Tristan's Law This bill allocates a portion of National Priority Safety Program funds for efforts to increase the safety of frozen dessert truck patrons. (The program provides grants to states to address selected priorities to reduce highway deaths and injuries.) In particular, the Department of Transportation (DOT) must award grants to states for implementing laws and regulations that require frozen dessert trucks to have signal lamps, stop signal arms, and other safety features. DOT must also study pedestrian injuries and fatalities related to frozen dessert trucks and ways to prevent and reduce such harms. Based on the study, the National Highway Traffic Safety Administration must issue guidance on methods to improve the safety of frozen dessert trucks and their patrons.