Morbi: Of the two main cables of the Morbi bridge that Ajanta Manufacturing Limited (Oreva Group) was responsible for operating and maintaining, one was corroded and nearly half of its wires "may be already broken" even before the cable snapped on October 30 evening, the special investigation team (SIT) appointed by the Gujarat government has found in its preliminary probe.
22 of 49 wires were corroded
"It was observed that out of the 49 wires (of that cable), 22 were corroded, which indicates that those wires may have already broken before the incident. The remaining 27 wires recently broke," the SIT said.
The SIT, appointed by the Gujarat government, found in its preliminary probe that corrosion on nearly half of the wires on a cable and welding of old suspenders with new ones were some of the major faults that led to the collapse of the suspension bridge in Morbi last year in which 135 people were killed.
The findings are part of the 'Preliminary Report on Morbi Bridge Incident' submitted by the five-member SIT in December 2022, which was recently shared with the Morbi Municipality by the state urban development department.
Lapses found in repair work
The SIT had found several lapses in repairs, maintenance and operation of the British-era suspension bridge on the Machchu river that collapsed on October 30 last year.
IAS officer Rajkumar Beniwal, IPS officer Subhash Trivedi, a secretary and a chief engineer from the state roads and building department and a professor of structural engineering were members of the SIT.
According to the SIT, the main cable on the upstream side of the river snapped, leading to the tragedy. Each cable was formed by seven strands, each comprising seven steel wires. Total 49 wires were clubbed together in seven strands to form this cable, the SIT report said.
It also found that during the renovation work, "old suspenders (steel rods which connect the cable with the platform deck) were welded with the new suspenders. Hence the behaviour of suspenders changed. In these types of bridges, single rod suspenders should be used to bear the load".
According to the SIT, there were nearly 300 persons on the bridge at the time of collapse, which was "far more" than the load bearing capacity of the bridge. It, however, said the actual capacity of the bridge will be confirmed by laboratory reports.
Important factor that contributed to the bridge collapse
The probe report also pointed out that replacing individual wooden planks with an aluminium deck also played a role in the collapse.
"Walking structure was made up of rigid aluminium panels instead of flexible wooden planks. If there were individual wooden planks (which were there before renovation), the number of casualties could have been lower. Moreover, no load test or structure test was conducted before opening the bridge," it said.
The aluminium honeycomb panels were fixed without any gap in between, which makes the deck less flexible to deform in its own plane, said the SIT, adding that the use of aluminium could have increased the overall weight of the bridge too.
