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Steel erection
Crane lifted workboxes
Types of workboxes
There are two types of workboxes.
One type are boxes used for lifting and hoisting materials such as:
- tools
- bolts
- steel fixings
- materials designed to AS4991-2004.
The other type of workbox are known as “man boxes". These are designed to AS1418.17 and are used for lifting and hoisting personnel. AS2550.1 should be referred to for safe use.
Crane lifted workbox cage
Types of crane lifted workboxes and goods cages known as manboxes.
Emergency rescue box
Use of workboxes
Crane lifted workboxes are used for:
- very high work, or
- isolated parts of a project where it may be difficult or impractical to provide scaffold or elevated working platform (EWP).
The workbox must be stamped or be provided with a stamped metal data-plate. This must be securely and permanently attached to it in a prominent position. This data-plate should provide the following information in kilograms:
- maximum hoisted load
- Working Load Limit (WLL)
- tare mass
- minimum allowable (rated) crane capacity
- identification reference.
The information must also be marked on the workbox permanently and legibly. The letters and numerals should be no less than 25 mm high and in a colour contrasting with the background.
Examples of workboxes.
Safety factors
Follow these rules to stay safe when operating in workboxes:
Workbox requirements
The workbox must be painted in high visibility colours.
The lifting slings must be permanently attached to its lifting lugs with moused shackles or similar.
An access door, if fitted, must only open inwards and must be able to be securely shut.
Certification
At least one person in the workbox must hold a dogging or rigging High Risk Working Licence (HRWL) to direct the crane operator from the workbox.
Crane requirements
Any crane used to lift people in a workbox must be:
- fitted with a safety hook
- equipped with controls that return to neutral and stop the crane when released
- equipped with power lowering
- equipped with a lockout control to prevent freefall
- fitted with an up-limit switch on the hoist motion
- fitted with a down-limit switch where the workbox is to be lowered below the crane's supporting surface.
Where a mobile crane is used, it must not travel while anyone is in the workbox.
Intended use
Only use the workbox for lifting persons and their equipment. Structural members must be independently lifted into position.
Crane operator
The crane operator must remain at the controls throughout the operation. All crane movements must be carried out under power. When the workbox is at the maximum intended radius, the crane's Working Load Limit (WLL) must be at least twice the total load of the workbox, or 1.5t, whichever is greater.
Communication
There must be an effective way for the dogman or rigger in the workbox and the crane operator to communicate with each other.
Safety harnesses
Every person in the workbox must wear a safety harness. This must be is attached to a purpose-designed anchorage within the workbox.
Carrying flammable liquids
Where it is necessary to carry oxyacetylene cylinders or any flammable liquids, these should be:
- in the minimum necessary quantities
- correctly secured
Make sure a suitable fire extinguisher is carried.
Climbing in and out of workboxes
Climbing in and out of workboxes at heights can be a dangerous practice. But where there is no alternative the workbox must be securely attached to the structure before anyone enters or exits.
Safety nets
Industrial safety nets are suitable for some types of structures, such as bridges and very high portal frames. They can provide fall protection while allowing the steel erectors freedom of movement on the structural framework.
Number of people
The number of people supported in the workbox must not be more than the number specified on the side of the box.