 The Federal Railroad Administration sponsored a major evaluation of the SAFTE biomathematical fatigue model (or simulation) to determine if it could predict increased risk of railroad accidents based on work schedule information (Hursh, Raslear et al., 2006).The project examined 30-day work histories of locomotive crews prior to 400 human factors accidents and 1000 nonhuman factors accidents.SAFTE estimated crew effectiveness (the inverse of fatigue) based entirely on work schedule information and opportunities to obtain sleep.