A rational procedure about how to collect and characterize the roughness in road networks is strongly required for operating pavement management systems. This study provides basic information about roughness data on municipal roads. For this purpose, we perform roughness measurement surveys in a local city of Hokkaido by use of a well-calibrated response type mobile profilometer. Using measurement longitudinal profile data, we perform power spectral density (PSD) analysis to characterize the difference of surface roughness between arterial and residential roads in terms of wavelength distribution of elevation profiles. According to the result, the difference is associated with resonance wavelengths corresponding to vehicle body vibration at driving speeds from 40 to 60 km/h. This study also develops a statistical model that represents frequency distribution of the International Roughness Index (IRI) in the municipal roads. Probability plots that assess the agreement between measured and approximated data sets reveal that the IRI distribution of municipal roads can be approximate to lognormal curves. Finally, this study introduces an effective method for visualizing collected IRI data as an attribute in a geographic information system (GIS). In this study, we provide the 1st, 2nd, and 3rd quantiles, that is, the 25, 50, and 75 percentiles, respectively, of IRI values obtained from the lognormal distribution model as a threshold to assess the severity of roughness in road networks. The findings of this study contribute to pavement management operation in municipalities.