Natural hazards are incidents affection transition as well as safety of road transportation, these anual damages. Impose plenty financial and body-accidental damages on universal transportation systems (especially on mountain routes). Results accompanied with this research were as following: A) the most important dangerous environmental parameter, in the half-south of this route is, fall of avalanches and in its half-north, exists, rock falls and sliding. B) In viewpoint of spatial distribution, the medical sections of the studied route (kilometers 43 to 128 from Karaj), are drastically affected on by the frozen. C) In viewpoint of spatial and temporal extent, the most important dangerous natural parameter is the rock falls, exists from Km34 to Km110 of Karaj as extant. D) Totally, about 57 percents of Karaj–Chalous route length, is under effective of the natural hazards, including the medial and central sections of the studied route (from the Km33 to Km118 of Karaj), in viewpoint of spatial situation.