When trucks drive down wet roads they usually generate a spray cloud around the wheels which can be hazardous to other drivers. Various methods of reducing truck Wheel spray are in existence but a method to accurately determine and rank the performance of spray suppressing devices had yet to be established. In order to remove the subjectivity from measuring the spray cloud, research was carried out to develop a system to objectively measure truck spray and hence quantify the effect of truck spray on the visual impairment of other road users.