The Panama Canal for all ships

Illustration | Bosch Rexroth AG / design hoch drei GmbH & Co. KG
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Illustration | Bosch Rexroth AG / design hoch drei GmbH & Co. KG Magnifier

Ever since 1914 the Panama Canal has been the shortest route between North America’s east and west coasts. This passage, 81.6 kilometers long, joins the ports at Christóbal on the Atlantic end and Balboa on the Pacific.

The Panama Canal Authority has launched a massive expansion of the Canal, to be completed by 2014, so that the larger ships of the post-Panamax class can also traverse the Canal.

The Panama Canal is being expanded and fitted with new, water-saving locks. Rexroth is delivering all the drive-related components needed for the rolling gates. They help ensure the canal’s uninterrupted operation.

 

In 1914 it was a sensation and in 2014 it will occupy the headlines once again: the Panama Canal. This is the shortest route for ships plying the seas between the east and west coasts of North America. Ten to eleven hours is the average time needed to traverse this passage, 81.6 kilometers long, between the Atlantic port of Christobal and the Pacific port of Balboa. Today, however, less than 40 percent of all the ships in the world’s commercial fleet can make use of this shortcut. Most container ships are too large for the Canal, the bed of which measures between 192 and 300 meters.

The passage – the so-called Gaillard Cut – between the man-made Gatún Lake and the Petro Miguel locks was widened and deepened again and again in the 1960s and the 1990s. For many of the maritime giants, however, this cut – 152.4 meters wide and 14.3 meters deep – is still too small. The Panama Canal Authority intends to eliminate this bottleneck with a massive expansion, finished by the canal’s centenary celebrations. Augmenting the locks now in place, the third set of locks will be built on both the Atlantic and Pacific ends, accommodating ships up to 366 meters long and 49 meters wide.

Saving water

This is no easy task for the engineers and contractors – in terms of both technology and scheduling. The expansion of the watercourse and the construction of the locks are to be concluded by 2014, the anniversary year. A further requirement: The new locks are to protect the region’s water regime. At present, about 208 million liters of fresh water are required for each passage – and the new locks are to be much larger than the old ones. That is why each of the three chambers will be connected to three water-saving basins. To raise the ships, the Rexroth drives will open the corresponding sluices and the water from the basins will flow by gravity into the lock chamber. In contrast to previous designs, not all the water flows into the sea during the lowering cycle. Most of it moves into the water reutilization basins.

Even though the new locks are much larger, this configuration will save about 290 million liters of water per lockage, reducing fresh water consumption by 60 percent. The remaining 40 percent of the water needed for lockage will be drawn from the artificial Gatún Lake. This technologically demanding solution offers dual benefits: It is more economical and, at the same time, protects the region’s resources.

The demands placed on the gates are great. They have to dependably control the large quantities of water passing from one chamber to the next. A South Korean manufacturer, Hyundai Samho Heavy Industries, is delivering the gates for the water-saving basins, for the conduits used to fill the lock chambers with water from Gatún Lake or from the adjacent chambers, and for the compensation gates between the lock’s chambers. A so-called rolling gate is the central element here. These steel structures, weighing many tons, regulate the flow of water as they are lowered or raised to stop the flow or allow water to pass.

Bosch Rexroth has worked with Hyundai for many years now and is fitting the total of 158 rolling gates with the required drives and control technology. Here the partners profit from the knowledge gained during Panama Canal projects of the past, such as the replacement of the technical equipment in the existing locks twelve years ago. The first component shipments will have to be made in April 2012. This is a specification that Rexroth, as an international system supplier, can satisfy thanks to its world-wide development and manufacturing capacities. Moreover, the requirement to conform with the standards adopted by the American Society of Mechanical Engineers presents no problem.

On the safe side

To ensure that the prior congestion point does not again become a bottleneck due to technical malfunctions, the greatest challenge for the technical design is to ensure continuous operability. That is why all the major systems are redundant. To empty a water-saving basin, for instance, only two gates are actually required. But each of the total of nine water-saving basins for a given set of locks is equipped with four gates. The same is true for the gates in the conduits used to fill the lock’s chambers.

Rexroth will be delivering a total of 158 drive units to Panama. That is because each rolling gate is fitted with a drive cylinder and the associated power unit. That unit, in turn, comprises two motor and pump units, a hydraulic reservoir, the filter system and valve technology, the piping, and the PLC control technology, also redundant in design. Rexroth is also delivering two stand-by units each for the gates regulating the water-saving basins, the sluices and the compensating gates. This solution ensures high availability.

Through the Canal, step by step

Illustration | Bosch Rexroth AG / design hoch drei GmbH & Co. KG Magnifier

Three water-saving basins for each lock chamber will help to reduce fresh water use. Once the lock chamber is closed, it is filled with water from the basins. When the water level is lowered, the water flows back into the basins, each of which holds about 20 percent of the volume required to raise or lower a ship. Consequently, only 40 percent fresh water will have to be made up from Gatún Lake – a saving of 60 percent per lockage.

 

This equipment at the rolling gates will ensure trouble-free passage through the locks in the future. A ship arriving from the Atlantic entrance channel is towed into the lowermost lock chamber. Once the outer gate has been closed, the water from the three water-saving basins is allowed to flow into that chamber.

At the same time the water in the middle chamber is lowered to match the level in the lower chamber. The inner gates are then opened and tugboats move the ship into the middle chamber. Once those gates have closed, the same process is repeated: Water from the upper chamber and the water-saving basins flows into the middle chamber until the levels in both chambers are identical.

The gates are opened and the ship is shifted into the upper chamber. Once the chambers are sealed again, the three associated basins empty and the remainder is made up with fresh water from Gatun Lake. Once the level in the chamber has risen high enough to permit exit, the upper gates are opened and the ship continues its journey toward the Pacific.