Crane Mats: The Complete Guide

A crane mat spreads a crane's outrigger load across a wide enough area of ground to keep bearing pressure within safe limits. The right size is determined by ground bearing capacity, actual load, and mat stiffness, not by guesswork.

ALIMATS® aluminium mats cover a plan area range of 1.34m2 to 8.07m2, reach a safe working load of up to 80 tonnes, and weigh just 13kg to 48kg per module for manual handling. Every SWL figure is independently verified with a Fellow of the Institution of Structural Engineers, and bending tests show aluminium deflecting in single-digit millimetres where a comparable UHMW-PE plastic mat deflected over 100mm under the same load, because stiffness, not just compressive strength, is what actually spreads load to the ground.

The same logic applies to tracked plant and powered access equipment, not just mobile cranes on outriggers. Anything that concentrates significant weight through a small contact patch with the ground, whether a crawler track, a MEWP wheel, or a spider crane foot, creates the same bearing pressure problem at a different scale, which is why the load-spreading principle extends into the powered access applications covered later in this guide.

Crane mats sit at the centre of this calculation on projects where the ground cannot be guaranteed, which in practice is most sites. Brilliant Ideas Ltd's ALIMATS system has been specified on projects including HS2, Hinkley Point C, Heathrow Airport, Gatwick Airport, Google's King's Cross headquarters, Euston Station, London Bridge, Manchester's Co-op Live Arena, Grangemouth Refinery, and major Scottish wind farm developments, alongside a residential build featured on a well-known national homebuilding television series.

Specifying a pad where the outrigger load actually needs a mat leaves the ground under-protected regardless of how good the pad material is, because no single small unit can spread a large load across the plan area it genuinely needs. Specifying a mat where a pad would do is not unsafe, but it is an unnecessary cost and handling exercise.

Separately from pad versus mat, there's a practical divide between handleable and non-handleable mat systems. ALIMATS aluminium modules range from 13kg to 48kg depending on size, light enough for two people to lift and interlock by hand without a forklift, telehandler, or spare crane standing by. Heavier timber and steel mat systems typically cannot be moved this way, meaning every repositioning on site needs mechanical handling.

That programme impact compounds over a job with multiple lifts or multiple crane positions. A non-handleable mat system that needs a telehandler or second crane on standby every time it moves adds a dependency to the programme that a handleable system simply does not have.

This is precisely the weakness of plastic mats. UHMW-PE and HDPE have workable compressive strength on paper, but their modulus of elasticity is low, meaning the mat flexes and load triangulates down through the flex point toward the ground beneath, rather than spreading evenly across the mat's full footprint. A design guide referenced across the industry, Construction Ground Condition for Plant (October 2014), draws out exactly this distinction between strength and stiffness, and flags a specific testing risk: a rigid test rig set up on a compressible base material, such as Ethafoam, can produce a safe working load claim that looks reassuring on a datasheet but does not reflect how the mat behaves on real, variable ground.

Ranked by compressive strength alone, from highest to lowest, the order is steel, aluminium, nylon, polyethylene, then timber. Ranked by stiffness, which matters more for load spread, the order changes: steel, aluminium, timber, nylon, then polyethylene. Aluminium sits second in both rankings, and unlike steel its low density keeps modules light enough to handle manually, which is why ALIMATS is built from alloy 6005A rather than steel or plastic.

Nylanite and timber both still have a place in a load-spreading system, just not the same place as a full crane mat. Nylanite's figures make it a sound choice for the smaller, single-unit crane pads under lighter outrigger loads. Timber's figures also vary sharply by species: Ekki/Azobe hardwood (D70 grade) outperforms Oak (D40 grade) on every measure in the table.

Material density is the other half of the comparison, because it decides whether a mat stays handleable once it is sized to spread a real crane load. Aluminium's density of around 2700 kg/m3 sits above the plastics and most timbers in the published figures, but its much higher stiffness and strength mean a thinner, smaller section achieves the same job, which is how a 38kg ALIMATS Standard module ends up lighter to lift than the comparable footprint in a lower-performing material would be.

Choosing a crane mat configuration starts with the ground, not the mat. A temporary works engineer needs the ground's bearing capacity from site investigation data, the crane's actual outrigger load for the lift being planned, and the resulting bearing pressure once that load is spread across a candidate mat's plan area.

The arithmetic is straightforward even if the inputs take real engineering judgement to establish: bearing pressure is the outrigger load divided by the plan area the load is spread across, and that pressure has to sit safely below the ground's allowable bearing capacity. Increase the plan area and the pressure falls, which is why the ALIMATS configuration range runs from 1.346m2 up to 8.073m2, giving an engineer enough steps to bring pressure within limits without over-specifying the mat.

This is also where stiffness earns its place back into the conversation, alongside plan area. Two mats with identical footprints do not necessarily spread load the same way if one flexes more than the other, because a flexing mat can let load concentrate toward the centre of the footprint rather than spreading evenly to the edges.

These five module sizes interlock into a core configuration range running from 1.346 square metres up to 8.073 square metres of plan area, built up in steps: 1.346m2, 2.018m2, 3.028m2, 4.037m2, 5.046m2, 6.055m2, 7.064m2, and 8.073m2.

Safe working load scales with configuration, reaching up to 80 tonnes across the core range, and ALIMATS configurations sit comfortably under cranes up to 150 tonnes. The Ainscough example referenced earlier used a 7.06m2 configuration for a Grangemouth job: a smaller Mini or Short footprint might be entirely adequate for a lighter static lift on reasonable ground, while a large infrastructure job on soft or made ground can call for the full 8.073m2 configuration, or the Half Loader module, to bring bearing pressure down to a safe figure.

Every SWL figure ALIMATS publishes is independently verified with a Fellow of the Institution of Structural Engineers, so the numbers a temporary works engineer designs against have been checked outside the business that manufactures the mat. In practice, configuration selection is a combination exercise: the five module sizes assemble to the plan area and orientation a specific lift needs, then the resulting bearing pressure is checked against the ground data for that exact spot on site.

Northern Ireland and Republic of Ireland postcodes are currently blocked on the public self-serve configurator and load calculator, so those enquiries need to go through the enquiries team directly rather than the online tools.

Which arrangement makes sense usually comes down to how often the mats are needed rather than any hard rule, but the same manufacturing standard, module range, and IStructE-verified SWL figures apply whichever way a job is commercially arranged.

Manufacturing from certified recycled extruded aluminium also means the environmental case and the engineering case point the same way. Aluminium is a genuinely recyclable structural material at end of life, so specifying it does not trade performance for sustainability, or the other way round.

Both developments follow the same underlying logic as the core mat range: keep the individual unit light enough to handle by hand, and let the interlocking geometry do the work of building up whatever plan area, load path, or tracking surface the specific piece of plant needs. Neither requires a different manufacturing process or aluminium specification from the standard ALIMATS modules.

Brilliant Ideas states that ALIMATS is trusted by more than 80 percent of the UK's top twenty Tier 1 contractors, and the named customer list runs well beyond the two testimonials quoted in this guide, including ABA, Ainscough, Atherstone, Bennett, Berry, Birmingham, Bob Francis, Bronzeshield, Cork, Davies, Dewsbury and Proud, DM, Emerson, Gerrard, King Lifting, Kranserv, Mac Salvors, Marsden, Marsh Plant, Radius Group, Raymond, Sangwin, Sparrow, and Steve Foster.

On the ground, that trust shows up as repeat use rather than one-off trials. Portakabin uses ALIMATS on nine out of ten jobs, and Ainscough Crane Hire has used the same handleability and turnaround speed to meet tight deadlines, including the 18-hour Grangemouth delivery referenced earlier in this guide.

Demand is not limited to the UK. Enquiries have come from Brazil, Angola, Australia, Qatar, Egypt, Argentina, the United Arab Emirates, Japan, Germany, France, Spain, and Belgium, and the most recent international shipments went to a global offshore oil and gas services company in Qatar and an integrated logistics company serving renewables and oil and gas in Angola. ALIMATS is already deployed across Australia and the Middle East in general commercial terms, alongside the UK infrastructure projects named earlier in this guide.

The through-line across every project on that list, from a nine-out-of-ten repeat customer like Portakabin to a national infrastructure programme like HS2, is the same one this guide opened with: the mat has to spread the load correctly, and the temporary works engineer has to be able to trust the numbers behind it.