Using 1971 vehicle classification counts and truck weights from nine Kentucky locations, equivalent axleloads (EAL's) were calculated by several methods. Apparent discrepancies led to a review of axleload equivalency factors used to estimate either EWL's (equivalent wheel loads) or EAL's.

Axleload equivalencies are determined as the ratio of the number of repetitions of a standard or reference load to the number of equivalent (damage-wise) repetitions of the load in question. The choice of equivalency factors can result in as much as a 40-percent difference in calculated EAL's. Most of Kentucky's traffic is made up of axleloads less than 80 kilonewtons (18 kips). The 1973 Kentucky design guide axleload factors are more severe than either the 1959 Kentucky or 1972 AASHO Interim Guide factors for axleloads less than 80 kilonewtons (18 kips). An extensive effort has been made herein to explain these differences. The AASHO Road Test has provided an independent source of data.

Report Date


Report Number

No. 405

Digital Object Identifier



The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Bureau of Highways. This report does not constitute a standard, specification, or regulation.