SOIL ENGINEERING INTERPRETATION FOR ROAD ALLOCATION IN SOKOTO STATE NIGERIA

摘要

The necessity for a rational soil interpretation system for the allocation of roads and other engineering purposes, and for the collation, storage and retrieval of relevant engineering information on regional basis has been recognized for sometime. A terrain evaluation scheme suitable for engineering purposes, for example road construction, should be the one that engineers can apply and interpret. No special skills should be required for its implementation. The scheme should be compatible with all facilities that geographic information system (GIS) should offer, so that information can be stored for future use. Soil engineering interpretation for roads in this research involves the use of soil and construction material properties determined both in laboratory and in the field ad modified rating tables. A terrain evaluation of the Sokoto area was conducted using remote sensing and GIS tools. Estimated soil properties significant to engineering and analytical data were put in tabular forms and interpreted using rating tables. The engineering properties of the mapping units and analytical tables were the summarized properties of soils and road construction materials. The rating tables (suitable and limiting) were used each for interpreting corresponding five selected road allocation attributes (local roads and streets, sands and gravel, shallow excavations, road fills, and top soils) The results of the interpretations were the products of the five attribute maps, which were in turn used for the production of unweighted and weighted suitability maps for road allocation. The final map showed four simulated roads and one existing road. In conclusion, it is found that the system embracing terrain evaluation using remote sensing and GIS is flexible enough to handle information at all levels and thus can be used to collate, store, retrieve at will, transform/analyze and display data accumulated during road planning, allocation and construction projects. The study shows that with the terrain evaluation and scenarios using five selected attributes relevant to road construction, road network can be planned and allocated. It is also noted that terrain evaluation for engineering purposes, use a classification similar to that widely adopted in agricultural and land use surveys.