Vehicle-into-iarge-truck accidents produce a disproportionately large number of fatalities. It is hypothesized that increasing a truck's visibility or conspicuity will reduce the number of vehicles colliding with trucks. The purpose of this project was to analyze thoroughly this specific accident problem, establish information requirements of other drivers, review the state of the art of conspicuity techniques, design and conduct a series of conspicuity experiments, design a new integrated lighting and marking system, design an augmented, low-cost reflectorized system for retrofitting on large trucks, and field test the augmented system on fleets of trucks. Approximately 2,000 trucks were fitted with the augmented system, and accident rates are currently being monitored and compared with those of a matched control group of 2,000 trucks. At the time of this writing, the 2-year field study is nearing completion. About 70 percent of the total accidents expected have been analyzed, and the results thus far indicate that the trucks treated with the reflectorized systems are being hit at a lower rate than are control trucks. Increasing conspicuity, therefore, appears to be an effective method of reducing vehicle-into-truck accidents.