Murray & Roberts, the main contractor whose responsibility it was to erect the pedestrian bridge near Grayston Drive, argued through its expert witness on Thursday that the quality of some of the couplers used to hold the scaffolding structure together had not been up to standard. A coupler is used to connect two tubes by clamping them together so they do not slip.
The questionable quality of some of the couplers could have contributed to the temporary structure not being able to withhold the force of the wind, argued Prof Roelf Mostert, head of the University of Pretoria's Materials Science and Metallurgical Engineering Department. He was at the scene on the day of the incident.
"The structure didn't show any noticeable movement until the time of collapse (on that day)," Mostert said.
However, legal counsel for Form-Scaff, the company that supplied the scaffolding to erect the bridge, countered this by accusing Murray & Roberts, SA's second largest construction company, of poor workmanship. Citing findings from an investigative report compiled by AMOG, an Australian consultancy that specialises in structural collapses, Form-Scaff said that evidence suggested the couplers had not been tightened adequately.
Michael Els, CEO of Waco Africa, of which Form-Scaff is a subsidiary, told Business Day on Thursday that "under certain conditions, if you under-tighten the coupler, it does not grip as well as it is designed to do".
But Mostert said he had found no evidence to back the theory that poor workmanship was at the root of the collapse. Instead he had found that the couplers provided by Form-Scaff had snapped and the structure could not withstand the force of the wind.
Murray & Roberts spokesperson Ed Jardim said on Thursday the construction group would respond to the report's allegations of poor workmanship as the inquiry continues.
On Friday, the construction group is expected to present three other witnesses to vindicate it from blame for the bridge collapse on October 14 that left two people dead and at least 19 others injured.
Form-Scaff's expert witness from AMOG is expected to provide submissions next week.
Other role-players include the City of Johannesburg, represented by the Johannesburg Development Agency (JDA); the Engineering Council of SA and engineering consulting company Royal HaskoningDHV.
The Department of Labour's inquiry, which has so far been delayed three times since investigations began six months ago, must make a finding on what went wrong and who is responsible.
In May the inquiry was postponed after the department said commissioner Lennie Samuel, a departmental forensic investigator, needed more time to study reports by major stakeholders.
These reports had allegedly been submitted after the stated deadline. But a representative from the JDA denied this.
Source: Business Day
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