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A better proposal for

the Panama Canal

by Bert G. Shelton

Locks designed using the Panama Canal’s own lock technology can out-perform the side-tank locks proposed by the ACP.

A single-step two-lane lock similar to the lock at Pedro Miguel can be operated in a highly efficient way with regard to water use by combining cross-locking of water and ship-by-ship lane reversal.

Two-lane locks, transiting ships in both directions in this fashion, will use 25% of the water per transit as compared to the 40% water-use claimed for the triple-side-tank system, which in truer comparison is more nearly 46.7%, given that lane reversals will add to the per ship use.

Reversing a lane ship by ship is normally slower than running a lane in one direction for a while before reversing. However, with Pedro Miguel style locks there are only two water manipulations and those are less time-consuming than the four of a triple-side-tank lock, because the average pressure-head is greater for an equal amount of water being moved.

Logic would suggest that half as many valves and pipes are needed, as well. Also, a side-tank is of the same length and width of the chamber it serves, but shallower. Therefore, a chamber and three side-tanks occupy twice the area of a two-lane lock step, which represents a lot of construction.

Two lanes of a Pedro Miguel style lock can be operated at the same time using just a little more water than is used to operate the single lane of the ACP’s side-tank lock; the same water can transit almost double the ships.

The shortage of water is not the main issue of concern in enlarging the Panama Canal.

The key issue lies with ship handling, which includes the managing of many more ships through the canal, as well as the transiting of the locks.

Pedro Miguel style locks, reduces the salt intrusion problem significantly in two ways:

·        Firstly, the mode of operation that brings in the most salt, which is to exit several ships in a row, is eliminated. With the Pedro Miguel style lock being reversed ship-by-ship, there will always be a ship in the chamber that is to be filled. Therefore, that chamber will contain the least amount of saltier water to be diluted by the water used to fill the chamber because the ship’s volume will have displaced a significant amount of saltwater from the chamber. With less saltwater to dilute, the resulting mixture will have a lower salt concentration.

·        Secondly, there is better dilution of the seawater involved. This is because 25% more water is involved in the dilution process with the Pedro Miguel style lock as compared to the water involved in operating triple-side-tank locks, which is due to ship-by-ship lane reversals.

In the final analysis, the Pedro Miguel style locks offer a significant improvement over the ACP’s proposed triple-side-tank system, whether they completely solve the salt intrusion problem, or not.

That includes being able to transit more ships. It would take two lanes of side-tank locks having six side-tanks per chamber to obtain the water-savings of a two-lane Pedro-Miguel style set of locks. And, that side-tank lock system would still not yield the same ship throughput because there are not enough hours in a day.

Bottom line:

If three separated two-lane single-step Pedro Miguel style locks are used at each end of the canal, water will be more effectively used --- with more ship transits per day --- and the lake will be better protected.

The author is an engineer and research scientist

Stimson, Moving a tree
Sirias, Hunter S. Thompson and Oscar Zeta Acosta
Shelton, A better way to do the post-Panamax locks
Pilgrim, Global warming --- Mother Earth's agony
Sánchez, Russia renews its Latin American ties
Silié, A new historical and geographical view of the Greater Caribbean
Reporters Without Borders, Freedom of the press threatened in Panama
Jackson, A fitting place for the legislature to do their dirty work

Bernal, A coup d'etat against freedom of expression