Dreamworld inquest: Engineers, electrical supervisors face grilling

Two senior engineers and electrical supervisors are expected to be grilled as day seven of the inquest into the Dreamworld tragedy begins today.

They will also be asked why the theme park didn't install a $2000-$3000 safety device that could have prevented the deaths of four people on the thunder river rapids ride.

Yesterday the court was shown a report by a safety consultant, hired by Workplace Health and Safety, who claimed the primary cause of the fatal accident in October 2016 was the lack of a water level detection system.

One was installed on the nearby log ride three years before the tragedy, but never equipped to the river rapids.

The system would have shut down the ride within seconds after noticing water levels started to drop.

That was what forced the raft Cindy Low, Kate Goodchild, Luke Dorsett and Roozi Aragahi were on to capsize.

Matthew Sullivan, a contract engineer, took to the witness stand yesterday, admitting he carried out $18,500 safety upgrades on the River Rapids, seven months before the disaster.

But he told the inquest he was never asked to install a water monitoring device.