REPORT OF THE BOARD OF ENGINEERS FOR RIVERS AND HAR- Hon. J. J. MANSFIELD, WAR DEPARTMENT, OFFICE OF THE CHIEF OF ENGINEERS, Chairman Committee on Rivers and Harbors, House of Representatives, Washington, D. C. MY DEAR MR. MANSFIELD: 1. The Committee on Rivers and Harbors of the House of Representatives, by a resolution adopted June 13, 1934, requested the Board of Engineers for Rivers and Harbors to review the reports on Cape Cod Canal, Mass., submitted in House Document No. 795, Seventy-first Congress, third session, with view to determining if the recommendations therein made should be modified. I enclose herewith the report of the Board in response thereto. 2. The Cape Cod Canal is a sea-level canal across the base of Cape Cod and extends from Cape Cod Bay on the north into Buzzards Bay on the south. It affords a protected route for coastwise shipping which is 65 statute miles shorter than the route around the Cape and through Pollock Rip Slue and the somewhat dangerous waters of Nantucket and Vineyard Sounds, and 165 miles shorter than the route in the open sea around Nantucket Shoals. The land cut across the cape is 7.7 miles in length, and the total length of the waterway including the dredged channel through the shallow water at the head of Buzzards Bay is 131⁄2 miles. The mean range of tide in Cape Cod Bay is 9.1 feet and in Buzzards Bay 3.9 feet. Strong currents through the canal are set up by these tides. 3. The canal was constructed by a private corporation with a minimum bottom width of 100 feet and depth of 25 feet. It was opened as a toll canal in 1914 and was purchased by the United States 104996-35- -1 in 1928 at a cost of $11,500,000 under authority of the River and Harbor Act of January 21, 1927. The average cost of maintenance dredging since its acquisition has been about $192,000 per annum, and for the operation and care of bridges and traffic control about $233,000 per annum. In the report under review the Chief of Engineers recommended that a tide lock 110 feet wide, 1,000 feet in usable length, with 40 feet over the sills, be constructed in the canal; that the canal be enlarged to provide a depth of 30 feet with a width of 250 feet in the land cut, a width of 400 feet in the straight alinement in Buzzards Bay, enlarged to 700 feet in the open waters of the bay, with a new highway bridge of adequate vertical clearance and a suitable railroad crossing, with other improvements, at an estimated cost of $23,250,000. With funds provided by the Public Works Administration amounting to $5,783,500 new bridges are being constructed to replace the inadequate bridges with draw spans 140 feet in width originally constructed, and the land cut is being widened to 205 feet. The obligations imposed upon the United States in acquiring the canal prevented the substitution of a single highway bridge for the two present crossings and two fixed highway bridges are therefore being constructed with a clear span of 550 feet and a vertical clearance of 135 feet above high water. A new railroad bridge, with a vertical lift of 500 feet span, affording a clearance of 135 feet above high water, is also being constructed. 4. The traffic through the canal has steadily increased from 1,405,782 cargo tons in 1928 to 2,804,998 tons in 1933. The gross tonnage of vessels using the canal has increased during the same period from 6,527,694 tons to 10,114,473 tons. The number of ships using the canal has increased from 9,312 in 1928 to 11,022 in 1933. The number of passengers has averaged about 200,000 per annum. At the present depth its use is limited to vessels of about 20-foot draft. The commerce through the canal is but about 20 percent of the coastwise commerce between Boston and southern ports. A relatively large portion of this commerce is carried in vessels of from 26 to 28 foot draft requiring a depth of 32 feet for safe navigation. An increase in depth in excess of 32 feet would afford but small increase in the prospective use of the canal. 5. The Board of Engineers for Rivers and Harbors, concurring with the conclusions and recommendations of the district and division engineers, finds that the present depth and width of the Cape Cod Canal are inadequate for the safe passage of the large, deep-draft vessels engaged in coastwise commerce to and from Boston and other ports in northern New England. Safe and adequate navigation could be afforded either by moderate channel enlargement and the installation of a lock to eliminate the tidal currents, or by widening the channel to such an extent that the vessels can be handled in safety in these currents. The difference in the initial cost of the two methods of improvement is not large. In the report under review the lock canal was recommended. Further investigations and additional experience in maintenance operation and in the partial enlargement of the canal show that an open canal amply safe for two-way navigation can be provided at reasonable initial cost and will serve commercial interests more satisfactorily than a lock canal. The possible obstruction of a lock canal by ice, the hazards to vessels entering the lock during high winds, the loss of time in lockage, all make an open canal referable. The Board's careful consideration of these advantages eads it to believe that an open canal would be more desirable than he lock canal previously recommended. With adequate bank proection it is estimated that the total cost of maintenance, operation, ind care will be reduced to $400,000 per annum. Prospective benefits h the saving of 65 miles in sailing distance for vessels engaged in oastwise traffic approximating 7,000,000 tons per year, the reduction in loss of life and damage to vessels on the Cape Cod coast which have averaged $500,000 per annum, and a reduction in delays due to adverse weather conditions, all appear to justify the improvement. The Board recommends that the existing project for Cape Cod Canal be modified so as to provide for an open canal 32 feet deep, for a width of 540 feet in the land cut, 500 feet in a straight channel in Buzzards Bay to Wings Neck, and 700 feet beyond Wings Neck, for a harbor of refuge for small vessels, mooring basins, an improved ighting system, and other accessory and minor features which may be deemed necessary and shall be in accordance with plans approved by the Chief of Engineers at an estimated cost of $26,000,000 for construction; with $400,000 annually for operation, care and maintenance of the entire project, including the maintenance of the new bridges now under construction. 6. After due consideration of these reports, I concur in the views and recommendations of the Board. Very truly yours, E. M. MARKHAM, Major General, REPORT OF THE BOARD OF ENGINEERS FOR RIVERS AND HARBORS WAR DEPARTMENT, THE BOARD OF ENGINEERS FOR RIVERS AND HARBORS, Washington, D. C., December 10, 1934. Subject: Cape Cod Canal, Mass. 1. This report is submitted pursuant to the following resolution, adopted June 13, 1934: Resolved by the Committee on Rivers and Harbors of the House of Representatives United States, That the Board of Engineers for Rivers and Harbors, created under section 3 of the River and Harbor Act, approved June 13, 1902, be, and is hereby, requested to review the reports on Cape Cod Canal, Massachusetts, submitted in House Document Numbered 795, Seventy-first Congress, third ession, with a view to determining if the recommendations therein made should De modified. 2. The Cape Cod Canal is a sea-level canal across the base of Cape Cod about 50 miles south of Boston. It connects Cape Cod Bay on the north with Buzzards Bay on the south and affords a protected route for coastwise shipping which is 65 miles shorter than the route around the Cape and through Pollock Rip Slue and the somewhat langerous waters of Nantucket and Vineyard Sounds, and 166 miles shorter than the route in the open sea around Nantucket Shoals. The land cut across the Cape is 7.7 miles in length, and the total ength of the waterway including the dredged channel through the shallow water at the head of Buzzards Bay is 131⁄2 miles. The mean range of tide in Cape Cod Bay is 9.1 feet and in Buzzards Bay 3.9 feet. Strong currents through the canal are set up by these tides. 3. The canal was constructed by a private corporation, with a minimum bottom width of 100 feet and depth of 25 feet, was opened as a toll canal in 1914, and was purchased by the United States on March 31, 1928, at a cost of $11,500,000, under authority of the River and Harbor Act of January 21, 1927. The average cost of maintenance dredging has been about $192,000 per annum, and for the operating and care of bridges and traffic control about $233,000 per annum. In the report under review the Chief of Engineers recommended that a tide lock 110 feet wide, 1,000 feet in usable length, with 40 feet over the sills be constructed in the canal; that the canal be enlarged to provide a depth of 30 feet with a width of 250 feet in the land cut, a width of 400 feet in a new straight alinement in the approach in Buzzards Bay to Wings Neck and 700 feet beyond Wings Neck, with a new highway bridge of adequate vertical clearance and a suitable railroad crossing, with other improvements, at an estimated cost of $23,250,000. With funds provided by the Public Works Administration amounting to $5,783,500, new bridges are being constructed to replace the inadequate bridges with draw spans 140 feet in width originally constructed, and the land cut is being widened to 205 feet. The obligations imposed upon the United States in acquiring the canal prevented the substitution of a single hignway oridge for the 2 present crossings and 2 fixed highway bridges are therefore being constructed with a clear span of 550 feet and a vertical clearance of 135 feet above high water. A new railroad bridge, with a vertical lift of 500 feet span, affording a clearance of 135 feet above high water, is being constructed. It is so designed that the bridge may be maintained in an open position except when closed for the passage of trains. 4. The commerce through the canal has steadily increased from 1,405,782 cargo tons in 1928, when the canal was taken over by the United States, to 2,804,998 tons in 1933. The gross tonnage for vessels using the canal has increased during the same period from 6,527,694 tons to 10,114,473 tons. The number of ships using the canal has increased from 9,312 in 1928 to 11,022 in 1933. The number of passengers has averaged about 200,000 per annum. At the present depth its use is limited to vessels of about 20-foot draft. The commerce through the canal is but about 20 percent of the coastwise commerce between Boston and southern ports. A relatively large portion of this commerce is carried in vessels of from 26-to 28-foot draft requiring a depth of 32 feet for safe navigation. An increase in depth in excess of 32 feet would afford but a small increase in the prospective use of the canal. 5. The district engineer reports that the information and experience gained since the last report indicates conclusively that an open canal will be preferable to a lock canal. Experience shows that it would be difficult, if not impracticable, to keep a still-water canal open throughout a severe winter. The difficulties experienced in constructing the foundations of the new bridges in the formation of loose running sand interspersed with large boulders through which the canal passes leads him to conclude that the construction of a lock would be more expensive than previously anticipated. The dredging in the strong currents of an open canal has been found to be much less difficult than was anticipated when the prior report was prepared, and the feasibility of providing an open canal of ample width in lieu of a lock canal of mited width is therefore firmly established. The experience since he widening of the canal has been begun has conclusively shown that he difficulties and hazards of navigation of the canal have been rimarily due to its narrow width. Considered solely from the viewjoint of navigation, the district engineer believes that a 500-foot open anal will allow ample room for passing vessels even under the worst onditions. The shoaling experienced in the present canal has been bund to be due principally to the wave wash on the banks and the aving in of large quantities of sand as a consequence. Adequate ank protection can be expected to remedy this situation. Mainenance of an open canal of adequate width does not therefore present serious problem. The delay imposed by the passage through a ock would be most objectionable to fast passenger-carrying ships. in an open canal the only shipping which would be delayed at all would be tows of insufficient power to move against the currents. This traffic moves slowly and saves 12 or 13 hours by using the canal. As the average delay awaiting favorable currents would be less than hours, it is clear that any advantages to tows through the installation. of a lock would be more than offset by the delays to more important ships which constitute the largest and increasing portion of the whole. The cost of an open canal 500 feet in width somewhat exceeds the cost of a lock canal with a single lock and with a width of 250 feet, but is less than the cost of a lock canal of the same width with locks in uplicate. The district engineer is of the opinion_that_duplicate ocks will be necessary to prevent interruption of traffic. In view of all of these circumstances, the district engineer is of the opinion that an open canal of adequate width is decidedly more advantageous than lock canal. The district engineer presents plans and estimates for a canal 32 feet in depth with a bottom width of 540 feet through the land cut, 500 feet through Buzzards Bay to Wings Neck, and 700 feet wide bevond Wings Neck, without locks, at $25,875,000. He reports hat if the allotment of funds is adequate to permit the work to proeed effectively and expeditiously, a saving of approximately $2,703,000 can be effected by removal of about 8,785,000 cubic yards of land prism in the dry, with a consequent reduction in the estinate to $23,172,000. A width of 540 feet is provided in the land cut n order that a canal 40 feet deep and 500 feet bottom width may be provided at some future time without impairing the revetnents and other works on the banks of the canal. The width of 500 feet is seected to afford ample passing room and to eliminate the danger that a arge vessel will ground bow and stern across the channel on a falling ide, since no vessel exceeding 500 feet in length is expected to use the anal. Two mooring basins are planned by the district engineer, one tear the east end of the canal and the other off the channel in Buzzards Bay,the easterly basin to be 2,000 feet long and the westerly 1,000 feet ong. The mooring basin nearest Cape Cod Bay is intended for the se of small vessels and tows delayed by storms in the bay. The asin in Buzzards Bay is intended for barges which must tie up at imes while the tug traverses the canal with part tow. To afford an nchorage for small craft adjacent to the canal, the district engineer ecommends the excavation of a channel 15 feet in depth and 100 feet vide into Onset Bay. The estimates include adequate bank protection. 6. The district engineer estimates the maintenance cost of the 500-foot open canal at $250,000 annually, for the operation and care |