This work is part of a new approach to the study of the planning of public transport in order to optimize accessibility by these means of travel in the Greater Skikda (Northeast Algerian). Isochronal indicators are used to measure spatial-temporal accessibility, an approach based on the use of new information technologies as a tool for analysis, such as Geographic Information Systems (GIS). Since the 1970s, the city of Skikda has experienced an urban dynamic, mainly due to high population growth, rural exodus and a number of other social, economic factors. This rapid urbanization has plunged the city into a multidimensional crisis, generating a multitude of problems: urban congestion, transport problem, environmental degradation, poor space management, etc. In addition to these factors, the centralization of commercial and administrative activities in the city, generate a lot of mobility by creating a large daily flow of travel. In this context public transit by bus should be the appropriate solution to facilitate mobility in the city and minimize road congestion. In this paper we analyzed the level of spatial-temporal accessibility by public transport and drew up a mapping that could be an effective tool for assisting local actors in decision-making in organizing the transport network and optimizing its performance.

The objective of this work is to capture the evolution of the urban spot (land use) of the city of Annaba (Algeria), between 2001 and 2019, through the diachronic analysis of satellite images, remote sensing indices and geographic information systems.The City of Annaba, like Algerian cities, has suffered and continues to suffer the effects of rapid urbanization and high population growth, resulting in uncontrolled spatial expansion. Socio-economic development has raised the agglomeration of Annaba to the rank of a regional metropolis.The problem of urbanizable land due to physical constraints (the coastline on the one hand, and the plains, forests and mountains on the other), has forced the city to spread out, on its ecologically vulnerable coastal strip, but also to the detriment of fertile agricultural land, in order to meet the high demand for housing and public services. As a result, a phenomenon of conurbation is being produced, which is amplifying an urban situation that is already very difficult to manage.

The contemporary city in the Mediterranean countries is undergoing a major transformation and is entering a new phase of urbanization that sees the evolution of ways of thinking and acting, making significant changes in its design, production and management essential; placing on the agenda the need to equip itself with new instruments capable of adapting to new challenges and ways of thinking and acting as a new urban planning. One of the phenomena resulting from these changes is urban sprawl, which directly reflects the aspect of land consumption, its intensity varies from one area to another according to several factors and parameters, the altitude or shape of the landforms play a considerable role in the configuration of urban sprawl within cities, we used this combination in our study by superimposing land use maps of the communes of Annaba and El Bouni on Altitude maps, this composition has allowed us to see clearly the distribution of urbanization according to the types of relief, this study comes to illustrate this reality in the bipolar space of the wilaya of Annaba (municipalities of Annaba and El Bouni, the latter has developed as a satellite city to the mother city and has now become the second largest urban pole in the wilaya.