A lorry crane pulls up on a service road in Jurong at half past eight. The outriggers come down, the boom comes up, and a pallet of steel sections is waiting on the kerb. The operator knows the crane, knows the load, and has done this hundreds of times. The question that decides whether the next twenty minutes go well is whether he checked the chart for this position, on this ground, at this radius.

Load charts get treated as paperwork. They are closer to a set of conditions, and the number printed against any given radius is only true if every one of those conditions is being met on the day.

A load chart is a grid, not a headline figure

A lorry crane does not have one lifting capacity. It has a grid of them, and each figure corresponds to a specific combination of boom length, working radius and outrigger configuration. Move any one of those and you are reading a different cell.

The Workplace Safety and Health Council's guidelines on the safe use of lorry cranes put the check before the work begins, advising that an operator should refer to the manufacturer's load chart and to the Ministry of Manpower's Certificate of Test and Thorough Visual Examination of Lifting Equipment before the start of any operation. Two documents, both before the first lift.

The Code of Practice on Safe Lifting Operations in the Workplaces treats the chart as equipment rather than reference material. It requires that load capacity charts are displayed in the operator cabin, and it states plainly that a crane operator must have the ability to read and understand the load capacity chart. Being able to find the chart and being able to use it are assessed as different things, and correctly so.

Radius is the number that moves everything else

Working radius is the horizontal distance from the crane's centre of rotation to the centre of the load, and it is the variable that changes capacity fastest. The Code of Practice states that lifting capacity depends on the load radius of the crane boom, and puts the relationship in one line: the closer the load is to the body of the crane, the higher the safe working load (SWL) of the equipment.

That relationship catches people out because radius changes during a lift without anyone deciding to change it. A load slewed out to reach past an obstruction, a pick-up point that turned out to be a metre further than estimated, or a boom extended to clear a fence all push the radius out, and the capacity available falls as they do. Our lorry crane course spends real time on this, because reading a chart in a classroom and estimating radius accurately on a live job are separate skills.

What the chart assumes about your set-up

Every figure on a load chart carries assumptions. When those assumptions do not hold on site, the figure does not hold either.

• The crane is level, on ground capable of taking the imposed loads
• The outriggers are deployed as the chart's configuration specifies
• The boom length and any extension match the column being read
• The radius is measured to the centre of the load, not the boom tip
• Rigging weight, lifting gear and any spreader are counted as part of the load

Outriggers, ground and the rated capacity limiter

Outriggers do more than steady the vehicle. They set the footprint the whole capacity calculation depends on, and the guidance is direct: when required, it is the duty of the crane operator to ensure any outrigger is fully extended and properly secured, with exceptions considered for lorry cranes fitted with a stability control system.

What sits beneath them decides whether that footprint means anything. The guidance asks for a pre-operational assessment of ground conditions to confirm the ground can take the forces imposed, and for stabiliser pads that spread those forces. Soft verges, backfilled trenches, covered drains and fresh reinstatement all look level and behave very differently under load. Understanding how ground conditions affect crane setup is part of reading the chart honestly, because a figure calculated for firm level ground means nothing on soft fill.

Modern lorry cranes help here. The stability control system includes a rated capacity limiter, which monitors the position of the stabilisers and limits lifting capacity according to how far they are deployed. That is a genuine safeguard and a poor substitute for planning, since a limiter stops an overload developing but tells you nothing about the pick you should have planned differently.

Where operators most often read it wrong

The commonest error is estimating radius by eye and estimating it short. A metre of optimism at the point of pick-up can move a lift from comfortably inside the chart to outside it, and the error always runs in the same direction.

The second is forgetting what hangs below the hook. Chains, slings, shackles, a spreader beam and a lifting frame all consume capacity before the load itself is counted, and on shorter lifts that gear can be a meaningful proportion of the figure. The chart gives capacity at the hook, and everything between the hook and the load comes out of it first.

Certification for lorry crane operators is its own track

Here is a distinction that surprises people. Lorry crane operators are not registered crane operators in the sense MOM uses the term. MOM's crane operator registration covers mobile cranes, explicitly excluding lorry loaders, and tower cranes.

Lorry crane operators sit under a separate training requirement. MOM's circular on the subject set out that operators must be certified under the Lorry Crane Operator Course, with a competency test route available to operators holding substantial experience. The Workplace Safety and Health Council's lorry crane guidelines also recommend periodic medical examinations for these operators.

The practical reading is that a lorry crane being smaller and vehicle-mounted does not make it a lesser piece of lifting equipment. It is set up quickly, often at the kerbside, frequently near traffic and public areas, and the consequences of getting a lift wrong are the same as they are anywhere else. MOM's national workplace safety and health statistics for 2025 recorded nine dangerous occurrences involving cranes, alongside one crane-related fatality, so the numbers are small and the outcomes severe.

Building the check into the routine

The chart check works best as a fixed sequence, done the same way every time so nothing gets skipped when the job is running late.

1. Confirm the ground and set the outriggers to the configuration you intend to read

2. Establish the actual working radius to the centre of the load, measured and not estimated

3. Read the chart cell for that radius and boom length, and note the capacity

4. Add rigging and gear weight to the load, then compare against that capacity with margin to spare

Conclusion

Lifting goes wrong in small increments. A radius a metre longer than assumed, an outrigger short of full extension because a kerb was in the way, a spreader beam nobody added to the total. Each looks minor on its own, and the chart is the one thing on site that tells you what the combination of them adds up to before the load leaves the ground.

Operators who read charts confidently make better decisions and slow a job down far less often than those who guess. If you want that confidence across your crew, our instructors bring years of site experience into the classroom and onto the practical yard. Have a look at the schedule and book a place with us when it suits your operations.

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