An investigation into the causes of the flyover collapse that killed two people in Belo Horizonte, Brazil last week should be completed by early August, the contractor has said.
Local firm Cowan was constructing the road bridge that fell on to a highway last Thursday.
It said in a statement that it had set up an investigation team that would report within 30 days.
UK-based structural experts were this week poring over footage and photographs of the collapse in an attempt to understand the causes.
Alastair Soane, director of UK safety improvement body Structural Safety, said a support failure was always a possibility when a large concrete bridge collapsed.
“Investigations will involve looking at the processes in place for design and construction,” he told NCE.
“It is possible that one or more supports have failed - whether permanent or temporary.”
Long span bridge expert and consultant Simon Bourne said the bridge appeared to have been self-supporting before it collapsed, which would rule out falsework failure.
He said a critical problem with a permanent pier was extremely unlikely, as was a failure of the concrete in the deck.
Bourne told NCE he believed one possibility would be failure of an anchorage or connection point for cables, if these were used to prestress the deck.
“It looks as though the span was up to 50m in length, so it’s very likely to have used prestressed concrete,” he said.
If an anchorage or coupler was used, and this had failed under stress, this could have sent a huge force through the bridge deck, triggering the collapse, said Bourne.
Cowan is based in Belo Horizonte and has been operating for 56 years in the heavy construction market.
It said that it has never recorded an accident of this nature. It added that all procedures and materials used on the flyover had passed tests and met required standards. It had been working on the project for six months.
“Cowan deeply regrets the incident and is making efforts to offer the necessary support to the victims and their families,” it added.
The firm said the structure would be completely demolished and rebuilt. It said that all necessary machinery was already on site at Avenida Pedro I to start the demolition process.
The company was awaiting the green light to begin from the authorities as NCE went to press.