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July 2011www.sname.org/sname/mt (historical note) Miguel would have a single ight to Culebra Cut, and Gatun locks would have three ights from Gatun Lake to the Atlantic r U P F O T V S F U I B U U I F O F X . J S B ë P S F T M P D L T B O E U I F Pedro Miguel locks would be a quarter mile west of the existing locks, while the new Gatun locks would be a half mile east of the existing locks r U P Q S P W J E F T B G F H V B S E T G P S U I F O F X M P D L T B H B J O T U T B C -otage and bombing from the foundations up. Engineers in the Special Engineering Section considered that the water supply in Gatun Lake and Miraores Lake would be sucient for the operation of both the old and the new lock systems. erefore, no water reservoirs or water-saving basins were incorpo- rated into the design of the new locks. A considerable amount of infrastructure renovation would be required, including the construction of new roads and bridges, relocation of the Panama Railroad and utilities over short distances, excavation of new approaches over a 10-mile distance, excavations for the new locks, and nally the construction of the new locks. Both dredging and land-based excavation went on for almost three years, and much of the required work was accomplished before work was halted due to the diver- sion of funds to support war eorts. So what was accomplished and how does this relate to the Panama Canal expansion today? While there was extensive excavation work accomplished, the 1939 third set of locks was not built, and there was little in the way of infrastructure improvements that survived. Most of the excavation was done at Miraores and at Gatun. While the jungle was cleared at Pedro Miguel, only a shallow excavation was completed, which has been used for the disposal of dredging material from channel maintenance. e Gatun area was excavated in sections, mainly through dredging, and there was not a lot of solid rock to be removed. Panamanian newspapers reported in May 1943 that the dry exca- vation is almost nished and contractors are expected to remove their equipment by the end of the month.? Functionally, this was the end of the ird Set of Locks Project of 1939. e current expansion program takes advantage of some of the excavation done more than 70 years ago, following a similar alignment at the Atlantic site, but not at the Pacic site, where the dugout will have to be lled before the construction of the water-saving basins can be completed. ese past eorts left a roadmap for the future that has been put to good use on the current expansion program, although driven by much dierent strategic and global forces. MTJay Carson is retired as vice president, engineering from General Dynamics NASSCO. He is editorial board chairman for (mt) magazine. LEARN MORE | For further information on the 1930s and 40s canal expansion project, check out the following sources: www.CZbrats.com/Articles/3rdlocks/3rdlocks.htm Alton P. Armagnac, Enlarging the Panama Canal for Bigger Battleships,? Popular Science , September 1940, Vol. 137, No. 3 Norman J. Padleford, The Panama Canal in Peace and War , 1942 Walter LeFeber, The Panama Canal: Crisis in Historical Perspective , (Oxford, 1990) The current expansion program takes advantage of some of the excavation done more than 70 years ago. World War II third locks excavations can be seen to the right of Mira?ores locks in this image from 1985. Courtesy the Panama Canal Authority.