The Panama Canal

File:Panama canal panoramic view from the top of Ancon hill.jpg

The history of the Panama Canal goes back to 16th century. After realizing the riches of Peru, Ecuador, and Asia, and counting the time it took the gold to reach the ports of Spain, it was suggested c.1524 to Charles V, that by cutting out a piece of land somewhere in Panama, the trips would be made shorter and the risk of taking the treasures through the isthmus would justify such an enterprise. A survey of the isthmus was ordered and subsequently a working plan for a canal was drawn up in 1529. The wars in Europe and the thirsts for the control of kingdoms in the Mediterranean Sea simply put the project on permanent hold.

Various surveys were made between 1850 and 1875 showed that only two routes were practical, the one across Panama and another across Nicaragua. In 1876 an international company was organized; two years later it obtained a concession from the Colombian government to dig a canal across the isthmus. The international company failed, and in 1880 a French company was organized by Ferdinand Marie de Lesseps, the builder of the Suez Canal.  In 1879, de Lesseps proposed a sea level canal through Panama. With the success he had with the construction of the Suez Canal in Egypt just ten years earlier, de Lesseps was confident he would complete the water circle around the world.  Time and mileage would be dramatically reduced when travelling from the Atlantic to the Pacific ocean or vice versa. For example, it would save a total of 18,000 miles on a trip from New York to San Francisco.  In 1899 the US Congress created an Isthmian Canal Commission to examine the possibilities of a Central American canal and to recommend a route. The commission first decided on a route through Nicaragua, but later reversed its decision. The Lesseps company offered its assets to the United States at a price of $40 million. The United States and the new state of Panama signed the Hay-Bunau-Varilla treaty, by which the United States guaranteed the independence of Panama and secured a perpetual lease on a 10-mile strip for the canal. Panama was to be compensated by an initial payment of $10 million and an annuity of $250,000, beginning in 1913. This strip is now known as the Canal Zone.

On August 15, 1914, the Panama Canal was inaugurated with the first passage of ship. A U.S. cargo and passenger vessel – the Ancon – crossed the American-built waterway, which connects the Atlantic and Pacific Oceans, 98 years ago.

Panama later pushed to revoke the Hay-Bunau-Varilla Treaty, and in 1977 U.S. President Jimmy Carter and Panamanian dictator Omar Torrijos signed a treaty to turn over the canal to Panama by the end of the century – which occurred on December 31, 1999.

The Construction

The length of the Panama Canal is approximately 51 miles. A trip along the canal from its Atlantic entrance would take you through a 7 mile dredged channel in Limón Bay. The canal then proceeds for a distance of 11.5 miles to the Gatun Locks. This series of three locks raise ships 26 meters to Gatun Lake. It continues south through a channel in Gatun Lake for 32 miles to Gamboa, where the Culebra Cut begins. This channel through the cut is 8 miles long and 150 meters wide. At the end of this cut are the locks at Pedro Miguel. The Pedro Miguel locks lower ships 9.4 meters to a lake which then takes you to the Miraflores Locks which lower ships 16 meters to sea level at the canals Pacific terminus in the bay of Panama. 

The Panama Canal was constructed in two stages. The first between 1881 and 1888, being the work carried out by the French company headed by de Lessop and secondly the work by the Americans which eventually completed the canals construction between 1904 and 1914.  The contract for the canals construction was signed on March 12th, 1881, and it was agreed the work would be carried out for 512 million French francs, but the contract was conditional in the sense it was not to become binding until two years had elapsed.

During 1882 the excavation of the Culebra Cut was started, but due to the lack of organization there were no tracks available to remove the spoil that the excavators were producing. After the problems had been overcome, the highest peaks of the cut were attacked. As work proceeded, the worry of landslides and what slope should be adopted to avoid them became a major concern.  In 1883 it was realized there was a tidal range of 20 feet at the Pacific, whereas, the Atlantic range was only about 1 foot. It was concluded that this difference in levels would be a danger to navigation. It was proposed that a tidal lock should be constructed at Panama to preserve the level from there to Colon. This plan would save about 10 million cubic meters of excavation.

The French company started to run into financial difficulties during 1885 and even applied to the French government to issue lottery bonds, as this had been successful during the construction of the Suez canal when that project was at the point of failure through lack of money. Rumors of these difficulties caused increased interest within the American government.  A report made by the Americans in 1886 noted that housing for the workforce was under construction and a great deal of plant was available. Unfortunately the plant required to construct the canal was is in short supply, there were too few dredgers, the French excavators were too light and were stopped by large boulders and too much work was being done by hand. The turnover of the labor force was immense, as the men wanted to return home to spend the savings they had accumulated and because of the inadequate medical care that was available.  It was realized that the solution to all the problems encountered, was that the construction of a high-level lock canal would reduce an enormous volume of excavation and prevent the landslides.  The abandonment of the scheme at this stage would cause financial ruin for all the investors and a severe blow to the French. It was suggested that the original plan should be modified and the lock system should be employed.

Eventually, in 1899 the French attempt at constructing the Panama Canal was seen to be a failure. However, they had excavated a total of 59.75 million cubic meters which included 14.255 million cubic meters from the Culebra Cut. This lowered the peak by 102 meters  The value of work completed by the French was about $ 25 million. When the French left, they left behind a considerable amount of machinery housing and a hospital. The reasons behind the French failing to complete the project were due to disease carrying mosquitoes and the inadequacy of their machinery.

The construction of the canal was recommenced by the Americans in 1904. The first step on the agenda was to improve the standard of living and ensure ill health would be a thing of the past.  The first American steam shovel started work on the Culebra cut on 11th November 1904. By December 1905 there were 2,600 men at work in the Culebra cut. Sidings and tracks for the spoil wagons had been laid, the dredging at both the Atlantic and Pacific portions of the canal were being carried out and a survey of the area for the largest dam along the canal had been started.  It wasn’t until June 1906 that the decision on type of canal was decided. It was to be a lock canal. This would enable the river Chagres to form a lake.

Peak excavation within the Culebra cut exceeded 512,500 cubic metres of material in the first three months of 1907 and the total workforce exceeded 39,000. The rock was broken up by dynamite, of which up to 4,535,000 kissograms were used every year.  The plant used in the Culebra cut included in excess of 100 Bucyrus steam shovels each capable of excavating approximately 920 cubic meters in an eight-hour day,  More than 4,000 wagons were used for the removal of the excavated material. Each wagon was capable of carrying 15 cubic meters of material. These wagons were hauled by 160 locomotives and unloaded by 30 Lidgerwood unloaders.

When the canal was first designed, the problem of landslides had been ignored. Slides of earth and more importantly rock, increased the amount of excavation within Culebra. The cross section of the canal was constantly being changed to accommodate for the landslides. The slides caused the upper edge of the cut to be taken back beyond their original lines. The original design for the banks comprised a series of narrow benches which acted as rock catchers, alternating with short steep slopes. It was first decided by the International Board of Consulting Engineers that the rock would be stable at a slope of 1 in 1.5, it was also stated the rock had the strength to stand at a height of 73.5 meters at 1 in 1.5. In fact the rock began to collapse from that slope at a height of only 19.5 meters.

The first major slide occurred in 1907 at Cucaracha. The initial crack was first noted on October 4th, 1907, then without warning approximately 382,000 cubic meters of clay, moved more than 4 meters in 24 hours. This slide caused many people to suggest the construction of the Panama Canal would be impossible. The clay was too soft to be excavated by the steam shovels and was eventually removed by sluicing with water from a high level.  The Cucuracha slide was to become a problem again in 1913, when it crossed the cut until it reached the opposite bank. The steam shovels excavated the slide as it was moving and eventually won the battle.  Further movements were experienced at the base of the cut, including the sudden upheaval of the ground at the middle and a sinking of the ground in other areas. These movements were caused by the pressure of the rock, which seemed to flow as soil and not having the typical behavior of rock. This problem was overcome by removing material from the upper levels of the cut thus, reducing the pressure. As a direct result of all the slides and upheavals encountered, excavation increased by 15.3 million cubic meters. This was about 25% of the total estimated amount of earth moved.

The Locks and Dams

Along the route of the canal there is a series of 3 sets of locks, the Gatun, Pedro Miguel and the Miraflores locks.  At Gatun there are 2 parallel sets of locks each consisting of 3 flights. This set of locks lift ships a total of 26 meters. The locks are constructed from concrete from which the aggregate originated from the excavated rock at Culebra. The excavated rock was crushed and then used as aggregate. In excess of 1.53 million cubic meters of concrete was used in the construction of the Gatun locks alone.  Initially the locks at Gatun had been designed as 28.5 meters wide. In 1908 the United States Navy requested that the locks should be increased to have a width of at least 36 meters  This would allow for the passage of US naval ships. Eventually a compromise was made and the locks were to be constructed to a width of 33 meters.  

Each lock is 300 meters long with the walls ranging in thickness from 15 meters at the base to 3 meters at the top. The central wall between the parallel locks at Gatun has a thickness of 18 meters and stands in excess of 24 meters in height. The lock gates are made from steel and measures an average of 2 meters thick, 19.5 meters in length and stand 20 meters in height.  When Colonel Geothals the American designer of the Panama Canal visited the Kiel Canal in 1912 he was told the canal should have been built 36 meters in width, but by then it was too late.  The smallest set of locks along the Panama Canal are at Pedro Miguel and have one flight which raise or lower ships 10 meters  The Miraflores locks have two flights with a combined lift or decent of 16.5 meters   Both the single flight of locks at Pedro Miguel and the twin flights at Miraflores are constructed and operated in a similar method as the Gatun locks, but with differing dimensions.

Many engineering aspects of the Panama Canal point out the concern for the protection of the environment and natural resources.  As the excavations were being carried out, an enormous amount of excess soil was produced. The French initially hauled the soil to an adjacent valley where the soil was dumped and allowed to build up. This itself caused many problems during the rainy season and was the cause behind many of the landslides.  When the Americans started work on the canal, the engineers decided to reuse this soil for the building of the Gatun dam. This dam held back the water from the Chagres river and thus creating the Gatun lake. As time passed, the soil would continue to settle thus, increasing the strength of the dam.  The dam itself is 1.5 miles in length and is nearly 0.5 mile wide at its base. The construction of the dam involved constructing 2 walls along its length using the excavated rock from the Culebra cut. The space between these 2 walls was then built up with impervious clay. This clay gradually dried and hardened into a solid mass almost equal to concrete in its water-resistant properties. This dam contains 16.9 million cubic meters of rock and clay, equivalent too about one tenth of the entire excavation of the canal.

The dams at Pedro Miguel and Miraflores are small in comparison to Gatun. Their foundations are on solid rock and are subjected to a head of water of 12 meters  whereas the Gatun dam is subjected to a 24 meter head.  The dam at Pedro Miguel is an earth dam approximately 300 meters in length with a concrete core wall.  At Miraflores there are two dams forming a small lake with an area of about 2 square miles. One of the dams is constructed of earth and is 210 meters in length. The second of the dams at Miraflores is 150 meters in length and is made from concrete.


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