The above photo depicts a mobile crane that just toppled over it self, this accident was caused by improperly used outrigger arms and/or outrigger pad supports and is completely avoidable. Due to the increased amount of safety and awareness that crane operators need to exhibit, I have compiled a list of links related to crane outrigger pad placement and lifting safety.
If you read one of these link this one is a must: The ABS's of Foundation Loadings Under Cranes. This thorough article will give you the knowledge to correctly select the correct outrigger pad and analyze your ground surface safely.
This is a rough terrain crane safety training manual provided by OHSA, it includes all necessary inspection and operational safety information.
Here is an expertly written article by: Kirk Ward - The Top five Ways to Reduce Crane Accidents.
The video of this New Zealand crane toppling over demonstrates the importance of having a stable and solid surface to lift from and how external factors such as weather can play a role in safety.
Alberta's guidelines for the safety training of crane operators and supervisors has a wide array of training requirements.
Side Note: These provided links are property of their respective owners and not Stabilitypads.com
The importance of outrigger pads can be outlined by an exert taken from Alberta's Occupational Heath and Safety Provincial Act Section 92.2:
"All crane outriggers are designed for good ground conditions. Poor ground conditions reduce the amount of load a crane can safely place on an outrigger. Because of this, many crane operations require additional supports or “floats”. These floats may be of wood, steel or synthetic material but must be of sufficient size, strength and rigidity to transfer the outrigger load to the full area of the float. A float that is smaller than the outrigger pad will increase the pressure on the ground and will cause an outrigger to “punch through”. If the outrigger is set on an unlevel float, the pad may slide causing the crane to tip. Many manufacturers stipulate that the crane must be within 1 percent of level before their load chart applies. In a 20-foot span this is only 2 inches off-level. Past that, the crane can lose 15 to 20 percent or more of its capacity.
When sizing outrigger floats, it is important to know the maximum pressure applied by the outrigger as well as the required float area. The area (square feet) of float can be estimated by dividing the maximum capacity of the crane by five (5). [Construction Safety Association of Ontario]
A reasonable approximation for maximum ground pressure (worst case) applied by the outrigger is:
Pressure (tons per ft2) applied by outrigger =
0.85 x total crane mass + maximum crane capacity
individual outrigger area
[Construction Safety Association of Ontario]
This can be then be used to calculate the required thickness of float."
This information is critical to crane operators and their employers to ensure paramount safety with lifting and rigging. I feel some critical elements of safety are left out of Section 92.2, such as the ineffectiveness and dangerous circumstance wooden pads can create.
Wooden outrigger pads offer an array of safety concerns such as:
In terms of longevity and effectiveness they often come up short compared to their superior synthetic counterparts, a wooden pad will often need to be replaced in more frequent intervals.
Their cost is significantly cheaper, however replacing a pad at more frequent interval will increase your cost in downtime and the amount spent on materials and production of more wooden pads.
If you find yourself replacing your outrigger pads frequently maybe its time to upgrade to a product that has all the benefits and none of negative qualities. Synthetic pads offer a lightweight, durable and strong alternative while providing maximum safety and longevity.
To conclude outrigger pads offer an increased surface area to distribute heavy loads across all ground surfaces. These pads will decrease risk of injury, increase crane stability, reduce chances of property damage and protect your most important assets.