CRANE MATS Ӏ SECTOR SPOTLIGHT


nature, perhaps over millions of


years. Without dedicated analysis you cannot see through it to whatever might, or might not, be underneath. The ground below may contain


voids, variations in consistency, or even infrastructure or pipelines that need to be protected. And even if you know the type of soil, and so theoretically its strength, that strength may not be constant, depending on the weather. Three days of rain can convert a good weight-bearing matrix to a next-to-liquid slurry whose state may only become apparent when you put your crane outriggers on it and find that it collapses at the first light load. There have been plenty of crane accidents from that cause. To establish the ground conditions, therefore, a ground survey is needed. Specialist companies can provide this service. On large sites, high-rises for example, this may have been performed already by the architects and design teams to ensure that the building itself can be supported long-term, but their figures may apply only to the immediate footprint of the building, so may not be valid for lifting operations some metres from the foundations.


GROUND COLLAPSE Soil does not settle evenly or sink steadily. Typically when a load – a vehicle, a crane, a building – is


Timber pads


from Mat and Timber Services


placed on it an immediate rapid linear sinking takes place; then, over time, a slower but longer- lasting period settlement follows. One method that specialist


companies use is to simply to drive a vehicle, or place a weight, on the ground and measure (over hours or possibly days) how fast it sinks. Tadano is working on a system


where the crane itself forms the test weight. Called Ground Collapse Prevention it was unveiled at the CES 2025 exhibition which took place in Las Vegas in January. The CES (Consumer Electronics Show) is one of the biggest and most influential tech trade shows in the world. The system evaluates ground


stability for each worksite before crane operations begin. It combines ground property measurements, load analysis, and overturning prevention controls and therefore helps ensure the stability of the crane. Using the crane’s own weight


spot-by-spot ground stability is measured, under each outrigger, during the setup phase. On-board sensors measure the settlement at each outrigger over time. This establishes the ground property data – the relationship between pressure and ground movement. That relationship between load and settlement is analysed for each worksite.


During operation, the downward


pressure exerted by each outrigger can be calculated. The system works out the crane’s overturning moment for all postures and load weight patterns, and hence the limits of safety on that particular soil. By combining multiple data points, the crane can stop operations before ground collapse occurs. This approach, says Tadano,


is most effective on soft ground surfaces. It is not applicable for paved roads or areas with underground cavities or buried


18 CRANES TODAY


pipes since the ground behaviour of such sites is much less predictable: voids can lead to sudden collapse with little or no prior warning. To enhance this technology Tadano is seeking partners specialising in crane-mountable ground- penetrating detectors.


KNOCK ON WOOD Once ground conditions, and lifting details, have been assessed crane users should have an idea of how much ground support they need under their crane’s outriggers; in other words, how large the outrigger pads used should be. A simple division sum tells the size of pad required. After that the key decision is what material the should outrigger pad be made of: wood, steel, or synthetic? Colin Ryder is operations manager of Stockport, UK- based Timbermat. The company supplies timber mats for all kinds of applications, crane mats and outrigger pads amongst them. “70 mm is the usual thickness,” he says. “We use Ekki, which is a tropical hardwood, and oak or beech sourced from Europe. “All our supplies are FSI


certified. They weigh from 370kg up to about 1.2 tonnes; we hire them or sell them – both methods are used by crane companies.” Wood has been used as ground


support for 5000 years or more and remains in high demand. Mat and Timber Services, a UK- based division of timber structure specialist Sarum Hardwood Structures, (itself a subsidiary of Dutch company Groot Lemmer), also supplies hardwood mats. Simon Lumley, operations manager there, confirms this. “Demand for wood has not declined,” he says. “Steel is an alternative but it is more expensive and heavier.” Steel does have its fans; the


third option, however, is to use synthetic pads.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55