Safety bunds are essential to any surface mining and quarry operation, but how safe are they?
In March 2020, a subcontractor tragically 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 the wake of this tragedy, Stevenson and Fulton Hogan invested in a research project partnering with the University of Newcastle, Australia, to examine the science behind bund design in quarries.
Stevenson General Manager Ben Hussey explains that Stevenson and Fulton Hogan took a proactive approach and wanted to invest in science-backed safety systems to better protect its people.
“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 says.
In designing the research parameters, multiple factors were considered like different dump truck chassis, speeds, approach angles, bund dimensions and materials.
“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,” says Hussey.
“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,” he says.
Collaboration was at every turn in this research project.
The partnership with the University of Newcastle provided Associate Professor Klaus Thoeni of the School of Engineering with the technical prowess and 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 to 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, a prestigious international journal showcasing the latest research in rock mechanics and geotechnical engineering,” says Associate Professor Thoeni.
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.
Fulton Hogan National Quarry Manager Peter Walsh explains that collaborating with other quarry operators was a no-brainer.
“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,” he says.
The project was successfully wrapped up in early 2023, and the last step was to implement the learnings and new standard.
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.
WorkSafe has now disseminated the research within its inspection teams so that the findings can be incorporated into its work with quarries around the country.
Fulton Hogan and Stevenson have used the research findings to develop a functional and straightforward standard that will be applied across all quarries.
“Our teams now have a simple matrix to follow when designing, building and maintaining bunds in their quarry,” says Walsh.
Truck type, maximum load capacity, approach conditions (straights or bends), and speed limits are critical factors in designing and building best-practice safety bunds.
Reflecting on the project and new standards, Hussey explains that we wanted to take a step back and apply some rigour using numerical simulations, which has been a ground-breaking piece of research in New Zealand that can be applied practically in our quarries.
“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 says.
View the published research paper here