Improvement of Axle Load Spectra Characterization by a Mixture of Three Distributions

AbstractTraffic is one of the most important variables used in pavement design methods. There are currently two methods for characterizing wheel load repetitions: equivalent single axle load (ESAL) and load spectra, which is a more precise characterization of traffic but relies on the same input data used to calculate ESALs. Although the load spectra are described using a bimodal mixture distribution, samples taken in Colombia indicate that the load spectra exhibit an intermediate region that can be modelled with an additional distribution. This research proposes the use of a mixture of three distributions: two log-normal distributions for the description of the peaks and a normal distribution for the intermediate region, finding a closed statistical solution for the formal evaluation of its properties, and deduces the expression of the nth moment that facilitates obtaining important features of the proposed distribution. In a case of application in two geographic regions of Colombia, with more than 53,00...