Based on certain assumptions, the requirements of emergency exits on buses and coaches are specified in ECE Regulation No.107. Different accident situations, real accidents proved that some of the original assumptions are not valid, so it is necessary to reformulate them. Accident statistics – containing some hundreds bus accidents – and in depth accident analysis were studied, concentrating on the evacuation of buses and the rescue possibilities of the bus occupants. Certain results and conclusions of evacuation tests are also considered which show the capabilities and limitations of different groups of passengers (men-women, young or elderly people, etc.) when evacuating the bus through different kind of emergency exits. The new assumptions to specify the required number and location of emergency exits of buses are based on the following perception:​ the usability of the individual emergency exits are different in different bus categories (e.g. low floor city bus, high-decker tourist coach, etc.) or even in one category (lower or upper level of a double-decker bus) and also in different accident situations (e.g. frontal collision, rollover, fire, etc.) The next step is to specify the “usability” in technical, measurable terms. The paper proposes four aspects, shortly:​ to open the exit, to creep through the exit, to step/jump down from the bus and the possibility of the continuous use of the exit. Some possible measures are proposed to these aspects. On the basis of these aspects, all the emergency exits may be qualified (good, acceptable, poor, not usable) in every bus categories and every accident situation. Finally the required number of emergency exits (how many good, acceptable exit) could be specified which shall be provided for the occupants in every essential accident situation.