The total estimated cost by the present canal commission for completing the work, including purchase price is $375,201,000, while the total estimated cost of the sea-level canal made by the same commission is $563,000,000. This latter sum is largely mere conjecture because of the many unknown elements entering into the problem; and there are successful engineers today who do not hesitate to state that a sea-level canal can be constructed for less than the present lock canal.
Very few question the statement that the sea-level canal would take longer for construction than a lock canal. The majority of the Board of Consulting Engineers estimated that from 10 to 13 years would be required. The Isthmian Canal Commission fixed the time at from 18 to 20 years and Lieutenant George W. Goethals, its chairman and chief engineer, states that the lock canal will be completed by January 1, 1915.
A great objection to the narrow sea-level canal is the difficulty of river control. The proposed plan was to construct a huge concrete dam 180 feet high across the Chagres at Gamboa. This of itself is a great undertaking but when done would not solve the question of flood control, for below Gamboa there are many more streams which if unregulated would plunge precipitately into the canal channel thereby not only creating cross-currents extremely unfavorable to navigation, and these would also erode the banks and settle deposits which would necessitate continual dredging for maintenance. If these rivers were not allowed to flow into the canal, the only other solution would be the construction of channels on either side of the canal to take care of this flow. This would be very expensive and decidedly dangerous since the rivers in places would be considerably above the canal. The old Chagres Channel and the old French diversion canal could be utilized for a part of the distance.
It is claimed that even a sea-level canal would require a lock at the Pacific end because of the enormous difference, sometimes 20’ between high and low tides. Even the majority of the Board of Consulting Engineers, the supporters of the sea-level type, considered such a lock necessary. Since they made their report, however, a noted scientist, Dr. C. Lely, formerly minister of waterworks of Holland, has made an extended study of the question and states that the currents in a sea-level canal at Panama would not exceed those now common at Suez, namely, 2½ miles per hour.
On the other hand six huge locks are to be built on the lock canal, and they must be used at every passage of a boat. Their upkeep and operation will be a constant source of expense which would not exist in a sea-level canal. If one pair of locks is destroyed or put out of commission, the whole canal will be disabled and useless. Not only is this so, but they are a constant source of danger. The destruction of the gates of an upper lock, which is by no means an unknown occurrence, would allow the upper lake to empty into the canal channel, and probably destroy everything to the sea, including the dams. That such accidents can occur was demonstrated at the Welland Canal when a small steamer struck one gate and continuing her progress crashed through four other separate gates, the locks being 240 feet long. Again, at the Manchester Canal a vessel collided with a gate and carried it away, allowing the water to escape in such great volumes that it caused the other gates to give way also. Some conception of the force held in leash by the gates at Panama may be gained when it is stated that the “fall from the upper lock at Gatun to the empty second lock is over five times the rate of fall in the Whirlpool Rapids at Niagara and the depth is greater”. It is true that various safety devices are to be installed at the locks but they can serve only to minimize not eliminate a danger which would not exist on a sea-level canal.
The curvature in the proposed sea-level canal is gentle, but for 19 miles of its course a large ship would continually be changing direction in a channel having a width of from one-fourth to one-fifth of her own length and in a current which may be as great as 5 feet per second. On the Manchester Canal all large vessels are aided by two tugs whose duty it is to help in steering. Through the above mentioned 19 miles speed could not exceed 6 miles an hour, and whenever a ship going the opposite direction passed, one or the other would have to stop and tie up to the shore as they do on the Suez Canal.
The courses on the lock canal are straight, giving a clear view ahead, and the vessels can pass without being forced to tie up. The great Gatun Lake will permit of full speed and in all ordinary cases in the passage from ocean to ocean enough time can be saved by reason of the wider and straighter channels of the lock canal to compensate for the time lost in passing through the locks.
While the question of flood control is solved by Gatun Lake the question of water supply is not. This lake must, under the present plans, furnish the water necessary for lockages. Experts have carefully studied this subject, and while most of them agree that there is water sufficient for immediate needs they also recognize the possibility of a scarcity in the future. General L. Abbot, one of the most enthusiastic supporters of the lock plan, states that there will be water for but 26 daily transits during the dry season which would accommodate from 30 to 40 million tons of annual traffic. Other prominent engineers are not so sanguine and some go so far as to say the supply will be totally inadequate even for the first years of canal operation. At any rate there is a considerable element of uncertainty in the matter which actual trial alone will settle. No such trouble, of course, would exist in the operation of the sea-level canal.
Much has been said about the relative vulnerability of the two types. The arguments are decidedly at variance and approach the ridiculous when placed side by side. Common sense dictates that both types are open to injury by earthquakes or the hand of man; neither is invulnerable. It also seems evident that a lock canal with its many artificial devices is more open to serious injury by earthquake than a sea-level canal. In fact it is easy to believe that a shock severe enough to put a lock out of commission would scarcely affect a sea-level canal at all, and all who say otherwise are prejudiced. In fairness be it said that the danger from this source is exaggerated and probably should not occupy as large a place in the discussion of canal problems as has been given to it.
Lock canal advocates say a narrow sea-level canal could easily be obstructed by an obstacle placed in the channel; sea-level advocates say that a bag of dynamite under the lock-gates could put the canal out of service. Both statements are true but the essential element of difference is in degree. The obstruction in the channel would be no real injury to the canal at all: it would necessitate merely a few days work at the most for its removal. An injury to the locks, however, might readily mean draining of the summit lake and the destruction of all between it and the sea not to speak of the indefinite period required for reconstruction. The point is that it is practically impossible for man to seriously injure a sea-level canal; it is easily possible for him to so injure a lock canal. However, lock canals can be more readily defended in time of war because the points of attack are known beforehand.