feet wide and 1,200 feet long in the clear, with a minimum depth over the sills of 42.5 feet. Satisfactory foundations for these locks have been found. The minimum depth of water in the canal would be 40 feet, while the width would vary from 300 to 1,000 feet. Adequate artificial harbors and terminal facilities would be provided at each end of the canal. The summit-level section would be 150.8 miles long, of which 70 miles would be in Lake Nicaragua. The regulated water elevation of the summit level would vary from 105.5 feet to 110 feet above the sea level. Two feet above 110 feet would be reserved for flood storage, although this additional storage would be seldom, if ever, needed. Flood damage is not feared. The water supply is ample. Such a canal could be constructed in 10 years and would cost $722,000,000, including $25,000,000 for acquiring rights, franchises, and land. The annual cost of maintenance would be $10,800,000. It is estimated that this canal would have a capacity in excess of 80,000,000 tons per year.

8. The present traffic seeking transit through the Isthmus and the prospective increase in such traffic in the next few years do not require that any steps be taken now to provide further capacity at Panama. A second canal would have important advantages, including a saving in time and increased dependability to shipping, an increase in trade and commerce, improvement in international relations, and added safety and special speed in the mobilization of our naval forces in the event of a national emergency. However, the advantages do not appear to be sufficient at the present time to warrant immediate action for the construction of a canal across Nicaragua.

9. I recommend that the reports herewith, together with their appendixes and maps, be published. Authorization should be made by the Congress to continue the collection of hydrological data in Nicaragua at an estimated cost of $5,000 per annum.

LYTLE BROWN,
Major General,
Chief of Engineers.

(Enclosures: Report of the Interoceanic Canal Board; report of the Governor of the Panama Canal; report of officer in charge, Nicaragua Canal survey, with seven appendixes, including maps.)

Senator MCKELLAR. I do not want all those enclosures referred to in this record. We can refer to them because they have been published in full, and I would not want to increase the publicatiion. They are all to be found in House Documents, volume 12, No. 139, United States Army and Interoceanic Canal Board Reports, Seventysecond Congress, first session, 1931–32.

The CHAIRMAN. That may be included in the record. At the same time I wish to introduce into the record a letter from the Secretary of War, dated March 16, 1939, transmitting the report of the Governor of the Panama Canal Zone.

(The document referred to is here printed in full, as follows:)

The PRESIDENT, UNITED STATES SENATE,

Washington, D. C.

WAR DEPARTMENT, Washington, March 16, 1939.

DEAR MR. PRESIDENT: Pursuant to the provisions of Public Resolution No. 85, Seventy-fourth Congress, approved May 1, 1936, I submit report, dated February 24, 1939, of the Governor of the Panama Canal of his investigation of the means of increasing the capacity of the Panama Canal for the future needs of interoceanic shipping.

I concur in the conclusions of the Governor, and in the interests of defense and of the future needs of interoceanic shipping, I recommend the immediate adoption of the project substantially as proposed in the report of the Governor. Very respectfully,

Enclosure.

HARRY H. WOODRING,
Secretary of War.

BALBOA HEIGHTS, C. Z., February 24, 1939.

The Honorable the SECRETARY OF WAR,

Washington, D. C.

SIR: 1. I submit herewith the following report, pursuant to Public Resolution No. 85, Seventy-fourth Congress, approved May 1, 1936, which reads as follows: "Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, That the Governor of the Panama Canal is hereby authorized and directed to investigate the means of increasing the capacity of the Panama Canal for future needs of interoceanic shipping, and to prepare designs and approximate estimates of cost of such additional locks or other structures and facilities as are needed for the purpose, and to make progress reports from time to time of the results thereof."

PRIOR STUDIES

2. The Canal administration has long foreseen that it would be necessary to increase the capacity of the Canal to meet the needs of increased commercial traffic by the construction of an additional system of locks. The administration has continuously felt the responsibility for studies of traffic trends with a view to predicting well in advance the time when the additional system of locks would be needed, and observation and studies on this important subject have been carried on through the years since the completion of the Canal. Until the year 1931, however, the results of this work were not consolidated or published in readily available form.

3. In accordance with Public Resolution No. 99, Seventieth Congress, approved March 2, 1929, a survey and investigation of a proposed canal in Nicaragua was made under the direction of the Chief of Engineers of the United States Army and the report was submitted to Congress by the President on December 20, 1931, and published in House Document No. 139, Seventy-second Congress, first .session. In connection with that report, there was also submitted a report by the Governor of the Panama Canal on a project for an additional system of locks at the Panama Canal. The latter report appears in House Document No. 139 at pages 23 to 31, inclusive. It will be referred to hereinafter as the 1931 report. For the 1931 report the data and experience accumulated by the Canal organization were available and were analyzed carefully to furnish the basis for the opinions and conclusions presented therein. All of that material has been considered in the preparation of this report, and reference to the printed 1931 report will serve to clarify detailed studies of the subject as presented in this one. As far as practicable, repetition of the discussions in the 1931 report has been avoided here. It does, however, seem desirable to quote the following: * the capacity of the Panama Canal is limited by the capacity of the locks, for the channel sections are entirely adequate now to transmit any number of ships that may be passed by the locks, and, with improvements under way and projected, this statement will still be true after the construction of a third set of locks."

*

4. In the 1931 report, the locations of the additional locks were proposed to be immediately adjacent to and alongside the present locks, and the lock chambers were to be 125 feet wide with 421⁄2 feet available depth. No special provision was made for protection from air attack and sabotage. The cost was estimated at $140,000,000 and the time required for construction at about 10 years. The report concluded that this additional system of locks would probably be necessary about 1970, but the Interoceanic Canal Board and the Chief of Engineers, United States Army, in reviewing the project, arrived at the conclusion that it would be needed by 1960. The additional study which has been given to the future needs of commercial traffic appears to support the conclusions of the Chief of Engineers and the Interoceanic Canal Board, as will be brought out later.

CURRENT STUDIES

5. Although it did not seem probable that the additional locks would be needed for commercial purposes before 1960, Public Resolution No. 85 was advisable because, first, in case the commercial needs were to be the governing factor, it was contemplated that the investigation be conducted with deliberation over a considerable period of time by a relatively small force, but at such a rate as would insure the completion of the plans in time to begin construc

tion of the additional lock system considerably ahead of the time when it would be required for commercial needs.

6. Early in the studies conducted under authority of Public Resolution No. 85, the matter of special protection for the locks was given careful study and consideration, and the definite conclusion was reached that it would be a serious mistake to construct them immediately adjacent to the present locks. Since reaching this conclusion, efforts have been directed toward the development of a project referred to hereinafter as the "bypass project," in which the locks would be located at a safe distance from the present locks and approach channels would be provided to connect the new locks with the present canal channel, thus securing many of the advantages of two canals.

NEED FOR ADDITIONAL LOCKS FOR COMMERCIAL TRAFFIC

7. The need for additional lock capacity may depend on commercial traffic or on defense considerations. In the 1931 report, it was shown that the maximum daily capacity of the present locks during the 3 or 4 months' biennial overhaul period is 27 lockages in 24 hours, 26 of which would be available for commercial vessels, and that the capacity during the overhaul period is a limitation which determines the annual capacity. However, if this maximum daily capacity is used for determining the average capacity of the canal during the period of the overhaul, there would be excessive delays to traffic since experience shows that when the daily average reaches 27 lockages per day, there would be many successive days during the overhaul period in which the traffic will be greater than the maximum daily capacity of the canal.

8. The 1931 report suggested that "the economic procedure will be to take care of 'peak days' by delaying transits and compensating rebates." This is one solution, but further study of this matter indicates that the attainment of maximum economy will probably not be the most desirable procedure. Such a procedure would add so much uncertainty to ship schedules and operation and be so irritating to shipping in general that it is undoubtedly better to make some compromise provision for taking care of successive peak days during overhaul periods so as to give a reasonably adequate service to shipping. In accordance with this idea, it is believed to be safer to assume that the present average daily capacity of the Canal during the 3 or 4 months' overhaul period is 24 lockages per day throughout the entire period (of which 23 lockages would be available for commercial ships), or that the maximum daily capacity is about 12 percent above the average daily capacity.

9. Excluding transits of the fleet, the highest average daily number of lockages for any month up to date is 18.32, reached in the fiscal year 1929. During that month (December 1928), the average number of vessels per lockage was 1.18. Assuming that the average might have been increased to 1.48, as suggested by the Interoceanic Canal Board in its review of the 1931 report, the number of lockages could have been reduced to a daily average of 14.6 per day. Thus, with an average capacity of 24 lockages per day, the average daily traffic in the maximum month of record was about 60 percent of capacity.

10. On a tonnage basis, the capacity of the Canal depends on the average tonnage per lockage. For the fiscal year 1938, a normal year, the average tonnage per vessel was 4,035 tons, new measurement basis. Applying the factor of 1.48 vessels per lockage gives 5,972 tons per lockage. Thus the tonnage capacity of the Canal for commercial traffic, based on capacity during the overhaul season of 23 lockages daily, is 137,000 tons per day, or 50,000,000 tons per year.

11. To predict when the traffic will reach the capacity of the Canal is a difficult problem. It requires a broad knowledge of all the factors that affect the growth of world commerce and shipping, and no prediction however carefully made, can be accepted with complete assurance. Fortunately, we have a recent prediction of future traffic which we consider to be the best obtainable with the information now available.

12. In connection with the investigation of Panama Canal tolls, rates, and measurement rules, made under authority of Congress in 1936, a study was made of the future growth of traffic at the Panama Canal. The report on

this study is printed in Senate Document No. 23, Seventy-fifth Congress, first session. This study, however, predicts only the average growth in traffic and not the traffic that may be expected in any particular year in the future. To obtain this from the traffic curves used, it is necessary to apply a factor for secular variation. During the year of maximum traffic, 1929, the total tonnage

on the new measurement basis was 27,600,000 tons. This was 4,600,000 tons or 20 percent in excess of the traffic that might have been expected in that year based upon the average normal growth of Canal traffic for the 20 years covered by the study. In other words, our past experience had indicated that the maximum annual tonnage in any 1 year may be about 20 percent greater than the average growth would indicate. Obviously, in predicting the annual tonnage for any particular year in the future the safe thing to do is to assume that the year will be at the peak of a "boom" cycle. Thus the tonnage to be used in connection with the curve of growth to determine when the Canal capacity will be reached is the annual tonnage capacity of the Canal, 50,000,000 tons, reduced by application of the above percentage, or 41,670,000 tons. This tonnage applied to the curve of future traffic shows that the capacity of the existing locks may be reached by 1961. Additional locks would be needed, therefore, by that date.

NEED FOR ADDITIONAL LOCKS FOR DEFENSE

13. The Canal must be kept open for transit of the fleet from ocean to ocean, and the locks, therefore, must be given the maximum possible physical protection from vital damage. It is, of course, apparent to the casual observer that structures such as the locks are subject to attack by sabotage or by air raids and that, if an additional system of locks were constructed, the chance of vital damage by such attacks resulting in serious closure of the Canal to traffic will be reduced. If, further, the additional locks were constructed in locations removed from the present locks, the chance of such vital damage would be further reduced. Detailed studies show that a great deal can be done in the design, construction, and operation of locks to give them protection from vital damage by air raids. Furthermore, closing new locks and the bypass channels to all traffic except the Navy, would give the highest practicable degree of assurance that no attack on the locks could close the Canal for more than a very short period of time.

14. Thus the provisions of the additional locks and bypass channels will increase the security of the Canal, and these additional facilities will be needed in any event for commercial purposes within a relatively short period of time.

ENGINEERING INVESTIGATIONS

15. With the funds appropriated under authority of Public Resolution No. 85, an initial organization and plans for carrying on the work have been developed and office studies have been made. In the field, a topographic map on a scale of 1 to 1,000 has been completed. This map covers the areas within which lie all the desirable locations for the proposed locks and bypass channels. Borings under the supervision of a competent geologist have been made at all lock sites to determine suitable foundations.

16. Investigation in the Gatun area: Surface observations: Topographically the Gatun area is a ruggedly dissected plain of low relief, 100 to 200 feet average, which breaks off somewhat abruptly to a low coastal marsh bordering Cristobal Bay to the north. Rock outcrops along highway, railroad, and Canal banks indicate the underlying rock consist of a series of sandstone and claylike beds dipping gently to seaward (northward).

Subsurface studies: Two lock sites were drilled at Gatun, one roughly parallel to and about 3,000 feet removed to the east of the present locks, line A-7, and the other, line A-1-A, parallel, to and about 500 feet east of the present lock. Nineteen holes were drilled at the proposed lock position along line A-7 and nine holes along line A-1-A. Roughly, 400 to 500 feet of rock strata underlying the immediate lock area were penetrated. Conclusions reached during surface reconnaissance were closely borne out. By far the largest portion of the rock strata is medium hard, very fine-grained sandstone, with interbedded claylike beds of volcanic ash. tuff, and pumice fragments, and several thin beds of coarse, gritty sandstone conglomerates. Due to the dip of the beds, the northern two-thirds of the lock would rest on sandstone, the southern third on alternating beds of volcanic ash, tuff, sandstone, and conglomerate. Only a very thin zone of weathered rock is present over the area, averaging perhaps under 6 feet. Practically all of the rock below this weathered zone is firm to medium hard, and sound. The bedrock is mantled with yellow and red silty and sandy clays of variable depths, averaging perhaps 20 feet more or less.

17. Investigations in the Pedro Miguel area: Surface observations: The area in which it is proposed to found the third set of locks at Pedro Miguel lies

immediately west of the present locks. The proposed lock site lies roughly parallel to, and about one-quarter of a mile removed from, the present locks. Topographically and geologically this area is typical of the region along the Pacific side of the Canal Zone, being characterized by numerous steep-sided conical-shaped hills of igneous, usually basaltic rock, rising to elevations of 100 to 700 feet above the surrounding country. These knobs usually occur in "nests" of several, with flat-floored river valleys intervening between the groups of hills. These flat valleys are usually underlain by sedimentary strata of interbedded shales, sandstone, conglomerates, volcanic ashes, and consolidated volcanic mud flows. The proposed lock site lies in the flat-floored valley of the Rio Grande, which here is bordered by high basaltic cones on the south, west, and north.

Subsurface studies: Sufficient core drilling has been done to indicate that a set of locks constructed here would be founded on substantially hard basalt, sandstone, and shale. Both ends of the lock would rest on basalt and the central portion, where it crossed the flat Rio Grande Valley would rest on very hard sandstone and some medium-hard shale. The rock is weathered and shattered to variable depths, but at all points explored with the drill, the top of firm, sound rock is well above the foundation level of the proposed lock. The overburden in the area consists of clay, silty sand, and small rock fragments with a few scattered boulders. Foundation rock has been explored to depths of over 100 feet below the proposed lock foundation level.

18. Investigations in the Miraflores area: Surface observations: The proposed third locks at Miraflores lie roughly parallel to, and about one-fourth mile removed to the west of, the present Miraflores locks. The site selected lies in a nest of volcanic rock cones and low hills. By far the largest part of the lock would be founded on hard, basaltic, igneous rock. The ends of the lock extend a short distance beyond the basalt hills the north end out into the Cocoli River Valley, and the south end out into a low swamp area.

Subsurface studies: The drilling has indicated that the locks will be founded on sound, igneous rock.

19. Seismic studies: In order to facilitate subsurface studies and assist the geologist in arranging an efficient drilling program, a geophysical specialist was obtained from the office of the Chief of Engineers, United States Army. Seismic studies have been coordinated with core drilling records in a practical and useful manner.

20. Sources of aggregate: Investigations indicate the presence of vast quantities of river gravel in the Chagres River Valley between the town of Gamboa and Madden Dam. All lock sites can be reached from there by water haul.. Crushed rock, hard basalt, can be obtained at Gatun by quarrying on several of the islands in Gatun Lake near Gatun. The basalt hills at the Pacific locks: sites are suitable sources of hard rock materials.

21. Cement materials: A study has been made of the limestone deposit along the Massambi River near Summit in anticipation of a request for a source of suitable materials for cement manufacture. Recently studies have been made of the vast deposits of corals in Cristobal Harbor and bordering the swamp areas around the harbor. Both deposits have been sampled and analyzed and have been declared suitable cement material. Recovery of the coastal coral deposit would be a dredging operation and probably far less expensive than quarrying on the Massambi.

22. Conclusions as to foundations: As a result of foundation investigations at the proposed lock sites, the following conclusions are reached:

(a) Locks constructed at the proposed sites at Gatun, Pedro Miguel, and Miraflores would be founded on sound rock.

(b) Foundation studies have been extended to include a sufficiently large area to permit minor shifting of the lock sites to obtain better approach channel alinement and to cover an area adjacent for a possible future fourth lock installation, without altering the conclusions reached in regard to foundation condition.

(c) No major rock profile irregularities or adverse foundation rock conditions, such as badly shattered fault zones, deeply weathered rock channels, overhangs, sharp folds, etc., have been encountered at the proposed sites.

(d) Adequate sources of concrete aggregate materials as well as most of the ingredients necessary for the manufacture of cement for the new locks are obtainable within the confines of the Canal Zone.