The SA National Roads Agency on Wednesday said it was probing what could have caused the collapse of a disused pedestrian bridge on the N3 near Bedfordview in Johannesburg.

Spokesman Vusi Mona said they had received reports that there was an earth tremor in the area at around the same time the bridge tumbled down‚ crushing several vehicles on the usually busy highway.

“We don’t know what caused it. It could have been due to the tremor or it could have been due to illegal mining in the area‚” said Mona.

“We want to emphasis that we don’t know what caused it.”

The bridge was built in 1978 and had been closed to the public for a number of years.

Mona said Sanral continued to maintain it.

“We were responsible for inspecting it. The engineers say it was not long ago that it was inspected for any [fault]‚” said Mona.

Demolition teams on site of N3 bridge collapse

Meanwhile‚ the N3 north and southbound between the M2 Geldenhuys and N3 Gillooly’s interchange remain closed as forensic investigations are under way.

Three people were injured when the bridge collapsed in the early hours of the morning.

One was airlifted to hospital while two were transported by ambulance.

Sanral had since deployed demolition experts to dismantle the remainder of the bridge.

This was expected to take two days.