May 18, 2010 > TechKnow Talk: The Panama Canal: the Ultimate Shortcut
TechKnow Talk: The Panama Canal: the Ultimate Shortcut
A hundred years ago, a ship sailing between Asia and the east coast of the Americas faced a difficult passage around the southern tip of South America. The trip was both time-consuming and dangerous, as strong winds and heavy seas are often encountered in rounding the Horn and along the Chilean coast.
Today, a ship traveling between the Atlantic and Pacific oceans can save thousands of miles and weeks of travel time using the Panama Canal instead. Remarkably, a voyage from San Francisco to New York is reduced more than 8000 miles by the canal.
The possibility of a canal through Central America had been contemplated for hundreds of years. In the mid-1800s, a railway system was opened across the Isthmus of Panama, for the first time enabling movement of large quantities of people and materials through this dense jungle region.
France made the first attempt to build a canal through the area in the 1880s. At that time, Panama was a province of Colombia, which agreed to allow construction of a sea level canal. However, cutting a sea level passage across the isthmus proved to be unachievable and the project was abandoned after more than a decade of struggling against the elements.
In addition to excavation-induced landslides, construction was hampered by inadequate equipment, lack of experience in maintaining equipment in a tropical environment and workforce turnover - more than 20,000 French workers died from yellow fever and malaria. It was not yet understood that mosquitoes are the carriers of these diseases.
The United States watched these developments with interest. By 1900, the role of mosquitoes in the transmission of disease had been discovered and the U.S. was poised to finish the work the French had begun. However, negotiations with the Colombian government were unsuccessful.
Refusing to be thwarted, President Teddy Roosevelt directed the U.S. military to support a separatist revolution in the region and suppress the Colombian response, leading to an independent Panama in 1903. A treaty was quickly signed with the new government, giving the U.S. control of a 10-mile-wide strip of land across the isthmus. The U.S. began construction in 1904.
It was soon realized that a sea level passage was not feasible, and a lock-based design was developed that would lift ships 85 feet to cross the Continental Divide, then lower them back to sea level. With improved equipment and disease control, the canal was completed in ten years, opening in August, 1914.
The U.S. operated the canal for the next 85 years. Panama received little benefit from the arrangement, and was a country divided by the U.S.-controlled Canal Zone. After increasingly violent protests in the 1960s, the U.S. agreed to a transition period culminating in ceding control of the canal to the Panamanian government in 1999. Despite concerns that efficiency and safety would suffer, Panama has done an excellent job of operating the canal.
The canal includes three lock systems, three dams, and two large lakes. Starting from the Atlantic, a ship passes through several miles of channel and canal before entering the Gatun locks, a set of three locks that lift the vessel a total of 85 feet above sea level and into Gatun Lake, which was formed by damming the Chagres River. After crossing the lake, the ship next encounters the eight-mile-long Culebra Cut, a massive excavation across the Continental Divide, ending in the Pedro Miguel lock, which lowers the ship 31 feet and deposits it in another man-made body of water, Miraflores Lake. Across the lake, the ship enters the Miraflores two-lock system which drops the ship the additional 54 feet back to sea level. After sailing through another eight miles of canal, the ship passes under the scenic Bridge of the Americas and emerges into the Pacific.
Several clever ideas were employed in the construction of the canal. Gravel and rock removed for the canal were used as aggregate in the concrete locks. Some of the excavated clay soil was used to build the dams which flooded large basins providing staging areas for ships and from which water is gravity-fed to the locks.
In addition, the dams generate hydro-electricity, which powers canal operations. This includes the "mules" used to pull ships through the locks. These are small electric locomotives, attached by cable to each side of the ship. These pull vessels into and out of the locks. There are two lanes of locks; each can be used to move ships in either direction.
The entire canal system is about 50 miles long. Due to the S-shaped curvature of the isthmus, the canal runs roughly NW to SE from the Atlantic to the Pacific, so a ship making the transit in that direction actually emerges from the canal slightly further east than when it entered. A typical transit from ocean to ocean requires roughly 10 hours, though there is sometimes a long queue and several days wait to enter. The canal operates 24 hours a day, every day of the year.
Tolls to transit the canal are based on the size, tonnage, and type of vessel. Small passenger ships may pass for less than $2000 (USD). A large container ship may pay more than $50,000. Cruise ships are charged based on the number of cabins and passengers; a large cruise ship may pay $250,000 or more.
The locks, at a width of 110 feet and a length of over 1000 feet, seemed huge at the time of their construction, and have spawned a class of ships, called Panamax, which fit snugly through. But many of today's ships, particularly supertankers, are far too large to be accommodated. Nonetheless, because of increasing shipping traffic and maintenance demanded by the aging infrastructure, the canal is running at capacity, passing more than 13,000 ships carrying over 300 million tons of cargo annually.
To address the issues of larger ships, increasing demand, and maintenance requirements, the Panama Canal Authority (ACP) has begun construction of an additional lane of new, larger locks running parallel to the existing canal.
The $5 billion project consists of two sets of three locks each, one on the Atlantic and one on the Pacific side. Channels will be cut to connect these locks to the main canal. Ships up to 160 feet wide will be shunted through these new locks to circumvent the original, smaller locks. Dredging in the Culebra Cut and Lake Gatun will deepen those channels to accommodate the larger vessels.
Like the older locks, the new ones will be filled and emptied from Lake Gatun, using only gravity. Though some of the water will be captured and reused at the locks, the level of Lake Gatun will be raised four feet to 89 feet to provide additional water capacity.
These upgrades, scheduled for completion in 2015, will not only open the canal to larger ships and greatly increase total capacity, but the third lane will allow the original, 100-year-old locks to be closed for maintenance with less impact to traffic.
There is a wealth of information on the Panama Canal at the ACP Website: http://www.pancanal.com.