(Demo) Road and Bridges May 2010 : Page 26
used ARRA dollars, 58% said it was less than 5% of the state’s total obligation. Replacing history around the historic As the Lake Champlain water level dropped in late 2009, Ted Zoli’s confi- dence level hit rock bottom. Cores of the piers of the Lake Champlain Bridge revealed very low strength and deep cracks in the supports, and an emergency dive inspection dropped the mood yet another notch when divers found the cracking below the water line encircling and running through the entire pier at some locations. “Now we were in circumstances where we are even more nervous,” Zoli, vice president at HNTB Corp., told ROADS & BRIDGES. Zoli is leading HNTB’s design efforts on a new structure over Lake Champlain. Further testing showed that every 10°C temperature change created an inch of movement of the piers, which were unreinforced and contained fro- zen bearings. Despite the degree of deterioration, which included corrosion in the truss members, crews were still thinking revival over replacement of the Lake Champlain Bridge, which was consid- ered a game-changer when it was built in 1929 because it advanced the use of criss-crossed steel girders from railroad bridges over to highway spans. Structure underpinning and post-tensioned jack- ets were discussed until the repair cost hit the ceiling. “I think the combination of an un- usual set of circumstances in lake ice and the lack of reinforcement in the piers If you were able to use your ARRA dollars to address your bridge inventory concerns, how much were you able to use? > 20% of my state’s total ARRA obligation 16–20% of my state’s total ARRA obligation 11–15% of my state’s total ARRA obligation 11% 6–10% of my state’s total ARRA obligation 6% 58% 10% < 5% of my state’s total ARRA obligation 10% ultimately led to the bridge’s demise,” said Zoli. “There was pier work done on the bridge in 1945, only 15 years after it was open, so the piers had been a prob- lem right from the beginning. “To a degree we were fighting a can- cer that was not progressing very rapidly, but it had gotten to a point where it needed some major surgery,” he added. The detour has been difficult on mo- torists and the DOT pocketbook. A ferry service—costing $30,000 a day—was put in place the day the bridge closed. Demolishing the structure did not How much do you think a new, six-year highway bill will help the bridge network in the U.S.? Most of the money will be used for other things, like road construction and transit, so the bridge network could suffer over the next six years. 8% It will not help improve the bridge network in the U.S. Source: ROADS & BRIDGES survey 26 May 2010 • ROADS&BRIDGES 47% It will help some. I can see a decent portion of bridges being taken off the functionally obsolete/structurally defi cient list. 33% 12% It will help substantially. I can see a large chunk of bridges being taken off the functionally obsolete/structurally deficient list. carry any degree of simplicity, either. Because the span connected two lands with history-enriched soil—Indians settled at Chimney Point, Vt., for thou- sands of years and Fort Crown Point is stationed on the New York side—it was important to build the new bridge in the same alignment as the old one. Also, the lake’s soft bottom required the corroded span to be broken in small enough pieces so cranes could handle the removal after demolition. “We were worried that if we lost the truss the truss would be buried in the mud and we would never be able to get it out,” said Zoli. The bridge was taken down on Dec. 28, and at press time the contractor had 80% of the cleanup complete. The design process involved the public, and HNTB offered two different cable-stayed alternatives, a steel com- posite version, a concrete segmental box design, a multigirder span and two varia- tions of an arch. Zoli said a modified network tied arch was the clear winner. “It is important to remember that the environment that the bridge is in, it is so high above the lake it really has a presence in the surrounding areas,” remarked Zoli. “I think that alone gives people a sense of place in the Lake Champlain Valley.” Two causeways were installed during the demolition process, which will serve as construction areas for the approaches. Zoli said the main span, which will be floated into place, could be erected at a couple of marina locations about a mile or two off the site. That will allow crews to work on the three main sections of the bridge simultaneously, making a fall 2011 deadline reachable. Construction was
