ABSTRACT
Roughness-induced dissipated energy has only been investigated mechanistically in a few studies. This paper evaluates two existing mechanistic roughness-induced fuel consumption models (Louhghalam et al. study, Kim et al. study), proposes an improved mechanistic model and compares their predictions with the empirical NCHRP 720 model for passenger cars. The comparison showed that the proposed mechanistic approach is able to predict, without the need for calibration, the field-observed effect of roughness up to 3.5 m/km. On the other hand, the Kim et al. model gives a significantly higher roughness effect than the NCHRP 720 model. Also, Kim et al. showed that the change in energy dissipated is linear with changes in speed, whereas in this paper it was shown that the trend should be nonlinear with speed. The NCHRP 720 model and the proposed mechanistic model appear to provide more reasonable results than the other models, which tend to overestimate the effect of roughness on vehicle fuel consumption.
