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