Two of the largest expansion joints ever built in North America are currently being installed at each end of the new Tacoma Narrows Bridge, Tacoma, Wash. The expansion joints are one of the last items of work for Tacoma Narrows Constructors as they prepare to open the structure to traffic in early July.
Each of the two Maurer System swivel-joist expansion joints, manufactured by The D.S. Brown Co., North Baltimore, Ohio, weighs close to 100 tons and measures 70 ft long and 15 ft wide.
With the extreme size of these joints, special equipment was designed and manufactured internally to achieve the very tight tolerances required. An entire test fixture along with computerized control and data recording was needed to accommodate the proof testing that was required for each joint. The joint assemblies are designed to accommodate up to 56 in. of longitudinal structural movement caused by wind, thermal changes, traffic loads and seismic conditions.
"The Maurer swivel joint is uniquely capable to handle the large movements expected on the New Tacoma Bridge. This style of expansion joint also has a proven track record with more than 40 installations in the U.S. and many more on very large structures all around the world," according to Mark Kaczinski, vice president of engineering for D.S. Brown.
The logistics of transporting such a large and heavy load across the country to the project site was a challenge. A single-lane truck measuring 149 ft long with 18 axles was used to transport the joints from Minnesota to Spokane, Wash. In Spokane the joints were trans-loaded to another truck using 3 cranes. This truck, 17 ft wide with 17 axles, traveled the final 330 miles in two lanes of traffic at about 25 mph. It consisted of a pull tractor, trailer and push tractor that totaled 180 ft in length. The last 30 miles were traveled at night to minimize traffic disruption.