422 ANNUAL REPORT SMITHSONIAN INSTITUTION, 194 7 



and type of structure. Moreover, our present knowledge of dam 

 building generally and of foundation conditions at the site is far 

 advanced over that of 40 years ago. 



IMPROVED CHANNEL ALIGNMENT 



One of the necessities for a safe canal of ample capacity is an align- 

 ment that permits easy handling and maneuvering of ships, and the 

 present canal is far below a reasonable standard in this respect. The 

 investigators have, therefore, devoted much attention to this subject, 

 since it is appropriate to any canal route that is to be chosen. 



As a target to shoot at and test, rather severe criteria were set up. 

 These include a 500- foot-wide channel bottom, a 50-foot depth, curves 

 of 20 degrees maximum deflection angle (some of the present ones 

 are near twice that) , sight distances on curves of not less than a mile, 

 and 5-mile tangents between curves. These dimensions and others, 

 both more severe and more conservative, are being tested in the Navy 

 model basin at Carderock, Md., where the handling of model ships 

 under various current conditions will also be studied. When conclu- 

 sions are reached, the outdoor sea-level model in the Canal Zone will 

 be rebuilt to the new criteria as a further check on performance. Since 

 all studies are based on providing ample canal capacity up to the year 

 2,000 such modern and future navigation aids as infrared lights, fog- 

 dispersal equipment, and radar and electronic devices are not being 

 overlooked. 



Whatever the alignment and dimensions chosen, they will materially 

 affect the cost and construction methods of a canal, lock or sea level, 

 since a greater or lesser bottom width or degree of curvature brings 

 different geological formations into the picture with their differing 

 side slopes that are safe from sliding. 



GEOLOGY POSES MANY PROBLEMS 



The area traversed by the present canal is noted for its upside-down 

 geology, hard rock occurring regularly on top of soft material. It 

 was the weight of this cap rock that initiated much of the disastrous 

 bank sliding in the early days of the present canal, and great care 

 is being taken to avoid any return engagements on future construc- 

 tion. Evidence of the seriousness of this situation is contained in the 

 figures of the amount of slide material removed from the present ca- 

 nal : 23 million yards before water was turned in in 1913, and about 

 50 million yards in the following 10 years. 



Every opportunity is, therefore, being used to gain new knowledge 

 through tests and study of past experience. Many data were col- 

 lected during the third locks design and construction, and continued 

 maintenance of the canal banks for over 30 years has produced many 

 more. 



