A traffic blocker is an object or device used to prevent the flow of traffic. The two crossword solutions for this term are NARC, which stands for National Association for Rational Control, and CARCRASH, which stands for Computer-Aided Road Crash Hazard Analysis System. NARC is an organization that works to reduce traffic fatalities by advocating for safer roads and vehicles. CARCRASH is a computer system developed to analyze road crash data and identify potential hazards. Both of these solutions are related to traffic safety and the prevention of traffic blockages.