The growth of fatality rate due to driving accidents has created remarkable concerns and attempts for recognizing and controlling causes of crashes occurrence from the part of responsible officials. Although the general belief is that human factor plays the main role in driving accidents, yet there are disputes over this issue. In road transportation, fatigue is one of the main causes of human errors which can lead to fatal accidents. Due to being unknown and difficult to be recognized as a factor involved in accidents, fatigue has been less paid attention. Fatigue in general means decline and collapse of an individual’s energy. Fatigue by itself made by extended and complicated factors. The driver’s fatigue impairs his ability to drive and make proper decisions that can lead to hazardous outcomes. Fatigue emerges with signs like slow reaction, devour of direct path, reduction of brake track, heaviness of eyelids and drowsiness. The role of place and time parameters has also been studied separately. Most accidents as a result of fatigue occurred in periods of 0 to 6 AM and 2 to 4 PM. As expected, two ways rural roads are the most possible spots for crash›s occurrence that their causes are fatigue. Action for improvement of road environment can play an important role in preventing from drivers, fatigue. In this study, we’ve tried to investigate main causing factors of drivers, fatigue. And if it is possible to present proper guidelines for addressing the problem, including installation of messaging signs warn for driving while tired risks and fatigue management, proper roads geometric design, legal surveillance, warning system and technical system of vehicles, and obligating drivers to take rest in the path along with considering rest places.