AN ALTERNATIVE APPROACH FOR MAP PROJECTION SYSTEM USED IN EGYPT
BY
Dr. Eng. Ahmed M. Youssry
Dr. Eng. Abdalla A. Saad
Dr. Eng. Ali A. Elsagheer
Shoubra Faculty of Engineering, 108 Shoubra St., Cairo, Egypt
Abstract
Mapping is one of the major aims of surveying. The obtained coordinates from the surveying operations are treated, according to the adopted technique, in the map projection section to obtain the national grid coordinates, which are suitable for mapping.
Mapping in Egypt is based on the Transverse Mercator projection. Egypt has been divided into three zones, with three numbering systems. Every zone has four degrees width of longitude, two degrees on both sides of its central meridian. At the time where the Transverse Mercator projection was chosen as a map projection system, most triangulation networks were in and around the cultivated area and the most effective part of the country was that area lying along the Nile Valley between longitudes 29ْ E and 33ْ E. This area includes most of cities, population, and activities, while the remainder areas of Egypt were neglected, which are mostly desert areas. So, the Transverse Mercator projection was a suitable projection for mapping in Egypt at that time. Recently, and after the highly precise surveying instruments and techniques are achieved, and the Egyptians started strongly to move out of the Nile Valley, the old projection system, with some defects, is not sufficient for the new needs of the current developments in Egypt. This research discusses some defects of the existed projection system in Egypt, and introduces modification for this system. The results showed that, the distortion can be reduced for the purpose of the surveying and geodetic work, and the numbering system can be modified for the purpose of the GIS work.
