At an organization where people take their children, I recently noticed that the swing-set was in poor condition, and being used hard by the children there. The entire apparatus would shake and sway and also was leaning in a direction as though it would fall over. I alerted the authorities of said organization, and they have removed the swings and locked the necessary doors to prevent access to it.
The organization wishes to repair or rebuild the swing set, but on the whole and given the rambunctiousness of the children I for one am uncertain how to proceed, though they await my suggestion and or action to correct the problem.
Metal and concrete sound the best, but there is still the issue of anchoring the swing set in place, and as I recall this is not a small matter as I had a swing set when I was a kid and due to lack of sufficient anchoring, my father took it down, never having found a solution to the anchoring issue.
Best Answer
A possible solution would be to drive stakes into the ground at the legs, once the stakes are secure enough, screw the leg of the swing set securely to the stake.