Determine how high a child might be able to climb on each play item.
The high points are the danger points.
As a rule of thumb, the fall zone extends outward a distance no less than the height of the fall.
Important Note: The above is very much a "rule of thumb". Australian Standard AS/NZS 4422:1996 contains "Guidance on Minimum Fall Zones"., which includes a "minimum fall zone " for a "supervised early childhood setting" of 1.9 m and for "other settings" a minimum of 2.5 m. In New South Wales, the Department of School Education specifies a minimum of 3.0 m fall zone around equipment.
You can obtain a copy of AS /NZS 4422:1996 from Standards Australia in your state or territory in Australia or in New Zealand. Outside Australia there are equivilant standards produced by other standards organisations.
Determining the height of fall isn't easy. Take a look at this item.
If you determined the fall zone by measuring from the deck, you would be wrong.
Because at this childcare centre, the children often climb up onto the top rail of the guard fence (which incidentally complies with the current Australian Standard).
Stand with legs straight in the fall zone at the location of the most likely crach landing.
Are you prepared to drop suddenly to your knees (as on a trampoline)? Or do you you think you might hurt yourself? (Don't actually try this.)
If you think you might hurt yourself, then the surface is probably not soft enough to prevent serious injury.
As a rule of thumb, there should be around 20cm of wood chip (compacted) or some other soft material beneath a fall of one meter.
Relax with a couple of soft drinks.
To complete this you will need:
All the equipment rails and bars (and cables and chains) should be about the same diameter as the bottle cap. Children can't grasp large timbers.
All the gaps and spaces which accept the can (in any orientation) should also accept the bottle (in any orientation).
If you can get the can through, but not the bottle you have found a potential strangulation point.