Abstract.Intersections are the key components of road networks considerably aff ecting capacity. As fl ow levels and experience have increased over the years, methods and means have been developed to cope with growing demand for traffi c at road junctions. Among various traffi c control devices and techniques developed to cope with confl icting movements, traffi c signals create artifi cial gaps to accommodate the impeded traffi c streams. Th e majority of parameters that govern signalised intersection control and operations such as a degree of saturation, delays, queue lengths, the level of service etc. are very sensitive to saturation fl ow. Th erefore, it is essential to reliably evaluate saturation fl ow for correctly setting traffi c signals to avoid unnecessary delays and confl icts. Generally, almost all guidelines support the constancy of saturation fl ow irrespective of green time duration. Th is paper presents the results of fi eld studies carried out to enable the performance of signalised intersections to be compared at diff erent green time durations. It was found that saturation fl ow decreased slightly with growing green time. Reduction corresponded to between 2 and 5 pcus/gh per second of green time. However, the analyses of the discharge rate during the successive time intervals of 6-seconds showed a substantial reduction of 10% to 13% in saturation fl ow levels aft er 36 seconds of green time compared to those relating to 6-36 seconds range. No reduction in saturation fl ow levels was detected at the sites where only green periods of 44 seconds or less were implemented.

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.

This work aims to explore black areas identification through a qualitative methodology based mainly on a series of question-