Stevenson has backed a science-based approach to improve the safety bunds in its quarries.
The change in approach comes after a sub-contractor died in an accident when the articulated dump truck they were driving travelled over a safety bund and fell to the bench below at the Stevenson quarry in Drury, Auckland in March 2020.
The tragedy spurred Stevenson and Fulton Hogan into action. The companies collaborated with the University of Newcastle to gain deeper insights into the science behind bund design in quarries. The research considered multiple factors, including different dump truck chassis, speeds, approach angles, bund dimensions and materials.
Stevenson general manager Ben Hussey said the company wanted to take a science-backed approach to safety systems.
“At the outset, it wasn’t clear how effective the bunds were at keeping our people safe and we wanted to understand what could be done differently or better to prevent similar accidents from happening in the future,” he said.
“We looked at what factors affected bund effectiveness and the safety controls we could change or improve in our quarries like truck speed to reduce accidents and harm to our people.
“We felt that the current guidelines here and overseas for safety bunds are the regulator’s best-guess at edge protection design. Using real-life simulations with articulated and rigid dump trucks really helped us understand the correlation between dump truck type, speed and bund geometry.”
The University of Newcastle provided the technical prowess of Associate Professor Klaus Thoeni of the School of Engineering and the necessary computing power to execute the numerical simulations.
In 2021, full-scale testing started with drivers manning test trucks, surveyors recording the smallest of details, and engineers setting up the test bunds.
Associate Professor Thoeni designed the project and managed the advanced numerical model which crunched the numbers and ran thousands of scenarios for around three months with a supercomputer at The University of Newcastle. This intensive computational effort provided detailed insights and robust data that were crucial for the project’s success.
A research paper outlining the project’s findings was recently peer-reviewed and published in the Journal of Rock Mechanics and Geotechnical Engineering (JRMGE).
“We’re pleased to have the research findings published by JRMGE as it’s a prestigious international journal showcasing the latest research in rock mechanics and geotechnical engineering,” Associate Professor Thoeni said.
Major quarry operators in Auckland, Kaipara Quarries Group in Brookby and Winstone Aggregates in Hunua, joined the research project and development of the new standards.
The research was presented at the annual Quarry NZ conference in July 2023 and was shared with WorkSafe, New Zealand’s work health and safety regulator.
Drivers and trucks completed various tests as part of the real-life simulations. Image: Stevenson
WorkSafe has now disseminated the research within their inspection teams to incorporate the findings into their work with quarries nationwide. Truck type, maximum load capacity, approach conditions (straights or bends), and speed limits are critical factors for designing and building best-practice safety bunds.
“We wanted the research to be as thorough as possible, so working with some other big operators meant the outcomes could be applicable to all quarries in New Zealand,” Fulton Hogan’s national quarry manager, Peter Walsh, said.
“Our teams now have a simple matrix to follow when designing, building and maintaining bunds in their quarry.”
Hussey said the company was proud of its achievements to make a safe workplace for all operators in the quarrying industry.
“We’ve achieved what we set out to do – to know how we can design, build and maintain safety bunds to stop dump trucks going over the edge in our quarries,” he said.
