When a crane set-up needs engineering

Outrigger loads from a mobile crane at full reach can be very large, and they're concentrated on a small area. The risk rises with soft ground, recently backfilled trenches, nearby excavations and retaining walls, and set-ups on suspended slabs or structures. Engineering the set-up in advance avoids surprises on lift day.

What we assess

Outrigger loads for the governing lift configuration, from the crane supplier's data or lift plan.
Ground bearing capacity, using available geotechnical information or conservative assumptions, with a recommendation for testing where the ground is uncertain.
Nearby hazards: excavations, trenches, underground services, retaining walls and basement walls within the zone of influence.
Supporting structures: a structural check where a crane sets up on a slab or other structure.
Pad options: crane mats, timber, steel or a concrete pad, chosen to suit the loads and the ground.

What's included

Outrigger load review for the lift configuration
Ground bearing assessment
Outrigger pad or mat sizing
Temporary concrete footing design where required
Checks of nearby structures and excavations
An engineering letter for the specific set-up

What you receive

Pad sizing calculationsFor each outrigger, for the governing configuration.
Set-up requirementsGround preparation, pad type and size, and exclusion zones for excavations.
Engineering letterConfirming the set-up within the stated scope and assumptions.
Temporary footing designWhere engaged, drawings and calculations for a concrete pad.

Scope, fee and programme are confirmed in a written proposal for your project before any engineering starts.

What we need from you

Crane make and model, and the lift configuration
Outrigger loads, or the lift plan
The set-up location on a site plan
Ground information: geotechnical report, test pits or known fill
Nearby excavations, services, retaining walls or structures

Don't have everything yet? Send what you have. We'll tell you what's missing and whether it affects the proposal.

How it works

Lift detailsSend the crane, configuration, loads and location.
ProposalWe confirm the scope and programme to suit your lift date.
AssessmentWe assess the ground and size the pads.
Letter and site notesYou receive the calculations and set-up requirements for the lift team.

Who does what

MEG provides

Pad sizing and ground bearing assessment
Temporary footing design
Engineering sign-off for the specific set-up assessed

Not included, or by others

Lift planning, crane selection or rigging design
Ground testing (arranged with a testing provider)
Supervision of the lift

Where a project needs another specialist, we can recommend one and coordinate with them. We make it clear who is responsible for each part.

Relevant experience

MEG's work includes outrigger pad and footing design for crane mobilisation on the Eastern Gas Pipeline reversal project at Longford, VIC. See project experience.

Questions

What do you need from the crane company?

The crane model, the lift configuration and the maximum outrigger loads, usually from the supplier's outrigger load calculator or the lift plan.

What if we don't have geotechnical information?

We can use conservative assumptions, which may lead to larger pads. On uncertain ground, a simple test, such as a plate load test by a testing provider, can justify a more efficient set-up.

Can a crane set up on a suspended slab?

Sometimes, but it needs a structural check of the slab and its supports, and often temporary propping. Tell us early.

Crane outrigger pads and heavy-lift footings