Stochastic Analysis of Rolling Resistance Energy Dissipation for a Tractor-Trailer Model

Rolling resistance because of road roughness is often the largest contributor to energy consumption in the environmental assessment of pavement life cycle. Although fuel consumption of passenger vehicles caused by roadway roughness is well studied, further research is needed for truck fuel consumption models utilizing mechanistic approaches. Existing models estimating trucks’ excess fuel consumption because of rolling resistance are based on empirical models or simplified mechanistic models such as the quarter car model. Such approaches may not fully capture the complex dynamic motion of a tractor-trailer. This study suggests a stochastic method utilizing the analytical solution based on a tractor-trailer model to calculate excess truck fuel consumption because of roughness and speed. The illustrative examples show that excess truck fuel consumption tends to increase nonlinearly with roughness; fuel consumption increases with speed but drops after 104 km/h (65 mph) because of a rapid increase in aerodynamic drag at very high speeds. The effect of new generation wide-base tires (NG-WBT) in lieu of the standard dual tire assembly was studied using the introduced model. Results indicate that NG-WBT reduced excess fuel consumption because of roughness by 11% and 8% at 56 km/h and 80 km/h (35 mph and 50 mph), respectively. Finally, Monte Carlo simulation was conducted at two speeds and the simulation results were in agreement with the analytical solution. The results from the developed model and the validation using illustrative examples confirm the impact of roughness and speed on truck fuel consumption in a quantitative manner.