The Acoustical Society of Japan (ASJ) has published a new revised version of road traffic noise prediction model “ASJ RTN-Model 2018”, in which the calculation formula for the A-weighted sound power level of each type of road vehicles is specified. The sound power level is given basically as a function of the running speed in consideration of practicality and convenience. The Research Committee in ASJ has been accumulating new data about noise emission of vehicles running on expressways and general roads over the last decade. As results, the sound power level of light vehicles, which include passenger cars, hybrid vehicles and small-sized vehicles, for the dense asphalt pavement was changed to a lower value than those in the previous model. In addition, the calculation formula for sound emission on the porous asphalt pavement was revised, and that on the road paved with the gap-graded asphalt mixture (GGAM, referred to as “KOUKINOU II”) was introduced into the model. In this paper, the revised model of the sound power level and power spectrum for road vehicles based on the newly acquired data are described.