This research study was conducted to evaluate the in-service performance of existing guardrail end treatments and unrestrained pre-cast concrete barrier in Washington State. For a selected area of the state highway system over a one-year period, local area maintenance personnel were tasked to document incidents, including extent of damage and repair costs, into a database using NCHRP Project 22-13 methodology. Additional information (accident severity, e.g.) from police reports was gathered from the incidents and added to the database. The installation characteristics measured for Breakaway Cable Terminals (BCT) and Slotted Rail Terminals (SRT), along with the related crash data for these devices, showed overall acceptable performance when struck. Review of the incident severities, together with the displacement and damage data on struck barriers in the study area, revealed no significant difference in BCT and SRT performance. The installation, damage, and displacement characteristics examined on struck concrete barrier showed that the pin and loop connections were holding well in incidents and the barrier displacements during incidents were within the WSDOT design specification for such systems.