How do I calculate the critical fall height on a playground?

The critical fall height of shock-absorbing playground surfacing is determined by a series of drop tests in accordance with BS EN 1177, not by a critical fall height calculator. A test headform fitted with an accelerometer is dropped from several heights onto points on the surfacing chosen in accordance with the standard. The critical fall height is the lowest drop height at which the impact produces a HIC value of 1000 or a peak acceleration (gmax) of 200 g. The least favourable test point determines the result.

That figure applies only to the surfacing construction tested under the conditions of the test. The test report therefore records the surfacing thickness, the substrate beneath it and the test conditions relevant to the result. On-site testing confirms whether the installed surfacing provides that level of shock absorption: the headform is dropped from a specified height at designated test points, and the readings are checked against the HIC and gmax limits.