For a mobile crane operating at maximum radius, exceeding what percentage of capacity requires radius verification?

• A. 60%
• B. 80%
• C. 90%
• D. 100%

Answer: (B)

As the radius of a mobile crane increases, the lifting capacity decreases, so working at a longer reach reduces the margin of safety. Radius verification is used when the planned lift would sit in the higher portion of the capacity chart at that radius, because real-world factors like rigging weight, boom deflection, wind, and ground conditions can shrink the actual capacity more than the chart indicates. The trigger value is eighty percent of the crane’s rated capacity at that radius; once you exceed eighty percent, you must perform radius verification to confirm the actual capacity before lifting. This check helps ensure the load won’t exceed what the crane can safely handle in that configuration. If your lift is at or below eighty percent, radius verification isn’t typically required; above that threshold, it’s necessary to verify.