A Story of Three Bridges: Essential Infrastructure and Suspenseful Roadside Attraction Utilize BAND-IT Galvanized Band and Buckle
December 15. 2022 | Essential Infrastructure
No series of articles around infrastructure would be complete without a discussion of bridges. And the grandest of all bridge types is the suspension bridge. Notable for its long spans between towers it is a favorite for crossing waterways with heavy shipping traffic, or large cargo vessels. Suspension bridges are also more adaptable to future needs due to the ability to widen or replace full sections of bridge.
Some of the most iconic suspension bridges are here in the United States: Brooklyn Bridge, Golden Gate Bridge, George Washington Bridge, Verrazzano-Narrows Bridge, and the scenic Royal Gorge Bridge in our home state of Colorado. Driving over these wonders of engineering you were probably more focused on the traffic than on the bridge’s construction or maintenance, but BAND-IT band and buckle are used to bind together the cables used in many suspension bridges including the George Washington Bridge and Verrazzano-Narrows Bridge.
Cable sample of the main suspension cables made 2 years prior to construction. (Photo courtesy of United States Steel)
Click for full size.
Construction of a suspension bridge involves running strands of high strength 4 or 6 gauge galvanized steel wire from the anchor point on one side, up to the first tower, across to the second tower and down to the second anchor point. Once the correct number of wire strands are run back and forth across the span the wires are bundled together using BAND-IT galvanized band and buckle. The bands take the unruly jumbles of cable and form them into the perfect round bundle. Think about running multiple extension cords across a room; they aren’t going to lay neatly together, they are going to tangle. The same is true of the wire for the suspension cable. Once organized into tidy compact bundles the suspension cable is covered in a protective metal sheathing to reduce corrosion and exposure to the salt water or rain.
In 2011 the Port Authority of New York and New Jersey announced a billion dollar plan to renovate the George Washington bridge, including the suspension cables. Construction officials determined there are more than 24,000 BAND-IT bands and buckles, equating to roughly 20 miles of banding currently installed on the bridge. As part of the rehabilitation project each of the bands will be replaced and the contractor again used BAND-IT galvanized band and buckle to bind the individual cable strands together and covered them with new steel protective sheathing.
And while we’re talking about suspension bridges, we can’t overlook the grand Royal Gorge Bridge in Cañon City Colorado. Completed in 1929, the deck of this suspension bridge is 955 ft (291m) above the Arkansas River running through the Royal Gorge. The bridge is 1260 feet long and 18 feet wide and has a timber decking that you’ll never forget once you’ve walked across. The Royal Gorge Bridge held the title as the world’s highest suspension bridge until 2001 and it’s still the highest in the United States.
The bridge is just a baby compared to the length or deck size of the two previous bridges, so the suspension cables aren't as large either. The smaller size and dry Colorado air meant that the cables weren’t covered in protective sheathing. Despite these differences, BAND-IT galvanized steel band and buckle are still used to bundle the cables together at each end of the bridge where they enter the anchor points. After the last vertical suspender cable the main suspension cable splits into approximately 25 smaller cable bundles 2" in diameter. BAND-IT bands are used to maintain compression of these bundles which reduces vibration and increases strength around splices in the cable.
The next time you are in Colorado make a stop at the Royal Gorge Bridge just outside Cañon City and look for the BAND-IT bands on the suspension cables!
BAND-IT solutions have also been used on other suspension spans, including the Mackinaw, Newport, Delaware Memorial Bridge and Tacoma Narrows bridges.
Details on the bridges, specifications, and renovations via Wikipedia.