Comment by vel0city

> A 1988 report by the Australian Road Research Board stated that the rule is a good approximation for rutting damage, but an exponent of 2 (rather than 4) is more appropriate to estimate fatigue cracking.

> The accuracy of the law of the fourth power is disputed among experts, since the test results depend on many other factors, such as climatic conditions, in addition to the factors mentioned above.

It's incredible one agency in the '50s did some small limited tests and everyone will parrot it as if it's tablets handed down from God.