Grayston bridge design responsibility rested solely with M&R, witness testifies

The person who drafted the design sketches of portions of the temporary works for the Grayston pedestrian bridge construction project never saw a design approved by a professional engineer as required.

Form-Scaff employee Gareth Edwards testified on Monday at the Department of Labour’s inquiry into the collapse of the temporary structure in October 2015 that killed two people and injured 19.

The structure spanned the busy M1 freeway in Sandton and construction operations were executed while the traffic continued to flow. The falling structure hit vehicles underneath in mid-afternoon traffic.

Edwards told the inquiry that he made the drawings for the purpose of quantifying the amount of components Form-Scaff would have to supply to the principal contractor, Murray & Roberts (M&R).

He said responsibility for designing the structure rests solely with the user, in this case M&R. M&R would therefore be responsible for doing the final checks and approving the design.

Erasmus admitted that he never saw any drawing of the complete temporary works.

Presiding inspector Phumudzo Maphaha put it to Edwards that construction regulations require the designer “when mandated by the client” to carry out inspections to see if the construction is done in accordance with the design.

Edwards said he was not mandated and was not involved on site.

Maphaha further pointed out that the regulations require the designer to take into account health and safety specifications supplied by the client.

Edwards said he did not take them into account and was not supplied with such specifications. He couldn’t say if they were provided to Form-Scaff.

He said Form-Scaff produced design drawings with the necessary calculations, but did not do any other duty in relation to the design.

Attorney Willem le Roux, on behalf of the Johannesburg Development Agency, which commissioned the construction, asked Edwards whether the pylon that would be part of the bridge was included in the calculations for the temporary works design.

Edwards confirmed that it was included. He also confirmed that the pylon was not constructed when he visited the site three or four days before the collapse.

Edwards confirmed that he was never requested to give any details about the sequence in which the temporary works was supposed to be constructed and therefore did not do so.

Form-Scaff engineer Jan Moll, one of the colleagues who should have approved Edwards’ drawings internally, could not during his testimony explain why the drawings were not signed off.

He did say that he did not “fully check” the drawings, and that he would have signed it if he had done  the full check. He did not have the time to do it in this case and only used the drawings to check the quantity of components, he testified.

He said that an appointed engineer would have signed it off, and speculated that in this case the designated person would have been engineer Roger Barker of M&R. Barker earlier testified that he was only responsible for checking the foundations of the structure.

Moll said the drawings by Edwards were not design drawings, merely a lay-out state drawing.

Moll testified that the pylon structure was designed to be part of the false work, and that the formwork and false work had to link with the pylon.

He said the temporary structure was dependent on piers, the pylon and abutments.

Moll said if he had to suggest remedial actions to prevent a similar event, he would have a professional engineer overseeing the design, including the temporary works as well as the sequencing of the construction.

The hearing will continue on Tuesday with what is expected to be the last witness from engineering consultants Royal HaskoningDHV.

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