How to Plan a Safe and Efficient Crane Lift
Whether you’re managing a small building site or a large-scale industrial project, careful planning is essential to ensure every crane lift is completed safely and efficiently. Poor preparation can lead to costly delays, damaged equipment, or even serious accidents.
At Bryn Thomas Cranes, safety lies at the heart of everything we do. In this guide, we’ll walk you through how to plan a crane lift correctly – from creating a detailed lift plan to understanding essential lifting calculations.
Why Lift Planning Matters
Every lifting operation carries some degree of risk. A well-prepared lift plan helps identify these risks in advance, ensuring that all personnel, equipment, and processes are ready for a smooth and safe operation.
Effective planning also helps you:
- Choose the right crane for the job
- Ensure the ground and environment are suitable for lifting
- Prevent overloading or instability
- Keep people, property, and infrastructure safe
What Should a Lift Plan Include?
A lift plan is the foundation of any safe crane operation. According to BS 7121 (the British Standard for safe use of cranes), every lifting activity must be properly planned, supervised, and carried out by competent personnel.
A thorough lift plan should include:
- Details of the lift – including the load type, weight, dimensions, and lifting points.
- Site assessment – information about ground conditions, overhead obstructions, and weather considerations.
- Crane selection – the type, capacity, and configuration of the crane, along with any required lifting accessories, such as slings or spreader beams.
- Personnel roles – identification of the appointed person, crane operator, lift supervisor, and slinger/signaller.
- Method statement – outlining the step-by-step process for the lift.
- Risk assessment – identifying potential hazards and the control measures in place to eliminate or reduce them.
- Communication plan – detailing how the team will communicate during the lift.
- Emergency procedures – in case of equipment failure or unexpected conditions.
If you choose contract lift hire with Bryn Thomas Cranes, our experts handle all of this on your behalf – ensuring the plan meets all safety standards and legal requirements.
How to Calculate Safety Factor for Crane Lifting
The safety factor ensures that lifting equipment is not loaded to its absolute limit. It provides a margin of safety to account for dynamic forces, minor miscalculations, and potential wear.
In the UK, the safety factor for lifting equipment typically ranges between 4:1 and 7:1, depending on the component and its application.
For example:
- Wire ropes and slings: usually have a safety factor of 5:1 or 6:1.
- Lifting hooks: commonly rated with a 4:1 safety factor.
- Shackles and lifting accessories: often have a 6:1 safety factor.
This means if a sling is rated with a 6:1 safety factor and is designed to safely lift 1 tonne, it has actually been tested to withstand 6 tonnes before failure.
Always refer to the manufacturer’s data and never exceed the Safe Working Load (SWL) of any equipment.
What is the Formula for a Crane Lift?
Before any lift, it’s vital to understand how to calculate the load weight and lifting radius, as these directly impact the crane’s capacity.
The basic formula used to determine lifting requirements is:
Load Moment = Load Weight × Radius
The radius is the horizontal distance between the centre of the crane’s rotation and the centre of the load.
For example:
If you are lifting a 5-tonne load at a 10-metre radius, the load moment is 50 tonne-metres.
The crane must have a rated capacity greater than this at that specific radius. Crane load charts are essential for determining whether the crane can safely handle the lift at a given radius and height.
What is the 3-3-3 Rule for Lifting?
Some sites use a practical on-site procedure called the 3-3-3 method to help confirm a load is secure before committing to a full lift. It’s a simple, safety-first routine that should be used in addition to (not instead of) a full lift plan and BS 7121/HSE requirements. The steps are:
- Lift 0.3 metres (30 cm) – only raise the load a short distance off the ground so you can check it under controlled conditions.
- Hold for 3 seconds – pause with the load at 0.3 m for roughly three seconds to check for any slipping, shifting, or unexpected movement (and to let any slack in slings settle).
- Keep 3 metres clear – ensure personnel and other site traffic remain at least three metres away from the suspended load while this check is carried out, so that anyone is out of harm’s way should the load fail.
Used correctly, the 3-3-3 method gives the team a quick, repeatable way to verify slings, attachments, and rigging before completing the full lift – reducing the risk of dropped loads or uncontrolled movement. Always record the check in the lift brief, and never bypass formal risk assessments, rated equipment checks, or the appointed person’s instructions.
The Role of the Appointed Person
Every lift must be supervised by a competent appointed person, as required by BS 7121. This individual is responsible for planning, supervising, and ensuring the lift is executed safely.
At Bryn Thomas Cranes, our appointed persons are fully trained and experienced in risk assessment, load calculation, and safe lifting practices. When you hire one of our cranes as part of a contract lift, this responsibility lies entirely with us – giving you peace of mind that your project is in expert hands.
Plan Your Next Lift with Bryn Thomas Cranes
From risk assessments and lift planning to crane selection and execution, Bryn Thomas Cranes delivers a complete service for safe and efficient lifting across the UK.
Whether you need a simple mobile crane for a short-term lift or a full contract lift solution for a complex project, our team is here to help.
Call us today on 01352 733 984 or email info@brynthomascranes.com
