Panama Canal

The Panama Canal is a canal 82 km (51 mi) long that cuts through the isthmus of Panama, connecting the Atlantic and Pacific Oceans in Central America. The canal has a huge impact on shipping, as it removes the need for ships to travel the long and dangerous route via the Drake Passage and Cape Horn (at the southernmost tip of South America). The canal saves a total of about 18,000 miles on a trip from New York to San Francisco by sea.

Description

The Panama Canal connects the Gulf of Panama, in the Pacific ocean, with the Caribbean Sea and the Atlantic. 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. 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 {{ref|acptraffic}}.

Related Topics:
Gulf of Panama - Pacific - Caribbean Sea - Atlantic - Isthmus of Panama

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The Pacific end of the canal is on average 24 cm (9 inches) higher than the Atlantic end, and has a much greater tidal range.

Related Topics:
Cm - Tidal range

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Layout

The canal consists of a man-made lake, 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:

Related Topics:
Man-made lake - Channel - Lock

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• 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
• Miraflores Lake is the next stage, about 1.6 km (a mile) long
• the single-stage Pedro Miguel lock is is the last part of the ascent, with a lift of 9.5 m (31 ft)
• the Culebra (Gaillard) 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.

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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) {{ref|biogeog}}.

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The 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.

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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 {{ref|rockscement}} (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.

Related Topics:
Culvert - London Underground

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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.

Related Topics:
Tonne - Kilowatt - Hp - Engine

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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.

Related Topics:
Railway - Mula

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Lake Gatún

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.

Related Topics:
Lake Gatún - Chagres River - Gatun Dam - 1906 - 1910

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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.

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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).

Related Topics:
Island - Barro Colorado Island - Smithsonian Tropical Research Institute

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The Anchorages

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.

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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.

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Crossings

There are several crossings over the canal. From south to north:

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• 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 {{ref|swingbridge}}
• a small service road bridge is built in to the lock structure at Miraflores, but is rarely used {{ref|mirabridge}}
• the Centennial Bridge crosses over the Culebra Cut; this major 6-lane road bridge opened in 2004
• 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 {{ref|canalmus}}

In addition, canal workers can walk across the lock gates when they are closed.

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