Analysis of the transverse distribution of traffic loading on highways

Traffic loading data were collected from 20 toll stations, and 25 highways were videotaped to obtain relevant traffic information in various provinces in China. Directional distribution factor (DDF), lane distribution factor (LDF) and their influential causes were analyzed. The results have shown that DDF is typically within 50%~60%, while the number of equivalent single axle load (ESAL) in heavy traffic direction is within 50%~85% of the total ESAL. Therefore, pavements should be designed for two traffic directions separately if the traffic characteristics in the two directions exhibit significant difference. Traffic configuration has great impact on LDF. LDF of expressway is larger than that of other highways for two-lane traffic, while LDF of other highways is larger for three-lane traffic. Typical values of LDF are recommended for expressways and other highways, which can be used in pavement analysis and design.