Reliability-based Estimation of Heavy Vehicle Rollover Probability on Two-Lane Highways

The horizontal curves of roads are design to avoid sliding of light vehicles. The heavy vehicle rollover is assumed to be controlled with the radius provided by this design method. Under this assumption, the rollover is not considered for designing horizontal curves. In this paper we developed an analytical model that allows to estimate the rollover probability of heavy vehicles in horizontal curves for 4 types of heavy vehicles. The model was obtained using the first order reliability method and the Gompertz’ logistic growth model. It was used to estimate the minimum radius required to avoid rollover for a certain probability. The minimum radii needed for obtaining zero rollover probability was compared with the minimum radii provides by Chilean geometrical design standards. It was concluded that the minimum radii to avoid rollover varies between 35 and 65 m for operating speed up to 60 km/h, and between 98 and 185 m for operating speed up to 120 km/h. The minimum radii recommended by geometrical design standards to avoid sliding do not ensure to avoid rollover. Only the range of minimum radii between 120 and 180 m for operating speeds between 70 km/h and 100 km/h ensure zero rollover probability.