Ground Conditions and Stability Flashcards

Before positioning a MEWP, what must be assessed about the ground conditions?

Answer: The load-bearing capacity, levelness, presence of voids or underground services, and surface condition

A thorough assessment of ground conditions must cover load-bearing capacity (can it support the machine's total weight?), levelness (is it within the machine's gradient limits?), presence of underground services (drains, cables, voids), and surface condition (soft, wet, loose, or unstable ground).

What is the primary risk of operating a MEWP on ground that is not level?

Answer: The machine may overturn due to the shifted centre of gravity

Operating on unlevel ground shifts the machine's centre of gravity, significantly increasing the risk of overturning — the most dangerous type of MEWP incident. Most MEWPs have a maximum operating gradient of 3-5 degrees, and exceeding this can be fatal.

What precaution must be taken when positioning a MEWP near an excavation or trench?

Answer: Maintain a safe distance equal to at least the depth of the excavation from the edge, to prevent collapse

A MEWP must be positioned at a safe distance from excavation edges — generally at least equal to the depth of the excavation. The weight of the MEWP can cause the excavation sides to collapse, potentially overturning the machine into the trench.

Why are spreader plates used under MEWP outriggers?

Answer: To distribute the point load over a larger area, preventing the outrigger from sinking into soft ground

Spreader plates distribute the concentrated point load from the outrigger foot over a much larger surface area. Without them, the outrigger can sink into soft ground, causing the machine to tilt and potentially overturn, especially when the platform is elevated with a load.

A MEWP is to be used on a suspended floor (such as a car park deck). What additional assessment is required?

Answer: The structural load capacity of the floor must be confirmed by a competent person before the MEWP is positioned

Before placing a MEWP on a suspended floor, the structural load-bearing capacity must be assessed by a competent structural engineer. The combined weight of the MEWP, operator, materials, and dynamic loads during operation must not exceed the floor's design load.

What is the danger of positioning a MEWP over an underground service such as a drain or utility cover?

Answer: The cover or ground above the service may collapse under the concentrated weight of the MEWP or outrigger

Drain covers, utility access chambers, and the ground above shallow services may not be designed to bear the concentrated point loads from MEWP wheels or outriggers. They can collapse, causing the machine to suddenly drop and potentially overturn.