Presentation on truck underrun accident prevention examining active safety system performance and rear underrun protection crashworthiness. ADAS testing of seven modern vehicles (2025-2026) at speeds 56-130 km/h toward stationary truck targets in four scenarios found systems currently unable to reliably prevent collisions on motorways. Conspicuity testing of trailers identified reduced performance with offset approaches and darkness. Crash testing of European UN R58.03 rear underrun protection against US IIHS Toughguard at 56 km/h demonstrated latest European RUP incapable of preventing underrun, with recommendation that regulation mandate tougher RUP standards.