|Double Trouble. Leg fell off second launching truss (above) after 8-month layoff due to failure of jobs first truss in February. (Photo courtesy of Ohio DOT)|
Workers with Fru-Con Construction Corp., Ballwin, Mo., had resumed construction Oct. 23 on the bridges main span after an eight-month delay following the Feb. 16 collapse of a 2-million-lb, $3-million custom-made launching truss that killed four workers (ENR 3/1 p. 12). After months of inspecting and modifying the second launching truss, identical to the first, engineers had determined that they could resume main span construction with it.
|Click here to view video of the Oct.23 Accident|
(Video courtesy of Ohio DOT. Requires Windows Media Player and Internet Explorer 5.1 or above for viewing)
But just hours after resuming construction, workers apparently raised one support lega 10-ft-long, 2.5-ton steel cylinder winch driven by a 4-hp electric motorrather than lowering it. This caused the 10-ft-long leg to pull up and the support cable to break, says Fru-Con project manager Dave Herron. The leg fell about 10 ft to the catwalk around the top of the pier.
"The front legs were being positioned," says Ohio Dept. of Transportation spokesman Joe Rutherford. "The winch lowering the cable is connected to the cylinder. The winch was unspooling but the cable was hung up."
Herron says the incident occurred because of an operational problem. But he says the winch should not have been designed with the capacity to break the cable. No one was injured, but officials must now decide how to dismantle the truss and whether they will use it again.
"Fru-Con will have to come up with a plan to move the truss backward and disassemble it," says Rutherford.
At ENR press time the contractor had not completely ruled out future use of the twin truss, though ODOT officials seemed adamantly against it. One option would be to bring in a truss currently placing beams on a Malaysian bridge. "Any equipment brought to the site will be examined and certified by independent professional engineers before its use," says Herron.
Fru-Con had hired consultant Wiss, Janney, Elstner Associates Inc., Northbrook, Ill., to identify improvements for the second truss after the Feb. 16 collapse.
Herron says Fru-Con will seek compensation from Paolo De Nicola S.p.A., the Italian manufacturer of the launching trusses. "We have not arrived at a final conclusion about the [February] accident," says Andrea Delia, a Paolo De Nicola engineer. "There is also a criminal investigation [so] I think it is not appropriate to speak of this matter."
Fru-Con had been 15 months ahead of schedule in February, but the accident pushed back the date to October 2006. It is unclear what impact the latest incident will have on the schedule.
The federal Occupational Safety and Health Administration had allowed for use of the second truss in its report on the February accident, but cited Fru-Con four times for improperly anchoring to pier caps the front legs and the roller beam for the back legs (ENR 8/9 p. 12). Fru-Con has appealed the $280,000 in fines. "Both parties continue to talk," says Herron. "We are optimistic that a settlement will be reached."
The 1,225-ft main span is to be built with some 3,000 precast concrete beams averaging 100 tons. Herron says 73% of the total project is complete but main span construction is delayed again.ight months after the first of two custom-made launching trusses collapsed at the site of Toledos $220-million Maumee River Bridge, a support leg fell 10 ft off the second onecausing work to halt again.