On Steady Ground: Reducing Equipment Setup Risk

Modern construction equipment generates far greater loads onto the ground than many contractors realize. Reviewing the site and determining the appropriate placement and travel paths for heavy equipment is critical. To improve coordination, reduce risk and streamline operations, the controlling entity (CE), general contractors and subcontractors must have an open dialogue on this topic.

While ground-bearing pressures are often discussed in the context of cranes, the issue is equally critical for equipment such as concrete pump trucks and mobile elevating work platforms (MEWPs). Without proper site preparation and clear communication among stakeholders, inadequate ground conditions can lead to costly delays at best, as well as significant safety hazards.

If subcontractors lack information about permissible ground-bearing pressures and underground hazards, equipment may arrive at the jobsite but be unable to operate, resulting in lost time or the need to completely revise the work plan. In the case of cranes, for example, it might mean renting a bigger crane with longer reach to position farther away from the original setup location. This has the potential to cause delays and increase costs.

And without a plan for equipment to operate below permissible ground-bearing pressures, the risk of tipovers is greatly increased.

Gather Data, Plan Ahead

Proper planning requires coordination with multiple entities. The first step is confirming who the controlling entity is for the jobsite. If the CE is not the prime contractor for the project, the CE role under the Occupational Safety and Health Administration (OSHA) 1926.1402(c)(1) is typically filled by the employer that has authority for the site to make or arrange for ground preparations needed to meet the requirements of 1926.1402(b).

Ideally, project planners can provide site information, such as allowable ground-bearing pressure (AGBP), based on civil engineering practices, along with maps of underground utilities and known hazards.

Geotechnical investigations provide empirical data on soil mechanics, including compaction, drainage and firmness. Soil boring and laboratory analysis help assess subsurface conditions, while dynamic cone penetration testing is used for surface and shallow-depth evaluations. With this information, the CE can determine what the AGBP is, which must then be communicated to subcontractors and equipment providers.

The CE is responsible for establishing the allowable ground-bearing pressure. The subcontractor is responsible for knowing the ground-bearing pressures or outrigger loads created by their equipment. If the pressures from the equipment exceed the AGBP, then there is a gap that must be resolved. In this case, either the ground needs to be improved, additional supporting materials are needed or a different location should be chosen for the equipment.

Unfortunately, however, the controlling entity is often unaware of its obligation to ensure the ground can support equipment loads, so this information does not get conveyed. If any uncertainties arise, it’s important for subcontractors to initiate a dialogue about the permissible ground-bearing pressure with the controlling entity, which may be the general contractor.

Stay Situationally Aware During Setup

Subcontractors (often the equipment owner and/or operator) are responsible for proper equipment and supporting materials selection. This includes evaluating the travel paths and placement of both primary and secondary equipment. Based on AGBP, it may be necessary to improve the ground with engineered fill, bring in access matting, and/or supporting materials for operations. Subcontractors are encouraged to establish and provide to the CE the required ground-bearing capacity to safely perform the work. Establishing a minimum ground-bearing capacity is essential to reducing risk and enhancing collaboration.

Once on-site, the subcontractor should assess the site and remain aware of any ground conditions that may impact equipment levelness, footing and stability. Equipment operators should perform their own visual site evaluations. Visual inspections should be focused on any presence of standing water, excavations and indicators of underground structures such as manhole lids, utility access points and catch basins. The intent is to ensure that all observable conditions match the information given by the CE. If inconsistencies or contradictions are found, they should be immediately discussed and reconciled before operations begin.

In the field, physical assessments, such as plate or roll tests, and visual inspections can be helpful to assess the current state. However, they should not be the primary method of assessing the ground conditions. These investigations can help determine if the ground needs to be improved, if the equipment needs to be relocated and which supporting materials — such as outrigger pads, mats, dunnage or cribbing — are needed.

Selecting Supporting Materials

Subcontractors are primarily the entity responsible for selecting the supporting materials. Supporting materials manufactured 
from steel, wood and synthetics can be used to distribute loads and to reduce the chances of ground failure. A qualified person should determine if the supporting materials are sufficient to effectively distribute the loads and pressures to the intended levels. Selection of supporting materials should take into account adequate strength (to avoid physical fatigue and failure), and adequate stiffness (to spread the equipment load/pressures to permissible or allowable levels).

Before use, supporting materials should always be inspected and determined to be suitable for the application. Inspection items differ depending on what the supporting materials are made from. For example, steel should be checked for bent structural components or signs of welding damage, wood should be inspected for rotting or cracking, and synthetic products should be checked for warping or chemical damage.

Understanding and preparing for ground conditions is not just a safety procedure — it’s a foundational aspect of successful equipment operation. By fostering open communication and prioritizing ground stability as a standard operating procedure, the industry can minimize risks and optimize project performance

Controlling entities must understand their regulatory responsibility for site conditions and collaborate with all parties to ensure safety and efficiency, while subcontractors initiate clear communication with the CE about ground-bearing pressures and setup locations.