Several years after the final report, there was a study of accidents and fatalities at the changed interchanges. These found a 20% reduction in both at the recommended locations for diagrammatic signs: left exits from Interstate highways. Overall, this was an unusual research project because it encompassed multiple sign testing methods ranging from the laboratory, through instrumented cars, on-highway, and before/after accident and fatality records. While my part was small, it provided a standard that I have remembered.