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This is a single suspension bridge from my historical inventory of suspension bridges. Follow the Inventory link for more information about the inventory.
1877 Cottaneva
Cottaneva Creek, Rockport, California, USA (Rockport Bay, Pacific Ocean)
Bridgemeister ID:1152
Principals:Pacific Bridge Co.
Use:Vehicular (one-lane)
Main cables:Wire (iron)
Suspended spans:1
Main span:270f
  • This bridge was part of the Rockport lumber mill (Mendocino County). The bridge stretched over ocean to a large rock in the bay.
  • Jakkula cites two sources describing the cables as steel.
  • Don Sayenga transcribed one of Jakkula's references, The Iron Age Volume XX , No. 3 (August 2, 1877) Page 1: "A Steel Wire Suspension Bridge In California"
    The Pacific Bridge Company are building in Mendocino county, California at Cottoneva, a suspension bridge which is described as follows "The distance from center to center of the saddles on the towers is 270 feet. The deflection or fall of the cable is 23 feet 6 inches. The cables are built in the same manner as those of the Clifton bridge at Niagara. The steel wire is about No. 11 Birmingham gauge, and is protected against rust by immersing in a bath which it a fine coat of zinc. There are eleven wires in each strand, seven strands in each rope, and seven ropes in each cable. The ropes are not twisted together to form the cable but gathered up every six feet by the suspender bands. Each rope is warranted to bear a strain of 60 tons. It is made fast to an independent anchor bar, 1 by 3 inches in diameter, and forming links 18 feet long, until connection is made with the anchors. The anchors are of cast iron, 3-1/2 by 3 feet in surface, weigh 1000 pounds each, and are placed 14 feet below the surface of the rock. Great care was taken in securing the anchors in place by means of cross I beams which run under the rock on either side. The lower part of each pit was enlarged to so as to form a hemispherical chamber, and the rock work, set in Portland cement, which is built upon the anchor, is so constructed that the upward strain is transmitted to the sides. The towers are of red wood. There are four posts 10 x 10 inches and two 10 x 12 inches, giving an effective area of 640 inches to withstand the strain of the cables on the tower. The wooden truss to prevent vertical vibration is 8 feet high and of the Howe truss pattern. The 270 feet of the bridge is divided into 45 pannels. The longest suspenders, 44 in number are of 7/8 inch steel wire, the 42 shorter ones are of 1-1/8 inch solid iron. The estimated dead load of the bridge is 1000 pounds per linear foot; live load, one ton per linear foot; in all, one and one half tons, or one fifth of actual breaking load. The bridge will be completed in about 30 days and promises to be a structure which the builders may well be proud of."
    Don writes: "[In] Jakkula's last citation, he is saying that this is factory-made wire rope... The construction of the wire rope (7 by 11) used in the main cables is not common for the USA as of 1877; in fact it is extremely uncommon. The wire ropes used at Clifton/Niagara were made in England -- it wouldn't surprise me if these were made in England too."

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