Preliminary site assessments are undertaken to determine the most suitable land-use in terms of development and planning, or for construction purposes. This exercise is not only suited for large corporate projects, but also beneficial for individuals, especially those engaged in construction projects in urban areas where pressures on land are great. Furthermore, its best practice to include a section of environmental impact assessment of the proposed project when carrying out this exercise.
To collect adequate data to prepare plan / map of area to be used for planning and design.
In this step the alternative routes which are proposed after a rough survey in the second step are surveyed in details using some advanced instruments like levels, chain and theodolite. Aerial Photogrammetry is best suited for this type of survey.
Types of Preliminary Survey
1. Control Surveys:
Control surveys are used to establish horizontal and vertical coordinates for each point of interest.
2. Aerial Surveys:
A rural or urban mapping scale for the project is determined during the survey meeting. This scale directly affects the altitude of the photography and the flight line target intervals.
3. Planimetric and Topographic Surveys
Planimetric and topographic surveys collect measurements of natural and man-made features. Every surveying observation can be used to determine horizontal and vertical coordinates. However, when some of the features are mapped the vertical component is not utilized. Additionally, not all features are graphically represented in the project mapping files.