Transit buses provide transportation within cities and counties. They have been involved in approximately 284,000 traffic accidents over the past five years with an average of 57,000 buses involved in accidents per year. Traffic Safety Facts reports show that rear impact is the third most common type of transit bus accident, causing deaths and a large number of injuries. Government standards are very limited for crashworthiness of transit buses, and manufacturers have done few studies on crashworthiness of transit buses. Most studies thus have concentrated on frontal impact scenarios, but very little attempt has been made to study rear impacts of transit buses. Physical testing of transit buses to study crashworthiness during rear impacts is costly, and data obtained from testing is limited, therefore, a so finite element (FE) analysis technique is used. A detailed Computer-Aided Design (CAD) model was obtained from the manufacturer for a typical 30-foot-long low-floor mass transit bus. Meshing was done for structural parts of the bus. Proper joints and connection were provided at appropriate locations. Mesh quality was kept superior so that the model could be used for multiple load cases. Material testing was done to obtain strain rate dependent material properties. The model was validated for front and rear bumper slowspeed tests by comparing FE simulation results with physical tests done by the manufacturer according to Standard Bus Procurement Guidelines (SBPG). Also a highspeed side impact simulation was done and validated. The interior of the bus was modeled in detail and then used to carry out a series of FE simulations for different impact velocities. They were found stable.