3

Is it true that the damage caused to a road surface is proportional to the 4th power of vehicle axle weight, and if it is, what factors cause it to be related by a power of 4, or is it just the results of some measurements?

I'm chiefly looking for the answer to "why?", although it'd be handy to know if it is indeed the 4th power, and if not the 4th power, then what?

Phil
  • 131
  • 3
    How do you quantify "damage caused to a road surface"? – Michael Oct 23 '13 at 05:12
  • Good question. Nothing I could find when trying to come to the answer made much mention of what is meant by damage. I presume they mean damage in the intuitive sense - the road deforms, cracks, etc. – Phil Oct 23 '13 at 05:15
  • 1
    From this article: - I found "It must be understood that the fourth power law includes all distress modes. The most important at the AASHO road test were rutting (caused by subgrade deformation) and roughness (unevenness) of the road. Cracking had a minor effect and deformation of bituminous mixtures was not important." – Michiel Oct 23 '13 at 05:32
  • 3
    Exponents like this should not be taken too seriously. They are typically found by making a log-log plot, finding its slope, and looking for a nearby integer, ratio of small integers, etc. It tends to be extremely difficult to determine the exponent with good precision unless the power law is really accurate and the experiment is really accurate. –  Oct 23 '13 at 05:48
  • See also? http://www.pavementinteractive.org/article/equivalent-single-axle-load/ – Colonel Panic Apr 01 '15 at 13:16

0 Answers0