The report describes the collection and analysis of heavy vehicle data with the objectives of developing appropriate procedures for establishing the design traffic parameter and determining traffic distribution design factors.
Heavy vehicle data has been obtained by video-taping four weigh-in-motion (WIM) sites around New Zealand and relating the video images to the axle load records so that the damaging effect of trucks carrying various commodities can be determined.
Traffic distribution factors have been calculated to allow for the difference in the exponent in the relationships for the damaging effect of axles and the performance of subgrade, asphalt and cement materials. The resulting factors are compared with the values currently in use in New Zealand as well as those found in a recent Australian study.
Daily and annual traffic factors (TDDF) have been investigated so that the data obtained in eight-hour traffic surveys can be converted to equivalent 24-hour data and then equivalent annual data. This has been investigated for two WIM sites.
Finally, a series of procedures have been developed for establishing the design traffic parameter for pavement design. The procedures range in complexity from the use of simple presumptive values to the use of commodity surveys with or without vehicle classifications.
Keywords: design traffic loading, commodity survey, equivalent standard axles weigh-in-motion