An enormous number of variables and risks affect heavy lifting and the transporting of oversize / overweight loads.
The laws of physics rank right at the top.
Regardless of what lift handling or transport equipment is used, every load handling activity generates reaction forces that end up being imposed on the ground.
Unless the ground can support those loads, bad things will most certainly happen.
This is not a surprise to anyone in our industry.
Although the industry has long known the vital importance of ground stability and load stabilization, neither has received the attention it merits.
Until recently, the only real available guidance on the subject came from three books: Lawrence and Jay Shapiro’s “Cranes and Derricks,” Keith Anderson’s “Rigging Engineering Basics,” and Dave Duerr’s “Mobile Crane Support Handbook”.
Dave has devoted a lifetime to the subject, and his handbook is a bible in this engineering arena.
The demand for increased load handling capacity has skyrocketed.
That, in turn, has led to bigger cranes that can lift more, which leads to increased ground force reactions.
Correspondingly, the industry is now recognizing the need to pay more attention to ground conditions and ways to distribute those reactions.
The increased recognition has led several organizations to focus on developing best practices and standards for ground support.
The number and variety of those organizations may surprise you.
ASME’s P30 Committee recently compiled a list of more than 80 documents about ground stability and load stabilization that are either already published or are in development.
This “Guide to the Guides” highlights some of the latest documents and identifies some of the foundational (pun intended) works that we regularly rely upon.
Now in Development
Documents currently in development include:
• The American Society of Mechanical Engineers (ASME) P30 Committee is preparing a non-mandatory appendix to ASME P30.1-2019.
The appendix (“Non-Mandatory Appendix D - Planning for LHE Foundation and Support”) is intended to provide those planning lift handling activities with guidance in assessing reaction forces and ground support capacity, and in identifying potential load distribution methods to safely support the load handling equipment.
The Appendix is scheduled to be published in December 2024, as part of ASME P30’s regular update cycle for the Standard.
• The North American Matting Association (NAMA) is actively developing a performance-based standard, titled “Wood Based Mat Production Standard.”
Drawing from a broad horizon of stakeholders (mat producers, users, specifier/engineers, and academic researchers), including both NAMA and non-NAMA members, the Association’s goal is to develop a voluntary, consensus-based document to offer guidance for the production and application of wood-
NAMA members are currently reviewing the draft Standard.
• The Specialized Carriers & Rigging Association (SC&RA) has convened the Outrigger Mat Resource Task Force to develop a compilation of recommended practices for the safe and efficient support of outrigger-based mobile equipment. The task force’s five work groups are drawn from the association’s members. The final document is intended to serve as a collection of practices to guide the industry in safely deploying lifting equipment. Publication is currently targeted for the first quarter of 2024.
• Field testing techniques to identify the condition of field deployed wood timber mats are also being advanced. Through a joint effort of the U.S. Department of Agriculture (USDA), the Forest Products Laboratory (FPL), and Mississippi State University, a new, General Technical Report (USDA FPL GTR) is nearing completion.
Quoting from the GTR’s abstract, the team is “working jointly to develop an inspection procedure that is comprehensive, fast, and portable.”
The GTR presents a summary of common engineering properties of wood, wood deterioration mechanisms, and presents current, state-of-the-art inspection techniques. Formal publication is targeted for later this year.
Current, already published documents that have been developed through international collaboration include:
• “Guide to Working Platforms,” practices for the stabilization of large and tall construction equipment, published in January 2020 jointly by the European Federation of Foundation Contractors (EFFC) and the Deep Foundations Institute (DFI) “Working Platforms Task Group.”
• “Recommended Industry Practices for Safe Working Platforms for Construction Equipment,” published in December 2020 by the Industry-Wide Working Platforms Working Group, a collaboration of the International Associations of Foundation “Drilling” (ADSC), the Deep Foundations Institute (DFI), and the Pile Driving Contractors Association (PDCA).
• “Assessment and management of outrigger loading,” published in September 2022 by the Temporary Works forum (TWf) in the United Kingdom. The document’s primary aim is to provide clarity and assistance in selecting and using outrigger mats or pads.
These guides and standards represent the latest in best practices for ground support stability and keeping folks safe.
Thankfully, real attention is now being brought to bear on the subject.
Selected Pads and Mats
Bigfoot Construction now offers American Armor steel crane mats.
They are made of high-grade American steel, engineer certified, built in standard or custom sizes, and designed to support cranes with capacities from 200 to 500 USt.
Bigfoot crane mats are engineered to exceed AISC load resistance factor design, and are welded by American Welding Society certified welders.
Every pad carries welded-on steel identification tags that tell its weight, capacity, and serial number.
Bigfoot also offers wood or Custom Composite outrigger pads, all made in the U.S.
A popular size for the cranes is the PR4820, a round, 48" diameter, 2" thick, Custom Composite pad that weighs 123 lbs., can be rolled into place, and has 130,000-lb. vertical load capacity.
Raptor Tech’s patent pending UHMW outrigger pads incorporate RFID & NFC technology and other design features to bring the industry new levels of transparency, innovation, and safety.
All Raptor Tech products are made in America with American-made materials.
Each pad comes with a material test report to show proof of origin and certification of quality.
For ease of use and safety, our pads have built-in handles and a removable lifting lanyard with a capacity rating for hand and crane lifting.
Lampson stocks steel crane mats for lease or sale individually or as part of an equipment rental package.
Standard 4'x16' steel mats feature fully welded 8'x12" steel tubing and have forklift pockets for easy handling.
They allow better ground bearing and resist the moisture and rot commonly seen in wooden mats.
“Mudboats” are made of 14 159-lb.wide-flange I-beams welded together with integral moment pin connections at each end.
That lets the mats to be linked structurally for a continuous load-transferring surface.
They mats can be fitted with transition ramps to allow usage as loading and unloading ramp systems for shore-to-barge operations or similar situations.
DICA’s patented EcoMax crane pads are made of alternating solid composite “timbers” connected to steel I-beams with through-bolts for maximum load distribution and minimum ground-bearing pressure.
They offer stiffness, strength, and performance similar to DICA’s FiberMax crane pads or steel pads, but at a lower price.
EcoMax pads are for customers who don’t need the lower weight of FiberMax but want an engineered crane pad that distrbutes concentrated loads from equipment with outriggers, including mobile cranes, and self-erecting tower cranes.
They come in four sizes from 20 to 40 sq. ft. and maximum rated capacities from 175,000 lbs. to 325,000 lbs.
Spartan Mat’s System7 is a heavy-duty interlocking composite mat system that’s manufactured in the U.S.
They are well-engineered access mats that form an overlapping and interlocking composite matting system to support heavy equipment, including cranes..
Spartan Composites engineered System7 from the ground up for strength, performance, and longevity.
An advanced plastics formula and manufacturing process ensure an excellent strength-to-weight ratio, high PSI ratings, rigidity, durability, and traction.
The connection system features extremely durable overlapping
flanges, and its lower weight reduces transportation costs while covering more ground.
Each mat weighs 1,025 lbs. and ships as an 8'x14'x4.25" piece that yields a usable size of 7'x13'x4.25" after overlapping and interlocking.
Editor’s note — Today, many groups in our industry are working to develop best practices, standards, and guides that encourage proper selection and use of pads and mats under lifting equipment.
A nationally recognized expert, Michael Walsh is a voting member of ASME’s P30 Standards Subcommittee; a member and subcommittee chair of the HBR (Houston) Crane, Rigging & Lifting Committee; a member of the North American Matting Association board of directors and its Technical Committee; vice chair of the Specialized Carriers & Rigging Association’s Allied Industries Committee, and a member of its Outrigger Mat Resource Task Force.
Walsh has written this article to tell readers what each group is doing.