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A canal tug, making its way down to the Caribbean end of the canal, waits to be joined by a ship in the uppermost chamber of the Gatun Locks.
A canal tug, making its way down to the Caribbean end of the canal, waits to be joined by a ship in the uppermost chamber of the Gatun Locks.
The Panama Canal is a major ship canal that traverses the isthmus of Panama in Central America, connecting the Atlantic and Pacific Oceans. The construction of the canal was one of the largest and most difficult engineering projects ever undertaken. It has had an enormous impact on shipping as ships no longer have to travel the long and treacherous route via the Drake Passage and Cape Horn at the southernmost tip of South America. A ship sailing from New York to San Francisco via the canal travels 9,500 kilometres (6,000 mi), well under half the distance of the previous 22,500 kilometre (14,000 mi) route around Cape Horn.Although the concept of a canal in Panama dates back to the early 16th century, the first attempt to construct a canal began in 1880 under French leadership. After this attempt collapsed, the work was finally completed by the United States; the canal opened in 1914. The building of the 77 kilometre (48 mi) canal was plagued by problems, including disease (particularly malaria and yellow fever) and massive landslides. As many as 27,500 workers are estimated to have died during construction of the canal.Since opening the canal has been enormously successful and continues to be a key conduit for international shipping. Each year the canal accommodates the passage of over 14,000 ships carrying over 203 million tonnes of cargo. By 2002 about 800,000 ships had passed through the canal.

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Description - Contents

The canal cuts through the Isthmus of Panama from the Pacific Ocean at the south-east end to the Atlantic Ocean at the north-west end.
The canal cuts through the Isthmus of Panama from the Pacific Ocean at the south-east end to the Atlantic Ocean at the north-west end.
The Panama Canal connects the Gulf of Panama in the Pacific Ocean with the Caribbean Sea and the Atlantic Ocean. Because of the S-shape of the Isthmus of Panama the canal runs from south-east at the Pacific end to north-west at the Atlantic; to avoid confusion the canal authorities classify transits of the canal as northbound (Pacific to Atlantic) and southbound (Atlantic to Pacific).The canal can accommodate vessels from small private yachts up to fairly large commercial ships. The maximum size of vessel which can use the canal is known as Panamax; an increasing number of modern ships exceed this limit and are known as post-Panamax vessels. A typical passage through the canal by a cargo ship takes around nine hours. 14,011 vessels passed through the canal in 2005, carrying a total capacity of 278.8 million tons, with an average of almost 40 vessels per day.

The canal consists of two artificial lakes, several improved and artificial channels, and three sets of locks. An additional artificial lake, Alajuela Lake, acts as a reservoir for the canal. The layout of the canal as seen by a ship transiting from the Pacific end to the Atlantic is as follows:
A schematic of the Panama Canal, illustrating the sequence of locks and passages.
A schematic of the Panama Canal, illustrating the sequence of locks and passages.
  • From the beginning of the buoyed entrance channel in the Gulf of Panama ships travel 13.2 kilometres (8.2 mi) up the channel to the Miraflores locks, passing under the Bridge of the Americas
  • The two-stage Miraflores lock system, including the approach wall, is 1.7 kilometres (1.1 mi) long, with a total lift of 16.5 metres (54 ft) at mid-tide
  • The artificial Miraflores Lake is the next stage, 1.7 kilometres (1.0 mi) long and 16.5 metres (54 ft) above sea level
  • The single-stage Pedro Miguel lock, which is 1.4 kilometres (0.8 mi) long, is the last part of the ascent with a lift of 9.5 metres (31 ft) up to the main level of the canal
  • The Gaillard (Culebra) Cut slices 12.6 kilometres (7.8 mi) through the continental divide at an altitude of 26 metres (85 ft) and passes under the Centennial Bridge
  • The Chagres River (Río Chagres), a natural waterway enhanced by the damming of Lake Gatún, runs west about 8.5 kilometres (5.3 mi), merging into Lake Gatun
  • Lake Gatún, an artificial lake formed by the building of the Gatun Dam, carries vessels 24.2 kilometres (15.0 mi) across the isthmus
  • The Gatún locks, a three-stage flight of locks 1.9 kilometres (1.2 mi) long, drop ships back down to sea level
  • A 3.2 kilometre (2.0 mi) channel forms the approach to the locks from the Atlantic side
  • Limón Bay (Bahía Limón), a huge natural harbour, provides an anchorage for some ships awaiting transit and runs 8.7 kilometres (5.4 mi) to the outer breakwater
A cargo ship transiting the Gatún locks northbound is guided carefully between lock chambers by "mules" on the lock walls to either side.
A cargo ship transiting the Gatún locks northbound is guided carefully between lock chambers by "mules" on the lock walls to either side.
The total transit from the Pacific entrance channel to the Atlantic breakwater is 76.9 kilometres (47.8 mi). The maximum tidal range on the Pacific side is from +3.35 metres (+11.0 ft) to -3.20 metres (-10.5 ft); hence the lift at Miraflores varies between 13.1 metres (43 ft) at extreme high tide and 19.7 metres (64.5 ft) at extreme low tide. The tidal range on the Atlantic side does not exceed 60 centimetres (24 in). Mean sea level at the Pacific end of the canal is on average about 20 centimetres (8 in) higher than at the Atlantic end.Limón Bay, on the Atlantic side, is a sheltered anchorage protected by a seawall; however, the space inside the bay is no longer adequate for the number and size of ships using the canal and many ships wait at anchor in the open sea outside the bay. The anchorage on the Pacific side is open although it is protected by the enclosed topography of the Gulf of Panama.

The lowest chamber of the east flight of the Gatún locks is seen here from the deck of a small boat about to enter.
The lowest chamber of the east flight of the Gatún locks is seen here from the deck of a small boat about to enter.
The most visually impressive feature of the canal is its locks. The lock chambers are 33.53 metres (110 ft) wide with a usable length of 304.8 metres (1000 ft). The available water depth in the lock chambers varies, but the least depth of 12.55 metres (41.2 ft) is at the south sill of the Pedro Miguel locks. These dimensions determine the maximum size of ships which can use the canal; this size is known as Panamax. All of the locks on the canal are paired; there are two parallel flights of locks at each of the three lock sites. In principle this allows ships to pass in opposite directions simultaneously. Despite this large ships cannot cross safely at speed in the Gaillard Cut; in practice ship traffic flows alternately, using both "lanes" of the locks in one direction at a time.Each lock chamber requires 101,000 cubic metres of water (26.7 million U.S. gallons) to fill; this water enters the chamber by gravity via a network of culverts beneath each lock chamber. Ships are hauled through the locks by small railway engines called mulas (mules, named after the animals traditionally used to pull barges), running on tracks on the lock walls; smaller vessels, such as small tour boats and private yachts, are taken as handline transits where mooring lines to the lock walls are handled manually by line handlers on the vessel.

Gatún and Alajuela lakes
Southbound sailboats entering the Banana Cut on Lake Gatún have their sails set to get a boost from the trade winds.
Southbound sailboats entering the Banana Cut on Lake Gatún have their sails set to get a boost from the trade winds.
Lake Gatún and the enhanced Chagres River (Río Chagres) are key components of the canal, carrying ships a significant part of the way across the isthmus. The lake also acts as a reservoir, storing water to allow the locks to continue operation during the dry season. The lake was formed, and the river widened and deepened, by the construction of the Gatun Dam on the Chagres River. This flooded the originally wooded valley; almost a century later, the stumps of old mahogany trees can still be seen rising from the water, and submerged snags form a hazard for small vessels that wander off the marked channels.There is a small "shortcut" channel through the lake, the "Banana Cut", providing a slightly shorter route; this is used by canal launches and yachts and to avoid the heavy ship traffic. Several islands are located within the Lake Gatún portion of the Panama Canal, including Barro Colorado Island, home of the world famous Smithsonian Tropical Research Institute (STRI).The volume of water used by ships passing through the locks, combined with the seasonal nature of the rainfall in Panama, makes it difficult to maintain the level of Lake Gatún, particularly in the dry season. An additional dam, the Madden Dam, was therefore built across the Chagres above Lake Gatun. This created Alajuela Lake — also known as Madden Lake — which provides additional water storage for the canal.

There are several crossings over the canal. At the south (Pacific) end is the Bridge of the Americas, a major road bridge which opened in 1962; for many years, this was the only permanent crossing of the canal. Before its construction, most traffic used a ferry at the same location. Further north, at the Miraflores locks, there is a swinging road/rail bridge; opened in 1942, it can only carry traffic when no ship is passing, and is now rarely used. At the same point, a small swinging road bridge is built in to the Miraflores lock structure; this is also rarely used.The newest crossing is the Centennial Bridge, which crosses over the Gaillard Cut just north of the Pedro Miguel locks; this major six-lane road bridge was completed in 2004 (although it opened to traffic in 2005). Finally, another small swinging road bridge is built in to the lock structure at the Gatún Locks; this bridge is only usable when the lock gates are closed, and has a very small capacity.In addition to the public crossings, canal workers may walk across the lock gates when they are closed.

History - Contents

This elevation map of the Panama Canal, prepared in 1923, shows the topography of the region through which the canal was cut.
This elevation map of the Panama Canal, prepared in 1923, shows the topography of the region through which the canal was cut.
The earliest mention of a canal across the isthmus of Central America dates back to 1534, when Charles V, Holy Roman Emperor and king of Spain, suggested that a canal in Panama would ease the voyage for ships travelling to and from Ecuador and Peru.Given the strategic situation of Central America as a narrow land dividing two great oceans, other forms of trade links were attempted over the years. The ill-fated Darien scheme was an attempt launched by the Kingdom of Scotland in 1698 to set up an overland trade route, but was defeated by the generally inhospitable conditions, and abandoned in 1700. Finally, the Panama Railway was built across the isthmus, opening in 1855. This overland link greatly facilitated trade, and this vital piece of infrastructure was a key factor in the selection of the later canal route.
Construction work on the Gaillard Cut is shown in this photograph from 1907.
Construction work on the Gaillard Cut is shown in this photograph from 1907.
An all-water route between the oceans was still seen as the ideal solution, and the idea of a canal was revived at various times, and for various routes; a route through Nicaragua was investigated several times. Finally, enthused by the success of the Suez Canal, the French, under Ferdinand de Lesseps, began construction on a sea-level canal (i.e., without locks) through Panama on January 1, 1880. In 1893, after a great deal of work, the French scheme was defeated by disease and the sheer difficulty of building a sea-level canal. The high death toll was one of the major factors in the failure: although no detailed records were kept, as many as 22,000 workers are estimated to have died during the main period of French construction (1881–1889).The United States, under Theodore Roosevelt, bought out the French equipment and excavations, and began work in 1904, after helping Panama to declare independence from Colombia in exchange for control of the Panama Canal Zone. A significant investment was made in eliminating disease from the area, particularly yellow fever and malaria, the causes of which had recently been discovered (see Health measures during the construction of the Panama Canal). With the diseases under control, and after significant work on preparing the infrastructure, construction of an elevated canal with locks began in earnest. The canal was formally opened on August 15, 1914, with the transit of the cargo ship Ancon.The advances in hygiene resulted in a relatively low death toll during the American construction; still, 5,609 workers died during this period (1904–1914). This brings the total death toll for the construction of the canal to around 27,500.By the 1930s it was seen that water supply would be an issue for the canal; this prompted the building of the Madden Dam across the Chagres River above Gatun Lake. The dam, completed in 1935, created Alajuela Lake, which acts as additional water storage for the canal. In 1939, construction began on a further major improvement: a new set of locks for the canal, large enough to carry the larger warships which the U.S. had under construction, or planned for future construction. The work proceeded for several years, and significant excavation was carried out on the new approach channels; but the project was cancelled after World War II.After the war, United States control of the canal and the Canal Zone surrounding it became contentious as relations between Panama and the U.S. became increasingly tense. Many Panamanians felt that the canal zone rightfully belonged to Panama; student protests were met by the fencing in of the zone and an increased military presence. Negotiations toward a more equitable settlement began in 1974, and resulted in the Torrijos-Carter Treaties. Signed by President of the United States Jimmy Carter and Omar Torrijos of Panama on September 7, 1977, this set in motion the process of handing the canal over to Panamanian control.Relations with the U.S. came to a new crisis when Manuel Noriega took control of the country in 1981. Accused of drug trafficking, he was indicted by a U.S. federal court in Miami in 1988; after he invalidated the election of Guillermo Endara and survived a bloody coup in 1989, President of the United States George H. W. Bush launched an invasion of Panama. Two weeks later, the invasion was over, and Noriega was behind bars in Miami; with military control over Panama effectively at an end, President Endara was sworn in, and Panama has continued under civilian governments. Though controversial within the U.S., the treaty came into force as planned on December 31, 1999 and control of the canal was handed over to the Panama Canal Authority.

Tolls - Contents

Car carriers, such as this one at  Miraflores locks, are among the largest ships to use the canal.
Car carriers, such as this one at Miraflores locks, are among the largest ships to use the canal.
Tolls for the canal are decided by the Panama Canal Authority and are based on vessel type, size, and the type of cargo carried.For container ships, the toll is assessed per " TEU" (Twenty-foot Equivalent Unit), which is the size of a container measuring 20 feet by 8 feet by 8.5 feet (6 m by 2.4 m by 2.6 m). Effective May 1, 2005, this toll is per TEU. This is scheduled to rise to on May 1, 2006, and again to on May 1, 2007. (A Panamax container ship may carry over 4,000 TEU.) A reduced toll is charged for container ships "in ballast"; ie. travelling empty, with no cargo or passengers.Most other types of vessel pay a toll per PC/UMS net ton, in which one "ton" is actually a volume of 100 cubic feet (2.8 m³). (The calculation of tonnage for commercial vessels is quite complex.) As of 2006, this toll is .96 per ton for the first 10,000 tons, .90 per ton for the next 10,000 tons, and .85 per ton thereafter. As with container ships, a reduced toll is charged for freight ships "in ballast".Small vessels are assessed tolls based on their length. As of 2006, these are:
Length of vessel Toll
Up to 15.240 metres (50 ft) 0
More than 15.240 metres (50 ft) up to 24.384 metres (80 ft) 0
More than 24.384 metres (80 ft) up to 30.480 metres (100 ft) ,000
More than 30.480 metres (100 ft) ,500
The most expensive toll for canal passage to date was charged on September 25, 2003 to the luxurious passenger vessel Coral Princess, which paid 6,194.25 for passage. The least expensive toll was 36 cents and is not credited to a ship, but to American adventurer Richard Halliburton who swam the canal in 1928. The average toll is around ,000.

Current issues - Contents

More than ninety years since its opening, the canal continues to enjoy great success. Even though world shipping — and the size and design of ships themselves — have changed beyond recognition since the canal was designed, it continues to be a vital link in world trade, carrying more cargo than ever before, with less overhead. Nevertheless, the canal certainly faces a number of potential problems.

Efficiency and maintenance
The administration Building of the Panama Canal is in Balboa, Panama.
The administration Building of the Panama Canal is in Balboa, Panama.
There were fears that efficiency and maintenance would suffer following the U.S. withdrawal; however, this does not appear to be the case, and the canal's efficiency appears to be improving under Panamanian control. Canal Waters Time (CWT), the average time it takes a vessel to navigate the canal, including waiting time, is a key measure of efficiency; according to the ACP, CWT is decreasing. At the same time, the rate of accidents is at a record low.Increasing volumes of imports from Asia which previously landed in the U.S. west coast ports are now travelling through the canal to the east coast. The total number of vessel transits in fiscal year 1999 was 14,336; this fell to a low of 13,154 in 2003, due at least in part to global economic factors, but has risen to 14,011 in 2005 (the canal’s fiscal year runs from October to September). However, this has been coupled with a steady rise in average ship size and in the numbers of Panamax vessels transiting, so that the total tonnage carried has risen steadily from 227.9 million PC/UMS tons in fiscal year 1999 to 278.8 million tons in 2005. Given the negative impact of vessel size on the rate of transits (for example, the inability of large vessels to cross in the Gaillard Cut), this represents significant overall growth in canal capacity, despite the reduction in total transits. The canal set a traffic record on March 16, 2004, with 1,005,551 PC/UMS tons of cargo transited in a single day.
A bucket dredge works to deepen and widen the canal.
A bucket dredge works to deepen and widen the canal.
The canal administration has invested nearly billion in widening and modernizing the canal, with the aim of increasing capacity by 20 percent. The canal authority cites a number of major improvements, including the widening and straightening of the Gaillard Cut to reduce restrictions on crossing vessels, the deepening of the navigational channel in Gatun Lake to reduce draft restrictions and improve water supply, and the deepening of the Atlantic and Pacific Entrances of the Canal. This is supported by new vessels, such as a new drill barge and suction dredger, and an increase of the tugboat fleet by 20 percent. In addition, improvements have been made to the operating machinery of the canal, including an increased and improved tug locomotive fleet, the replacement of more than 16 kilometres of locomotive track, and new lock machinery controls. Improvements have been made to the traffic management system to allow more efficient control over ships in the canal.The withdrawal of the U.S. has allowed Panama to sell excess electricity produced by the canal's dams, which was previously prohibited by the U.S. government. Only 25% of the hydroelectric power produced in the canal system is required to run the canal.

The canal is presently handling more vessel traffic than had ever been envisioned by its builders. In 1934 it was estimated that the maximum capacity of the canal would be around 80 million tons per year; as noted above, canal traffic in 2005 consisted of 278.8 million tons of shipping.Despite the gains which have been made in efficiency, the canal is soon expected to approach its maximum capacity. An additional complication is that the proportion of large (close to Panamax-sized) ships transiting is increasing steadily; this may result in a further reduction in the number of transits, even if cargo tonnage rises. In any case, if the canal is to continue to serve the needs of world shipping, action will be required to increase its capacity.
Gatun Lake, pictured here in 2000, is having difficulty supplying water for the canal's operation.
Gatun Lake, pictured here in 2000, is having difficulty supplying water for the canal's operation.

Despite having enjoyed a privileged position for many years, the canal is increasingly facing competition from other quarters. Speculation continues over a possible new canal that will be capable of accommodating post-Panamax vessels, through Mexico or Colombia, and there are at least three proposals for the construction of cargo routes across Nicaragua: a major, post-Panamax canal proposed by the government, and two private proposals for a railway linking ports on the two coasts.Critics have also voiced their concerns over the planned increase in canal tolls, suggesting that the Suez Canal may become a viable alternative for cargo en route from Asia to the U.S. East Coast. Nevertheless, demand for the Panama Canal continues to rise.The increasing rate of melting of ice in the Arctic Ocean has led to speculation that the Northwest Passage may become viable for commercial shipping at some point in the future. This route would save 9,300 kilometres (5,800 mi) on the route from Asia to Europe compared with the Panama Canal, possibly leading to a diversion of some traffic to that route. However, such a route would still hold significant problems due to ice, as well us unresolved territorial issues.

Water issues
A significant problem is the decreasing average amount of water in Gatún Lake, caused largely by deforestation. 52 million gallons of fresh water from the lake are dumped into the sea by the locks every time a ship transits the canal. The issue is the seasonal nature of rainfall in Panama; the rainforest plays a role by absorbing this rain, and then releasing it at a steady rate into the lake. With the reduction in vegetation, rain flows quickly down the deforested slopes into the lake, from where the excess is spilled out into the ocean; this results in a shortfall of water during the dry season, when there is comparatively little water flowing to the lake to replenish it. Deforestation also causes silt to be more easily eroded from the area around Gatún Lake and collect at its bottom, reducing its capacity.

The future - Contents

With demand rising, the canal is positioned to be a significant feature of world shipping for the foreseeable future. However, changes in shipping patterns — particularly the increasing numbers of post-Panamax ships — may necessitate changes to the canal. Plans have been floated for a major expansion of the canal; a reincarnation of the 1939 Third Lock Scheme, or something like it, has been proposed, to allow for a greater number of transits, and the ability to handle larger ships. The current proposals are for a set of locks capable of handling ships of up to 150,000 tons, over twice the Panamax limit. This would need to be coupled with widening of the Gaillard Cut to handle the larger ships, which would be a major engineering effort.Any such scheme is likely to be hampered by cost, as well as water supply issues (see above). Current proposals are to address the water issue by expanding the reservoir capacity; however, this has led to concerns over environmental damage to the watershed area. An alternative proposal is to use water recycling, in which fresh water discharging from the lock chambers is pumped back up into the lake to limit water wastage.
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