Saverio Ferrari blamed the Genoa bridge collapse on the decision of the original building team not to build the supporting piles with anti-seismic materials.
Mr Ferrari, who worked as an engineer for the company that built the Morandi bridge, argued the flaw in the structure and the failure of authorities to redirect heavy traffic to alternative routes were the main reasons behind the deadly collapse.
Speaking to Corriere della Sera, the retired engineer said: “I worked with the Condotte company. Everything always collapsed when the failed company was involved.
“When the structure was put up, the supporting piles were not made to sustain earthquakes.”
Mr Ferrari claimed civil engineer Riccardo Morandi, who designed the bridge and whose name was given to the structure, had been aware of the decision and had complained to the building team.
He explained the trials to ensure the support capacity of the piles had been rushed and that the Morandi bridge already showcased major issues less than two years after its inauguration.
Mr Ferrari continued: “Mr Morandi got mad at the engineer in charge, he said ‘it needs to have a specific weight base to hold up.’ The piles were not anti-seismic.
“When the carrying capacity is not calculated you need to test the foundations. The test was done over five days. The chemical reaction of concrete cannot be completed within five days yet they kept on building.
“In 1969 I stopped near the centre of the central span of the bridge and the oscillation of the structure from right to left was off by seven or eight centesimal.”
He added: “They did not learn how to redirect the heavier traffic from the 1980s onwards. That’s why the bridge gave out.”
Witnesses to the tragedy say the bridge collapsed during heavy rain “like flour” on to the railway lines and buildings below.
Rescue workers searching the rubble confirm 39 people have died and 15 are injured, numbers expected to rise.
A baby is reported to have died as well as two people who were in their homes after the enormous bridge collapsed.