This thesis explores how vehicle-mounted smartphones can monitor road pavement roughness, which is critical for safe driving and effective road maintenance. It examines and mitigates the impact of practical factors, like driving speed, vehicle type and smartphone mounting configuration, on measurement accuracy and consistency. The research develops methods of characterising roughness conditions and validates the proposed method against current commercial Apps and professional survey instruments. By crowdsourcing data from public vehicles, this study offers a more scalable and accessible way to monitor road pavement conditions.