In this research it was examined how fatigue in the working process affected the speed of reaction on a complicated
stimulus, and also on the frequency of inadequate reactions. The investigation was carried out by means method of combine
reaction time (CRT). CRT is the shortest time that passes from the moment when a person is affected by a complicated stimulus until the moment when the person responds to the stimulus, by making adequate and complicated reaction. CRTwas registrated in working population of railroad employees who were divided in two groups:group of locomotive drivers (n= 44) and group of a railroad employees (n=25). In the group of locomotive drivers it was taken into the consideration whether the type of locomotive was electrical or diesel power. In both groups, CRT was registrated in two phases of working process; before and after daily work. Results showed that in both examined groups CRT got significantly extended after the
working process. Duration of CRT was longer before and after working process in the group of electrical power locomotive
drivers compared to diesel power locomotive drivers. Fatigue did not affect significantly on the frequency of incorrect answers