A BHP spokesman told Australia's Mining Monthly that after a lengthy and thorough internal investigation, the direct cause of the incident that led to Houston's death could not be determined.
"While we were unable to establish conclusively the cause, there are a number of insights that we have gained from the investigation around our regular safety practices, management of risks and use of medications," he said.
"We are actively sharing the learnings from the investigation throughout our operations, with contracting partners and the broader resources industry.
"We are committed to safe operations at all of our mines, and will continue to work with government and our industry partners to ensure all people return home safely at the end of each day."
The bulldozer was traversing - with the blade not in contact with the ground - a bench in an area where three bulldozers were pushing overburden material, according to the Queensland Mines Inspectorate which is also conducting an investigation into the fatality.
An inspectorate spokeswoman told Australia's Mining Monthly that it was finalising the investigation into the incident.
"The QMI has received and reviewed BHP's internal report into the incident," she said.
"Following completion of its investigation, the inspectorate will consider next steps, including potential compliance action and release of further information about the incident."
According to the inspectorate the bulldozer operated by the deceased, for a reason yet to be determined, went over the bench's crest and rolled downwards approximately 20m.
"The bulldozer came to rest on its roof in an area of mud and water approximately 2m deep," it said.
According to the inspectorate, another bulldozer operator who witnessed the incident "called in" the emergency immediately and an emergency response team attended at the site.
"Queensland Police Service attended at the mine and handed over control of the scene to the Queensland Mines Inspectorate," it said.