Conventional evaluation indices for road ride comfort cannot adapt to scenarios where vibration information is distributed randomly in the space or time domains. To overcome these deficiencies, local impact and vibration perception window concepts are proposed to characterize vibration information; a characteristic vibration dose value is determined to demonstrate that humans are sensitive only to major vibrations and the proximity between successive vibrations. The proposed index is optimized using an orthogonal test and shows better correspondence with actual human sensations when compared to the results of frequency weighted root mean square, maximum transient vibration value, and vibration dose value.