424 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1947 



must be quite flat, 1 : 5 or more. For safety and eventual economy, 

 much of the overlying hard rock would have to be removed. 



The third locks cuts indicate that Gatun sandstone will stand on a 

 6 vertical to 1 horizontal slope, and that 12 : 1 is safe for agglomerate 

 and basalt : for the latter, berm widths and spacing criteria have also 

 been established. Extensive loading tests have demonstrated that 

 Cucaracha will safely carry 6 tons per square foot, while the harder 

 Culebra, upon which the Pedro Miguel locks are founded, will carry 15 

 tons. It is facts such as these that give the investigators confidence 

 in designs and construction methods being assumed for the purpose 

 of their estimates. 



As to devising actual construction methods, the present studies 

 are going only so far as is necessary to prepare the cost estimates for 

 construction periods of either 10 or 15 years. It is, nevertheless, un- 

 derstood that one of the most promising possibilities for moving the 

 huge quantities of dry excavation involved has been shown by the stud- 

 ies to be a combination of batteries of 30-yard shovels and barge dis- 

 posal. Some recasting of material by draglines would be necessary 

 to reach the barges, or this could be largely eliminated by digging 

 auxiliary channels into the banks through which the barges could be 

 towed to within reach of the shovels. With a half billion yards of 

 dry excavation to be handled large and expensive plant lay-outs are 

 obviously justified. 



TWO CANALS IN PLAGE OF ONE 



Earlier in this article mention was made of the possibility of a rec- 

 ommendation that would provide for building a new sea-level canal 

 while at the same time the present lock canal would be kept in service. 

 San Bias, Caledonia Bay, and Atrato-Truando were among the possible 

 locations, but there are also routes near the present canal, and particu- 

 larly one known as the Panama Parallel Route, that have also been 

 seriously studied. 



This Panama Parallel Route, whose alignment corresponds closely 

 to that of the present canal except that it eliminates the big bends in 

 the latter, is an original conception of the present investigators grow- 

 ing out of their studies of several routes having a Pacific terminus in 

 Chorrera Bay a short distance outside the west boundary of the Canal 

 Zone. One of these routes crosses the isthmus to the small town of 

 Lagarto and is entirely outside the Zone. It has the advantage of 

 offering dry excavation for the major part of its length, but the yard- 

 age would be formidable and the construction of new ports and har- 

 bors at both ends would entail tremendous expense, with Lagarto being 

 practically in the open sea. 



