The notion of mobility within the geographical space was founded on the decisions and activities of humans, whether in their daily life or certain specific professions (railway stations, airports, hospitals). The state of the transport structure networks and the efficiency and quality of their functioning create a spatial heterogeneity which results in more or less uncomfortable access conditions for the movement between two locations, thus affecting travel time. Measurements obtained through complete microscopic simulations determine any increase in value in travel time, which in turn makes it possible to predict network performance within congestion situation (functional vulnerability). In this paper, the authors suggest a GIS method in under to evaluate the intrinsic degrees of vulnerability based on travel time in the road network of Tlemcen city (Algeria) as well as on the structural and functional state of the road network and the way length in order to optimize the travel time required for a hospital emergency service. This may reduce casualities, all too often caused by choosing an inappropriate route.