As if it were a practical joke on a grand scale, Ray Bell Construction crews kicked the piers from underneath the James White Parkway Bridge in Knoxville, Tenn.
Early Jan. 7, demolition crews ignited explosives placed underground and inside the piers underneath the 800-ft. (244 m) bridge.
With a series of bangs and flashes at ground level the bridge structure fell straight to the ground, minimizing the amount of debris that flew skyward to avoid damage to structures in the neighboring Old City Knoxville.
The demolition is a part of Tennessee’s largest road project — the $85 million SmartFIX40 project.
Superintendent Jeff Walker said the 250 lbs. (113 kg) of explosives spread among 73 columns didn’t quite do the trick. Seven of the 10 spans fell as planned; the remaining three needed “a little persuasion” from a Caterpillar 322 excavator to fall all the way to the ground.
Crews spent the next two weeks cleaning up the 12,000 cu. yds. (9,200 cu m) of debris — mostly concrete — created from the bridge demolition. Walker said crews worked 110 hours on the first week and 90 on the second to get the job done.
There were two portions of the demolition in which Ray Bell chose to perform solid pick-up operations. Walker said the portion of James White Parkway that ran over Willow Street was brought down with machinery so it didn’t fall on the 24-ft.-wide (7.3 m), 16-ft.-tall (4.9 m) box culvert. This work began Dec. 18 and ended just after the new year.
Crews had to bring in a special piece of equipment when taking down the portion of roadway that ran over the Norfolk Southern Railroad. A 90-ton (82 t) Grove crane from Steel City Inc. in Birmingham, Ala., was placed on a bolt-on railroad carriage and was stationed on the railroad tracks to make its lifts. Ray Bell worked with Norfolk Southern to schedule five hours each day during which there would be no train traffic from Dec. 26 to Jan. 5. When their time was up, the crane rolled down the rail to a storage line and the rail was switched over to the main line. It was not removed from the track until this portion of the demolition was complete.
Aside from the train track-ready crane, the manual demolition called upon a bevy of NPK hammers attached to Caterpillar 320 and 322 excavators. Walker said the NPK processor, attached to a Cat 325 excavator, was “instrumental” in the demolition.
The processor, while excellent at cutting through rebar, is not designed to deal with the prestressed beams and cables that were inside of the James White Parkway’s structure. In order to cut through this material, workers had to walk in with torches, Walker said.
The demolition debris was trucked off-site to a landfill.
Overall, the SmartFIX40 project is 70 percent complete and well on-target to meet its September deadline.
Crews still need to construct three bridges, a retaining wall and repave approximately 2 mi. (3.2 km) of City Street.
While the volume of work has passed its peak, Walker said two of the remaining bridges are among the largest structures in the project. A 900-ft. (274 m) span measures 150 ft. (46 m) wide and a 500-ft. (152 m) span measures 66 ft. (20 m) wide.
The final phase will shift the project’s focus onto Interstate 40. This portion of the job will widen the interstate to three lanes in each direction from I-275 to Cherry Street. During this work, I-40 will be completely closed and traffic will be rerouted to I-640. Access to downtown Knoxville will be available on the completed James White Parkway ramp built during the second phase. This work is scheduled for completion in mid-2009.
Completely closing off road to traffic reduced the construction timeline by two years, according to a Tennessee DOT news release.
I-40 carries approximately 103,000 vehicles per day. CEG