On the Stabilizing Effect of Weigh Stations on Truck Equivalency Factors for Pavement Design

Abstract

In Costa Rica, weigh stations for trucks and commercial vehicles were reinstated in 2008. Since then, a stabilizing trend in the percentage of heavy vehicles with excess loading was observed. For pavement design purposes, this resulted in reduced variability in truck equivalency factors. These were statistically validated by processing all the weight data collected at different stations located throughout the national road network between 2008 and 2011. Using linear regressions, it was verified that given a constant noncompliance percentage, the truck equivalency factor for C2, C3, and T3-S2 vehicles tended to stabilize at 0.20, 0.66, 1.19, respectively. These results were consistent with additional power regression performed on the data. Higher weight enforcement on the T3-S3 vehicles’ tandem axle would result in a 0.17 decrease in the truck equivalency factor. The findings presented herein should aid countries that have yet to implement weigh stations, considering the benefits of exploring the evolution of truck factors if weigh stations were installed. This weigh station implementation case study exhibits the reality and development of pavement loading over time. Therefore, government authorities should be encouraged to control truck traffic with weigh stations to reduce pavement damage.