Road roughness characteristics in car and truck wheel tracks

Road longitudinal profile data were collected on both car and truck wheel tracks for a number of road sections to study the differences in their surface roughness characteristics. Roughness was measured in terms of the heavy articulated truck index (HATI), a measure of pavement ride quality as perceived by heavy truck occupants. Roughness variation between the outer and inner wheel tracks was also investigated. The results showed that lane average values of HATI in truck wheel tracks were higher than in car wheel tracks for about 60% of the studied network. These differences are relatively small but are statistically significant. The results also revealed that subgrade soil type and shoulder seal width influenced roughness variations between the truck and car wheel tracks. Overall, HATI values determined from profile data collected on car wheel tracks resulted in ride perception ratings that matched those determined from measurement in truck tracks for 90% of the studied network.