4 ms·
> road damage scales as the fourth power of the axle weight Is there a theoretical basis for this? It looks like the "fourth power law" comes from an empirical
by nemo1618 3y ago
> road damage scales as the fourth power of the axle weight
Is there a theoretical basis for this? It looks like the "fourth power law" comes from an empirical test conducted in the 50s: https://en.wikipedia.org/wiki/AASHO_Road_Test https://en.wikipedia.org/wiki/AASHO_Road_Test
However, that article says:
> ...critics point out that its data is only valid under the specific conditions of the test with regard to the time, place, environment, and material properties present during the test. Extrapolating the data to different situations has been "problematic".[3] Other studies have attempted to refine the results, either through further empirical studies, or by developing mathematical models, with varying success.
I have some intuition for why certain physical systems would scale quadratically or cubically, but where on earth is the quartic scaling coming from here??
- cyberax 3y ago> I have some intuition for why certain physical systems would scale quadratically or cubically, but where on earth is the quartic scaling coming from here?? Two quadratic processes working at the same time, perhaps? My guess: increased weight pushes tires deeper into the pavement, allowing them to grab and dislodge larger particles. At the same time, axle weight is a good proxy for torque, so a vehicle with a larger weight can also exert more force on the particles that it grabbed.
- mcmoor 3y agoYeah I remember searching to mathematical justification because it sounds like it'd be interesting, only to come up empty. Disappointing especially when I've seen some suggestions to base tax on it.