The Louisiana Department of Transportation and Development has given the green light for Boh Bros. Construction to resume suspended activities on the $803-million I-10 Twin Spans bridges in New Orleans. The DOTD has approved use of a modified procedure to prevent girders from rolling, which occurred on Oct. 30 when a girder rolled off a bent during a deck-form flipping operation, sending 10 workers into the water, critically injuring two and killing Eric Troy Blackmon, 44, a foreman and 11-year Boh employee.
“We have not determined why the girder rolled off the bridge, but we are confident that these new procedures will prevent girders from rolling, regardless of the cause,” says Gordon Nelson, La. DOTD assistant secretary, announcing the approval Dec. 16.
Blackmon was killed when his crew was setting an overhang form for the bridge deck, says Ann Barks, a spokeswoman for New Orleans-based Boh. “They were tied to the girder when it fell. They were all in harnesses and life vests and fell an estimated 30 ft. into water that was estimated at 8-10 ft. depth.”
The concrete girder beam the men were working from rotated off the concrete support caps, said Robert Boh, president. The La.DOTD’s Nelson says further explanation would be speculation, pending the outcome of investigations by Boh Bros., the DOTD and the Occupational Safety and Health Administration.
Work resumed on the project three days after the accident but Boh was prohibited from working on concrete forms attached to the girders until it provided additional safety measures and DOTD approved them.
The new procedures Boh submitted include bracing the Bulb T edge girders with angle irons at the top and a tie rod between the top flanges, Nelson says. The contractor will also place 4-by-4 wood posts at the base of the girders for additional bracing. “We know that providing this additional bracing will keep girders from overturning,” Nelson says. “We feel those are adequate to prevent that rolling from occurring again,” Nelson says.
The design and integrity of the bridges are not suspect, Nelson says, adding that the erection process is the greatest time of stress for a bridge and requires additional bracing for stability.
However, the DOTD has not gone so far as to introduce the new safety precautions to other projects throughout the state. “Until we know the cause of the accident, it is difficult to say we are going to impose this on everything,” Nelson says. “We are relying on our investigation as guidance into what happened. These same Bulb T girders are used all over the U.S.”
Boh spokeswoman Barks says the company has been in compliance with industry standards and safety measures throughout the project and will continue to be so. “The safety of its employees is paramount to Boh Bros., and the company believes the plans for additional bracing of the girders in this situation gives us confidence to allow our employees back to this vital part of the project,” she says. “The entire Boh Bros. family feels a sense of urgency and commitment to getting this crucial bridge into service for the community and to complete it on schedule.”
Boh Bros. holds a $379-million contract for construction of the 4.5-mile low-rise portion of the bridge. The joint venture of Traylor Bros. Inc., Evansville, Ind., Kiewit Southern Company, Peachtree City, Ga. and Massman Construction Co., Kansas City, has a $166.6 million contract to construct the high-rise portion of the new Twin Spans. Both are on schedule.
Fully funded by the Federal Highway Administration, the bridges are to replace the east-west artery that was severely damaged in Hurricane Katrina. In addition to performing in record time the emergency repairs to the damaged bridges, Boh won the contract to open the westbound span of the new bridge by next Oct. 22, and the eastbound span by Aug. 3, 2011.