Evaluating the Effect of Truck Size on the Amount of Air Pollutants Emission Due To Consumption Fuel

Easy access, doortodoor nature of service, and the existence of a sophisticated road network are the merits that guarantee the status of road transport as the dominant mode of transportation. however, the complete reliance of road transport on fossil fuels makes it a major source of emission and environmental damage. it is widely believed that the size of a freight truck has an impact on the emission generation, and when loaded to maximum capacity, larger trucks are more efficient than smaller ones. the present paper reexamined the effect of truck size on the fuel consumption and the resulting emission. the results show that, contrary to common belief, larger trucks are not more efficient and do not have a lower fuel consumption and emission per unit of net transported cargo. this misconception originates from the mistake of calculating the truck’s maximum load capacity based on its axle capacities regardless of the maximum load that each axle can apply to the road pavement. when the axle capacity is greater than the equivalent capacity of the road, the difference will have a damaging impact on the road pavement. the magnitude of this damage will progressively increase with the degree of violation of standard equivalent 18kip singleaxle load criteria. this damage results in deformation and settlement in the surface pavement, which leads to reduced road safety and service level. hence, the maximum load capacity of a truck is limited by the equivalent capacity of the road it traverses. from this perspective, the size of the truck does not have a significant impact on the amount of emission that will be produced for transporting a certain amount of cargo.