The Global Positioning System (GPS) is a world-wide resource which enables us to determine our positions anywhere on the earth at any time. The areas in which the Global Positioning System (GPS) is suitable for use as the primary surveying system have grown considerably in recent years. Because of significant improvements in the design of receivers, the software processing and analysis of the collected data, the greater accuracy and efficiency that these have produced, engineering surveys have seen an increased use of GPS techniques. This paper is concerned with the use of GPS technology in establishing third order geodetic networks. For this purpose, a local traditional third order geodetic network was established in a test area at Helwan City.

The network covers 10 km2 area with third order network specifications. The network consists of five stations, observed by the traditional Hybrid technique, in which all horizontal angles and distances were measured, and tied to the first order triangulation station O1. GPS relative observations are taken at all stations of this network. Then, such GPS observations were processed in the network mode. This research was performed in order to asses the GPS system in replacing the traditional techniques, in both the accuracy obtainable and relevant economic aspects, on local basis of establishing geodetic control. In this context, the results of both traditional and GPS techniques have been compared in terms of the relevant geometrical aspects of the established network. Finally, based on the obtained results, conclusion and recommendations are given.