The structural engineer behind the collapsed Cabagan-Santa Maria Bridge in Isabela has rejected the claims of a design flaw, asserting that the bridge was constructed in strict accordance with the Bridge Code of the Philippines.

In an interview over DZRH, engineer Alberto Cariloria Cañete, the bridge’s original designer and author of the 1997 and 2015 Bridge Code of the Philippines, defended the integrity of his design, stating that the collapse was primarily caused by overloading and not a faulty blueprint.

Cañete said that he designed the 990-meter bridge in 2012 and 2013, incorporating an efficient arch geometry, a time-tested design that has been proven effective since Roman times.

“I used an efficient arch geometry in the design because arches have long been proven to be strong since Roman times,” Cañete explained in Filipino. “The arch is what supports the bridge, and that’s what makes my design economical.”

He emphasized that if there had been a design flaw, the collapse would have occurred at the first arch, not the tenth. He pointed out that the 102-ton dump truck successfully crossed nine arches before the structure gave way at the tenth arch.

Construction of the bridge began in November 2014 and was completed on 1 February 2025 for P1.225 billion.

Cañete said the original design followed the 1997 Bridge Code, but in 2015 new standards were introduced, increasing the force requirements for bridges. To comply with these updated standards, the first eight arches were retrofitted in 2015.

He emphasized that his role was strictly limited to designing the bridge and that he had no involvement in the construction or the selection of materials, in accordance with Department of Public Works and Highways policy.

Calls for forensic investigation

Asked about President Ferdinand Marcos Jr.’s statement attributing the collapse to a design flaw, Cañete refused to engage in a blame game.

Instead, he urged the authorities to conduct a forensic engineering investigation to determine the real cause of the collapse.

“This is similar to when an airplane crashes. You don’t immediately conclude the cause until you retrieve the black box and conduct a thorough investigation,” Cañete said.

“The same should apply here. We need to analyze the design and inspect the construction through forensic engineering,” he said.

The engineer expressed his willingness to cooperate with the investigation to clear his name, lamenting that his reputation was put into question despite the lack of official findings.

“It’s important that we be careful about what we conclude. There should be a forensic engineering investigation to analyze the design and construction before releasing a final report,” he said.