Mobile Crane Types, Uses and Singapore Lifting Rules

A mobile crane is a crane mounted on a truck, crawler or wheeled carrier that can travel to where it is needed and set up for a lift in hours rather than weeks. On building projects it erects steelwork, places precast units, lifts plant onto roofs and assembles the tower cranes that do the rest of the work. Its flexibility is its strength, and its dependence on ground conditions and correct set-up is its main risk.

This guide explains how a mobile crane works, the main types, where they are used on a building project and the lifting framework that applies in Singapore, including the lifting plan, the lifting supervisor and the requirements for crane operators, riggers and signalmen.

What counts as a mobile crane

The Workplace Safety and Health (Operation of Cranes) Regulations 2011 define a mobile crane as a crane mounted on a truck, crawler or on wheels, including the types listed in the regulations’ First Schedule. The regulations apply to any workplace in which a crane is in use. In everyday site language, mobile cranes include:

Truck-mounted cranes: a telescopic or lattice crane mounted on a road-going truck chassis, covered in more detail in our sibling guide to the truck mounted crane.
All-terrain cranes: multi-axle carriers with all-wheel drive and steering, combining road speed with some off-road ability.
Rough-terrain cranes: two-axle machines with large tyres for unpaved sites, driven from the crane cab.
Crawler cranes: cranes on tracks, often with lattice booms, for heavy lifts and long-duration work, covered in our guide to the crawler crane.
Mini and spider cranes: compact cranes for confined spaces, described in our guide to the spider crane.

Lorry loaders, the articulated arm cranes fitted behind the cab of a lorry, are treated separately in the regulations.

How a mobile crane works

Most truck-mounted and all-terrain cranes use a telescopic boom: a series of steel sections that extend hydraulically. The boom is raised and lowered (luffed) by hydraulic cylinders, the superstructure slews on a slewing ring, and a wire rope hoist raises and lowers the hook. Counterweights on the superstructure balance the load.

Before lifting, the crane extends its outriggers and raises its wheels off the ground, so the crane stands on four pads. Outrigger loads can be very large and concentrated, which is why ground conditions dominate mobile crane planning.

The load chart

A crane’s capacity is not a single number. It depends on the boom length, the radius from the slewing centre to the load, the outrigger extension, the counterweight fitted and the direction of the lift. The load chart sets out the safe working load for each configuration. Capacity falls rapidly as radius increases, which is why a crane that can lift a heavy load close in may only lift a fraction of it at the far edge of a site. Modern cranes have a rated capacity indicator that compares the actual load with the chart and cuts out hazardous motions when the limit is approached.

Where the mobile crane is used on a building project

Erecting and dismantling tower cranes.
Steel erection, particularly on low-rise and wide-span buildings.
Placing precast elements, bathroom pods and prefabricated modules.
Lifting plant such as chillers and generators onto roofs.
Short-duration lifts where a tower crane is not justified, or out of reach of one.

Ground conditions and outriggers

Many mobile crane overturning incidents trace back to ground failure under an outrigger. The WSH Council’s Code of Practice on Safe Lifting Operations in the Workplaces stresses that the ground must be level with sufficient bearing capacity, that outriggers be evenly and fully extended where required by the configuration, and recommends steel plates or mats of adequate strength and size under the outrigger pads. Hidden voids, recent backfill over trenches, basement walls, drains and the edges of excavations are all common hazards.

Where a crane stands on a slab, a basement roof, a podium or near a retaining wall, the outrigger loads should be checked by a qualified engineer against the structure or the temporary works design. Our guide to temporary works design explains how crane platforms and outrigger loads are assessed.

Singapore lifting requirements

Lifting plan

Under the Operation of Cranes Regulations, the responsible person, meaning the crane operator’s employer or the principal under whose direction the crane is operated, must establish and implement a lifting plan. The WSH Council’s code describes the lifting plan’s contents, including the load’s weight and dimensions, rigging points, crane and gear selection, positions before and after the lift, ground and environmental factors, communication, and whether to cordon off the area. Routine lifts may need a basic lifting plan; complex or high-risk lifts need additional engineering input.

Lifting supervisor

The responsible person must appoint a lifting supervisor before any lifting operation involving a crane. The supervisor must have completed a training course acceptable to the Commissioner and have at least one year of relevant lifting experience. Their duties include co-ordinating lifting activities, supervising mobile and tower crane lifts in accordance with the lifting plan, ensuring that only registered crane operators and appointed riggers and signalmen take part, ensuring that ground conditions are safe for mobile crane lifts, briefing the team on the plan, and acting on any unsafe condition reported to them.

Appointed person

The Singapore Standard code of practice for the safe use of mobile cranes, SS 536, calls for an appointed person with overall control of the crane operations, appointed in writing. In practice, this is the competent person who plans the lift and prepares the lifting plan for complex operations, and the WSH Council’s code recognises this role within the lifting team for more complex lifts.

Operators, riggers and signalmen

Mobile cranes with a safe working load exceeding 5 tonnes must be operated by a registered crane operator. Since 1 January 2016, operators of mini cranes, mobile cranes not exceeding 5 tonnes, may instead hold a certificate from a training course for mini cranes acceptable to the Commissioner. Riggers and signalmen must be appointed by the responsible person and trained for the role.

Examination and maintenance

Mobile cranes are lifting machines that must be registered with MOM and tested and examined by an Authorised Examiner, an MOM-approved Professional Engineer. Under MOM’s revised requirements effective 12 September 2025, mobile cranes are examined every 12 months, or every 6 months if used to lift personnel. Only approved crane contractors may install, repair, alter or dismantle mobile cranes.

Frequently asked questions

What is a mobile crane?

It is a crane mounted on a truck, crawler or wheeled carrier that can travel between sites and set up quickly, including truck-mounted, all-terrain, rough-terrain, crawler and mini cranes.

Why do mobile cranes overturn?

Most overturning incidents involve ground failure under an outrigger, lifting beyond the load chart at the actual radius, or incorrect set-up, which is why ground checks, outrigger mats and rated capacity indicators are essential.

Who needs to operate a mobile crane in Singapore?

Mobile cranes with a safe working load exceeding 5 tonnes must be operated by a registered crane operator, while mini cranes not exceeding 5 tonnes may be operated by someone who has completed a training course acceptable to the Commissioner.

What does a lifting supervisor do?

The lifting supervisor co-ordinates and supervises the lift according to the lifting plan, briefs the team, ensures only registered operators and appointed riggers and signalmen participate, checks ground conditions for mobile cranes and acts on unsafe conditions.

Can a mobile crane stand on a basement roof or slab?

Only after the outrigger loads have been checked by a qualified engineer against the slab or structure, since concentrated outrigger reactions can exceed what the structure was designed to carry.

Need outrigger loads or a crane platform checked? Talk to our consultancy or get in touch.