How should percent truck data be reported for HPMS sample sections where there is not site-specific data available?
Every sample section needs to have percent truck data coded; zero should only be coded if there is no truck traffic on the section or if the percent trucks is less than one-half of one percent (result of rounding to nearest whole percent). Zero should not be coded if the percent of trucks is unknown; an estimate of the value should be used instead. Coding only sections for which there is an actual measured value results in too many sample sections with zero trucks; since the HPMS uses a single expansion factor for all variables, this practice distorts the information resulting from the expanded sample. Where States are collecting data that results in rounded percent truck values of zero, a note in the submittal comment file is appropriate. This may be the case on high volume routes, especially in urban areas, where the volume of trucks may be significant but their percent of total AADT is insignificant. The preferred way to eliminate this problem over time is to upgrade equipment used
