The objective of this study is to estimate the vehicle kilometer traveled (VKT) and on-road emissions using the traffic volume in urban.We estimated two VKT;one is based on registered vehicles and the other is based on traffic volumes.VKT for registered vehicles was 2.11 times greater than that of the applied traffic volumes because each VKT estimation method is different.Therefore,we had to define the inner VKT is moved VKT inner in urban to compare two values.Also,we focused on freight modes because these are discharged much air pollutant emissions.From analysis results,we found middle and large trucks registered in other regions traveled to target city in order to carry freight,target city has included many industrial and logistics areas.Freight is transferred through the harbors,large logistics centers,or via locations before being moved to the final destination.During this process,most freight is moved by middle and large trucks,and trailers rather than small trucks for freight import and export.Therefore,these trucks from other areas are inflow more than registered vehicles.Most emissions from diesel trucks had been overestimated in comparison to VKT from applied traffic volumes in target city.From these findings,VKT is essential based on traffic volume and travel speed on road links in order to estimate accurately the emissions of diesel trucks in target city.Our findings support the estimation of the effect of on-road emissions on urban air quality in Korea.