Safety drives design of mine roads
Studies have identified vehicle interaction as one of the biggest hazards on a construction or mine site.
The implementation of appropriate risk minimisation measures and safeguards is however often less than optimal.
Adopting a safe system approach to road safety on mine haul roads recognises that as humans we are fallible and will continue to make mistakes. It accepts that an inevitable mistake should not result in injury or loss of life.
A safe road system incorporates the zero harm target for operations. Key principles are:
- People will continue to make mistakes and accidents will continue to occur
- Road users should not suffer death or serious injury because of such mistakes
- The limit of the human body to violent forces is a key factor in survival of crashes
- Speed is the single greatest influence on these forces in a crash
- Vehicle size difference is a critical industry specific factor in mining
Safeguarding human and economic risk
In a safe system, the design of road and vehicle selection should aim to reduce the incidence and severity of crashes, when they do occur. There are two key ways to achieve this:
- Designing, constructing and maintaining a road system (roads, vehicles and operating requirements) to dramatically reduce injury
- Improving roads and roadsides to reduce the incidence of crashes and minimise harm
The focus should be on designing forgiving roadsides and providing clear driver guidance. In areas where large numbers of pedestrians use verges or where there is substantial collision risk, speed management supplemented by road and roadside treatments is a key strategy for limiting crash forces.
On existing roads, a well conducted audit will identify all the safety deficiencies on the haul road network. It will result in improved intersections, installation of signage and delineation as per Australian Standards and avoidance of potentially hazardous locations. All of which make the overall mine site a safer work environment.
Good road safety design is more than meeting standards
Instead of just building a road, a good road safety designer will look at all vehicle interactions from an end user perspective, to better respond to the interplay between users. This knowledge allows for the delivery of an integrated safety and design package. The benefits include reduced incidents and increased efficiency on site through a reduction in interaction with vehicles. It also meets requirements to provide safe facilities. This fits in to a mine’s zero harm and OHS policies as opposed to just meeting Australian standards.
A case study: Safe road design in practice
The preliminary design of a new mine development in Europe included 10km of haul roads, 5km of plant access roads, and an 8km local road realignment.
The mine planners provided basic road designs based on generic cross sections and forged through the area on a flat earth ground model. While meeting the minimum road standards the designs lacked safe design aspects.
Using this basic design approach as the basis for the mine haul roads bulk earthworks quantities led to an incomplete understanding of the challenging mountainous terrain and the geometrics for the mine vehicles for final operation. Not only were the quantities for cut and fill greatly underestimated, there was a negative impact on the safety performance on the design.
The safe design approach comprised three tasks.
- The first task was to sit down with the mining operations personnel and establish the correct cross-sections for the appropriate design vehicles ensuring the meeting of safe interaction between vehicles
- The second was to agree on the various parameters for the horizontal and vertical geometry and create alignments for the various roads including a focus on safe design principals. When applied to the cross section these parameters generated cut and fill volumes for each alignment, including a number of iterations for each option to reduce the risk for the operating mines vehicles
- The final task was to sit down with geologists, quantity surveyors and site engineers to work through items which included material types suitable for embankment construction, confirming cut and fill slopes, proposing most suitable material for upper sub grade, advising on appropriateness of retaining structures, optimising haul distances (creating an earthworks balance, minimising haul distances, hauling cut downhill) and quantifying with the quantity surveyor on material types, possible handling costs and final out turn costs for the contract
A detailed design road safety audit followed design finalisation to ensure the inclusion of all safety aspects.
Confidence the mine is operating safely
Road incidents constitute one of the top five risks on a mine site. Improvements in health and safety as well as economic factors are driving the growing recognition of the importance of addressing road safety. Safe road design involves highways, access roads and pedestrians - anywhere there is interaction with vehicles.
A cost benefit analysis quickly demonstrates the value of a holistic approach to road safety; one incident can close a mine for a week.
The implementation of road improvements incorporating safety will deliver the confidence that the mine is operating safely and efficiently. This is because effective delineation, signage, layout, separation of vehicle classes and interaction will all be contained in the design.
Richard has a long history of Crash Investigation and Road Safety Audit experience after receiving formal training in Crash Investigation and Road Safety Audit through the Royal Society for the Prevention of Accidents in the UK. Richard currently manages projects relating to mining road safety, research, traffic and safety including knowledge transfer, development of training packages and programme management.
You can contact Richard at Richard.jois@aurecongroup.com.
This article first appeared in Australian Journal of Mining.
