Main Cable PaintingMain Cable Photo GalleryThe painting of the two main cables of the Golden Gate Bridge began with the delivery of 400 feet of scaffolding on February 23, 2011. Before paint operations could begin, over the next five weeks, the scaffolding was installed along the 400-foot-long portion of the main cable running south from midspan. Painting of the first 400-foot-long section began in began in early April 2011 and was completed at the end of September 2011. Next, beginning on October 10, 2011, the scaffolding was disassembled and moved to the 400-foot-long section running north from midspan. The reassembly and additional pre-painting preparations on were completed on November 23. Painting along this section will begin in December 2011. On November 15, 2011, a separate installation of scaffolding began along the east side main cable which will take about 4 to 5 weeks to complete, and be followed by paint operations getting underway on the east side main cable Main Cable Painting Project - Scaffolding Assembly Begins - February 23, 2011 Main Cable Painting Project - Scaffolding is Delivered - February 22/23, 2011 Main Cable Construction - 1935/1936The Golden Gate Bridge has two massive main cables which pass over the tops of the 746-foot tall towers. The main cables serve as the “hanger” for the vertical suspender ropes which, in turn, hold the Bridge’s roadway. The diameter of each of the main cable, including their exterior wire wrapping, is 36 and 3/8 inches and each main cable is 7,650 feet long. The total length of wire used in both main cables is 80,000 miles. Each of the main cables contains 27,572 galvanized wires which are bundled into 61 strands that contain 454 wires each. The combined weight of the main cables, vertical suspender cables and accessories is 24,500 tons. Before the main cables could be constructed, for added safety and maneuverability, the workers built work platforms which hung under the area where the main cables would then be spun (pictured below left). The wire used to build the main cables was laid by a loom-type shuttle that moved back and forth as it laid the wire in place that formed the cables. The spinning of the main cable wires was completed in six months and nine days. The cable stringing operation was accomplished using 4 spinning carriages, two working from each anchorage. As one carriage left its anchorage base and went up and over the main tower, down to midspan, where it was then met by another carriage bringing the wire form the opposite anchorage. The wire bights were exchanged and each carriage returned to its starting point. Cable formers used vertical separators, in a frame, to keep each of the 61 strands in proper relation with one another—in vertical rows (pictured below middle). Compacting machines were used to “squeeze” the cables into their circular shape. Each consisted of a frame which surrounded the cable with 12 hydraulic jacks around the circle (pictured below right). Cable bands are attached to the main cable with large bolts at the point of attachment of each the 250 pair of vertical suspender ropes. Occasional re-tensioning of main cable band bolts becomes necessary because constant temperature and load changes in the main cable produce minute changes in the cable diameter, and those changes in cable diameter, together with temperature effects on the cable band itself, cause tension in the bolts to relax. In 1954, the cable band bolts were retightened for the first time since original construction.
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