Working near, or on, tip trucks and tipper trailers

Purpose

The purpose of this safety alert is to highlight the risk of crushing or fatal injuries due to overturning tip trucks, tipper trailers or uncontrolled movement of tipper trays. The term “tipper” will be used to describe tip trucks and dump trucks that operate on and off road and includes trailer tippers. All tippers, including those that tip in line with the truck body and side tippers, are covered by this alert.

There is a risk of serious injury or death when workers are in close proximity during unloading a tipper, or when working on a vehicle under a raised tipper body. Suitable props and exclusion zones should be implemented as control measures and monitored to ensure correct use.

Photograph 1 - Examples of a side tipper

Background

There have been several incidents where a tipper has overturned during unloading. Whilst there are several factors considered, generally issues related to the ground slope or ground condition in the area used for unloading. The ground slope, in some circumstances, was too steep and outside the limits for operation of the tipper. The other issue was unstable or soft ground, particularly on civil constructions sites, that contributed to instability during unloading.

In a recent incident a worker on a civil construction site was fatally injured when a tipper overturned during unloading. It is possible that soft, uneven ground partially gave way and the tipper leant to one side, became unstable and overturned hitting the nearby worker.

There have also been several incidents where workers have been crushed under a tipper during operation, repairs, maintenance or inspection. Failures occurred that allowed the tipper body to lower unexpectedly while a worker was in the area under the tipper body. There have also been examples of hydraulics leaking down slowly, trapping the worker, or suddenly dropping and crushing the worker between the tipper body and the chassis.

In a recent incident, a worker was checking for a possible fault on a trailer. The side tipper had been partially raised to allow easier access to the area of the suspension. While leaning in over the chassis a fault in the hydraulic system allowed the tipper to lower on to the worker. The manufacturer supplied prop couldn’t be located on site.

Photograph 2 - Example of bad ground conditions

Contributing factors

Ground conditions on site can vary depending on the work being undertaken. Soft ground, backfilled excavation and side slope can increase the risk of a tipper overturning, particularly during unloading. Information on the ground conditions on site should be kept up to date and provided to any tipper drivers entering the site to unload. Soft edges and changes to ground level may need to be monitored during some civil construction activities.

The size and type of tipper should be considered based on the site conditions. An over axle semi-trailer tipper may be at a greater risk of overturning due to soft or uneven ground. The height required to fully raise a tipper body should consider any overhead obstructions on site. This may limit the areas where some types of tippers can be unloaded.

Pedestrians working in areas where unloading and manoeuvring is being done are at risk of being hit by mobile plant. If a tipper overturns, workers may be crushed by the tipper or from any spilt load.

In some situations, sticky dirt or product can stay in the top of the tipper and this can increase the risk of the tipper and truck overturning.

Hydraulic hoisting systems commonly used on tippers can fail and cause the tipper body to drop either suddenly or slowly due to:

• creep in hydraulic cylinders due to internal leaks in valve seals
• external leaks in fittings and hoses
• damage and failure of hoses, piping, valves and cylinders
• wear and damage to control cables
• inadvertent activation of the lowering control

Faults in hydraulic systems can lead to lowering of the raised tipper body that may trap or crush someone who is accessing areas under the tipper body.

Action required

Working near tippers

Where there is a need for workers, mobile plant and tippers to be working in close proximity on site the following should be in place:

• clear delineation between pedestrian areas and areas for movement of vehicles and mobile plant on site
• exclusions zones where there is a risk of being hit by mobile plant
• designated communication equipment and procedures between pedestrians, vehicle and plant operators
• providing clear instructions for truck drivers and ensuring a trained traffic controller is responsible for providing instructions.

Unloading tippers

Where unloading operations occur on site there may be a need to implement the following based on site conditions:

• The truck driver being aware of maximum ground slope and orientation of the truck during tipping (this information should be provided by the tipper manufacturer).
• Up to date information on ground conditions and slope is available and provided to drivers that cover the areas where unloading is occurring. This includes information on uncompacted and waterlogged ground.
• Identification of appropriate zones where unloading is to be done where the risk of roll over is minimised. These may need to, not only identify where a load may be unloaded, but the orientation of the truck to minimise the risk of overturning. For example, in hilly areas where there is no level ground there may also need to be instructions to ensure the tipper body is raised in line with the slope and not across the slope. Exclusion zones will need to be implemented to keep workers and pedestrians away during times when unloading is taking place.
• Not locating unloading zones near overhead power lines that could be struck by the raised tipper body.
• Allowing for the adverse effect of high winds on raised and light tipper bodies.
• Implementing spotters where obstructions pose a risk to the tasks, e.g. overhead obstruction near an unloading area for tippers.
• Clear maneuvering areas to allow for truck and trailer access and turning on site.
• Implementing risk control measures to address the issue of product sticking in the tipper body, e.g. if the unloading zone isn’t on flat, level ground.
• Ensuring the requirements related to tipper operations on site are communicated to anyone who is accessing the site, e.g. by including information in the site induction.

Working under tippers

Where any work is required to be completed under a raised tipper body, a well-designed prop that can safely withstand the load from a fully loaded tipper will be required to prevent lowering of the tipper body.

Photograph 4 – Example of body prop

The use of a permanently installed prop that is supplied by the tipper manufacturer is the preferred method to isolate the stored energy of the raised tipper body. These props should be designed to be quick to use and not slip out of the way when the load is applied. This is a much better option than trying to use another temporary prop that could bend, break or slip out of the way when the load is suddenly applied.

Photograph 5 - Example of safety sign fitted to tipper

The hydraulic system for hoisting tippers should include safety features to prevent over-pressuring and a means of controlling the rate of descent of a raised tipper body if a hose fails. The location of the system components should minimise the need for any inspection, maintenance or repairs needing to be completed in the area under a raised tipper body, e.g. positioning the control valves on the outside of the chassis rail as shown in photograph 6.

Photograph 6 – example of positioning valve block