Investigators preliminary report out this week into the catastrophic suspension bridge collapse in East Borneo has pointed the blame to a shear failure on the bridge hangers.
Engineers from the Universitas Gadjak Mada (UGM) in Indonesia leading the investigation into the collapse said the preliminary evidence points to a shear failure on the nuts and bolts connecting the bridge hanger to the bridge deck.
“It is clear that the main cable imported from Canada was okay, cable hanger from Austria was okay, but the nuts and bolts had failed,” said UGM professor Nur Ilham, part of the investigation team. “Furthermore, on the connections of the bolts and nuts, there was locally produced old metal that had gone black and cracked.”
UGM Investigation team leader professor Bambang Suhendro said: “The only vital component which had allegedly initiated or triggered the collapse was the connection system between the main cable to the hanger (wire hanger).”
“The phenomenon of shear failure is the failure phenomena of material that is brittle, thus the sudden collapse that is not preceded by other phenomena such as enlarged deflection or deformation,” added Suhendro.
The investigation team added that before the collapse, the main components of the cables, hangers, truss road deck, pylon, foundations and anchor blocks had appeared to function well.
The team have 30 days to produce a technical report for Indonesia’s Ministry of Public Works who will in turn act on any findings.
The three span 710m long Kutai Kertanegara suspension bridge collapsed into the River Mahkam in the East Kaliminta province last month leaving only the bridge cables and tower in place.