The Panama Canal bisects the continents of North and South America, cutting through the isthmus of Panama, and connecting the Atlantic and Pacific Oceans in Central America. The canal, whose building was one of the largest and most difficult engineering projects ever undertaken, has a huge impact on shipping, as it removes the need for ships 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 Panama Canal travels a distance of 5,264 miles (8,472 km), a savings of more than 7,800 miles (12,500 km) — or approximately 20 days — over the 13,100 mile (21,000 km) route around Cape Horn.
Although the concept of a canal in Panama dates back to the early 1500s, the first attempt to construct a canal began in 1880, under French leadership. The building of the 51 mile (82 km) canal was plagued by problems, including disease (particularly malaria and yellow fever), and massive landslides. The work was finally completed by the United States, and the canal opened in 1914.
The canal has been enormously successful, and continues to be a key factor in world shipping. Each year the canal accommodates the passage of over 14,000 ships, carrying over 203 million tonnes of cargo. Approximately 800,000 ships have passed through the Panama Canal since its completion .
The Panama Canal connects the Gulf of Panama, in the Pacific Ocean, with the Caribbean Sea and the Atlantic Ocean. Due to the S-shape of the Isthmus of Panama, the canal actually 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, meaning from Pacific to Atlantic, or southbound meaning 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 are larger than this size, and known as post-Panamax vessels. A passage through the canal by ship takes around nine hours. Canal traffic in 2004 consisted of 14,035 vessels carrying 203 million tonnes of cargo, an average of almost 40 vessels per day .
The canal consists of two man-made lakes, several improved and man-made channels, and three sets of locks. The layout of the canal, as seen by a ship transiting from the Pacific end to the Atlantic, is as follows:
- from the sea buoy in the Gulf of Panama, ships pass through the Pacific anchorage where ships await transit, and up a buoyed entrance channel 11 km (7 miles) to the Bridge of the Americas
- from there, a dredged estuary runs 5.1 km (3.2 miles) to Miraflores locks
- the 2-stage Miraflores lock system itself is almost 1.5 km (a mile) long, with a total lift of 16.5 m (54 ft) at mid-tide
- the artificial Miraflores Lake is the next stage, about 1.6 km (a mile) long, and 16.5 metres (54 feet) above sea level
- the single-stage Pedro Miguel lock is the last part of the ascent, with a lift of 9.5 m (31 ft), up to the main level of the canal
- the Gaillard (Culebra) Cut, about 11 km (7 miles), slices through the continental divide at an altitude of 26 m (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 11 km (7 miles)
- Lake Gatún itself, a man-made lake formed by the building of the Gatun Dam, carries vessels 19 km (12 miles) across the isthmus
- the Gatún locks, a 3-stage flight of locks drops ships back down to sea level
- a 2.9 km (1.8 mile) channel forms the approach to the locks from the Atlantic side
- Limón Bay (Bahia Limón), a huge natural harbour, provides an anchorage for some ships awaiting transit, and runs 7.4 km (4.6 miles) to the outer breakwater
- ships finally pass through the Atlantic Anchorage 3 miles (4.8 km) to the Atlantic sea buoy
The total transit is about 50 miles (78 km) from sea buoy to sea buoy.
The maximum tidal range on the Pacific side is from +3.35 metres (+11.0 feet) to -3.20 metres (-10.5 feet); hence the lift at Miraflores is actually from 13.1 metres (43 feet) at extreme high tide to 19.7 metres (64.5 feet) at extreme low tide. The tidal range on the Atlantic side does not exceed 60 cm (24 inches) .
- Main article: Panama Canal Locks
The most visually impressive feature of the canal is its locks. The lock chambers are 33.53 meters (110 ft) wide by 320.0 meters (1050 ft) long, with a usable length of 304.8 metres (1000 ft). 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; that is, there are two parallel flights of locks at each of the three lock sites. This, in principle, allows ships to pass in opposite directions simultaneously; however, large ships cannot cross safely at speed in the Gaillard Cut, so in practice ships pass in one direction for a time, then in the other, using both "lanes" of the locks in one direction at a time.
Each lock chamber requires 101,000 cubic meters of water (26.7 million U.S. gallons) to fill. Water enters the chamber through a system of culverts, the largest of which are 6.7 metres (22 feet) in diameter  (almost double the diameter of the London Underground's deep lines); from these main culverts, smaller lateral culverts extend under the lock chamber to 100 openings in the chamber floor. Water enters the chamber by gravity when the upper valves are opened, filling a lock chamber in approximately eight minutes; there is significant turbulence in the lock chamber during this process.
The massive steel gates of the triple locks at Gatun are 21 metres (70 feet) high and weigh 745 tonnes each, but are so well counterbalanced that a 30-kilowatt (40 hp) engine suffices to open and close them. The largest gates are at the Pacific end of the canal, to cope with the extreme tidal range there. The end gates on each set of locks are doubled for safety in case of a gate failure (such as a ship running into a gate), which could otherwise release a devastating flood of water downstream. Each chamber also contains a pair of auxiliary gates which can be used to divide the chamber in two; this is designed to allow for the transit of smaller vessels — such as canal tugs — without using the full quantity of water. In practice, though, these gates are rarely used; instead, small boats such as tour boats, tugs, and yachts are passed in groups.
Ships are hauled through the locks with small railway engines called mulas (mules), running on tracks on the lock walls. These have powerful winches which are used to keep the ship centred in the lock while moving it from chamber to chamber; with as little as 60 cm (2 feet) of space on each side of a ship, considerable skill is required on the part of the operators.
Lake Gatún, and the enhanced Chagres River (Río Chagres), are a key component of the canal, carrying ships a significant part of the way across the isthmus. The lake was formed, and the river widened and deepened, by the construction of the Gatun Dam on the Chagres River in 1906–1910. This flooded the originally wooded valley; the stumps of old mahogany trees can still be seen rising from the water, and submerged snags form a hazard for any small vessels that wander off the marked channels.
A small "shortcut" channel, the "Banana Cut", exists in the lake, providing a slightly shorter route through the lake. This is used by canal launches and yachts to cut a little time off the crossing, and to avoid the heavy ship traffic.
Limón Bay, on the Atlantic side, is an excellent anchorage protected by a huge seawall; this is an impressive structure 5.6 km (3.5 miles) long. However, the space inside the bay is no longer adequate for the quantity and size of ships using the canal, and many ships wait at anchor in the open sea outside the bay. The bay continues to be a major base of operations for the canal authority, and also provides an anchorage for small boats, as well as being home to the Panama Canal Yacht Club.
The anchorage on the Pacific side is open, though it is protected by the enclosed nature of the Gulf of Panama; since the main winds are trade winds blowing over from the Atlantic, the isthmus itself makes the Pacific side fairly sheltered.
There are several crossings over the canal. From south to north:
- the Bridge of the Americas, a major road bridge, opened in 1962 in Balboa, near the Pacific end of the canal
- a swinging road/rail bridge crosses at the Miraflores locks, although it is now rarely used 
- a small service road bridge is built in to the lock structure at Miraflores, but is rarely used 
- a small service road bridge is built in to the lock structure at Gatún Locks; this bridge is only usable when the lock gates are closed, and has a very small capacity 
In addition, canal workers can walk across the lock gates when they are closed.
- Main article: History of the Panama Canal
The earliest mention of a canal across the isthmus of Central America dates back to 1524, 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, particularly for ships loaded with gold. Although a survey of the isthmus and a working plan for a canal were drawn up in 1529, the European political situation and level of technology available made the scheme impossible.
Given the strategic situation of Central America as a narrow land dividing two great oceans, other forms of trade links were tried through the years. The ill-fated Darien scheme was an attempt launched by 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 until the opening of the canal, it carried the heaviest volume of freight per unit length of any railroad in the world. This vital piece of infrastructure was key in the selection of the later canal route.
An all-water route between the oceans was still seen as the ideal solution, and so 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 (ie. without locks) through Panama on January 1, 1880. After a great deal of work, this scheme was defeated by disease and the sheer difficulty of a sea-level canal, and the French effort collapsed in 1893.
The United States under Theodore Roosevelt bought out the French equipment and work to date, and began work in 1904, after helping Panama to declare independence from Colombia in exchange for control of the Canal Zone. A great investment was made in eliminating disease from the area, particularly yellow fever and malaria, and 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 canal and the zone surrounding it were originally administered by the United States. However, on 7 September 1977, U.S. President Jimmy Carter signed the Torrijos-Carter Treaty, which set in motion the process of handing over the canal to Panamanian control. Although controversial within the United States, the treaty came into force on 31 December 1999, since when the canal has been run by the Panama Canal Authority (ACP).
There is no question that the Panama Canal continues to be one of the most successful engineering projects of all time. Even though world shipping — and the size and design of ships themselves — have changed beyond recognition since the canal was designed, it not only continues to be a vital link in world trade, but is in fact carrying more cargo than ever before, and with less overhead. Nevertheless, the canal certainly faces a number of potential problems.
Efficiency and maintenance
There were widespread 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 for passage, is a key statistic relating to efficiency; according to the ACP, CWT is decreasing while the number of transits handled is increasing. At the same time, the rate of accidents is at a record low .
In fact, 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 . Canal traffic increased between 2002 and 2004 from 191 million tonnes to 203 million tonnes, while the number of transits increased from 13,183 to 14,035 Template:Ref num. The canal set a traffic record on March 16 2004 with 1,005,551 tons of cargo transited in a single day .
The canal administration has invested nearly $1 billion in widening and modernizing the canal, with the aim of increasing capacity by 20 percent . Significant improvements cited by the canal authority  include:
- widening and straightening the Gaillard Cut to reduce restrictions on crossing vessels
- deepening the navigational channel in Gatun Lake to reduce draft restrictions and improve water supply
- deepening of the Atlantic and Pacific Entrances of the Canal
- increased and improved tug locomotive fleet and the replacement of more than 16 kilometers of locomotive track
- replacing and modernising equipment, including the construction of a new drill barge, launch and suction dredger, new lock machinery controls, and an increase of the tugboat fleet by 20 percent
- improvements and modernisations to the traffic management system
In addition, the withdrawal of the U.S. allows 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.
When the Canal was built in 1914, it was designed to be large enough to accommodate any vessel in the world. Shipbuilding technology has advanced rapidly since then, and many vessels today are too large to pass through the canal. It is estimated that half of all canal transits will be by Panamax vessels by the year 2006; that 60% of ships being planned for construction in 1999 were post-Panamax and 30% of the global shipping fleet is projected to be post-Panamax size by 2020.
Despite this, the Panama canal presently experiences congestion due to the large amounts of traffic travelling through. In 2004, 14,035 vessels passed through the canal (an average of 38.3 vessels/day), and it is expected that the canal will soon approach its maximum capacity. In 2004, the ACP estimated that canal was operating at about 93 percent of capacity.
Despite having enjoyed a priviledged 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, Colombia or Nicaragua. There are at least three current proposals for 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.  (See: Nicaragua Canal)
Critics have also voiced their concerns over the planned increase in canal tolls, suggesting that the Suez Canal may become a viable alternative for cargoes from Asia to the U.S. East Coast. Nevertheless, demand for the Panama Canal is so far continuing to rise.
A significant problem is the decreasing average amount of water in Gatún Lake, due largely to 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.
Plans have been floated for a major expansion of the canal; a re-incarnation of the 1939 Third Lock Scheme, or something like it, is proposed , in order to allow for a greater number of transits as well as the ability to handle larger ships. Current proposals are for a set of locks capable of handling ships up to 150,000 tons, over twice the size of a Panamax ship .
Any such scheme is liable to be hampered by cost, as well as water supply issues (see above). Although the water issue could be addressed by expansion of the reservoir capacity, which would be damaging to the environment of the watershed, it is possible that water recycling could be used instead, where fresh water discharging from the lock chambers would be pumped back up into the lake to limit water wastage. 
The toll for the canal is determined by vessel type, size, and the type of cargo carried .
For container vessels, the toll is assessed per "TEU", which is the size of a container measuring 20 ft by 8 ft by 8.5 ft (6 m by 2.4 m by 2.6m). As of May 1, 2005, this toll is $42 per TEU. This is scheduled to rise to $49 on May 1, 2006, and again to $54 on May 1, 2007. (A Panamax container ship may carry over 4,000 TEU.)
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). As of July 1, 2003, this toll is $2.96 per ton for the first 10,000 tons, $2.90 per ton for the next 10,000 tons, and $2.85 per ton thereafter.
|Up to 15.240 meters (50 feet)||$500.00|
|More than 15.240 meters (50 feet) up to 24.384 meters (80 feet)||$750.00|
|More than 24,384 meters (80 feet) up to 30.480 meters (100 feet)||$1,000.00|
|More than 30.480 meters (100 feet)||$1,500.00|
The most expensive toll for canal passage to date was charged on September 25, 2003 to the luxurious passenger vessel Coral Princess, which paid $226,194.25 for passage. The least expensive toll was 36 cents and is not credited to a ship, but to athlete Richard Halliburton who swam the canal in 1928 . The average toll is around $54,000.
- Official website of the Panama Canal Authority — Has a simulation that shows how the canal works
- Canal Zone Brats — Comprehensive information on the canal and the zone
- History of the Canal Zone — including much canal information, from CZ Brats
- Panama Canal Webcams
- Template:Es icon Dr. Alonso Roy's short essays on Panama Canal History
- Judicial Watch, Inc. v. Panama Canal Commission case (archived)
- Structurae: Panama Canal
- Satellite view in Google Maps
- Map of Panama Canal
- General information regarding Panama Canal
- Information on early history
- Current Issues since the return to Panama
- Panama Canal Yacht Club
- ^ The Panama Canal, from Global Perspectives
- ^ Panama Canal Traffic — Fiscal Years 2002–2004, Panama Canal Authority
- ^ The Panama Canal as a Passageway for Fishes, Samuel F. Hildebrand, Zoologica (New York), 1939
- ^ Cement And Concrete, from The Builders of the Panama Canal, CZ Brats
- ^ Photo: The Opening of the Miraflores Bridge, CZ Brats
- ^ Costa Rica Tour and Panama Cruise — Photos and text by Jack Yeazel, with detail pictures of the locks
- ^ Picture of the Gatún locks road bridge, canalmuseum.com
- ^ A Man, A Plan, A Canal: Panama Rises, Smithsonian Magazine, March 2004
- ^ Tonnage Increases; Canal Waters Time and Accidents Drop, Panama Canal Authority, December 09, 2003
- ^ New York Port Hums Again, With Asian Trade, Eric Lipton, New York Times, November 22, 2004
- ^ Panama Canal Sets Historic Record in Tons of Cargo, Panama Canal Authority, March 18, 2004
- ^ Transfer heavy on symbolism, light on change, Steve Nettleton, CNN Interactive
- ^ Modernization & Improvements, Panama Canal Authority
- ^ NICARAGUA: Plan for Inter-Ocean Canal Reborn, an analysis of several proposed land and water routes for cargo across Nicaragua, from Inter Press Service
- ^ The Panama Canal, Business in Panama (an article on proposed future development of the canal)
- ^ Enlarging Panama Canal is engineers' chance of lifetime, Pittsburgh Tribune-Review, September 18, 2005
- ^ Pumping Up the Panama Canal, Mechanical Engineering Magazine (an article on recycling lock water)
- ^ Maritime Operations — Tolls, Panama Canal Authority
- ^ Panama Canal Authority FAQ
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