Two reports on variables related to highway advisory radio are presented. In one study, warning material in short, staccato messages was compared to warning material in long, detailed messages. The long, detailed messages were retained consistently better than the short, staccato ones. The second experiment investigated the effect of route numbers as directions in navigation messages on message retention. The results indicate conclusively that as the frequency of route numbers in messages increases, the frequency of route errors increases. In both experiments, the material was presented visually as well as aurally.