The building of the Panama Canal is considered one of the greatest engineering feats in history. Conceived as a "lock and lake" canal, it was designed before the Titanic was even on the drawing boards.

Cut through one of narrowest saddles of the isthmus that joins North and South America, the Panama Canal is approximately 80 kilometers long between the Atlantic and Pacific Oceans. The waterway uses a system of locks — compartments with entrance and exit gates — that function as water lifts. The locks raise ships from the Atlantic side to a lake formed by damming. Ships then cross the lake and descend to the Pacific side by another series of locks to the level of Gatun Lake (26 meters above sea level), and ships from all parts of the world then sail the channel through the Continental Divide. (Photo Credit, right: Panama Canal Authority)

Yet 93 years after it first opened for business (August 1914), the Panama Canal is finally maxed out.

Today it handles more traffic than its builders probably ever imagined. Some 13,000 to 14,000 vessels use the Canal every year. In fact, commercial transportation activities through the Canal represent approximately 5 percent of the world trade: 280 million tons of ocean cargo. Moreover, according to Global Insight, container traffic through the canal will nearly triple by the year 2025. An August 2006 traffic jam, caused when crews had to shut down one of two lanes for routine maintenance, made it clear just how much the Panama Canal was both "a vital artery and a worrisome bottleneck," as Popular Science noted in its February 2007 issue.

Transiting ships crowd Miraflores Locks and Miraflores Lake.
Credit: A. Grover Metheney/Popular Mechanics

As such, a $5.25 billion project is underway to expand and modernize the Canal.

"It is more than just an infrastructure project," Aleman Zubieta, CEO of the Panama Canal Authority, recently said at the 25th International Association of Ports and Harbors (IAPH) Conference. The expansion will consist of dredging, widening and deepening of existing waterways, as well as designing and building a new set of locks.

The Panama Canal Authority (ACP, in Spanish) reviewed dozens of options before deciding to complete the Depression-era U.S. work. ACP deputy administrator Manuel Benitez told Popular Mechanics: "On the Atlantic side, all of the American excavations are usable. On the Pacific side, we can use part of the excavations."

The expansion program will include two new sets of single-lane, three-step locks, which will double the tonnage capacity and allow the transit of substantially larger vessels; two new navigational channels to connect the new locks; and deeper, wider versions of existing shipping lanes. In all, Canal crew will dredge 130 million cubic meters of rock and soil —"enough to fill the Empire State Building nearly 130 times," as Popular Science put it.

More than half the $5.25 billion budgeted for the expansion project — $3.35 billion — will be spent on the new single-lane, three-step locks at the Atlantic and Pacific entrances, as well as on new channels. The new locks will not replace but rather augment the existing locks.

To connect those locks to existing shipping lanes, nearly five miles of channels will be excavated. The current route through Gatun Lake will be deepened by 5 ft. and widened, from today's 500 ft. minimum, to 920 ft. on straight-aways and 1,200 ft. in the turns. Then Gatun Lake will be raised 1.5 ft., providing an extra 550 million gallons of water each day for the locks.

About 130 million tons will be excavated. Dry excavation could begin this year; work on the new locks could start in 2008 and on Gatun Lake in 2011.

Credit: Panama Canal Authority

The new locks will use paired rolling gates rather than hinged miter gates. The gates will roll out of wall recesses on tracks to seal the chambers. For repairs and maintenance, one gate will continue to operate while the other is returned to its recess, which is then sealed and pumped dry.

The new locks will accommodate 1200-ft.-long post-Panamax ships displacing 170,000 tons and hauling up to 12,000 Twenty-foot Equivalent Units (TEU). The current maximum capacity is 5000 TEUs.

The new reinforced-concrete lock chambers will be 1,400 ft. long, 180 ft. wide and 60 ft. deep, with each lock complex measuring more than a mile and a half in length.

"This will be by far the longest lift complex in the world," Agustin Arias, ACP's director of engineering, told Popular Mechanics.

The biggest challenge that engineers face is the need to save water, which is an increasingly scarce resource in Panama. Between deforestation and supplying drinking water to 95 percent of the population surrounding the waterway, the problem isn't so much rainfall — it is after all a tropical country — as it is storage.

The biggest tax on the water supply, though, is the Panama Canal itself. On average, it requires more than 2 billion gallons per day to fill the locks for passing ships. An expansion plan that included bigger locks with a traditional design would have doubled water consumption. According to Popular Mechanics:

Although the new locks will be 65 percent larger than the current locks, the new design incorporates recycling basins that will reduce the amount of water for each transit by 7 percent. Currently, each transit flushes about 52 million gallons of fresh water — enough to supply a city of 250,000 people — into the Atlantic and Pacific oceans.

The new plan goes like this:

Three shallow basins adjacent to each chamber in the new locks will collectively capture 60 percent of the water from the locks as they are emptied. This water will be used to partially refill the locks when another ship comes through. As a result, although the new lock chambers will hold 65 percent more water than the originals, they will use 7 percent less water per transit. The canal authority also will raise the level of Gatun Lake, making an additional 550 million gallons of water available each day.

"In effect, you are able to reuse water that would otherwise be flushed out to sea," according to Raúl Brostella, an ACP port captain.

The agency expects the expansion to be completed by 2014 — or, 100 years after the Panama Canal was opened — with fewer than 7,000 workers — that is, less than 10 percent of the number who toiled on the original American construction from 1904-1914.

Resources

The Panama Canal's Ultimate Upgrade
by Brad Reagan
Popular Mechanics, February 2007

Panama Canal Master Plan
Panama Canal Authority (ACP)

Global Insight

First tender is for dry excavation
Panama Canal Authority, May 14, 2007

Panama Canal, Modal Shift-Short Sea Shipping and New Innovations Highlight Thursday's World Ports Conference Work Sessions
International Association of Ports and Harbors, May 3, 2007