This paper presents an investigation of the influence of vehicle transverse in-lane position on bridge traffic load effects. To analyze the influence, both finite-element analysis and statistical analysis methods are used, and various technical aspects are studied, including statistics of vehicle-transverse-in-lane positions, histogram of stress spectrum, and equivalent stress range. Four sets of vehicle transverse in-lane position data were collected by weigh-in-motion systems installed on highways in different regions of France. These data sets are statistically analyzed to investigate their distribution features and relationship with vehicle types, loading condition, vehicle speed, and lane profile. Two case studies are presented, which investigate the influence of vehicle transverse in-lane position on load effects of different types of bridge deck. The results show that transverse stresses experienced by these two bridge decks are significantly influenced by vehicle transverse position, and fatigue analysis demonstrates that the fatigue damage in terms of equivalent stress range for critical details of an orthotropic steel deck is very sensitive to the transverse-in-lane position of heavy vehicle traffic .