North Carolina has adopted the use of flashing yellow arrows (FYA+Y11 in many intersections across the state as a means of providing protected/permissive left turns while minimizing driver confusion that can accompany the operation. In 2014, North Carolina Department of Transportation (NCDOT) completed a study to develop crash modification factors (CMF) associated with the conversion of left turn protection at intersections to FYA. Since that study, additional information has become available including data regarding FYA at dual left turn lanes. this project plans to use that additional data to refine the CMFs developed by the department, in addition to answering new safety questions regarding FYA. In addition to this safety work, the project intends to develop guidelines for the implementation of permissive left turn phasing by time of day and the resulting delay impacts to all users