There is limited information regarding usability and safety during wheelchairseated passenger ingress/egress activities in large accessible transit vehicles (LATVs). The purpose of this study was to review and characterize wheelchair ingress and egress activities occurring on LATVs and examine factors that may contribute to adverse events. Through a review of wheelchair boarding and alighting video events, 108 ingress and 108 egress events were captured and documented in a database form with limited predetermined response options. In this study, 26 of 216 (12%) total ingress/egress events resulted in passenger difficulty or an incident. Factors appearing to contribute to adverse ingress events involved the use of a rear-facing orientation (64%, n=14). Factors relating to ramp slope, which is influenced by ramp extension level, appeared to contribute to adverse events, primarily during ingress due to increased angle of incline of the ramp. Human factors directly related to the wheelchair-seated passenger contributed to 17 (77%) adverse ingress events and all egress (n=4) events. Through an evaluation of adverse events with respect to ADA guidelines, ramp width and ramp threshold appeared to play a role in passenger difficulties and incidents. Design and training recommendations were made to improve safety, accessibility, and usability of future ramp designs to help transit providers enhance LATV operator procedures.