DPWH-6 confirms soft soil underneath Aganan Flyover

By John Noel Herrera

It appears that the P560-million Aganan Flyover in Pavia, Iloilo might be facing the same fate as the P680-million Ungka II Flyover, and commuters will continue to suffer from heavy traffic and possible safety hazards, as both structures are reported to be sitting on soft soil.

In a committee hearing conducted by the Sangguniang Panlalawigan (SP) of Iloilo on June 2, 2023, Department of Public Works and Highways (DPWH)-6 regional director Nerie Bueno confirmed that the soil underneath the Aganan Flyover is also soft.

“I asked the central office, together with the Ungka to make a review of that Aganan (design), but then they replied to me that if you believe tama yung test, pumasa, then why do you have to change yung design. Why do you have to doubt? But what I did, I also bore a hole and then I found out malambot din siya (soil),” Bueno said.

Citing the condition of the soil, she stressed that there is really a need to review the design and conduct a geotechnical investigation of the structure.

“So, I am now forcing that you do a review on the design of that bridge,” she said.

In January 2023, Bueno first confirmed suspending the construction of the Aganan Flyover as it is situated in the same road line as the Ungka II Flyover, and its contractor, International Builders Corp (IBC), was not amenable to its design.

The DPWH also earlier reported that they are considering changing some parts of the design of the structure, noting that they might replace some of the flyover’s girders with steel instead of concrete.

Bueno, however, noted that they could not immediately make the possible interventions for Aganan Flyover as the agency still needed to solve the problem of the Ungka II Flyover.

As to the Ungka Flyover, the Iloilo SP has already passed a resolution supporting the move of Sangguniang Bayan of Pavia urging the Senate to investigate, in aid of legislation, the sinking Ungka Flyover.

4th district board member Rolando Distura added that they will include the investigation of the Aganan Flyover in the said resolution.

Gorriceta also said that the House of Representatives is expected to tackle the construction quirks surrounding the Ungka Flyover as it was already referred to the House Committee on Public Works and Highways, but it will not happen after July 24, 2023 as the Congress is on recess.

Meanwhile, the DPWH-6 chief said that the hired third-party consultant, Abinales Associates+Consultants, will give the final recommendation and result of the investigation on June 30, 2023, and the DPWH Bureau of Design (BOD) will choose what intervention will be applied among the three schemes presented by the consultant.

The investigation, which cost another P13.8 million, revealed that all 16 piers of the flyover have been sinking since May 13, 2022, with three piers sinking by almost two feet.

The Abinales Firm earlier recommended three options that will cost at least an additional P250 million and a 10-month construction duration for the flyover, which include adding bored piles to support the existing piers (piers 4,5,6); providing portal frames to support piers 4, 5, and 6; and underpinning or jet grouting the 13 other piers.

Bueno said that additional works would most likely start in 2024 as the DPWH still need to look for additional funds for the repair of the flyover, noting that funding under the 2023 national budget is unavailable.

Iloilo-based structural engineer Nilo Jardeleza, on the other hand, also proposed another scheme that could be used to rehabilitate the Ungka Flyover, noting that the process is less expensive and will not take more time.

Jardeleza suggested that the DPWH can use “piled raft footing” or underground shallow footing using the Hydraulic Static Pile Driver that can be bought in Indonesia.

He explained that the equipment uses hydraulic pressure to drive piles into the ground and, unlike other pile driving methods that rely on a hammer or vibrator, the equipment uses a hydraulic clam to hold the pile in place while pressure is applied to the top of the pile.