From 1976-1981 the Minnesota Department of Transportation (Mn/DOT) conducted a research study to evaluate several new types of bridge deck protective systems in an effort to reduce the extent of reinforcing steel corrosion. These systems included membranes with bituminous overlays, modified concrete overlays, and coated rebars. When the study concluded, it was felt that a long term study was needed to provide a better indication of service life. Two decks from each system type which appeared promising were selected for extended testing. This extended study continued the evaluation program through 1990