i used to have this collection of gory bus accident around the world, usually. other than passenger were thrown outside the bus because there were no seatbelt. another main culprit for mass death in bus accident is the weak roof, when the bus got out of control, usually they roll, when the bus roll upside down the roof of the bus give way under the weight of the bus body, engine and etc thus smashing the passenger inside. i think beside adding seatbelts maybe ekspress bus should add roll bar cage to make the upper part of the bus stronger.