In August 2022, a worker’s leg was crushed by a steel sheet weighing approximately four tonnes. Investigations found he was attempting to move the sheet of steel from the back of a flatbed truck with an overhead travelling crane and lifting magnet attachment. For reasons not yet established, the sheet of steel became dislodged from the crane and dropped.
These findings are not yet confirmed, and investigations are continuing into the exact cause.
Overhead travelling cranes (sometimes known as bridge cranes), comprise of a bridge beam mounted to a pair of elevated runway beams or girders. The bridge beam can travel along the overhead runway and is fitted with one or more hoists (lifting component of the crane) that travel along the bridge beam. Bridge cranes can be operated from within a cabin mounted on the crane or remotely from the ground, for example by a hard-wired pendant or radio control.
Bridge cranes are used to handle heavy loads and, as such, create the potential for serious injury or death. Some of the common risks associated with bridge cranes include:
- unsecured and dropped loads (falling objects)
- operators falling while accessing the crane or performing maintenance
- mechanical or structural failure of the crane
- damaged lifting gear
- crane instability from overload.
Figure 1: Bridge crane
Ways to manage health and safety
Taking steps to manage risks is a condition of doing business in Queensland. Effective risk management starts with a commitment to health and safety from those who manage the business. If an incident occurs, you'll need to show the regulator that you’ve used an effective risk management process. This responsibility is covered by your primary duty of care in the Work Health and Safety Act 2011.
Use the hierarchy of controls to help decide how to eliminate and reduce risks in your place of work. The hierarchy of controls ranks types of control methods from the highest level of protection and reliability to the lowest. It’s a step-by-step approach to eliminating or reducing risks. You must work through the hierarchy of controls when managing risks, with the aim of eliminating the hazard, which is the most effective control.
Possible control measures to prevent similar incidents
The Work Health and Safety Act 2011 includes duties for persons conducting a business or undertaking, owners and suppliers of plant.
A bridge crane owner’s responsibilities include, but are not limited to ensuring:
- policies and procedures are developed for the use of the crane
- the crane operator has the knowledge and training required to operate the crane
- if a pendant style remote control is used it is clearly labelled
- there’s a thorough equipment maintenance and inspection program
- equipment is maintained and inspected in accordance with the crane manufacturer’s requirements and other relevant technical standards.
High risk work licensing
A Bridge and Gantry Crane High Risk Work licence is required to operate a bridge or gantry crane that is:
- controlled from a permanent cabin or control station on the crane, or
- remotely controlled with more than three powered operations;
including the application of load estimation and slinging techniques to move a load.
Crane controls should:
- have ‘fail-safe’ control buttons e.g. constant pressure type
- have function buttons appropriately labelled, and
- be fitted with a manually reset emergency stop button.
Modern cabin-controlled bridge and gantry cranes will normally have joysticks to control movement of the crane.
Cabins may be cramped so controls should be protected so the operator getting in and out of the cabin seat will not cause accidental operation. A dead-man’s brake pedal or mechanical protection of the joy stick control levers can prevent this.
Hard-wired pendant controls should:
- be energised by extra-low voltage that is not greater than 50 V AC or 12 V DC, and
- have the support cable and catenary insulated from the crane structure.
Non-positive lifting attachments
A positive lifting device is one where the lifted load cannot inadvertently detach and is typically a lifting hook with a working safety latch.
A non-positive lifting device is a device where the load could inadvertently drop if power to the device is interrupted, or the load is knocked. Non-positive lifting devices include:
- lifting magnets,
- Lifting magnets rely on the power supplied to the magnet, the surface condition of the load and type of steel being lifted.
- vacuum lifters
- Vacuum lifters rely on a constant vacuum being supplied (i.e. by a vacuum pump) and the surface type of the load being lifted.
- plate clamps.
- Plate clamps are often used to lift with a steel plate hanging vertically from the clamp. In this situation the plate clamp relies on the clamping force and friction between the jaws of the plate clamp and the steel plate.
As it is difficult to guarantee that the load cannot inadvertently drop with non-positive lifting devices, workers should never be permitted in an area where they could be struck if the load falls. Exclusion zones to ensure workers cannot be struck by the falling or toppling load need to be implemented.
Isolation and lockouts
To operate bridge and gantry cranes safely there should be an ability to isolate or lock them out, for example to:
- prevent unauthorised use when the crane is not being used
- ensure the safety of maintenance workers or operators when the crane is being worked on
- prevent use when the crane is deemed unfit for use either after an incident, inspection or before commissioning, and
- de-energise the crane when people are working near potential power sources, such as buzz bars and electrical tracks.
Lockable isolation switches
Lockable isolation switches should also be fitted to other plant within the crane’s operating area.
Interlocking devices prevent more than one piece of plant being operated in one area at the same time. For example, to prevent two bridge or gantry cranes colliding where they operate in the same area.
This might occur where the runways are either above or below each other or cross over each other. This could require a bridge or gantry crane to be limited to a set area or parked while the other one is working in a designated area.
There are a number of safety devices that can be fitted to bridge and gantry cranes including:
- Anti-collision devices to prevent:
- a bridge or gantry crane colliding with the end of the runway, and
- two or more bridge or gantry cranes that operate on the same runway from colliding with each other.
- Deceleration devices to slow the bridge or gantry crane down—regardless of what control is being pressed when a travelling crane is approaching the end of the runway—to prevent end stop collision or over run e.g. limit switches and two-stage decelerators.
- Load-limiting and movement controlling devices to assess the load and prevent lifting should the rating capacity of the crane be exceeded.
- Upper and lower limit devices to prevent the hoist from winding the hook into the hoist drum or winding the hoist rope off the hoist drum.
- Anti-fall devices to prevent falls of plant in the event of travel-wheel failure e.g. anti-drop plates.
The crane classification and working load limit of the crane must be displayed on bridge and gantry cranes.
Planning and coordinating overhead travelling crane operations
Planning for overhead travelling crane operations should start as early as possible. This involves:
- consultation with people engaged such as the crane hirer, crane supplier, engineer and crane operator
- implementing effective exclusion zones around the overhead travelling crane and adjoining areas to prevent people from entering the area (the size of the exclusion zone should be based on a written risk assessment).
Inspecting and maintenance
Routine inspection and maintenance should be carried out in accordance with the manufacturer’s instructions. Bridge and gantry crane inspection and testing must include:
- a major inspection
- regular inspection and testing required for the crane, and
- inspection and testing for plant item re-registration.
Inspections should include:
- all functions and their controls for speed, smoothness of operation and limits of motion
- all emergency and safety switches and interlocks, including limiting and indicating devices
- lubrication of all moving parts
- visual inspection and measurements as necessary
- signage, including warning signs and control markings
- additional items nominated in the manufacturer’s instructions
- ensuring lifting hooks have operable safety latches.
All replacement parts should be identical or equivalent to the original parts or components. A lifting equipment register, containing inspection dates for all lifting equipment should be kept at the workplace.
A written report should be supplied upon completion of the inspection.
Bridge and gantry crane operators must have a comprehensive knowledge of the operating capabilities of the crane and be competent to carry out the lifting operation. It is a must for crane operators to:
- know the particular model of crane to be operated, its characteristics, functions and limitations
- know the information in the crane’s operating manual
- ensure loads are evenly balanced and well secured
- hold the appropriate high risk work licence (if required) for the type of crane being operated, and completed refresher training as required
- know proper inspection and maintenance procedures to be followed in accordance with the guidelines of the manufacturer and owner
- complete a pre-operational visual inspection and functional test before the commencement of each work shift, including inspecting and testing the following:
- all relevant items indicated in the operations manual
- operating and emergency controls
- visual inspection of the structure.
You must minimise any remaining risk with suitable personal protective equipment. For example: hard hats, protective footwear, eye protection, safety vest.
The control measures put in place should be reviewed regularly to make sure they work as planned.
- How to manage work health and safety risks code of practice 2021 (PDF, 0.65 MB)
- Guidance - Cranes
- Alert: Plate clamps and dropping loads (22 May 2014)
- AS 2759: Steel wire rope – Use application and maintenance
- Bridge and gantry crane - Information sheet | Safe Work Australia
Support for people affected by a serious workplace incident
For advice and support: