Characterization and development of closed form solutions for axle load spectra associated with trucks circulating the highways of Colombia

An appropriate design of pavement structures requires estimation of the
effects produced by traffi c loads. For this reason, it is necessary to predict the number of
vehicles traveling on road surfaces, identifying the axle confi gurations and the magnitude
of the load. Thirty-eight (38) mobile weigh stations were positioned on different strategic
points of the Colombian national road network to characterize the traffi c condition of the
country, 59,622 trucks were observed. This paper presents Axle Load Spectra that could
be used to characterize the traffi c condition of the Colombian’s highway network. Data
showed that the different axle confi gurations (Single, Tandem and Tridem) exhibit two peaks,
associated with loaded and unloaded truck conditions. It was noted that a signifi cant number
of axles exceeds the permitted load limit, which could explain the critical state of the road
network in Colombia. Finally, a mixture of three (3) theoretical distributions was used to
characterize the overall axle load distributions. The proposed model presents acceptable
predictive capabilities; therefore, it has potential to be used as a tool in the design process
of the pavement.