Stability and the Strength of the Structure
  • Post category:Safety

Safe Work Australia Code of Practice: Managing risk of plant in the workplace (2016) requires workplaces to implement effective safety management through risk control measures, which need to be reviewed to ensure that they are working and effective in eliminating or mitigating the risk or risk levels.

As warehouses and factories utilise forklifts their safety process needs to be implemented. When assessing forklift risk in the workplace one of the safety strategies is to take into account traffic movement in the workplace. Therefore, traffic management control measures are to be considered where the highest hazards cause serious or significant risk.

Forklifts are very sturdy, compact and close to the ground. When stationery they are low risk, but when in motion and dependent on their speed the level of risk rises. Further to that if they have an added load then that risk level increases. So, in considering risk management strategies all risk factors need to be considered

Bollards and barricades are used to manage hazards related to forklifts and high vehicle traffic areas.

Bollards and barricades are made of metal and designed to grab the attention of vehicle operators in order to prevent crashes around designated areas. They are installed to control traffic and prevent access to various locations, as they provide the physical strength needed to deter and control traffic and keep sites safe, yet offer protection from low and high-speed collisions.

Rigid barriers are usually concrete, steel or a combination of both, are used for protection against both heavy and rapidly moving vehicles. Examples of these barriers are posts at truck access doors or at the corners of buildings, or proprietary barriers in construction zones. As rigid barriers have limited movement, yield or deformation during impacts they are generally able to sustain multiple impacts without repair.

The force that a vehicle barrier must withstand is dependent on the mass and velocity of the vehicle. For instance, the force required to stop a large vehicle at a relatively low speed may be equivalent to stop a much smaller vehicle traveling at a higher speed. This hypothesis is expressed in terms of the kinetic energy (KE) of the moving vehicle. The key to an effective vehicle security barrier is to determine a way to dispel or absorb the kinetic energy of the vehicle

newtons third law

"For every action, there is an equal and opposite re-action."

Newton’s Law state that; the net force on an object is equal to the mass of the object multiplied by the acceleration of the object. Or some simply say: Force equals mass time acceleration. For example, a forklift weighing 2-tons moving at approximate 17 km/h with a load of 2.5-ton load has the potential destructive force of 1794964.34 Meter Kilograms (m kg). That’s equivalent impact to a large car at 33 km/h. Even at low speeds, forklift collisions result in devastating impacts and can cause serious injury or fatalities of operators and/or pedestrians or major damage to property due to their mass.

Bollards will need to be structured to yield or so they can absorb the energy of the impact.

Put simply, the amount of force to stop a forklift and lift truck is enormous, so traffic barriers are used to keep vehicles within their traffic lanes and prevent collisions. Roadside guardrails and crash barriers are important for low and high traffic areas where speed limits range from 50 km/h – 110 km/h. Road safety barriers not only protect drivers and their vehicles from the detrimental effects of rebounding, vaulting or rolling over, they also offer protection to pedestrians and property.

When determining the requirements to manage the risk using bollard and level resistance and absorption of energy needs to be calculated to choose the appropriate design. What is important is the depth and embedment of a bollard, where the base allows the structure to absorb the energy of the impact when struck by a forklift or vehicle in motion. There should have sufficient foundation strength to resist being pushed by a large 4*4 vehicle.

AS/NZS 3845:1999 provides substantial information for designers and installers of road safety barriers.

The Industry standards AS/NZS 3845:1999 for Road safety barrier systems provides the bench mark when erecting bollards and barriers. This Standard sets out the requirements for both permanent and temporary road safety barrier systems including: longitudinal road safety barriers (rigid, semi-rigid and flexible); terminals; crash cushions; interfaces, including transitions; and longitudinal barrier gates. NB: Bollards, pedestrian fences and channelizers, truck or trailer mounted attenuators, truck underrun barriers, sign support structures and poles are specified in AS/NZS 3845.2*.

The required compliances of the AS/NZS 3845:1999 for “Road safety barrier systems” includes:

  • issues that have to be addressed when specifying installation of these devices
  • erection and maintenance practices necessary to achieve an acceptable level of performance
  • the process necessary to assess the nature of repairs to a road safety barrier system, or to a crash attenuator system following a crash
  • methods to test road safety barrier and crash attenuator systems.
strong bollards sydney

AS/NZS 3845:1999 also sets out general requirements for road safety barrier systems. It states that, to comply with the standard, road safety barrier systems shall be:

  • erected in accordance with the manufacturer’s instructions
  • maintained in a manner that reflects the specified requirements
  • returned into service following a crash only after professional evaluation and execution of repairs
  • fitted with end treatments and interface devices that are appropriate to the system being used.

The Standard is to ensure that road safety barriers and systems are able to absorb kinetic energy when impacted by a vehicle under specified conditions and in most cases provide redirection and containment capability when impacted by a vehicle or provide controlled absorption of the kinetic energy of a vehicle that is on a collision course with a more hazardous obstacle or with other road users.

Essentially, if bollards and barriers are to mitigate the risk, they need to withstand the impact of the industrial vehicle.