Ironworkers busy installing suspender ropes on the Oakland-Bay Bridge.
HHiperlift slings and Crosby Shackles lift the second set of sections of the massive new self-anchored suspension tower.
Copyright (2010) California Department of Transportation, Photographer: Bill Hall
spanning from 60 to 229 feet long and the weights vary from 559 to 1,669 tons each. Each roadway piece was then slid via a tram of rollers to their respective locations. T e main cable’s tower was then constructed. Once the tower was completed and the main cable’s saddle, the main cable stay was then strung into place and installed wire by wire. Cable bands were used to temporarily bind together the wire bunch along the length of the entire cable. Suspender ropes were then hung from the main cable and suffi ciently attached to the main cable. T e bridge’s weight was then transferred from the temporary supports to the main cable via the tensioning of the suspender ropes. In December of 2012, the temporary supports were in the process of being removed. Once fi nished, the main cable will be covered and protected, leaving the work complete.
A giant crane barge called the Left Coast Lifter was a massive shear leg crane barge used to build the SAS. T e crane’s boom weighs 992 tons, runs 328 feet long, and can lift up to 1,873 tons, which is an amazing feat for a barge to do from the water. T e crane’s primary purpose was to bring steel to the site for the temporary support structure for the SAS. Secondarily, the crane helped to lift and place the deck segments from the eastbound and westbound roadways of the SAS. Holloway Houston supplied HHiperlift slings capable of lifting up to 600 metric tons each to lift the bridge road way sections into place, some as large as 2.6 million pounds. HHiperlift High Performance synthetic round slings were supplied for lifting the sections of the bridge’s tower. Holloway Houston’s slings were manufactured with Honeywell fi bers that can handle up to 4 million pounds at a time and are 80 percent lighter than traditional steel slings. “Spectra fi ber’s lightweight strength makes it ideal for use in extreme lifting applications,” says Phil Wojcik, global business director for Honeywell’s Advanced Fibers and Composite business. Four hydraulic compaction devices were used to compress the
suspender ropes along the main cable. Compaction of the main cable stay began at the top of the 525-foot tall tower. T e compactors were then moved downward along the cable at 1.5 meters at a time. At each step, temporary galvanized carbon steel bands were wrapped around the cable’s strands. Permanent cable bands were then attached in place
26 MARCH-APRIL 2013 WIRE ROPE EXCHANGE Copyright (2012) California Department of Transportation, Photographer: Bill Hall
of the temporary bands and were used as the permanent attachment locations for the suspender ropes. T e pressure of the strand compaction process went up to 9,350 pounds per square inch. Each steel compactor machine contained six hydraulic jacks and weighed 30,000 lbs.
MANUFACTURING THE SUSPENDER ROPES WireCo WorldGroup provided the entire shipment of the suspender wire ropes, the handrail cables, wire rope for the cat walk assemblies, and the tower tie back strands for the SAS. T e suspender ropes are galvanized steel of varying types and sizes including some with 6 strands and others with 8 strands. “Working with Caltrans was an effi cient and smooth process. A full-time inspector from Caltrans stayed at our manufacturing plant for a full year to oversee the quality of the wire ropes,” says Richard Humiston, Global Market Director of WireCo WorldGroup. WireCo cables represent the majority of domestic made steel wire
rope used in the bridge. Humiston adds, “We are proud of the fact that our company was chosen and of the jobs generated here in the US.” While Caltrans developed a video of the construction of the bridge, they included footage of WireCo’s manufacturing process for the suspenders. T is footage will soon be available via a movie that is soon to be released about the construction of the SAS. T e San Francisco- Oakland Bay Bridge project was the largest shipment that WireCo WorldGroup had made at the time. A little bit later, WireCo started a larger order of suspender ropes for the Manhattan Bridge reconstruction project. Humiston says, “T ere was a time when we were shipping ropes to the East and West coasts at the same time. It started to get hectic, but we were able to handle the heavy load and to supply each bridge successfully, even ahead of schedule in some instances.” Humiston summarized the Bay Bridge SAS by highlighting an
interesting fact about bridge construction. For the older Manhattan Bridge, the wire ropes WireCo manufactured were designed replacements for the product that was originally installed on the bridge. For the revitalized San Francisco-Oakland Bay Bridge, Humiston says, “T is is a new project designed with revolutionary engineering that has now become the fi rst, longest SAS Bridge in the world that can withstand the next Big One.” ❙
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