This paper discusses a project designed to determine the feasibility of developing and using a low-cost, portable device for testing driver fatigue. The result was the development of a Truck Operator Proficiency System (TOPS) which combined a psychomotor test, a divided attention test, and a part-task driving simulator. Baseline testing was accomplished with professional truck drivers. Using the first TOPS trial, and comparing data from drivers' beginning their driving day with those completing 8 to 10 hours of driving, found measurable differences between the groups. This sensitivity is most likely the result of fatigue, however further testing will be needed to validate the causal relationship.