kitchens for 30 cents per day.
The Canal s Job
About 32 oceangoing vessels pass through the canal daily. They pay an average of $28,000 for passage, for an estimated total yearly income of 330 million dollars, a little bit less than Nicaragua s yearly exports. Some massive ships pay tolls several times this amount. The fees are well spent, for the trip of some eight to ten hours through the canal saves many miles and many days of travel. If there were no Panama Canal, a ship going from San Francisco, California to New York City would have to sail down around the tip of South America, an additional 7,900 nautical miles, some of it in very rough seas.
An almost endless variety of commodities pass through the canal day after day. About 140 million tons of oceangoing commercial cargos are shipped through the canal in a single year. The main commodity group, petroleum and petroleum products, makes up about 22 percent of the annual cargo tonnage. Grains compose about 16 percent. A significant development in canal cargo has been the increase in automobile trade. Over 2.4 million tons of automobiles are moved through the canal every year, most being transported from Japan to the United States. A small percentage of the world’s water shipping is routed through the canal. The greatest user is the United States, which transports much of its imports from Latin American neighbors through the watercourse.
In fiscal 1915, the first year of operation, about 5 million tons of cargos were shipped through the Panama Canal. In 1924, 27 million tons were carried through it. Between 1925 and 1941 the annual tonnage varied between 18 million and 31 million. There was a dip in total cargo during World War II, but since then nearly every year has shown an increase. The figure for 1950 was some 30 million tons. By the early 1960s the volume had almost doubled. During the late 1960s, largely as a result of the Suez Canal blockade, tonnage rose to much more than 100 million tons annually
As much as the Canal brings benefits to Panama it also brings tons of problems. Some are similar to those of land highways. Increasing traffic has required widening the lanes. “Street lights” have been put in for night safety. One-way traffic is necessary at times. Modern traffic control systems have been installed. The comparison with land travel, however, has limits. The Panama Canal, because of its location, size, and type of construction, has problems unlike those of any other transportation link in the world.
Design of the Locks
The original lock canal plan called for one three-step set of locks at Gatun, one step at Pedro Miguel and a two-step set at Sosa Hill. In late 1907, it was decided to move the Sosa Hill locks further inland to Miraflores, mostly because the new site provided a more stable construction foundation, but also because it afforded greater protection against sea bombardment.
The locks took their names from geographic names already in common use before the Canal was built. All lock chambers have the same 110 by 1,000 feet dimensions, and they are built in pairs. That is, two lanes of chambers run side by side to accommodate two lanes of traffic, either in opposite directions at the same time or in the same direction, depending on transit needs. Gatun Locks consists of three steps or pairs of chambers, there is one step at Pedro Miguel and two at Miraflores, making six pairs, 12 chambers in all. The locks have been called the structural triumph of the Panama Canal and are a unique aspect of the waterway. At the time of their construction, their overall mass, dimensions and innovative design surpassed any similar existing structures, and they are still considered to be an engineering wonder of the world.
It took four years to build all of the locks from the first concrete being laid at Gatun on August 24, 1909. Until the late 1800s, concrete, a combination of sand, gravel and cement, had been little used in building, and then mostly for floors and basements. There was still a great deal to be learned and numerous decisions to be made in the science of concrete which requires specific, controlled measurements of water/cement/sand ratios and aggregate size, as well as careful timing of a streamlined delivery system from source to site. The concrete work in Panama was an unprecedented challenge that would not be equaled in total volume until construction of Boulder Dam in the 1930s.
In spite of the newness of the science, the results were extraordinary. After more than 80 years of service, the concrete of the Panama Canal locks and spillways is in near perfect condition, which to present-day engineers is among the most exceptional aspects of the entire Canal.
Canal organization ships, the Ancon and the Cristobal, brought all of the cement to build the locks, dams and spillways from New York. On the Atlantic side, gravel and sand came by water from areas east of Colon, the gravel from a large crushing plant in Portobelo and the sand from Nombre de Dios. For the Pacific side, rock was quarried and crushed at Ancon Hill; the sand came from Punta Chame in Panama Bay.
Three men, Lieutenant Colonel Harry Hodges, Edward Schildhauer and Henry Goldmark, were largely responsible for the engineering design of the locks. The work took years of advanced planning. Hodges was an Army officer and an invaluable assistant to Goethals. He had overall responsibility for the design and construction of the lock gates, arguably the most difficult technical responsibility of the entire project. Goethals was to state that the Canal could not have been built without Hodges. Schildhauer was an electrical engineer and Goldmark was in charge of lock gate design.
The key factor in the whole Canal enterprise, of course, was, and is, water. Water lifts ships 85 feet above sea level to the surface of Gatun Lake, floats them across the Continental Divide and lowers them again to sea level in the opposite ocean. Water also serves to generate electrical power for the Canal to run the electric motors that open and close the gates and valves and the electric locks locomotives.
No pumps are used at the Panama Canal, the water does its work by force of gravity alone. Water is admitted or released through giant tunnels, or culverts, eighteen feet in diameter, running lengthwise within the center and sidewalls of the locks. Branching off at right angles to these culverts, smaller culverts run laterally under the floor of each lock chamber, 20 to each chamber. Each cross culvert has five openings for a total of 100 holes in each chamber for the water to enter or drain, depending on which valves are opened or closed. This large number of holes distributes the water evenly over the full floor area to control turbulence
To fill a lock, the main valves at the lower end of the chamber are closed, while those at the upper end are opened. The water pours from the lake through the large culverts into the cross culverts and up through the holes in the chamber floor. To release the water from the lock, the valves at the upper end are closed, while those at the lower end are opened.
The lock gates, or miter gates as they are known because they close in a wide V , are the Canal s most dramatic moving parts. The gates swing like double doors. The hollow, watertight construction of their lower halves makes them buoyant in the water, greatly reducing the working load on their hinges. All gate leaves (gates sustaining water) are 64 feet wide by 7 feet thick. However, they vary in height from 47 to 82 feet, depending on their position. For example, the Miraflores Locks lower chamber gates are the highest because of the extreme variation in the Pacific tides.
The design and manufacture of all of the lock gates was one of the Canal s great engineering challenges and one of its greatest triumphs. Edward Schildhauer designed the simple, yet powerful gate operating mechanism. In its design he had no established model to go by. Yet every aspect of this critical mechanism had to be precision engineered and manufactured to work flawlessly and dependably. The gates had to swing easily, yet withstand enormous pressures. To operate, the lock gates leaves are connected by steel arms, called struts, to huge bull wheels constructed within the lock walls. Each 20-foot-diameter, horizontal-lying bull wheel is geared to an electric motor. When in operation, wheel and strut work like the driving wheel and connecting rod on a railroad locomotive to open and close the gates.
At Miraflores Locks, each lock chamber, except for the lower locks, has a set of intermediate gates. The purpose of these is to conserve water by reducing the size of the chamber, if the ship in transit is not one of the Panamax giants and can be accommodated by a 600-foot chamber.
As the lock gates themselves are a form of dam and are above sea level, precautions were taken to protect them from damage that could allow the lake water to escape and flow out to sea. One measure was to have double gates ahead of the vessel, an operating gate and a guard gate, at points where damage to a gate could join the two levels, that is, at the upper and lower ends of the upper lock in each flight and at both ends of the Pedro Miguel single-step lock.
Also, iron fender chains were installed to stretch across the chambers between the lock walls to protect the guard gates. Only after the ship was in proper position and under towing locomotive control was the chain lowered. The idea was that if a ship went out of control and struck the chain, an automatic release would let the chain out slowly until the ship came to a stop, thus limiting possible damage. The expense of their upkeep against the extreme unlikelihood of their use caused the Board of Directors to approve fender chain removal in July 1976, except at the upper ends of Gatun and Pedro Miguel locks; these remaining chains were removed in October 1980.
Yet another devise stood as safeguard should a ship break through a guard gate. That was what was called an emergency dam installed on the sidewalls at the entrance of each upper lock between the fender chain and the guard gates. It is a big steel apparatus mounted to swing across the lock entrance in about two minutes in case of emergency. A series of wicket girders would descend forming runways down which huge steel plates would be dropped until the channel was sealed off. Never put to use, the emergency dams were removed in the 1950s.
Electricity was the power that ran Canal construction-era cableways, cranes, rock crushers and cement mixers. An all-electric canal was an innovation in the first decade of the 20th century. Locks operations required some 1,500 electric motors, as all controls were electrical. The General Electric Company produced about half the electrical equipment needed during construction and virtually all of the permanent motors, relays, switches, wiring and generating equipment. They also built the original locks towing locomotives and all of the lighting.